U.S. patent application number 14/617449 was filed with the patent office on 2015-08-20 for graphene current collectors in batteries for portable electronic devices.
This patent application is currently assigned to APPLE INC.. The applicant listed for this patent is Apple Inc.. Invention is credited to Ramesh C. Bhardwaj, Richard M. Mank.
Application Number | 20150236371 14/617449 |
Document ID | / |
Family ID | 46800363 |
Filed Date | 2015-08-20 |
United States Patent
Application |
20150236371 |
Kind Code |
A1 |
Bhardwaj; Ramesh C. ; et
al. |
August 20, 2015 |
GRAPHENE CURRENT COLLECTORS IN BATTERIES FOR PORTABLE ELECTRONIC
DEVICES
Abstract
The disclosed embodiments provide a battery cell. The battery
cell includes a cathode current collector containing graphene, a
cathode active material, an electrolyte, an anode active material,
and an anode current collector. The graphene may reduce the
manufacturing cost and/or increase the energy density of the
battery cell.
Inventors: |
Bhardwaj; Ramesh C.;
(Fremont, CA) ; Mank; Richard M.; (Los Altos,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Apple Inc. |
Cupertino |
CA |
US |
|
|
Assignee: |
APPLE INC.
Cupertino
CA
|
Family ID: |
46800363 |
Appl. No.: |
14/617449 |
Filed: |
February 9, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13273116 |
Oct 13, 2011 |
8951675 |
|
|
14617449 |
|
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Current U.S.
Class: |
429/149 ;
429/231.8; 429/231.95; 429/234; 429/322 |
Current CPC
Class: |
H01M 10/056 20130101;
Y02E 60/10 20130101; H01M 4/583 20130101; H01M 4/667 20130101; H01M
4/133 20130101; H01M 4/382 20130101; H01M 2220/30 20130101; H01M
10/0562 20130101; H01M 4/663 20130101; H01M 4/668 20130101; H01M
10/052 20130101 |
International
Class: |
H01M 10/052 20060101
H01M010/052; H01M 4/66 20060101 H01M004/66; H01M 4/38 20060101
H01M004/38; H01M 4/583 20060101 H01M004/583; H01M 10/056 20060101
H01M010/056; H01M 4/133 20060101 H01M004/133 |
Claims
1. A battery cell, comprising: a cathode current collector; a
cathode active material; an electrolyte; an anode active material;
and an anode current collector; wherein the cathode current
collector compromises a non-conducting layer covered on each side
by only one graphene monolayer, wherein the only one graphene
monolayer on each side of the non-conducting layer is sandwiched by
the non-conducting layer and the cathode active material, and
wherein the only one graphene monolayers from each side of the
non-conducting layer are electrically connected to each other to
form a continuous current collector.
2. The battery cell of claim 1, wherein the anode current collector
comprises graphene.
3. (canceled)
4. The battery cell of claim 3, wherein the electrolyte is a solid
electrolyte.
5. The battery cell of claim 4, wherein the solid electrolyte
comprises lithium phosphorus oxynitride (LiPON).
6. The battery cell of claim 3, wherein the cathode active material
comprises a lithium compound, and wherein the anode active material
comprises lithium metal.
7. The battery cell of claim 1, wherein the non-conducting layer
comprises a polyamide layer.
8. The battery cell of claim 7, wherein the polyamide layer is
about two microns thick, and wherein the graphene is about one
micron thick.
9. The battery cell of claim 7, wherein the graphene is deposited
on one or both sides of the polyamide layer.
10. The battery cell of claim 7, wherein the cathode active
material comprises a lithium compound, and wherein the anode active
material comprises graphite.
11. A portable electronic device, comprising: a set of components
powered by a battery pack; and the battery pack, comprising: a
battery cell, comprising: a cathode current collector comprising
graphene; a cathode active material; an electrolyte; an anode
active material; and an anode current collector; wherein the
cathode current collector compromises a non-conducting layer
covered on each side by only one graphene monolayer, wherein the
only one graphene monolayer on each side of the non-conducting
layer is sandwiched by the non-conducting layer and the cathode
active material, and wherein the only one graphene monolayers from
each side of the non-conducting layer are electrically connected to
each other to form a continuous current collector.
