U.S. patent application number 17/642344 was filed with the patent office on 2022-09-22 for all-solid-state lithium ion secondary battery system and charging device for all-solid-state lithium ion secondary batteries.
The applicant listed for this patent is Nissan Motor Co., Ltd., Renault S.A.S.. Invention is credited to Osamu Aoki.
Application Number | 20220299572 17/642344 |
Document ID | / |
Family ID | 1000006445187 |
Filed Date | 2022-09-22 |
United States Patent
Application |
20220299572 |
Kind Code |
A1 |
Aoki; Osamu |
September 22, 2022 |
All-Solid-State Lithium Ion Secondary Battery System and Charging
Device for All-Solid-State Lithium Ion Secondary Batteries
Abstract
A means for detecting the generation of electrodeposition of
metal lithium in an all-solid-state lithium-ion secondary battery
in a real-time manner is developed even when charging the battery
without depending on the specifications of the battery. A system
measures alternate current impedance of an all-solid-state
lithium-ion secondary battery when charging the battery, and judges
whether electrodeposition of metal lithium has generated in a
solid-electrolyte layer forming the battery based on the
relationship between the amplitude of the response signal at
discharge direction of the impedance and the amplitude of the
response signal at charge direction of the impedance.
Inventors: |
Aoki; Osamu; (Kanagawa,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nissan Motor Co., Ltd.
Renault S.A.S. |
Yokohama-shi, Kanagawa
Boulogne-Billancourt |
|
JP
FR |
|
|
Family ID: |
1000006445187 |
Appl. No.: |
17/642344 |
Filed: |
September 13, 2019 |
PCT Filed: |
September 13, 2019 |
PCT NO: |
PCT/IB2019/001127 |
371 Date: |
March 11, 2022 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02J 7/00712 20200101;
H01M 10/0585 20130101; H02J 7/005 20200101; H01M 10/48 20130101;
H01M 10/46 20130101; H01M 10/0525 20130101; G01R 31/392 20190101;
G01R 31/389 20190101 |
International
Class: |
G01R 31/389 20060101
G01R031/389; H01M 10/0525 20060101 H01M010/0525; H01M 10/48
20060101 H01M010/48; H01M 10/0585 20060101 H01M010/0585; H01M 10/46
20060101 H01M010/46; H02J 7/00 20060101 H02J007/00; G01R 31/392
20060101 G01R031/392 |
Claims
1. An all-solid-state lithium ion secondary battery system
comprising: an all-solid-state lithium ion secondary battery
including a power generating element including a positive electrode
including a positive electrode active material layer containing a
positive electrode active material, a negative electrode including
a negative electrode active material layer containing a negative
electrode active material containing metal lithium, and a solid
electrolyte layer interposed between the positive electrode active
material layer and the negative electrode active material layer; a
charger that charges the all-solid-state lithium ion secondary
battery; an AC impedance measuring device that measures an AC
impedance of the all-solid-state lithium ion secondary battery; and
a controller that determines whether or not electrodeposition of
metal lithium has occurred in the solid electrolyte layer based on
a relationship between an amplitude of a response signal in a
discharge direction and an amplitude of a response signal in a
charge direction of an AC impedance measured by the AC impedance
measuring device when the charger charges the all-solid-state
lithium ion secondary battery.
2. The all-solid-state lithium ion secondary battery system
according to claim 1, wherein the AC impedance measuring device
applies an alternating current to the all-solid-state lithium ion
secondary battery and acquires a response voltage as the response
signal; and the controller determines that the electrodeposition
has occurred in a case where at least one amplitude of the response
voltage in the charge direction of the AC impedance becomes smaller
than at least one amplitude of the response voltage in the
discharge direction.
3. The all-solid-state lithium ion secondary battery system
according to claim 2, wherein the controller determines that the
electrodeposition has occurred in a case where an amplitude of the
response voltage in the charge direction of the AC impedance
becomes a predetermined ratio or less with respect to an amplitude
of the response voltage in the discharge direction in a previous
cycle.
4. The all-solid-state lithium ion secondary battery system
according to claim 1, wherein the AC impedance measuring device
applies an AC voltage to the all-solid-state lithium ion secondary
battery and acquires a response current as the response signal; and
the controller determines that the electrodeposition has occurred
in a case where at least one amplitude of the response current in
the charge direction of the AC impedance becomes larger than at
least one amplitude of the response current in the discharge
direction.
5. The all-solid-state lithium ion secondary battery system
according to claim 4, wherein the controller determines that the
electrodeposition has occurred in a case where an amplitude of the
response current in the charge direction of the AC impedance
becomes a predetermined ratio or more with respect to an amplitude
of the response current in the discharge direction in a previous
cycle.
6. The all-solid-state lithium ion secondary battery system
according to claim 1, wherein the controller stops charging when it
is determined that electrodeposition of metal lithium has occurred
in the solid electrolyte layer.
7. The all-solid-state lithium ion secondary battery system
according to claim 1, wherein in a case where it is determined that
electrodeposition of metal lithium has occurred in the solid
electrolyte layer, the controller changes a condition of the
charging so that the electrodeposition becomes less likely to
occur.
8. The all-solid-state lithium ion secondary battery system
according to claim 6, wherein in a case where it is determined that
electrodeposition of metal lithium has occurred in the solid
electrolyte layer, the controller stops the charging and then
discharges the all-solid-state lithium ion secondary battery with a
current smaller than a charging current for the charging.
9. A charging device for charging an all-solid-state lithium ion
secondary battery including a negative electrode active material
layer containing a negative electrode active material containing
metal lithium, the charging device comprising: a charger that
charges the all-solid-state lithium ion secondary battery; an AC
impedance measuring device that measures an AC impedance of the
all-solid-state lithium ion secondary battery; and a controller
that determines whether or not electrodeposition of metal lithium
has occurred in a solid electrolyte layer based on a relationship
between an amplitude of a response signal in a discharge direction
and an amplitude of a response signal in a charge direction of an
AC impedance measured by the AC impedance measuring device when the
charger charges the all-solid-state lithium ion secondary battery.
Description
TECHNICAL FIELD
[0001] The present invention relates to an all-solid-state lithium
ion secondary battery system and a charging device for
all-solid-state lithium ion secondary batteries.
BACKGROUND
[0002] In recent years, in order to cope with global warming, a
reduction in amount of carbon dioxide is strongly desired. In the
automobile industry, there are increasing expectations for a
reduction of carbon dioxide emissions by introduction of electric
vehicles (EV) and hybrid electric vehicles (HEV), and development
of non-aqueous electrolyte secondary batteries such as secondary
batteries for motor driving, which are key to practical application
of such vehicles, has been actively conducted.
[0003] A secondary battery for motor driving is required to have
extremely high output characteristics and high energy as compared
with a lithium ion secondary battery for consumer use used in a
mobile phone, a notebook computer, and the like. Therefore, a
lithium ion secondary battery having the highest theoretical energy
among all practical batteries has attracted attention, and is
currently being rapidly developed.
[0004] Lithium ion secondary batteries that are currently
widespread use a combustible organic electrolyte solution as an
electrolyte. In such a liquid-type lithium ion secondary battery,
safety measures against liquid leakage, short circuit, overcharge,
and the like are more strictly required than other batteries.
[0005] Therefore, in recent years, research and development on an
all-solid-state lithium ion secondary battery (hereinafter also
referred to as an "all-solid-state battery") using an oxide-based
or sulfide-based solid electrolyte as an electrolyte have been
actively conducted. The solid electrolyte is a material mainly made
of an ion conductor that enables ion conduction in a solid.
Therefore, in an all-solid-state battery, in principle, various
problems caused by combustible organic electrolyte solution do not
occur unlike the conventional liquid-type lithium ion secondary
battery. In general, use of a high-potential and large-capacity
positive electrode material and a large-capacity negative electrode
material can achieve significant improvement in output density and
energy density of a battery. An all-solid-state battery using a
sulfide-based material as a positive electrode active material and
metal lithium as a negative electrode active material is a
promising candidate.
[0006] Meanwhile, a negative electrode potential of a lithium ion
secondary battery decreases with progress of charging. When the
negative electrode potential decreases to be lower than 0V (vs.
Li/Li.sup.+), metal lithium is precipitated at the negative
electrode, and dendrite (dendritic) crystals are precipitated (this
phenomenon is also referred to as electrodeposition of metal
lithium). When electrodeposition of metal lithium occurs, there is
a problem that the deposited dendrite penetrates an electrolyte
layer, thereby causing an internal short-circuit of the battery. In
addition, in a liquid-type lithium ion secondary battery, there is
also a problem that an organic electrolyte solution constituting an
electrolyte reacts with highly active dendrite to be reductively
decomposed. Meanwhile, in an all-solid-state battery using metal
lithium as a negative electrode active material, growth (that is,
occurrence of electrodeposition) of the negative electrode active
material (metal lithium) is a charge phenomenon. However, when
dendrite grows to a solid electrolyte layer due to this
electrodeposition, a short circuit or the like may also occur.
[0007] In addition, in a lithium ion secondary battery, there is
also a problem that an active material layer of an electrode
deteriorates due to, for example, local current concentration in
the active material layer with progress of charging and
discharging, and a capacity of the battery decreases.
[0008] For example, a method described in Japanese Patent
Application Laid-Open No. 2012-212513 is known as a method for
detecting a state of a lithium ion secondary battery such as the
presence or absence of electrodeposition or deterioration of metal
lithium. Specifically, Japanese Patent Application Laid-Open No.
