U.S. patent application number 16/196546 was filed with the patent office on 2020-07-23 for battery cell comprising an ultra thin layer of carbon fibers.
The applicant listed for this patent is AIRBUS DEFENCE AND SPACE GMBH AIRBUS OPERATIONS GMBH. Invention is credited to Leif ASP, Peter LINDE, Christian METZNER, Fredrik OHLSSON, Maciej WYSOCKI, Dan ZENKERT.
Application Number | 20200235402 16/196546 |
Document ID | / |
Family ID | 63965464 |
Filed Date | 2020-07-23 |
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United States Patent
Application |
20200235402 |
Kind Code |
A9 |
LINDE; Peter ; et
al. |
July 23, 2020 |
BATTERY CELL COMPRISING AN ULTRA THIN LAYER OF CARBON FIBERS
Abstract
A battery cell includes an anode, a cathode, and a separator
between the anode and the cathode, wherein at least one of the
anode or the cathode includes at least a carbon fiber ply
comprising carbon fibers, the carbon fiber ply having a thickness
of less than 90 micrometers. Also disclosed are a battery and an
aircraft including such battery cell, and a method for
manufacturing such battery cell.
Inventors: |
LINDE; Peter; (Buxtehude,
DE) ; ASP; Leif; (Molndal, SE) ; ZENKERT;
Dan; (Lidingo, SE) ; WYSOCKI; Maciej;
(Molndal, SE) ; OHLSSON; Fredrik; (Ravlanda,
SE) ; METZNER; Christian; (Gmund, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AIRBUS DEFENCE AND SPACE GMBH
AIRBUS OPERATIONS GMBH |
Taufkirchen
Hamburg |
|
DE
DE |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20190181452 A1 |
June 13, 2019 |
|
|
Family ID: |
63965464 |
Appl. No.: |
16/196546 |
Filed: |
November 20, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 4/62520130101; H01M
2220/20 20130101; H01M 4/523 20130101; H01M 4/806 20130101; H01M
2300/0082 20130101; H01M 4/8657 20130101; B64D 41/00 20130101; H01M
4/366 20130101; H01M 4/926 20130101; H01M 2/1613 20130101; H01M
10/0565 20130101; H01M 4/9083 20130101 |
International
Class: |
H01M 4/62 20060101
H01M004/62; H01M 10/0565 20060101 H01M010/0565; H01M 2/16 20060101
H01M002/16; H01M 4/52 20060101 H01M004/52; H01M 4/36 20060101
H01M004/36; B64D 41/00 20060101 B64D041/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 11, 2017 |
DE |
10 2017 129 475.9 |
Claims
1. A battery cell comprising: an anode; a cathode; a separator
between the anode and the cathode; wherein at least one of the
anode or the cathode comprises at least a carbon fiber ply
comprising carbon fibers, the carbon fiber ply having a thickness
of equal to or less than 90 micrometers.
2. The battery cell according to claim 1, wherein the carbon fiber
ply comprises a spread tow tape.
3. The battery cell according to claim 1, wherein at least one of
the anode or the cathode comprises a carbon fiber laminate
comprising a plurality of carbon fiber plies.
4. The battery cell according to claim 3, wherein the carbon fiber
laminate comprises a plurality of carbon fiber plies, each ply
having a thickness of less than or equal to 90 micrometers.
5. The battery cell according to claim 1, wherein the anode and the
cathode each comprise at least a carbon fiber ply having a
thickness of equal to or less than 90 micrometers.
6. The battery cell according to claim 1, wherein the separator
comprises at least a glass fiber ply comprising glass fibers, the
glass fiber ply having a thickness of equal to or less than 100
micrometers.
7. The battery cell according to claim 1, comprising a solid-state
polymer layer forming a first electrolyte between the anode and the
separator, and a solid-state polymer layer forming a second
electrolyte between the cathode and the separator.
8. The battery cell according to claim 1, wherein the cathode
comprises carbon fibers coated with a ferritic oxide.
9. The battery cell according to claim 1, wherein the carbon fibers
have an average diameter of between 1 and 10 micrometers.
10. The battery cell according to claim 1, wherein the carbon fiber
ply has an area weight of equal to or less than 100 grams per
square centimeter (g/cm.sup.2).