12. The portable electronic device of claim 11, wherein the anode
current collector comprises graphene.
13. (canceled)
14. The portable electronic device of claim 13, wherein the
electrolyte is a solid electrolyte.
15. The portable electronic device of claim 14, wherein the solid
electrolyte comprises lithium phosphorus oxynitride (LiPON).
16. The portable electronic device of claim 13, wherein the cathode
active material comprises a lithium compound, and wherein the anode
active material comprises lithium metal.
17. The portable electronic device of claim 11, wherein the
non-conducting layer comprises a polyamide layer.
18. The portable electronic device of claim 17, wherein the
polyamide layer is about two microns thick, and wherein the
graphene is about one micron thick.
19. The portable electronic device of claim 17, wherein the
graphene is deposited on one or both sides of the polyamide
layer.
20. The portable electronic device of claim 17, wherein the cathode
active material comprises a lithium compound, and wherein the anode
active material comprises graphite.
Description
RELATED APPLICATION
[0001] The present patent is a continuation of, and hereby claims
priority under 35 U.S.C .sctn.120 to, pending U.S. patent
application Ser. No. 13/273,116, entitled "Graphene Current
Collectors in Batteries for Portable Electronic Devices," by
inventors Ramesh C. Bhardwaj and Richard M. Mank, filed on 13 Oct.
2011 (Attorney Docket No. APL-P11741US1).
BACKGROUND
[0002] 1. Field
[0003] The present embodiments relate to batteries for portable
electronic devices. More specifically, the present embodiments
relate to the use of graphene in the anode and/or cathode current
collectors of batteries for portable electronic devices.
[0004] 2. Related Art
[0005] Rechargeable batteries are presently used to provide power
to a wide variety of portable electronic devices, including laptop
computers, tablet computers, mobile phones, personal digital
assistants (PDAs), digital music players and cordless power tools.
The most commonly used type of rechargeable battery is a lithium
battery, which can include a lithium-ion or a lithium-polymer
battery.
[0006] Lithium-polymer batteries often include cells that are
packaged in flexible pouches. Such pouches are typically
lightweight and inexpensive to manufacture. Moreover, these pouches
may be tailored to various cell dimensions, allowing
lithium-polymer batteries to be used in space-constrained portable
electronic devices such as mobile phones, laptop computers, and/or
digital cameras. For example, a lithium-polymer battery cell may
achieve a packaging efficiency of 90-95% by enclosing rolled
electrodes and electrolyte in an aluminized laminated pouch.
Multiple pouches may then be placed side-by-side within a portable
electronic device and electrically coupled in series and/or in
parallel to form a battery for the portable electronic device.
[0007] Recent advances in battery technology have also led to the
development of solid-state batteries, in which electrodes and a
thin solid electrolyte are layered on top of a non-conducting
substrate. Because the solid electrolyte takes up less space and/or
weighs less than the liquid electrolyte of a comparable lithium-ion
and/or lithium-polymer battery, the solid-state battery may have a
higher energy density than the lithium-ion and/or lithium-polymer
battery. In addition, the solid-state battery may be safer and/or
more reliable than conventional lithium-ion and/or lithium-polymer
batteries. For example, the use of a non-flammable, solid
electrolyte in the solid-state battery may allow the solid-state
battery to sidestep liquid electrolyte hazards such as spilling,
boiling, gassing, and/or fires.
[0008] However, solid-state batteries are typically associated with
much higher manufacturing costs than other types of batteries. For
example, the cathode current collector of a solid-state battery may
be made of an expensive metal such as gold or platinum. In
addition, the layers of the solid-state battery may be formed using
a complex and/or costly technique such as vacuum deposition.