2012-212513 discloses a method for detecting a state of a lithium
secondary battery including discharging the lithium secondary
battery until an SOC (State of Charge (Charge Rate)) becomes 10% or
less; measuring an impedance (reaction resistance) of the
discharged battery; and detecting the state of the battery on the
basis of a measured value of the obtained impedance (reaction
resistance). According to Japanese Patent Application Laid-Open No.
2012-212513, according to such a state detection method, since the
impedance of the battery is measured when the SOC is a
predetermined value of 10% or less in a discharge step (the
measured value of the impedance greatly changes depending on the
presence or absence of lithium precipitation at a negative
electrode), a precipitation state of lithium at the negative
electrode (deterioration state of the battery) can be easily and
accurately detected.
SUMMARY
[0009] Detection of a precipitation state of lithium at a negative
electrode (deterioration state of a battery) by using the technique
described in Japanese Patent Application Laid-Open No. 2012-212513
has a problem that it is necessary to find a threshold value of
impedance (reaction resistance) in advance for each specification
of the battery. In addition, since occurrence of electrodeposition
can be detected only under a specific condition for which a
threshold value of impedance (reaction resistance) has been found,
there is also a problem that electrodeposition occurring during
charging of a battery cannot be detected in real time.
[0010] Therefore, an object of the present invention is to provide
a means capable of detecting occurrence of electrodeposition of
metal lithium in a solid electrolyte layer in real time even during
charging regardless of battery specification in an all-solid-state
lithium ion secondary battery.
[0011] An all-solid-state lithium ion secondary battery system
according to an embodiment of the present invention includes: an
all-solid-state lithium ion secondary battery; a charger that
charges the all-solid-state lithium ion secondary battery; an AC
impedance measuring device that measures an AC impedance of the
all-solid-state lithium ion secondary battery; and a controller
that determines whether or not electrodeposition of metal lithium
has occurred in the solid electrolyte layer of the battery. The
all-solid-state lithium ion secondary battery includes a power
generating element including a positive electrode including a
positive electrode active material layer containing a positive
electrode active material, a negative electrode including a
negative electrode active material layer containing a negative
electrode active material containing metal lithium, and a solid
electrolyte layer interposed between the positive electrode active
material layer and the negative electrode active material layer.
The controller determines whether or not electrodeposition of metal
lithium has occurred in the solid electrolyte layer based on a
relationship between an amplitude of a response signal in a
discharge direction and an amplitude of a response signal in a
charge direction of an AC impedance measured by the AC impedance
measuring device when the charger charges the all-solid-state
lithium ion secondary battery
[0012] A charging device for an all-solid-state lithium ion
secondary battery according to another embodiment of the present
invention is a charging device for charging an all-solid-state
lithium ion secondary battery including a negative electrode active
material layer containing a negative electrode active material
containing metal lithium. Further, the charging device includes a
charger that charges the all-solid-state lithium ion secondary
battery, an AC impedance measuring device that measures an AC
impedance of the all-solid-state lithium ion secondary battery, and
a controller that determines whether or not electrodeposition of
metal lithium has occurred in the negative electrode active
material layer.
[0013] The controller determines whether or not electrodeposition
of metal lithium has occurred in the solid electrolyte layer based
on a relationship between an amplitude of a response signal in a
discharge direction and an amplitude of a response signal in a
charge direction of an AC impedance measured by the AC impedance
measuring device when the charger charges the all-solid-state
lithium ion secondary battery.
[0014] According to the present invention, in the all-solid-state
lithium ion secondary battery, occurrence of electrodeposition of
metal lithium in the solid electrolyte layer can be detected in
real time even during charging, regardless of the specification of
the battery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a block diagram for explaining a configuration of
an all-solid-state lithium ion secondary battery system according
to an embodiment of the present invention;
[0016] FIG. 2 is a flowchart illustrating a procedure of charging
processing in the all-solid-state battery system 1;
[0017] FIG. 3 is a subroutine flowchart of step S109 in FIG. 2;
[0018] FIG. 4 is a graph illustrating a transition of a state of an
interface between a negative electrode active material layer and a
solid electrolyte layer before and after occurrence of
electrodeposition of metal lithium in the negative electrode active
material layer of the all-solid-state battery, and curves of a
response voltage of an AC impedance corresponding to respective
states;
[0019] FIG. 5 is a cross-sectional view schematically illustrating
an overall structure of a laminate type (internal parallel
connection type) all-solid-state lithium ion secondary battery
(laminate type secondary battery) according to an embodiment of the
present invention;
[0020] FIG. 6 is a cross-sectional view schematically illustrating
a bipolar type (bipolar type) all-solid-state lithium ion secondary
battery (bipolar type secondary battery) according to an embodiment
of the present invention; and
[0021] FIG. 7 is a perspective view illustrating an appearance of a
flat lithium ion secondary battery, which is a representative
embodiment of a laminate type secondary battery.
DETAILED DESCRIPTION
[0022] Hereinafter, an embodiment of the present invention
described above will be described with reference to the drawings,
but the technical scope of the present invention should be
determined on the basis of the description of the claims and is not
limited only to the following aspects. Hereinafter, the embodiment
of the present invention will be described by taking, as an
example, a case where a secondary battery is a laminate type
(non-bipolar type) all-solid-state battery. Furthermore, the
following takes, as an example, a case where an input signal
applied from an impedance measuring device to the all-solid-state
battery is an alternating current made up of a single frequency
component and where impedance of the all-solid-state battery to be
measured is an AC impedance (complex impedance). Note that
dimensional ratios in the drawings are exaggerated for convenience
of description and may be different from actual ratios.
[0023] [Secondary Battery System]
[0024] FIG. 1 is a block diagram for explaining a configuration of
an all-solid-state lithium ion secondary battery system according
to an embodiment of the present invention.
[0025] The all-solid-state lithium ion secondary battery system
(hereinafter also referred to as an "all-solid-state battery system
1") includes an all-solid-state battery 2. Furthermore, the
all-solid-state battery system 1 includes a voltage sensor 3 that
measures a cell voltage (voltage between terminals) of the
all-solid-state battery 2, a temperature sensor 4 that measures an
outer surface temperature (environmental temperature) of the
all-solid-state battery 2, a voltage current adjustment device 5
that supplies charge power to the all-solid-state battery 2, a
current sensor 6 that measures a charge/discharge current of the
all-solid-state battery 2, an impedance measuring device 7 that
measures impedance of the all-solid-state battery 2 by applying an
input signal (alternating current) to the all-solid-state battery 2
and acquiring a response voltage to the input signal, and a
controller 8 that controls charging and discharging of the
all-solid-state battery 2. The voltage current adjustment device 5
is connected to an external power supply 9 and receives supply of
electric power during charging, whereas electric power is
discharged to the external power supply 9 side via the voltage
current adjustment device 5 during discharging (details will be
described later).
[0026] Details of each unit will be described below.
[0027] The all-solid-state battery 2 is a normal all-solid-state
lithium ion secondary battery, and includes a power generating
element including a positive electrode including a positive
electrode active material layer containing a positive electrode
active material capable of occluding and releasing lithium ions, a
negative electrode including a negative electrode active material
layer containing a negative electrode active material capable of
occluding and releasing lithium ions, and a solid electrolyte layer
interposed between the positive electrode active material layer and
the negative electrode active material layer. Details of the
all-solid-state lithium ion secondary battery will be described
later.
[0028] The voltage sensor 3 may be, for example, a voltmeter, and
measures a cell voltage (voltage between terminals) between the
positive electrode and the negative electrode of the
all-solid-state battery 2. The cell voltage (voltage between
terminals) measured while the all-solid-state battery 2 is not
energized is an open circuit voltage (OCV) of the all-solid-state
battery 2. On the other hand, the cell voltage (voltage between
terminals) measured during charging and discharging of the
all-solid-state battery 2 is a value changed from the open circuit
voltage (OCV) by a voltage drop (.DELTA.V=.DELTA.I.times.R) caused
by internal resistance (R) of the all-solid-state battery 2. That
is, the voltage sensor 3 can function as an SOC detector or an OCV
detector. An attachment position of the voltage sensor 3 is not
limited in particular as long as the cell voltage (voltage between
terminals) between the positive electrode and the negative
electrode can be measured in a circuit connected to the
all-solid-state battery 2.
[0029] The temperature sensor 4 measures the outer surface
temperature (environmental temperature) of the all-solid-state
battery 2. The temperature sensor 4 is attached, for example, to a
surface of a case (exterior body, housing) of the all-solid-state
battery 2. In the present embodiment, the outer surface temperature
of the all-solid-state battery 2 is measured as an indication of
the temperature of the all-solid-state battery 2. The outer surface
temperature is not an accurate indication of an internal
temperature but is at least almost the same as a temperature of a
single battery layer close to an outermost layer of the
all-solid-state battery. In some cases, the controller 8 may
estimate the temperature inside the battery according to a
predetermined algorithm.
[0030] During charging of the all-solid-state battery 2, the
voltage current adjustment device 5 adjusts a voltage and a current
of power from the external power supply 9 based on a command from
the controller 8, and supplies the power to the all-solid-state
battery 2. During discharging of the all-solid-state battery 2, the
voltage current adjustment device 5 releases electricity discharged
from the all-solid-state battery 2 to the external power supply 9.
In this manner, the voltage current adjustment device 5, the
external power supply 9, and the controller 8, which will be
described later, function as a charger that charges the
all-solid-state battery 2.
[0031] The external power supply 9 is a power supply for an
electric vehicle, which is used for charging an electric vehicle or
the like and is referred to as a power supply grid or the like, and
outputs a direct current. Such a power supply for an electric
vehicle converts commercial power (alternating current) into a
direct current of a voltage and a current necessary for charging
the all-solid-state battery 2 and provides the direct current.