11. The battery cell according to claim 1, wherein the carbon fiber
ply comprises a spread tow fabric.
12. A battery comprising at least one battery cell according to
claim 1.
13. An aircraft comprising at least one structural part comprising
at least a battery cell according to claim 1.
14. A method for manufacturing a battery cell comprising: forming
an anode; forming a cathode; obtaining a separator and placing the
separator between the anode and the cathode; spreading a tow
comprising carbon fibers for obtaining a thin carbon fiber ply;
integrating at least part of the thin carbon fiber ply in at least
one of the anode or the cathode for forming the anode or the
cathode.
15. The method according to claim 14, comprising spreading the tow
comprising carbon fibers so as to obtain a thin carbon fiber ply
with a thickness of equal to or less than 90 micrometers.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to German Patent
Application No. 10 2017 129 475.9 filed Dec. 11, 2017, the entire
disclosure of which is incorporated by reference herein.
TECHNICAL FIELD
[0002] The disclosure herein relates to batteries and in particular
to batteries with a high ratio of energy per unit of volume and per
unit of weight. More particularly, it relates to battery cells with
a high ratio of energy per unit of volume and per unit of weight
and to methods of manufacturing such battery cells.
BACKGROUND
[0003] The volume and weight of a battery are an important
limitation of its use in many applications. The current limitations
in the energy density of the batteries induce that the volume and
weight dedicated to batteries in many applications such as mobile
electronic devices or electrical vehicles remains important in
regards to the total volume available for systems. In particular in
vehicles such as aircrafts the volume and the weight available for
the batteries are very small. Lightweight batteries with a high
energy density are essential factors in the design of electrically
powered vehicles, in particular in the aeronautical sector.
Moreover, compact and lightweight batteries mean more space and
weight is available for other functional systems, for payload or
for embarking more batteries.
[0004] Besides, in order to reduce the overall weight of an
electrically powered vehicle, the batteries will have to have more
than one function, and be used as mechanical components of the
vehicle as well. Current batteries, in particular lithium-based
batteries are particularly fragile to deformation and to failure
under mechanical stress.
[0005] Also, the charging rate of batteries is another essential
factor in rendering the use of electrical batteries in the
transportation sector industrially feasible.
[0006] EP0331275 and U.S. Pat. No. 5,747,195 disclose battery
collectors comprising a layer comprising carbon fiber for the
manufacturing of a lightweight solid-state battery.
[0007] However, the compactness of these batteries, as well as
their energy density and in particular their density is not
optimal.
[0008] Moreover such battery cells have limited mechanical
properties, which render them subject to failure, and which in any
case does not allow to use these batteries as structural
elements.
SUMMARY
[0009] The disclosure herein aims to provide a compact and
lightweight battery. The disclosure herein also aims at providing a
battery with a high energy density. The disclosure herein also aims
at providing a battery with an improved charging rate. The
disclosure herein also aims at providing a battery with good
mechanical properties and in particular a battery that can endure
mechanical stress. The disclosure herein aims at providing a safe
battery, in particular a battery that would meet the aeronautics
safety requirements. The disclosure herein furthermore aims at
providing a battery that is easy to manufacture and to
assemble.
[0010] The disclosure herein proposes a battery cell comprising:
[0011] an anode, [0012] a cathode, [0013] a separator between the
anode and the cathode, wherein at least one of the anode or the
cathode comprises at least a carbon fiber ply comprising carbon
fibers, the carbon fiber ply having a thickness of less than 90
micrometers.
[0014] In the whole text, the term `less than` is used to mean
`equal to or less than`.
[0015] In the whole text, the term `electrode` is used as a
standard denomination for anode or cathode, therefore applying to
the anode and/or the cathode.
[0016] In the whole text, the terms `fiber` and `filament` are used
indifferently to designate a single elongated piece of material
which is non-divisible except by breaking the fiber or filament
apart.
[0017] By providing a very thin cathode and/or anode, a battery
cell of the disclosure herein is very compact and light. Therefore
a very compact and light battery may be obtained.
[0018] A battery according to the disclosure herein may be made
particularly thin, such that it may be placed in many different
places of a vehicle.