Consequently, manufacturing techniques for solid-state batteries
may be cost-prohibitive to consumer applications of the solid-state
batteries.
SUMMARY
[0009] The disclosed embodiments provide a battery cell. The
battery cell includes a cathode current collector composed of
graphene, a cathode active material, an electrolyte, an anode
active material, and an anode current collector. The graphene may
reduce the manufacturing cost and/or increase the energy density of
the battery cell.
[0010] In some embodiments, the anode current collector is also
composed of graphene.
[0011] In some embodiments, the cathode current collector is
disposed on a non-conducting substrate. For example, the cathode
current collector may be deposited onto the non-conducting
substrate to form a solid-state battery cell. The electrolyte of
the solid-state battery cell may also be a solid electrolyte. For
example, the solid electrolyte may include lithium phosphorus
oxynitride (LiPON). In addition, the cathode active material of the
solid-state battery cell may include a lithium compound, and the
anode active material of the solid-state battery cell may include
lithium metal.
[0012] In some embodiments, the cathode current collector also
contains a polyamide layer. The polyamide layer may be about two
microns thick, and the graphene may be about one micron thick.
[0013] In some embodiments, the graphene is deposited on one or
both sides of the polyamide layer.
[0014] In some embodiments, the cathode active material includes a
lithium compound, and the anode active material includes graphite.
For example, the lithium compound and graphite may be used in the
cathode and anode active materials of a lithium-ion and/or
lithium-polymer battery cell.
BRIEF DESCRIPTION OF THE FIGURES
[0015] FIG. 1 shows a cross-sectional view of a battery cell in
accordance with the disclosed embodiments.
[0016] FIG. 2 shows a top-down view of a battery cell in accordance
with the disclosed embodiments.
[0017] FIG. 3 shows a set of layers for a battery cell in
accordance with the disclosed embodiments.
[0018] FIG. 4 shows a set of layers for a battery cell in
accordance with the disclosed embodiments.
[0019] FIG. 5 shows a portable electronic device in accordance with
the disclosed embodiments.
[0020] In the figures, like reference numerals refer to the same
figure elements.
DETAILED DESCRIPTION
[0021] The following description is presented to enable any person
skilled in the art to make and use the embodiments, and is provided
in the context of a particular application and its requirements.
Various modifications to the disclosed embodiments will be readily
apparent to those skilled in the art, and the general principles
defined herein may be applied to other embodiments and applications
without departing from the spirit and scope of the present
disclosure. Thus, the present invention is not limited to the
embodiments shown, but is to be accorded the widest scope
consistent with the principles and features disclosed herein.
[0022] The data structures and code described in this detailed
description are typically stored on a computer-readable storage
medium, which may be any device or medium that can store code
and/or data for use by a computer system. The computer-readable
storage medium includes, but is not limited to, volatile memory,
non-volatile memory, magnetic and optical storage devices such as
disk drives, magnetic tape, CDs (compact discs), DVDs (digital
versatile discs or digital video discs), or other media capable of
storing code and/or data now known or later developed.
[0023] The methods and processes described in the detailed
description section can be embodied as code and/or data, which can
be stored in a computer-readable storage medium as described above.
When a computer system reads and executes the code and/or data
stored on the computer-readable storage medium, the computer system
performs the methods and processes embodied as data structures and
code and stored within the computer-readable storage medium.
[0024] Furthermore, methods and processes described herein can be
included in hardware modules or apparatus. These modules or
apparatus may include, but are not limited to, an
application-specific integrated circuit (ASIC) chip, a
field-programmable gate array (FPGA), a dedicated or shared
processor that executes a particular software module or a piece of
code at a particular time, and/or other programmable-logic devices
now known or later developed. When the hardware modules or
apparatus are activated, they perform the methods and processes
included within them.