Furthermore, the external power supply 9 has a power regeneration
function, and can perform regeneration to the commercial power
supply by converting a direct current into an alternating current
when there is discharge from the all-solid-state battery 2. Note
that a known power supply having a power regeneration function may
be used as a device constituting such an external power supply 9,
and therefore a detailed description thereof is omitted here
(examples of a power supply having a power regeneration function
include those disclosed in Japanese Patent Application Publication
No. 7-222369A and Japanese Patent Application Publication No.
10-080067A, for example).
[0032] In a case where the external power supply 9 is not connected
to an external power supply device such as a commercial power
supply, for example, in a case where the all-solid-state battery 2
is charged while using another secondary battery or the like
installed outside as a power supply, power discharged from the
all-solid-state battery 2 is preferably stored in the other
secondary battery. This can reduce waste of energy.
[0033] The current sensor 6 is, for example, an ammeter. The
current sensor 6 measures a current value of power supplied from
the voltage current adjustment device 5 to the all-solid-state
battery 2 during charging of the all-solid-state battery 2, and
measures a current value of power supplied from the all-solid-state
battery 2 to the voltage current adjustment device 5 during
discharging of the all-solid-state battery 2. An attachment
position of the current sensor 6 is not limited in particular as
long as the current sensor 6 is disposed in a circuit that supplies
electric power from the voltage current adjustment device 5 to the
all-solid-state battery 2 and can measure a current value during
charging and discharging.
[0034] The impedance measuring device 7 is configured to measure an
AC impedance (complex impedance) of the all-solid-state battery 2
by applying an alternating current as an input signal to the
all-solid-state battery 2 and acquiring a response voltage to the
alternating current. Conversely, an alternating-current voltage may
be applied as an input signal, and a response current may be
acquired. In the present embodiment, the input signal is an
alternating current made up of a single frequency component.
[0035] Any one selected from those conventionally used as a general
AC impedance measurement device can be used as the impedance
measuring device 7. For example, the impedance measuring device 7
can be one that measures AC impedance of the all-solid-state
battery 2 by changing the frequency of an alternating current with
time by an AC impedance method. The impedance measuring device 7
may be one that can simultaneously apply a plurality of AC
perturbation currents having different frequencies. A method for
measuring an AC impedance by the AC impedance method is not limited
in particular. For example, a digital method such as a digital
Fourier integration method or a fast Fourier transform method by
noise application can be appropriately adopted. The frequency of
the input signal may be, for example, any value within a range such
that a value of an amplitude of a response signal of AC impedance Z
measured by the impedance measuring device 7 changes between a
discharge direction and a charge direction when electrodeposition
occurs in a solid electrolyte layer. An amplitude and the like of a
waveform (for example, a sinusoidal wave) of the alternating
current applied to the battery are not limited in particular, and
can be appropriately set. A measurement result of the AC impedance
measured by the impedance measuring device 7 is sent to the
controller 8 as an output of the impedance measuring device 7.
[0036] The controller 8 is, for example, a computer including a CPU
81, a memory 82, and the like. The controller 8 estimates a state
(here, the presence or absence of occurrence of electrodeposition
in the solid electrolyte layer of the all-solid-state battery 2) of
the all-solid-state battery 2 based on the AC impedance (complex
impedance) of the all-solid-state battery 2 measured by the
impedance measuring device 7 when performing charging processing on
the all-solid-state battery 2 according to a procedure described
later. That is, the controller 8 also has a function as a state
estimation unit that estimates the state of the all-solid-state
battery 2. Furthermore, in the present embodiment, in a case where
it is determined that electrodeposition has occurred in the solid
electrolyte layer of the all-solid-state battery 2, the controller
8 changes conditions of the charging processing so that the
electrodeposition is less likely to proceed (control performed upon
electrodeposition detection). As such a controller 8, for example,
an electronic controller (ECU) or the like may be used in an
electric vehicle.
[0037] The memory 82 includes a non-volatile memory in addition to
a RAM used as a working area by the CPU 81. The non-volatile memory
stores therein a program for performing control for estimating
occurrence of electrodeposition in the present embodiment, control
performed upon electrodeposition detection, and the like.
[0038] [Charging Processing]
[0039] A procedure of the charging processing in the secondary
battery system 1 configured as described above will be
described.
[0040] This charging processing is performed in a state where the
secondary battery system 1 is connected to the external power
supply 9 and charging power can be supplied to the all-solid-state
battery 2. In addition, control of the charging processing in the
present embodiment uses a constant current constant voltage (CC-CV)
charging method in which the charging processing is performed by a
constant current charging method until the voltage of the
all-solid-state battery 2 reaches a predetermined voltage and is
performed by a constant voltage charging method after the voltage
of the all-solid-state battery 2 reaches the predetermined
voltage.
[0041] In the charging processing in the present embodiment, when
the charging processing is performed on the all-solid-state battery
2, the AC impedance (complex impedance) of the all-solid-state
battery 2 is measured, and the state (here, the presence or absence
of occurrence of electrodeposition in the solid electrolyte layer)
of the all-solid-state battery 2 is estimated based on the measured
AC impedance (complex impedance) of the all-solid-state battery 2.
In the present embodiment, in a case where it is estimated that the
electrodeposition has occurred, the conditions of the charging
processing is changed so that the electrodeposition becomes less
likely to proceed. Note that this charging processing is performed
by the controller 8 unless otherwise specified. A procedure of this
charging processing will be described below with reference to FIG.
2. FIG. 2 is a flowchart illustrating a procedure of the charging
processing in the all-solid-state battery system 1.
[0042] First, the controller 8 acquires a current temperature from
the temperature sensor 4 and acquires a current voltage from the
voltage sensor 3 (S101).
[0043] Subsequently, the controller 8 starts control for performing
the charging processing of the all-solid-state battery 2.
Specifically, electric power is introduced from the external power
supply 8 to the voltage current adjustment device 5, and charging
processing is started (normally, constant current (CC) charging is
started) (S102). At the same time, the controller 8 controls the
impedance measuring device 7 to start superimposing an AC
perturbation current as an input signal for measuring the AC
impedance of the all-solid-state battery 2 (S102). In this step, it
is preferable to prevent a superimposed current from flowing
through a path that is not a measurement target by using the
principle of an AC bridge as in an internal resistance measurement
device like the one described in FIG. 2 of International
Publication No. 2012/077450. With such a configuration, influence
of a load or the like connected to the all-solid-state battery 2 on
a measurement result of the AC impedance can be reduced, and the AC
impedance can be measured with high accuracy.
[0044] As described above, the constant current constant voltage
(CC-CV) charging method is used for the control of the charging
processing in the present embodiment. Therefore, after starting the
charging processing, the controller 8 determines whether or not the
current voltage acquired from the voltage sensor 3 is equal to or
higher than a predetermined voltage (threshold voltage) determined
in advance as an index indicating a timing of switching from
constant current (CC) charging to constant voltage (CV) charging
(S103). In a case where the current voltage is not equal to nor
higher than the threshold voltage (S103: NO), the controller 8
continues charging by the constant current (CC) charging method
(S104). In this case, the controller 8 performs control (estimation
of whether or not electrodeposition has occurred in the solid
electrolyte layer of the all-solid-state battery 2) according to
the present invention, which will be described later.
[0045] Meanwhile, in a case where the current voltage is equal to
or higher than the threshold voltage in step S103 (S103: YES), the
controller 8 performs charging by the constant voltage (CV)
charging method (S105). In this case, the controller 8 determines
whether or not the current electric current (charging current)
acquired from the current sensor 6 is equal to or less than a
predetermined current (termination current) determined in advance
as an index indicating a timing of termination of constant voltage
(CV) charging (S106). In a case where the current electric current
(charging current) is equal to or less than the termination current
(S106: YES), the controller 8 finishes this processing. Thereafter,
the charging processing is also finished as necessary.
[0046] Meanwhile, in a case where the current electric current
(charging current) is larger than the termination current in step
S106 (S106: NO), the controller 8 also performs the control
(estimation of whether or not electrodeposition has occurred in the
solid electrolyte layer of the all-solid-state battery 2) according
to the present invention, which will be described later.
[0047] In a case where the constant current charging of the
all-solid-state battery 2 is performed (S104) or in a case where
the constant voltage charging of the all-solid-state battery 2 is
performed and the current electric current (charging current) is
larger than the termination current (S106: NO), the controller 8
determines whether or not an elapsed time (charging time) from the
start of charging acquired from a built-in timer (not illustrated)
is equal to or longer than a predetermined time (first threshold
time) (S107). In a case where the charging time is not equal to nor
longer than the first threshold time (S107: NO), the controller 8
repeatedly performs this determination until the charging time
becomes equal to or longer than the first threshold time. The
current value is unstable in an initial stage of application of the
charging current, and a transient change in the current value may
influence the control according to the present invention
(estimation of whether or not electrodeposition has occurred in the
solid electrolyte layer). The reason why step S107 is performed is
to improve accuracy of determination of whether or not
electrodeposition has occurred in the solid electrolyte layer by
eliminating this influence. A specific value of the first threshold
time can be appropriately set, and is, for example, several tens to
several hundreds of milliseconds.