[0019] Thanks to very thin plies in a battery according to the
disclosure herein, the distance to travel for the electrons between
an anode and an electrode is short and therefore the charging
duration of such battery is beneficially short. Moreover, the power
that such battery may provide may be high, which is particularly
beneficial when used in a vehicle, in particular in an aircraft to
provide high power during take-off for example.
[0020] The use of carbon fiber has the advantage of being
compatible with at least the current most widespread battery type
based on lithium: the lithium-ions batteries. Besides the carbon
fibers are both lightweight and mechanically very resistant to many
forms of mechanical stress. It is therefore beneficial to use
carbon fibers to form an electrode of a battery cell according to
the disclosure herein because such battery cell may therefore
assume other functions than the energy storage function such as for
example a mechanical function.
[0021] Besides the carbon fiber ply is beneficially flexible.
[0022] Indeed such a thin carbon fiber ply may easily be flexed and
therefore it may allow to create batteries of any shape. Therefore
such batteries may be used with a secondary function such as for
example a mechanical function and/or an aerodynamic function.
[0023] A thin battery may be used in different portions of a
vehicle, and in particular of an aircraft, which do not need much
thickness, more particularly if the battery can assume other
functions that energy storage such as for example mechanical load
bearing. For example the body of a terrestrial vehicle or the
fuselage of an aircraft may only need to be of one millimeter in
some areas. In such areas, only batteries having very thin battery
cells may be used. The disclosure herein allows it by making
possible electrodes comprising very thin plies.
[0024] A battery according to the disclosure herein may be used at
least as a portion of a structural part of a vehicle, in particular
of an aircraft.
[0025] In the whole text the term `structural part` is understood
as any part with a mechanical function such as a frame, a skin of a
body or fuselage, an interior fitting, a cabin lining, a floor
panel, etc. The structural part may be subjected to at least some
mechanical loads in at least some mode of functioning of the
aircraft, including aerodynamic loads.
[0026] The thickness the carbon fiber ply may beneficially have a
thickness of less than 50 micrometers, more particularly of less
than 40 micrometers, for example of about or less than 30
micrometers.
[0027] The carbon fiber ply may comprise a spread tow tape.
[0028] Such spread tow tape may have been obtained by spreading a
tow comprising carbon fibers into a thin carbon fiber ply. The
spreading of the tow may be made through many known techniques such
as for example a mechanical compression of the tow over an edge,
vacuum suction, etc.
[0029] The spread tow tape beneficially has a thickness of less
than 90 micrometers. The spread tow tape may beneficially have a
thickness of less than 50 micrometers, more particularly of less
than 40 micrometers, for example of about or less than 30
micrometers.
[0030] The carbon fiber ply may comprise in average less than ten
carbon filaments in its thickness, in particular less than five
carbon filaments, for example about two or three filaments.
[0031] Beneficially the carbon fibers of the carbon fiber ply are
arranged unidirectionally side by side. This allows obtaining a ply
with a very high mechanical resistance to longitudinal strain.
[0032] The fibers of the carbon fiber ply are close to each other
with a low variance of the distances between two neighboring
fibers. Thereby the maximal distance between two consecutive fibers
is low, thus improving the mechanical resistance of a composite
material comprising such fiber ply.
[0033] In a ply obtained by spreading a tow, the distance between
the individual filaments is lower than the distance between two
tows used as such to form a ply. Therefore the mechanical
resistance in a direction orthogonal to the main direction of the
fibers is also higher in a spread tow ply. This may be explained by
the fact that only the resin impregnating the ply between the
fibers provides mechanical strength in the portion between the
filaments (respectively between the tows), and the resin has a
lower mechanical strength than the fibers.
[0034] The spread tow tape may be impregnated with a resin so as to
form a carbon fiber ply. Alternatively or in combination, a
consolidation step may be applied to the spread tow tape in which
the tape is submitted to heat and/or pressure so as to melt or
soften a thermoplastic surrounding the carbon fibers. This allows
the carbon fibers to stick together in the form of a thin tape.