[0025] The disclosed embodiments relate to a battery cell. The
battery cell may contain a cathode current collector, a cathode
active material, an electrolyte, an anode active material, and an
anode current collector. To increase the energy density and/or
reduce the manufacturing cost of the battery, the cathode and/or
anode current collectors may be composed of graphene. For example,
a single layer of graphene may be used as a current collector in
the battery cell in lieu of a more expensive and/or thicker
material such as gold, platinum, aluminum, and/or copper. In
addition, the graphene may be substituted for the cathode and/or
anode current collectors in a variety of batteries, including
solid-state batteries, lithium-ion batteries, and/or
lithium-polymer batteries.
[0026] FIG. 1 shows a cross-sectional view of a battery cell 100 in
accordance with the disclosed embodiments. As shown in FIG. 1,
battery cell 100 includes a substrate 102, a cathode current
collector 104, a cathode active material 106, an electrolyte 108,
an anode active material 110, and an anode current collector
112.
[0027] More specifically, FIG. 1 shows a cross-sectional view of a
solid-state battery cell 100. The components of battery cell 100
may be formed by depositing layers of different materials onto
substrate 102 and/or one another. For example, substrate 102 may
correspond to a non-conducting substrate such as mica, polyamide,
and/or polyether ether ketone (PEEK). A vacuum deposition technique
may be used to deposit cathode current collector 104 as a layer of
platinum and/or gold onto substrate 102 and anode current collector
112 as a layer of copper onto substrate 102. Next, a sputtering
technique may be used to deposit a lithium compound corresponding
to cathode active material 106 onto cathode current collector 104,
along with a thin film of lithium phosphorus oxynitride (LiPON)
corresponding to a solid electrolyte 108 over cathode current
collector 104, cathode active material 106, substrate 102, and/or
anode current collector 112. A layer of lithium may then be
thermally evaporated onto the LiPON to form anode active material
110. Finally, battery cell 100 may be sealed in a protective
package 114 such as a polymer frame and/or flexible pouch.
[0028] Those skilled in the art will appreciate that the materials
and/or techniques described above may cause battery cell 100 to be
significantly more expensive to produce than other types of
batteries, such as lithium-ion and/or lithium-polymer batteries.
For example, a gold and/or platinum cathode current collector 104
in battery cell 100 may be associated with a higher materials cost
than an aluminum cathode current collector in a lithium-ion and/or
lithium-polymer battery. Similarly, the vacuum deposition and/or
sputtering techniques used to form battery cell 100 may be more
complex and/or costly than the stacking, rolling, and/or sealing
techniques used to manufacture lithium-ion and/or lithium-polymer
batteries. In turn, the manufacturing cost of battery cell 100 may
be prohibitive to the use of battery cell 100 in portable
electronic devices such as laptop computers, mobile phones, tablet
computers, portable media players, and/or digital cameras.
[0029] In one or more embodiments, the manufacturing cost of
battery cell 100 is reduced by substituting graphene for metals
used in cathode current collector 104 and/or anode current
collector 112. More specifically, a graphene monolayer with a high
electrical conductivity and/or tensile strength may be deposited on
substrate 102 as cathode current collector 104 and/or anode current
collector 112 in lieu of metals such as platinum, gold, and/or
copper. For example, the graphene monolayer may be formed on copper
and/or nickel foil and transferred to substrate 102 by dissolving
the foil in a solution and spraying the solution onto substrate
102. The graphene monolayer may remain on substrate 102 after the
solution evaporates. After the graphene monolayer is deposited onto
substrate 102, the remainder of battery cell 100 may be formed by
disposing cathode active material 106, electrolyte 108, anode
active material 110, and/or package 114 over substrate 102 and/or
the graphene monolayer.
[0030] Graphene may also be used in the cathode and/or anode
current collectors of other types of batteries, such as lithium-ion
and/or lithium-polymer batteries. As discussed below, the graphene
may increase the energy densities of the batteries by decreasing
the thicknesses of the cathode and/or anode current collectors.