[0048] Subsequently, in a case where the charging time is equal to
or longer than the first threshold time in step S107 (S107: YES),
the controller 8 determines whether or not an elapsed time (AC
perturbation current superimposition time) from the start of
superimposition of the AC perturbation current acquired from the
built-in timer (not illustrated) is equal to or longer than a
predetermined time (second threshold time) (S108). In a case where
the AC perturbation current superimposition time is not equal to
nor longer than the second threshold time (S108: NO), the
controller 8 repeatedly performs this determination until the AC
perturbation current superimposition time becomes equal to or
longer than the second threshold time. Also regarding the AC
perturbation current superimposed for measuring the AC impedance,
the current value is unstable in initial stage of application, and
a transient change in the current value may influence the control
according to the present invention (estimation of whether or not
electrodeposition has occurred). The reason why step S108 is
performed is to improve accuracy of the determination of whether or
not electrodeposition has occurred in the solid electrolyte layer
by eliminating this influence. A specific value of the second
threshold time can be appropriately set, and is, for example,
several tens to several hundreds of milliseconds.
[0049] Subsequently, in a case where the AC perturbation current
superimposing time is equal to or longer than the second threshold
time in step S108 (S108: YES), the controller 8 estimates whether
or not electrodeposition has occurred in the solid electrolyte
layer of the all-solid-state battery 2 based on the AC impedance
measured by the impedance measuring device (S109).
[0050] FIG. 3 is a subroutine flowchart of step S109 in FIG. 2.
[0051] In the subroutine illustrated in FIG. 3, the controller 8
first acquires, as an output signal of the impedance measuring
device 7, a waveform of a response voltage (or positive and
negative amplitude values calculated from the waveform) as
illustrated in FIG. 4 as a measurement result of the AC impedance
measured by the impedance measuring device 7. At this time, the
controller 8 removes noise caused by a high-frequency component in
the output from the impedance measuring device 7 by using a
low-pass filter (LPF) and the like (S201).
[0052] Subsequently, the controller 8 determines whether or not the
amplitude of the response voltage in the charge direction is a
predetermined ratio or less with respect to the amplitude of the
response voltage in the discharge direction in a previous cycle
when comparing two adjacent cycles regarding the waveform of the
response voltage (normally, a sine wave) as the output signal of
the impedance measuring device 7 acquired in step S201 (S202).
Here, as illustrated in FIG. 4, when electrodeposition of metal
lithium occurs in the solid electrolyte layer of the
all-solid-state battery 2, there occurs a phenomenon that the
amplitude of the response voltage in the charge direction becomes
smaller than the amplitude of the response voltage in the discharge
direction regarding the response voltage of the AC impedance
obtained by applying an alternating current having a specific
frequency and a constant amplitude. This will be explained as
follows with reference to FIG. 4.
[0053] FIG. 4 is a graph illustrating a transition of a state of an
interface between the negative electrode active material layer and
the solid electrolyte layer before and after occurrence of
electrodeposition of metal lithium in the solid electrolyte layer
of the all-solid-state battery 2, and curves of a response voltage
of an AC impedance corresponding to respective states. In the
response voltage curve illustrated in FIG. 4, the solid line graph
indicates a response voltage assumed when electrodeposition occurs
in the present embodiment, and the broken line graph is a virtual
line indicating a response voltage obtained when electrodeposition
does not occur. First, as a premise, in a case where an alternating
current having a constant amplitude is applied (superimposed), a
value (V) of the response voltage also decreases when an internal
resistance value (R) of the battery decreases according to Ohm's
law (V=I.times.R). On the other hand, when R increases, V also
increases. In addition, occurrence of electrodeposition (dendrite)
means that lithium ions easily permeate the inside of the solid
electrolyte layer, and thus when electrodeposition occurs, the
internal resistance value of the battery decreases as electrolyte
resistance decreases, and as a result, the response voltage also
decreases.
[0054] Here, a state in which an alternating current in the
discharge direction is applied when electrodeposition (dendrite) of
metal lithium does not occur in the solid electrolyte layer is the
state A illustrated in FIG. 4. The application of the alternating
current in the discharge direction acts to offset the charging
current from the external power supply 9, and therefore acts to
suppress occurrence of electrodeposition (dendrite). For this
reason, it is usually unlikely that electrodeposition starts to
occur when an alternating current is applied in the discharge
direction as in the state A. Next, when the state A changes to the
state B, an application direction of the alternating current is
switched to the charge direction. Since the application of the
alternating current in the charge direction acts to increase the
charging current from the external power supply 9, and therefore
acts to promote occurrence of electrodeposition (dendrite). For
this reason, electrodeposition generally starts to occur when an
alternating current is applied in the charge direction as in the
state B. When electrodeposition (dendrite) occurs in the state B,
the amplitude of the response voltage (in the charge direction)
decreases due to a decrease in the internal resistance value of the
battery as described above. In step S202 of the present embodiment,
the controller 8 determines whether or not this phenomenon is
occurring. Specifically, it is determined whether or not the
amplitude of the response voltage in the charge direction (here,
the amplitude of the state B) is a predetermined ratio or less with
respect to the amplitude of the response voltage in the discharge
direction (here, the amplitude of the state A) in the previous
cycle when two adjacent cycles such as a cycle including the state
A and a cycle including the state B are compared. Note that a
specific value of the predetermined ratio is not limited in
particular, and can be appropriately set in consideration of
required accuracy of detection of electrodeposition (dendrite), for
example. When the application of the alternating current is
continued even after the state B, the occurrence of
electrodeposition (dendrite) is suppressed and the amplitude
recovers to be slightly larger than that in the state B in the
state C in which the alternating current in the discharge direction
is applied. Thereafter, in the state D in which the alternating
current in the charge direction is applied, the occurrence of
electrodeposition is further promoted, and the amplitude changes so
as to become smaller than that in the state C (and that in the
state B). When the application of the alternating current is
continued without changing the charging conditions even after the
occurrence of electrodeposition (dendrite), a similar profile is
repeated. In the present embodiment, the controller 8 determines
whether or not the amplitude of the response voltage in the charge
direction is a predetermined ratio or less with respect to the
amplitude of the response voltage in the discharge direction in the
previous cycle when comparing two adjacent cycles, as described
above. The controller 8 may compare the state A and the state B
illustrated in FIG. 4, may compare the state B and the state C, or
may compare the state C and the state D. Thus detecting occurrence
of electrodeposition has an advantage that the occurrence of
electrodeposition can be promptly known in real time and it is not
necessary to set a threshold value such as a reaction resistance
value in advance.
[0055] In a case where it is determined in step S202 that the
amplitude of the response voltage in the charge direction is not a
predetermined ratio or less with respect to the amplitude of the
response voltage in the discharge direction in the previous cycle
when two adjacent cycles are compared (S202: NO), it is estimated
that electrodeposition has not occurred in the solid electrolyte
layer of the all-solid-state battery 2 at that time. Meanwhile, in
a case where it is determined in step S202 that the amplitude is
the predetermined ratio or less (S202: YES), it is estimated that
electrodeposition has occurred in the solid electrolyte layer of
the all-solid-state battery 2 at that time.
[0056] See the flowchart illustrated in FIG. 2. In a case where it
is estimated in step S202 that electrodeposition in the solid
electrolyte layer has not occurred (S110: NO), the controller 8
restarts the processing from step S103. Meanwhile, in a case where
it is determined in step S202 that electrodeposition has occurred
in the solid electrolyte layer (S110: YES), the controller 8
performs control performed upon electrodeposition detection (S111).
After performing the control performed upon electrodeposition
detection, the controller 8 resumes the processing from step
S103.
[0057] A specific form of the control performed upon
electrodeposition detection is not limited in particular, but the
control performed upon electrodeposition detection is preferably
processing for changing the conditions of the charging processing
so that the electrodeposition at the negative electrode becomes
harder to proceed. For example, the controller 8 can perform
control for stopping charging as the control performed upon
electrodeposition detection. In this case, if necessary, the user
may be notified that the charging has stopped. Alternatively, the
controller 8 may perform, as the control performed upon
electrodeposition detection, discharging processing for a
predetermined time at a predetermined current value (C rate)
smaller than the charging current during the charging after
stopping the charging. In this case, if necessary, the user may be
notified about this. In a case where such control performed upon
electrodeposition detection is performed, the progress of the
electrodeposition in the solid electrolyte layer in subsequent
charge and discharging processing can be prevented by appropriately
setting conditions (the current value (C rate) and the time) of the
discharging processing in advance. Alternatively, as illustrated in
FIG. 2, the controller 8 may perform, as the control performed upon
electrodeposition detection, control for continuing the charging
processing while decreasing the charging current (C rate). In this
case, if necessary, the user may be notified about this or that a
time required for charging up to a predetermined voltage will be
extended. Also in a case where such control performed upon
electrodeposition detection is performed, the progress of the
electrodeposition in the solid electrolyte layer in subsequent
charging processing can be prevented by appropriately setting the
conditions (the current value (C rate) and the time) of the
charging processing after the change of the conditions in advance.
Further, for example, in a case where it is determined in step S202
that electrodeposition has occurred in the solid electrolyte layer,
when a measured value of the battery temperature measured by the
temperature sensor 4 is lower than a predetermined threshold
temperature, the controller 8 may increase the battery temperature
by heating the battery by using a heater (not illustrated) or the
like. According to such control, there is an advantage that values
of yield stress and Young's modulus of the negative electrode
active material layer composed of metal lithium decrease, and the
electrodeposition that has occurred becomes harder to progress into
the solid electrolyte layer.
[0058] Although the control according to the present invention has
been described in detail above, the embodiment described with
reference to the drawings is merely an example, and appropriate
modifications of the present invention may be made within the scope
of the technical idea of the invention described in the claims.