[0035] A spread tow tape has a very low percentage of crimp (or
undulation). Therefore the ratio between the surface of fibers on
each face of the tape and the total length of fibers in the tape is
very high. The surface of the fiber ply is therefore particularly
flat. This allows for better mechanical and electrical contact
between the tape and other elements such as for example another ply
or tape.
[0036] Thus the amount of exposed carbon fibers in each ply of the
battery cell is very high, so that a high percentage of carbon
fibers are active elements of the battery cell and the energy
density of the battery is also very high. The energy density of the
battery cell is thus higher than the energy density of conventional
battery cells. Indeed the spread carbon-fiber tow ply is very flat
on a large surface, such that the contact surface between the
different layers and components of the battery is very high. In
particular the contact surface between the electrolyte and an
electrode comprising a face with such spread tow ply is optimal and
allows an easy transportation of charges between the electrode and
the electrolyte. This moreover allows for an excellent charging
rate of such batteries.
[0037] At least one of the anode or the cathode may comprise a
carbon fiber laminate comprising a plurality of carbon fiber
plies.
[0038] Thereby an electrode according to the disclosure herein has
a sufficient mechanical resistance to be handled and placed in the
battery cell during manufacturing. Besides, such battery cells also
have good mechanical properties, such as high tensile modulus,
compression strength and interlaminar shear strength.
[0039] Such laminate may in particular comprise one or more spread
tow tapes. Thin and flat plies such as spread tow tapes also allows
to obtain a laminate with a very thin inter-plies distance A thin
inter-plies distance also ensures a good electrical transmission
between two successive plies, and a good mechanical resistance.
[0040] The carbon fiber laminate may comprise at least four plies,
more particularly at least eight plies.
[0041] The plies of a laminate according to the disclosure herein
may be attached to each other according to different techniques,
such as for example: stitched together, woven (or interlaced),
glued, heat-pressed, etc.
[0042] The plies of a laminate according to the disclosure herein
may be arranged so as to obtain a laminate with a similar
mechanical resistance in multiple directions. The plies may be
arranged with an axial symmetry around an axis placed in the middle
of the plies stack. The plies may be arranged so as to obtain a
non-crimp fabric by orientating at least two plies with a 45
degrees angle between the longitudinal directions of their
respective fibers. For example a laminate may comprise, from one of
its faces to its opposite face, eight plies arrange as follows: a
first ply may be placed with fibers oriented in a reference
direction of zero degrees, a second ply with fibers oriented in a
direction at 90 degrees, a third ply with fibers oriented at 45
degrees, a fourth ply with fibers oriented at 135 degrees, a fifth
ply with fibers oriented at 45 degrees, a sixth ply with fibers
oriented at 135 degrees, a seventh ply with fibers oriented at 90
degrees, an eighth ply with fibers oriented at zero degrees.
[0043] According to the disclosure herein, it is therefore possible
to obtain a battery cell with a total thickness of less than one
millimeter, although having eight plies in each electrode, a
separator and two electrolyte layers between the separator and the
electrodes. Thereby such battery has a high, isotropic, mechanical
resistance and a very low thickness, allowing to use it in some
portions of a vehicle where only a very thin layer of material is
necessary such as for example the skin of the fuselage of an
aircraft.
[0044] The carbon fiber laminate may comprise a plurality of carbon
fiber plies, each ply having a thickness of less than 90
micrometers.
[0045] The carbon fiber laminate may comprise a plurality of plies
each having a thickness of less than 50 micrometers, more
particularly of less than 40 micrometers, for example of about or
less than 30 micrometers.
[0046] The carbon fiber laminate may comprise alternatively or in
combination: [0047] plies comprising fibers comprising one material
only, [0048] plies comprising fibers from a first material and at
least a second different material, [0049] plies comprising fibers
of a first material and plies comprising fibers of at least a
second different material.
[0050] A battery cell or a battery according to the disclosure
herein may comprise at least one ply comprising carbon fibers,
and/or glass fibers, and/or bore fibers, and/or aramid fibers. Such
ply may for example be used for its electrically insulating
properties. In particular the carbon fiber laminate may comprise at
least one ply comprising carbon fibers, and/or glass fibers, and/or
bore fibers, and/or aramid fibers.
[0051] The anode and the cathode each comprise at least a carbon
fiber ply having a thickness of less than 90 micrometers.