[0031] FIG. 2 shows a top-down view of a battery cell 200 in
accordance with the disclosed embodiments. Battery cell 200 may
correspond to a lithium-polymer cell that is used to power a
portable electronic device. Battery cell 200 includes a jelly roll
202 containing a number of layers which are wound together,
including a cathode with an active coating, a separator, and an
anode with an active coating. More specifically, jelly roll 202 may
include one strip of cathode material (e.g., aluminum foil coated
with a lithium compound) and one strip of anode material (e.g.,
copper foil coated with carbon) separated by one strip of separator
material (e.g., conducting polymer electrolyte). As discussed below
with respect to FIGS. 3-4, graphene may be used in lieu of the
metals in the cathode and/or anode to increase the energy density
of battery cell 200. The cathode, anode, and separator layers may
then be wound on a mandrel to form a spirally wound structure.
Jelly rolls are well known in the art and will not be described
further.
[0032] During assembly of battery cell 200, jelly roll 202 is
enclosed in a flexible pouch, which is formed by folding a flexible
sheet along a fold line 212. For example, the flexible sheet may be
made of aluminum with a polymer film, such as polypropylene and/or
polyethylene. After the flexible sheet is folded, the flexible
sheet can be sealed, for example by applying heat along a side seal
210 and along a terrace seal 208.
[0033] Jelly roll 202 also includes a set of conductive tabs 206
coupled to the cathode and the anode. Conductive tabs 206 may
extend through seals in the pouch (for example, formed using
sealing tape 204) to provide terminals for battery cell 200.
Conductive tabs 206 may then be used to electrically couple battery
cell 200 with one or more other battery cells to form a battery
pack. For example, the battery pack may be formed by coupling the
battery cells in a series, parallel, or series-and-parallel
configuration.
[0034] FIG. 3 shows a set of layers for a battery cell in
accordance with the disclosed embodiments. The battery cell may
correspond to a lithium-ion and/or lithium-polymer battery cell
that is used to power a portable electronic device such as a mobile
phone, laptop computer, tablet computer, portable media player,
and/or digital camera. The layers may be wound to create a jelly
roll for the battery cell, such as jelly roll 202 of FIG. 2.
Alternatively, the layers may be used to form other types of
battery cell structures, such as bi-cell structures.
[0035] The layers may include a cathode current collector 302, a
cathode active material 304, a separator 306, an anode active
material 308, and an anode current collector 310. As mentioned
above, cathode current collector 302 may be aluminum foil, cathode
active material 304 may be a lithium compound (e.g., lithium cobalt
oxide), anode current collector 310 may be copper foil, anode
active material 308 may be carbon (e.g., graphite), and separator
306 may include polypropylene and/or polyethylene.
[0036] In addition, the energy density of the battery cell may be
influenced by the relative thicknesses of the layers. For example,
the active components of the battery cell may include
100-micron-thick layers of cathode active material 304 and anode
active material 308. On the other hand, the non-active components
may include an aluminum cathode current collector 302 that is 15
microns thick, a polypropylene separator 306 that is 16-20 microns
thick, and a copper anode current collector 310 that is 10 microns
thick. The presence of non-active components in the battery cell
may reduce the energy density of the battery cell, while the
thicknesses of the non-active components may be limited by the
manufacturing processes associated with the non-active
components.
[0037] To increase the energy density of the battery cell, cathode
current collector 302 and/or anode current collector 310 may be
composed of graphene instead of metal foils. More specifically, the
high current-carrying capacity and tensile strength of graphene may
provide the charge-collecting functionality of cathode current
collector 302 and/or anode current collector 310 at a thickness of
one angstrom to a few microns instead of 10-15 microns.