[0059] For example, in the above embodiment, the controller 8
determines whether or not electrodeposition has occurred by
determining whether or not the amplitude of the response voltage in
the charge direction is a predetermined ratio or less with respect
to the amplitude of the response voltage in the discharge direction
in the previous cycle when comparing two adjacent cycles regarding
the waveform of the response voltage (normally a sine wave) as the
output signal of the impedance measuring device 7. Alternatively,
for example, the controller 8 may determine whether or not
electrodeposition has occurred by also performing similar
comparison between different cycles that are not adjacent to each
other and determining whether or not an amplitude of a response
voltage in the charge direction is a predetermined ratio or less
with respect to an amplitude of a response voltage in the discharge
direction in a preceding or later cycle in a similar manner to that
described above.
[0060] Further, according to still another embodiment of the
present invention, there is also provided a charging device for an
all-solid-state lithium ion secondary battery for charging an
all-solid-state lithium ion secondary battery including a negative
electrode active material layer containing a negative electrode
active material containing metal lithium. Specifically, the
charging device for an all-solid-state lithium ion secondary
battery includes a charger for charging the all-solid-state lithium
ion secondary battery, an AC impedance measuring device for
measuring an AC impedance of the all-solid-state lithium ion
secondary battery, and a controller that determines whether or not
electrodeposition of metal lithium has occurred in the solid
electrolyte layer. The controller determines whether or not
electrodeposition of metal lithium has occurred in the solid
electrolyte layer based on a relationship between an amplitude of a
response signal in a discharge direction and an amplitude of a
response signal in a charge direction of an AC impedance measured
by the AC impedance measuring device when the charger charges the
all-solid-state lithium ion secondary battery.
[0061] Further, according to still another aspect of the present
invention, there is also provided a method for charging an
all-solid-state lithium ion secondary battery for charging an
all-solid-state lithium ion secondary battery. According to the
method for charging an all-solid-state lithium ion secondary
battery, when a charger charges the all-solid-state lithium ion
secondary battery, it is determined whether or not
electrodeposition of metal lithium has occurred in a solid
electrolyte layer of the battery on the basis of a relationship
between an amplitude of a response signal in a discharge direction
and an amplitude of a response signal in a charge direction of an
AC impedance of the all-solid-state lithium ion secondary
battery.
[0062] An all-solid-state lithium ion secondary battery
constituting the all-solid-state lithium ion secondary battery
system according to the present embodiment will be described
below.
[0063] FIG. 5 is a cross-sectional view schematically illustrating
an overall structure of a laminate type (internal parallel
connection type) all-solid-state lithium ion secondary battery
(hereinafter also simply referred to as a "laminate type secondary
battery") according to an embodiment of the present invention. A
laminate type secondary battery 10a illustrated in FIG. 5 has a
structure in which a substantially rectangular power generating
element 21 in which a charge discharge reaction actually proceeds
is sealed inside a laminate film 29 which is a battery outer casing
body.
[0064] As illustrated in FIG. 5, the power generating element 21 of
the laminate type secondary battery 10a of the present embodiment
has a configuration in which a positive electrode in which a
positive electrode active material layer 13 is disposed on both
surfaces of a positive electrode current collector 11', a solid
electrolyte layer 17, and a negative electrode in which a negative
electrode active material layer 15 is disposed on both surfaces of
a negative electrode current collector 11'' are laminated.
Specifically, the positive electrode, the solid electrolyte layer,
and the negative electrode are laminated in this order so that one
positive electrode active material layer 13 and the negative
electrode active material layer 15 adjacent thereto face each other
with the solid electrolyte layer 17 interposed therebetween. In
this way, the positive electrode, solid electrolyte layer, and
negative electrode that are adjacent constitute one single battery
layer 19. Therefore, it can be said that the laminate type
secondary battery 10a illustrated in FIG. 5 has a configuration in
which a plurality of single battery layers 19 are laminated to be
electrically connected in parallel. Although the positive electrode
active material layer 13 is disposed on only one surface of each of
outermost positive electrode current collectors located in both
outermost layers of the power generating element 21, the active
material layer may be provided on both surfaces. That is, instead
of using a current collector exclusively for an outermost layer
provided with the active material layer only on one surface
thereof, a current collector provided with the active material
layer on both surfaces thereof may be used as it is as an outermost
current collector. Furthermore, the positions of the positive
electrode and the negative electrode may be made reverse to those
in FIG. 5, so that an outermost negative electrode current
collector is disposed in both outermost layers of the power
generating element 21 and the negative electrode active material
layer is disposed on one side or both sides of the outermost
negative electrode current collector.
[0065] A positive electrode current collecting plate 25 and a
negative electrode current collecting plate 27 which are
electrically conductive with the respective electrodes (the
positive electrode and the negative electrode) are respectively
attached to the positive electrode current collector 11' and the
negative electrode current collector 11'' and are led to an outside
of the laminate film 29 so as to be sandwiched between end portions
of the laminate film 29. The positive electrode current collecting
plate 25 and the negative electrode current collecting plate 27 may
be attached to the positive electrode current collector 11' and the
negative electrode current collector 11'' of the respective
electrodes with a positive electrode terminal lead and a negative
electrode terminal lead (not illustrated) interposed therebetween,
respectively by ultrasonic welding, resistance welding, or the like
as necessary.
[0066] In the above description, one embodiment of the
all-solid-state battery according to one embodiment of the present
invention has been described by taking a laminate type (internal
parallel connection type) all-solid-state lithium ion secondary
battery as an example. However, the type of the all-solid-state
battery to which the present invention can be applied is not
limited in particular, and the present invention can also be
applied to a bipolar type (bipolar type) all-solid-state battery
including a bipolar type electrode having a positive electrode
active material layer electrically coupled to one surface of a
current collector and a negative electrode active material layer
electrically coupled to an opposite surface of the current
collector.
[0067] FIG. 6 is a cross-sectional view schematically illustrating
a bipolar type (bipolar type) all-solid-state lithium ion secondary
battery (hereinafter also simply referred to as a "bipolar type
secondary battery") according to an embodiment of the present
invention. A bipolar type secondary battery 10b illustrated in FIG.
6 has a structure in which a substantially rectangular power
generating element 21 in which a charge discharge reaction actually
proceeds is sealed inside a laminate film 29 which is a battery
outer casing body.
[0068] As illustrated in FIG. 6, the power generating element 21 of
the bipolar type secondary battery 10b of the present embodiment
has a plurality of bipolar type electrodes 23 in which a positive
electrode active material layer 13 electrically coupled to one
surface of a current collector 11 is provided and a negative
electrode active material layer 15 electrically coupled to an
opposite surface of the current collector 11 is provided. The
bipolar type electrodes 23 are laminated with a solid electrolyte
layer 17 interposed therebetween to form the power generating
element 21. The solid electrolyte layer 17 has a configuration in
which a solid electrolyte is formed in layers. The bipolar type
electrode 23 and the solid electrolyte layer 17 are alternately
laminated such that the positive electrode active material layer 13
of one bipolar type electrode 23 and the negative electrode active
material layer 15 of another bipolar type electrode 23 adjacent to
the one bipolar type electrode 23 face each other with the solid
electrolyte layer 17 interposed therebetween. That is, the solid
electrolyte layer 17 is interposed between the positive electrode
active material layer 13 of one bipolar type electrode 23 and the
negative electrode active material layer 15 of another bipolar type
electrode 23 adjacent to the one bipolar type electrode 23.
[0069] The positive electrode active material layer 13, the solid
electrolyte layer 17, and the negative electrode active material
layer 15 that are adjacent to each other constitute one single
battery layer 19. Therefore, it can also be said that the bipolar
type secondary battery 10b has a configuration in which the single
battery layers 19 are laminated. The positive electrode active
material layer 13 is provided only on one surface of an outermost
current collector 11a on the positive electrode side located in an
outermost layer of the power generating element 21. Further, the
negative electrode active material layer 15 is provided only on one
surface of an outermost current collector 11b on the negative
electrode side located in an outermost layer of the power
generating element 21.
[0070] Further, in the bipolar type secondary battery 10b
illustrated in FIG. 6, a positive electrode current collecting
plate (positive electrode tab) 25 is disposed so as to be adjacent
to the outermost current collector 11a on the positive electrode
side and is extended to be led out from the laminate film 29 which
is a battery outer casing body. Meanwhile, a negative electrode
current collecting plate (negative electrode tab) 27 is disposed so
as to be adjacent to the outermost current collector 11b on the
negative electrode side and similarly is extended to be led out
from the laminate film 29.
[0071] The number of times of lamination of the single battery
layers 19 is adjusted according to a desired voltage. In the
bipolar type secondary battery 10b, the number of times of
lamination of the single battery layers 19 may be reduced as long
as sufficient output can be secured even if the thickness of the
battery is reduced as much as possible. Also in the bipolar type
secondary battery 10b, it is preferable to employ a structure in
which the power generating element 21 is sealed in the laminate
film 29, which is a battery outer casing body, under reduced
pressure, and the positive electrode current collecting plate 25
and the negative electrode current collecting plate 27 are taken
out to the outside of the laminate film 29 in order to prevent
external impact and environmental deterioration during use.
[0072] Main components of the laminate type secondary battery 10a
described above will be described below.
[0073] [Current Collector]
[0074] A current collector has a function of mediating transfer of
electrons from one surface in contact with a positive electrode
active material layer to the other surface in contact with a
negative electrode active material layer. A material of which the
current collector is made is not limited in particular. As the
material of which the current collector is made, for example, a
metal or a resin having electric conductivity can be adopted.
[0075] Specific examples of the metal include aluminum, nickel,
iron, stainless steel, titanium, copper, and the like. In addition
to these, a clad material of nickel and aluminum, a clad material
of copper and aluminum, or the like may be used. Further, a foil in
which a metal surface is coated with aluminum may be used. Above
all, aluminum, stainless steel, copper, and nickel are preferable
from the viewpoint of electron conductivity, a battery operating
potential, adhesion of a negative electrode active material by
sputtering to the current collector, and the like.
[0076] Examples of the latter resin having electric conductivity
include a resin obtained by adding an electrically conductive
filler to a non-electrically-conductive polymer material as
necessary.
[0077] Examples of the non-electrically-conductive polymer material
include polyethylene (PE; high density polyethylene (HDPE), low
density polyethylene (LDPE), and the like), polypropylene (PP),
polyethylene terephthalate (PET), polyether nitrile (PEN),
polyimide (PI), polyamide imide (PAI), polyamide (PA),
polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR),
polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl
methacrylate (PMMA), polyvinyl chloride (PVC), polyvinylidene
fluoride (PVdF), polystyrene (PS), and the like. Such a
non-electrically-conductive polymer material can have excellent
potential resistance or solvent resistance.
[0078] An electrically conductive filler may be added to the
electrically conductive polymer material or the
non-electrically-conductive polymer material as necessary. In
particular, in a case where a resin serving as a base material of
the current collector is composed only of a
non-electrically-conductive polymer, an electrically conductive
filler is essential to impart electric conductivity to the
resin.
[0079] The electrically conductive filler can be used without
particular limitation as long as the electrically conductive filler
is a substance having electric conductivity. Examples of a material
excellent in electric conductivity, potential resistance, or
lithium ion blocking property include metals and electrically
conductive carbon. Examples of the metals are not limited in
particular but preferably includes at least one kind of metal
selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, Cr,
Sn, Zn, In, and Sb, or an alloy or a metal oxide containing these
metals. The electrically conductive carbon is not limited in
particular. Preferably, examples of the electrically conductive
carbon include at least one kind selected from the group consisting
of acetylene black, Vulcan (registered trademark), Black Pearl
(registered trademark), carbon nanofiber, Ketjen black (registered
trademark), carbon nanotube, carbon nanohorn, carbon nanoballoon,
and fullerene.
[0080] An added amount of the electrically conductive filler is not
limited in particular as long as sufficient electric conductivity
can be imparted to the current collector, and is generally 5 mass %
to 80 mass % with respect to 100 mass % of the total mass of the
current collector.
[0081] The current collector may have a single-layer structure made
of a single material or may have a laminated structure in which
layers made of these materials are appropriately combined. From the
viewpoint of weight reduction of the current collector, it is
preferable that the current collector includes at least an
electrically conductive resin layer made of a resin having electric
conductivity. From the viewpoint of blocking movement of lithium
ions between single battery layers, a metal layer may be provided
in a part of the current collector.
[0082] [Negative Electrode Active Material Layer]
[0083] A negative electrode active material layer contains a
negative electrode active material. The negative electrode active
material preferably includes a metal lithium simple substance (Li)
or a lithium-containing alloy. The kind of these negative electrode
active materials is not limited in particular, but examples of the
Li-containing alloy include an alloy of Li and at least one of In,
Al, Si, and Sn. In some cases, two or more kinds of negative
electrode active materials may be used in combination. Needless to
say, a negative electrode active material other than the ones
described above may be used.
[0084] Examples of a shape of the negative electrode active
material include a particulate shape (a spherical shape, a fibrous
shape) and a thin film shape. In a case where the negative
electrode active material has a particle shape, an average particle
diameter (D.sub.50) thereof is, for example, preferably within a
range of 1 nm to 100 .mu.m, more preferably within a range of 10 nm
to 50 .mu.m, still more preferably within a range of 100 nm to 20
.mu.m, and particularly preferably within a range of 1 to 20 .mu.m.
In the present specification, the value of the average particle
diameter (D.sub.50) of the active material can be measured by a
laser diffraction scattering method.
[0085] The content of the negative electrode active material in the
negative electrode active material layer is not limited in
particular, but for example, is preferably within a range of 40
mass % to 99 mass %, and more preferably within a range of 50 mass
% to 90 mass %.
[0086] The negative electrode active material layer preferably
further contains a solid electrolyte. In a case where the negative
electrode active material layer contains a solid electrolyte, ion
conductivity of the negative electrode active material layer can be
improved. Examples of the solid electrolyte include a sulfide solid
electrolyte and an oxide solid electrolyte, but the negative
electrode active material layer preferably contains a sulfide solid
electrolyte from the viewpoint of being hardly affected by crystal
grain boundaries in general and therefore having a large
substantial fracture toughness value (that is, cracks caused by
dendrite are less likely to develop) and having high ion
conductivity.
[0087] Examples of the sulfide solid electrolyte include
LiI--Li.sub.2S--SiS.sub.2, LiI--Li.sub.2S--P.sub.2O.sub.5,
LiI--Li.sub.3PO.sub.4--P.sub.2S.sub.5, Li.sub.2S--P.sub.2S.sub.5,
LiI--Li.sub.3PS.sub.4, LiI--LiBr--Li.sub.3PS.sub.4,
Li.sub.3PS.sub.4, Li.sub.2S--P.sub.2S.sub.5,
Li.sub.2S--P.sub.2S.sub.5--LiI,
Li.sub.2S--P.sub.2S.sub.5--Li.sub.2O,
Li.sub.2S--P.sub.2S.sub.5--Li.sub.2O--LiI, Li.sub.2S--SiS.sub.2,
Li.sub.2S--SiS.sub.2--LiI, Li.sub.2S--SiS.sub.2--LiBr,
Li.sub.2S--SiS.sub.2--LiCl,
Li.sub.2S--SiS.sub.2--B.sub.2S.sub.3--LiI,
Li.sub.2S--SiS.sub.2--P.sub.2S.sub.5--LiI,
Li.sub.2S--B.sub.2S.sub.3,
Li.sub.2S--P.sub.2S.sub.5--Z.sub.mS.sub.n (where m and n are
positive numbers, and Z is any of Ge, Zn, and Ga),
Li.sub.2S--GeS.sub.2, Li.sub.2S--SiS.sub.2--Li.sub.3PO.sub.4, and
Li.sub.2S--SiS.sub.2--Li.sub.xMO.sub.y (where x and y are positive
numbers, and M is any of P, Si, Ge, B, Al, Ga, and In). The
description "Li.sub.2S--P.sub.2S.sub.5" means a sulfide solid
electrolyte using a raw material composition containing Li.sub.2S
and P.sub.2S.sub.5, and the same applies to other descriptions.
[0088] The sulfide solid electrolyte, for example, may have a
Li.sub.3PS.sub.4 skeleton, may have a Li.sub.4P.sub.2S.sub.7
skeleton, or may have a Li.sub.4P.sub.2S.sub.6 skeleton. Examples
of the sulfide solid electrolyte having a Li.sub.3PS.sub.4 skeleton
include LiI--Li.sub.3PS.sub.4, LiI--LiBr--Li.sub.3PS.sub.4, and
Li.sub.3PS.sub.4. Examples of the sulfide solid electrolyte having
a Li.sub.4P.sub.2S.sub.7 skeleton include a Li--P--S-based solid
electrolyte called LPS (for example, Li.sub.7P.sub.3S.sub.11). As
the sulfide solid electrolyte, for example, LGPS expressed by
Li.sub.(4-x)Ge.sub.(1-x)P.sub.xS.sub.4 (x satisfies 0<x<1) or
the like may be used. Above all, the sulfide solid electrolyte is
preferably a sulfide solid electrolyte containing a P element, and
the sulfide solid electrolyte is more preferably a material
containing Li.sub.2S--P.sub.2S.sub.5 as a main component.
Furthermore, the sulfide solid electrolyte may contain halogen (F,
Cl, Br, I).
[0089] In a case where the sulfide solid electrolyte is
Li.sub.2S--P.sub.2S.sub.5 based, a molar ratio of Li.sub.2S and
P.sub.2S.sub.5 is preferably within a range of
Li.sub.2S:P.sub.2S.sub.5=50:50 to 100:0, and particularly
preferably Li.sub.2S:P.sub.2S.sub.5=70:30 to 80:20.
[0090] The sulfide solid electrolyte may be sulfide glass, may be
crystallized sulfide glass, or may be a crystalline material
obtained by a solid phase method. Note that the sulfide glass can
be obtained, for example, by performing mechanical milling (ball
milling or the like) on a raw material composition. The
crystallized sulfide glass can be obtained, for example, by
heat-treating sulfide glass at a temperature equal to or higher
than a crystallization temperature. Ion conductivity (for example,
Li ion conductivity) of the sulfide solid electrolyte at a normal
temperature (25.degree. C.) is, for example, preferably
1.times.10.sup.-5S/cm or more, and more preferably
1.times.10.sup.-4S/cm or more. Note that a value of the ion
conductivity of the solid electrolyte can be measured by an AC
impedance method.
[0091] Examples of the oxide solid electrolyte include a compound
having a NASICON-type structure. Examples of the compound having a
NASICON-type structure include a compound (LAGP) expressed by a
general formula
Li.sub.1+xAl.sub.xGe.sub.2-x(PO.sub.4).sub.3(0.ltoreq.x.ltoreq.2)
and a compound (LATP) expressed by a general formula
Li.sub.1+xAl.sub.xTi.sub.2-x(PO.sub.4).sub.3 (0.ltoreq.x.ltoreq.2).