[0038] For example, a graphene monolayer may be deposited directly
on cathode active material 304 and/or anode active material 308 to
form cathode current collector 302 and/or anode current collector
310. Alternatively, cathode current collector 302 and/or anode
current collector 310 may be formed by depositing graphene onto one
side of a two-micron-thick layer of polyamide. The polyamide layer
may then be disposed above cathode active material 304 (e.g., with
the graphene facing down) such that the deposited graphene contacts
cathode active material 304. Similarly, the polyamide layer may be
disposed below anode active material 308 (e.g., with the graphene
facing up) in a way that allows the deposited graphene to contact
anode active material 308. As discussed in further detail below
with respect to FIG. 4, the graphene may also be deposited on both
sides of the polyamide layer to form a two-sided current collector
for the battery cell.
[0039] FIG. 4 shows a set of layers for a battery cell in
accordance with the disclosed embodiments. As with the battery cell
of FIG. 3, the layers may be used in a lithium-ion and/or
lithium-polymer battery cell. In addition, the layers may be
stacked and/or wound to create a jelly roll, bi-cell, and/or other
battery cell structure.
[0040] In particular, the battery cell of FIG. 4 includes two
layers of cathode active material 402-404, two layers of separator
406-408, and two layers of anode active material 410-412. Cathode
active material 402-404 may contain a lithium compound, separator
406-408 may contain polypropylene and/or polyethylene, and anode
active material 410-412 may contain carbon. The layers of separator
406-408 may be formed from a single sheet of separator material by
placing the sheet underneath both layers of anode active material
410-412, folding the sheet over the top of anode active material
410, and placing both layers of cathode active material 402-404
over the folded portion.
[0041] In addition, two current collectors are sandwiched between
the layers of cathode active material 402-404 and anode active
material 410-412, respectively. As shown in FIG. 4, each current
collector includes a layer of polyamide 414-416 that is covered on
both sides by graphene 418-424. The layers of graphene 418-424 may
additionally be connected at the ends of the polyamide 414-416
layers to form a continuous current collector instead of two
disparate current collectors. For example, the cathode current
collector may include polyamide 414 and graphene 418-420 layers,
while the anode current collector may include polyamide 416 and
graphene 422-424 layers. Graphene 418-420 layers may be connected
to the right of polyamide 416, allowing the cathode current
collector to conduct current to and from both layers of cathode
active material 402-404. Graphene 422-424 layers may similarly be
connected to the right of polyamide 416, allowing the anode current
collector to conduct current to and from both layers of anode
active material 410-412.
[0042] The composition of the cathode and anode current collectors
may allow the current collectors to occupy a fraction of the
thickness of comparable metal current collectors within the battery
cell. In turn, the reduced thickness of the current collectors may
increase the energy density of the battery cell and facilitate the
use of a portable electronic device with the battery cell. For
example, a total of one micron of graphene 418-424 may be deposited
onto a two-micron thick layer of polyamide 414-416 to form a
three-micron-thick cathode and/or anode current collector for the
battery cell. In contrast, an aluminum cathode current collector
may be manufactured with a minimum thickness of 15 microns, and a
copper anode current collector may be manufactured with a minimum
thickness of 10 microns.
[0043] The above-described rechargeable battery cell can generally
be used in any type of electronic device. For example, FIG. 5
illustrates a portable electronic device 500 which includes a
processor 502, a memory 504 and a display 508, which are all
powered by a battery 506. Portable electronic device 500 may
correspond to a laptop computer, mobile phone, PDA, tablet
computer, portable media player, digital camera, and/or other type
of battery-powered electronic device. Battery 506 may correspond to
a battery pack that includes one or more battery cells. Each
battery cell may include a cathode current collector, a cathode
active material, an electrolyte, an anode active material, and an
anode current collector. The cathode and/or anode current
collectors may include graphene. In addition, the graphene may be
disposed on a non-conducting substrate and/or on one or both sides
of a polyamide layer.
[0044] The foregoing descriptions of various embodiments have been
presented only for purposes of illustration and description. They
are not intended to be exhaustive or to limit the present invention
to the forms disclosed. Accordingly, many modifications and
variations will be apparent to practitioners skilled in the art.
Additionally, the above disclosure is not intended to limit the
present invention.
* * * * *