Other examples of the oxide solid electrolyte include LiLaTiO (for
example, Li.sub.0.34La.sub.0.51TiO.sub.3), LiPON (for example,
Li.sub.2.9PO.sub.3.3N.sub.0.46), and LiLaZrO (for example,
Li.sub.7La.sub.3Zr.sub.2O.sub.12).
[0092] Examples of a shape of the solid electrolyte include a
particle shape such as a true spherical shape and an elliptical
spherical shape, a thin film shape, and the like. In a case where
the solid electrolyte has a particle shape, an average particle
diameter (D.sub.50) is not limited in particular, but is preferably
40 .mu.m or less, more preferably 20 .mu.m or less, and still more
preferably 10 .mu.m or less. On the other hand, the average
particle diameter (D.sub.50) is preferably 0.01 .mu.m or more, and
more preferably 0.1 .mu.m or more.
[0093] The content of the solid electrolyte in the negative
electrode active material layer is, for example, preferably within
a range of 1 mass % to 60 mass %, and more preferably within a
range of 10 mass % to 50 mass %.
[0094] The negative electrode active material layer may further
contain at least one of a conductive aid and a binder in addition
to the negative electrode active material and the solid electrolyte
described above.
[0095] Examples of the conductive aid include, but are not limited
to, metals such as aluminum, stainless steel (SUS), silver, gold,
copper, and titanium, alloys or metal oxides containing these
metals; and carbon such as carbon fibers (specifically, vapor grown
carbon fibers (VGCF), polyacrylonitrile-based carbon fibers,
pitch-based carbon fibers, rayon-based carbon fibers, and activated
carbon fibers), carbon nanotubes (CNT), and carbon black
(specifically, acetylene black, Ketjen black (registered
trademark), furnace black, channel black, thermal lamp black, and
the like). In addition, a particle-shaped ceramic material or resin
material coated with the metal material by plating or the like can
also be used as the conductive aid. Among these conductive aids,
the conductive aid preferably contains at least one selected from
the group consisting of aluminum, stainless steel, silver, gold,
copper, titanium, and carbon, more preferably contains at least one
selected from the group consisting of aluminum, stainless steel,
silver, gold, and carbon, and still more preferably contains at
least one kind of carbon from the viewpoint of electrical
stability. These conductive aids may be used alone or may be used
in combination of two or more kinds thereof.
[0096] A shape of the conductive aid is preferably a particle shape
or a fibrous shape. In a case where the conductive aid has a
particle shape, the shape of the particles is not limited in
particular, and may be any shape such as a powder shape, a
spherical shape, a rod shape, a needle shape, a plate shape, a
columnar shape, an irregular shape, a scaly shape, or a spindle
shape.
[0097] In a case where the conductive aid has a particle shape, an
average particle diameter (primary particle diameter) is not
limited in particular, but is preferably 0.01 .mu.m to 10 .mu.m
from the viewpoint of electrical characteristics of the battery. In
the present specification, the "particle diameter of the conductive
aid" means a maximum distance L among distances between any two
points on a contour line of the conductive aid. As a value of the
"average particle diameter of the conductive aid", a value
calculated as an average value of particle diameters of particles
observed in several to several tens of fields of view by using an
observation means such as a scanning electron microscope (SEM) or a
transmission electron microscope (TEM) is adopted.
[0098] In a case where the negative electrode active material layer
contains a conductive aid, the content of the conductive aid in the
negative electrode active material layer is not limited in
particular, but is preferably 0 mass % to 10 mass %, more
preferably 2 mass % to 8 mass %, and still more preferably 4 mass %
to 7 mass % with respect to the total mass of the negative
electrode active material layer. Within such ranges, a stronger
electron conduction path can be formed in the negative electrode
active material layer, and it is possible to effectively contribute
to improvement of battery characteristics.
[0099] On the other hand, the binder is not limited in particular,
and examples thereof include the following materials.
[0100] Examples of the binder include thermoplastic polymers such
as polybutylene terephthalate, polyethylene terephthalate,
polyvinylidene fluoride (PVDF) (including a compound in which a
hydrogen atom is substituted with another halogen element),
polyethylene, polypropylene, polymethylpentene, polybutene,
polyether nitrile, polytetrafluoroethylene, polyacrylonitrile,
polyimide, polyamide, an ethylene-vinyl acetate copolymer,
polyvinyl chloride, styrene-butadiene rubber (SBR), an
ethylene-propylene-diene copolymer, a styrene-butadiene-styrene
block copolymer and hydrogenated products thereof, a
styrene-isoprene-styrene block copolymer and hydrogenated products
thereof, fluorine resins such as a
tetrafluoroethylene-hexafluoropropylene copolymer (FEP), a
tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), an
ethylene-tetrafluoroethylene copolymer (ETFE),
polychlorotrifluoroethylene (PCTFE), an
ethylene-chlorotrifluoroethylene copolymer (ECTFE), and polyvinyl
fluoride (PVF), and vinylidene fluoride fluorine rubber such as
vinylidene fluoride-hexafluoropropylene fluorine rubber (VDF-HFP
fluorine rubber), vinylidene
fluoride-hexafluoropropylene-tetrafluoroethylene fluorine rubber
(VDF-HFP-TFE fluorine rubber), vinylidene
fluoride-pentafluoropropylene fluorine rubber (VDF-PFP fluorine
rubber), vinylidene
fluoride-pentafluoropropylene-tetrafluoroethylene fluorine rubber
(VDF-PFP-TFE fluorine rubber), vinylidene fluoride-perfluoromethyl
vinyl ether-tetrafluoroethylene fluorine rubber (VDF-PFMVE-TFE
fluorine rubber), vinylidene fluoride-chlorotrifluoroethylene
fluorine rubber (VDF-CTFE fluorine rubber), and epoxy resins. Above
all, polyimide, styrene-butadiene rubber, carboxymethyl cellulose,
polypropylene, polytetrafluoroethylene, polyacrylonitrile, and
polyamide are more preferable.
[0101] A thickness of the negative electrode active material layer
varies depending on the configuration of the intended
all-solid-state battery, but is preferably, for example, within a
range of 0.1 .mu.m to 1000 .mu.m.
[0102] [Positive Electrode Active Material Layer]
[0103] A positive electrode active material layer contains a
positive electrode active material. The kind of the positive
electrode active material is not limited in particular, but a
sulfur simple substance (S8) or a reduction product (any of
compounds Li.sub.2S.sub.8 to Li.sub.2S) of sulfur containing
lithium is preferably used. Here, for example, the sulfur simple
substance (S.sub.8) has an extremely large theoretical capacity of
about 1670 mAh/g, and has an advantage of low cost and abundant
resources. In this case, in a case where the all-solid-state
lithium ion secondary battery is provided in a charged state, a
sulfur simple substance (S.sub.8) is contained as the positive
electrode active material. In a case where the all-solid-state
lithium ion secondary battery is provided in a discharged state, a
reduction product (any of the compounds Li.sub.2S.sub.8 to
Li.sub.2S described above) of sulfur containing lithium is
contained as the positive electrode active material.
[0104] The positive electrode active material layer may contain a
positive electrode active material other than the sulfur simple
substance (S.sub.8) or a reduction product (any of the compounds
Li.sub.2S.sub.8 to Li.sub.2S described above) of sulfur containing
lithium described above. However, a ratio of the sulfur simple
substance or the reduction product of sulfur containing lithium in
the positive electrode active material contained in the positive
electrode active material layer is preferably 50 mass % to 100 mass
%, more preferably 80 mass % to 100 mass %, still more preferably
90 mass % to 100 mass %, further still more preferably 95 mass % to
100 mass %, particularly preferably 98 mass % to 100 mass %, and
most preferably 100 mass %.
[0105] [Examples of the positive electrode active material other
than the sulfur simple substance or the reduction product of sulfur
containing lithium include disulfide compounds, sulfur-modified
polyacrylonitrile represented by the compounds described in
International Publication No. 2010/044437, sulfur-modified
polyisoprene, rubeanic acid (dithiooxamide), polysulfide carbon,
and the like. Inorganic sulfur compounds such as S-carbon
composite, TiS.sub.2, TiS.sub.3, TiS.sub.4, NiS, NiS.sub.2, CuS,
FeS.sub.2, MoS.sub.2, MoS.sub.3, and the like may also be used.
Furthermore, examples of a positive electrode active material that
does not contain sulfur include layered rock salt type active
materials such as LiCoO.sub.2, LiMnO.sub.2, LiNiO.sub.2,
LiVO.sub.2, and Li (Ni--Mn--Co)O.sub.2, spinel type active
materials such as LiMn.sub.2O.sub.4 and
LiNi.sub.0.5Mn.sub.1.5O.sub.4, olivine type active materials such
as LiFePO.sub.4 and LiMnPO.sub.4, and Si-containing active
materials such as Li.sub.2FeSiO.sub.4 and Li.sub.2MnSiO.sub.4.
Examples of the oxide active material other than those described
above include Li.sub.4Ti.sub.5O.sub.12. In some cases, two or more
kinds of positive electrode active materials may be used in
combination. Needless to say, a positive electrode active material
other than the ones described above may be used.
[0106] Examples of a shape of the positive electrode active
material include a particle shape (a spherical shape, a fibrous
shape) and a thin film shape. In a case where the positive
electrode active material has a particle shape, an average particle
diameter (D.sub.50) thereof is, for example, preferably within a
range of 1 nm to 100 .mu.m, more preferably within a range of 10 nm
to 50 .mu.m, still more preferably within a range of 100 nm to 20
.mu.m, and particularly preferably within a range of 1 .mu.m to 20
.mu.m. In the present specification, the value of the average
particle diameter (D.sub.50) of the active material can be measured
by a laser diffraction scattering method.
[0107] The content of the positive electrode active material in the
positive electrode active material layer is not limited in
particular, but is, for example, preferably within a range of 40
mass % to 99 mass %, and more preferably within a range of 50 mass
% to 90 mass %. As with the negative electrode active material
layer described above, the positive electrode active material layer
may further contain at least one of a solid electrolyte, a
conductive aid, and a binder as necessary. Since specific forms of
these materials are similar to those described above, detailed
description thereof is omitted here.
[0108] [Solid Electrolyte Layer]
[0109] A solid electrolyte layer of a bipolar type secondary
battery according to the present embodiment is a layer that
contains a solid electrolyte as a main component and is interposed
between the positive electrode active material layer and negative
electrode active material layer described above. Since a specific
form of the solid electrolyte contained in the solid electrolyte
layer is similar to that described above, detailed description
thereof is omitted here.
[0110] The content of the solid electrolyte in the solid
electrolyte layer is, for example, preferably within a range of 10
mass % to 100 mass %, more preferably within a range of 50 mass %
to 100 mass %, and still more preferably within a range of 90 mass
% to 100 mass %.
[0111] The solid electrolyte layer may further contain a binder in
addition to the solid electrolyte described above. Since a specific
form of the binder that can be contained in the solid electrolyte
layer is similar to as that described above, detailed description
thereof is omitted here.
[0112] A thickness of the solid electrolyte layer varies depending
on the configuration of the intended bipolar type secondary
battery, but is, for example, preferably within a range of 0.1
.mu.m to 1000 .mu.m, more preferably within a range of 0.1 .mu.m to
300 .mu.m.
[0113] [Positive Electrode Current Collecting Plate and Negative
Electrode Current Collecting Plate]
[0114] A material of which the current collecting plate (25, 27) is
made is not limited in particular, and can be a known highly
electrically conductive material conventionally used as a current
collecting plate for a secondary battery. As the material of which
the current collecting plate is made, for example, a metal material
such as aluminum, copper, titanium, nickel, stainless steel (SUS),
or an alloy thereof is preferable. From the viewpoint of
lightweight, corrosion resistance, and high electric conductivity,
aluminum and copper are more preferable, and aluminum is
particularly preferable. The same material or different materials
may be used for the positive electrode current collecting plate 27
and the negative electrode current collecting plate 25.
[0115] [Positive Electrode Lead and Negative Electrode Lead]
[0116] Although not illustrated, the current collector 11 and the
current collecting plate (25, 27) may be electrically connected
with a positive electrode lead or a negative electrode lead
interposed therebetween. As a material of which the positive
electrode and the negative electrode lead are made, a material used
in a known lithium ion secondary battery can be similarly adopted.
A portion taken out from an outer casing is preferably covered with
a heat resistant and insulating heat shrinkable tube or the like so
as not to affect a product (for example, an automotive component,
in particular an electronic device and the like) due to electric
leakage caused by contact with peripheral equipment, wiring, or the
like.
[0117] [Battery Outer Casing Body]
[0118] As a battery outer casing body, a known metal can case can
be used, and a bag-shaped case using the laminate film 29
containing aluminum that can cover a power generating element as
illustrated in FIGS. 5 and 6 can be used. As the laminate film, for
example, a laminate film or the like having a three-layer structure
constituted by PP, aluminum, and nylon laminated in this order can
be used, but the laminate film is not limited thereto. A laminate
film is desirable from the viewpoint of high output and excellent
cooling performance, and suitable application to batteries for
large equipment for EV and HEV. Furthermore, the outer casing body
is more preferably a laminate film containing aluminum from the
perspective of easy adjustment of a group pressure applied to the
power generating element from an outside.
[0119] FIG. 7 is a perspective view illustrating an appearance of a
flat lithium ion secondary battery which is a representative
embodiment of a laminate type secondary battery.
[0120] As illustrated in FIG. 7, a flat laminate type secondary
battery 50 has a rectangular flat shape, and a positive electrode
tab 58 and a negative electrode tab 59 for extracting electric
power are drawn out from both side portions thereof. A power
generating element 57 is wrapped by a battery outer casing body
(laminate film 52) of the laminate type secondary battery 50, a
periphery thereof is thermally fused, and the power generating
element 57 is sealed in a state where the positive electrode tab 58
and the negative electrode tab 59 are drawn out to the outside. The
power generating element 57 corresponds to the power generating
element 21 of the laminate type secondary battery 10a illustrated
in FIG. 5 described above.
[0121] The lithium ion secondary battery is not limited to a
laminate type flat shape. A wound type lithium ion secondary
battery is not limited in particular, and, for example, may have a
cylindrical shape or may have a rectangular flat shape obtained by
deforming such a cylindrical shape. As for the lithium ion
secondary battery having the cylindrical shape, there is no
particular limitation, and for example, a laminate film may be used
or a conventional cylindrical can (metal can) may be used for an
outer casing body thereof. Preferably, the power generating element
is covered with an aluminum laminate film. According to this form,
weight reduction can be achieved.
[0122] Furthermore, a way in which the tabs 58 and 59 illustrated
in FIG. 7 are taken out is not limited in particular. There is no
limitation to the configuration illustrated in FIG. 7, and for
example, the positive electrode tab 58 and the negative electrode
tab 59 may be taken out from the same side or the positive
electrode tab 58 and the negative electrode tab 59 may be divided
into a plurality of portions and taken out from each side. As for
the wound type lithium ion battery, for example, a terminal may be
formed by using a cylindrical can (metal can) instead of a tab.
[0123] [Assembled Battery]
[0124] An assembled battery is constituted by a plurality of
batteries connected to one another. Specifically, an assembled
battery is constituted by at least two batteries connected in
series, in parallel, or both. By connecting the batteries in series
and/or in parallel, capacitance and voltage can be freely
adjusted.
[0125] A plurality of batteries may be connected in series or in
parallel to form an attachable detachable compact assembled
battery. Further, a plurality of such attachable and detachable
compact assembled batteries may be connected in series or in
parallel to form an assembled battery having a large capacity and a
large output suitable for a power source for driving a vehicle and
an auxiliary power source which require a high volume energy
density and a high volume output density. How many batteries are
connected to produce an assembled battery and how many stages of
compact assembled batteries are laminated to produce a
large-capacity assembled battery may be determined according to a
battery capacity or output of a vehicle (electric vehicle) on which
the assembled battery is to be mounted.
[0126] When the charging method according to the present invention
is performed on an assembled battery, for example, the charging
processing can be performed while measuring an internal resistance
value of each of individual batteries (unit cells) constituting the
assembled battery. With such a configuration, it is possible to
perform the charging processing while separately monitoring
occurrence of electrodeposition in each of the individual batteries
(unit cells).
[0127] [Vehicle]
[0128] The non-aqueous electrolyte secondary battery of the present
embodiment maintains a discharge capacity even when used for a long
period of time and has good cycle characteristics. Furthermore, a
volume energy density is high. In vehicle applications such as an
electric vehicle, a hybrid electric vehicle, a fuel cell vehicle,
and a hybrid fuel cell vehicle, a higher capacity, a larger size,
and a longer life are required as compared with electric/portable
electronic device applications. Therefore, the non-aqueous
electrolyte secondary battery can be suitably used as a power
source for a vehicle, for example, a power source for driving a
vehicle or an auxiliary power source.
[0129] Specifically, a battery or an assembled battery constituted
by a combination of a plurality of batteries can be mounted on a
vehicle. According to the present invention, a long-life battery
having excellent long-term reliability and output characteristics
can be provided, and therefore mounting such a battery can provide
a plug-in hybrid electric vehicle having a long EV traveling
distance or an electric vehicle having a long one charge traveling
distance. This is because a log-life and highly reliable automobile
is provided when the battery or an assembled battery constituted by
a combination of a plurality of such batteries is used, for
example, for a hybrid vehicle, a fuel cell vehicle, or an electric
vehicle (each encompasses a four-wheeled vehicle (a passenger car,
a commercial car such as a truck or a bus, a light vehicle, and the
like), a two-wheeled vehicle (motorcycle), and a three-wheeled
vehicle) in the case of an automobile. However, the application is
not limited to automobiles, and for example, the present invention
can also be applied to various power supplies of other vehicles,
for example, moving bodies such as a train and can also be used as
a mounting power supply of an uninterruptible power supply device
or the like.
REFERENCE SIGNS LIST
[0130] 1 All-solid-state lithium ion secondary battery system
[0131] 2 All-solid-state lithium ion secondary battery [0132] 3
Voltage sensor [0133] 4 Temperature sensor [0134] 5 Voltage current
adjustment device [0135] 6 Current sensor [0136] 7 Impedance
measuring device [0137] 8 Controller [0138] 9 External power supply
[0139] 10a, 50 Laminate type secondary battery [0140] 10b Bipolar
type secondary battery [0141] 11 Current collector [0142] 11'
Positive electrode current collector [0143] 11'' Negative electrode
current collector [0144] 11a Outermost current collector on
positive electrode side [0145] 11b Outermost current collector on
negative electrode side [0146] 13 Positive electrode active
material layer [0147] 15 Negative electrode active material layer
[0148] 17 Electrolyte layer [0149] 19 Single battery layer [0150]
21, 57 Power generating element [0151] 23 Bipolar type electrode
[0152] 25 Positive electrode current collecting plate (positive
electrode tab) [0153] 27 Negative electrode current collecting
plate (negative electrode tab) [0154] 29, 52 Laminate film [0155]
58 Positive electrode tab [0156] 59 Negative electrode tab [0157]
81 CPU [0158] 82 Memory
* * * * *