[0052] A battery according to the disclosure herein is particularly
thin and compact when thin plies are used both in the anode and the
cathode.
[0053] The separator may comprise at least a glass fiber ply
comprising glass fibers, the glass fiber ply having a thickness of
less than 100 micrometers.
[0054] A thin separator also allows obtaining a compact and light
battery cell. The separator may have a thickness of less than 50
micrometers, more particularly of less than 40 micrometers, for
example of about or less than 30 micrometers.
[0055] The glass fiber ply may be obtained by spreading a tow
comprising glass fibers into a thin glass fiber ply.
[0056] The contact surface of the separator with the electrolyte is
also improved by the use of a spread tow ply. It permits a fast
transportation of charges at the interfaces between the separator
and the electrolyte layers situated on each side, on opposite faces
of the separator. Moreover, a thin separator also reduces the
duration of transportation of charges from one side of the
separator to the other side of the separator thereby reducing the
battery's charging duration.
[0057] The separator may also comprise a plurality of fiber plies,
in particular a plurality of glass fiber plies. Similar to the
electrode plies, the plies of the separator may be in amount and
arranged so as to obtain a mechanical resistance similar in many
directions.
[0058] The battery cell may comprise a solid-state polymer layer
forming a first electrolyte between the anode and the separator,
and a solid-state polymer layer forming a second electrolyte
between the cathode and the separator.
[0059] The solid-state polymer layers forming electrolyte layers
may be doped with ions so as to facilitate the transport of
charges, for example lithium ions, between an electrode and the
separator.
[0060] The cathode may comprise carbon fibers coated with a
ferritic oxide.
[0061] Thereby a cathode is formed for a lithium ions battery
cell.
[0062] The carbon fibers may have an average diameter of between 1
and 10 micrometers.
[0063] More particularly, the carbon fibers may have an average
diameter between 3 and 8 micrometers, for example between 5 and 7
micrometers.
[0064] This allows for particularly thin and compact batteries.
[0065] The carbon fiber ply may have an area weight of less than
100 grams per square centimeter (g/cm.sup.2).
[0066] A battery cell according to the disclosure herein is
particularly lightweight and thin.
[0067] The carbon fiber ply may have an area weight of less than 50
g/cm.sup.2, in particular less than 30 g/cm.sup.2.
[0068] Also the glass fiber ply of the separator may have an area
weight of less than 100 grams per square centimeter (g/cm.sup.2),
in particular of less than 50 g/cm.sup.2, for example less than 30
g/cm.sup.2.
[0069] The carbon fiber ply may comprise a spread tow fabric.
[0070] The carbon fiber ply may comprise a woven spread tow fabric
in which spread tow tapes are woven with each other.
[0071] The disclosure herein also extends to a battery comprising
at least a battery cell according to the disclosure herein. In
particular the disclosure herein extends to a battery comprising a
plurality of battery cells according to the disclosure herein. The
plurality of battery cells may be electrically connected in series
and/or in parallel.
[0072] The disclosure herein also extends to a vehicle and in
particular to an aircraft comprising at least a battery cell
according to the disclosure herein. The disclosure herein envisions
an aircraft comprising a battery according to the disclosure
herein.
[0073] The disclosure herein also encompasses a vehicle and more
particularly an aircraft comprising at least a battery cell having
a first function of storing energy and at least a second function
such as a mechanical function. In particular the disclosure herein
also extends to an aircraft comprising at least one structural part
comprising at least a battery cell. In particular the aircraft
comprises at least one structural part comprising at least a
battery cell according to the disclosure herein, so that the
battery cell supports mechanical loads in at least some operation
modes of the aircraft. The battery cell or battery according to the
disclosure herein may form, in an aircraft, at least part of at
least one of the following structural elements: a frame--including
a rib, a longeron, etc., a skin of a body or fuselage, an interior
fitting including a dividing wall, a galley, an overhead locker, a
seat, a cabin lining, etc., a floor panel, etc.
[0074] The disclosure herein also extends to a method for the
manufacturing of a battery cell comprising: [0075] forming an
anode, [0076] forming a cathode, [0077] obtaining a separator and
placing the separator between the anode and the cathode,
[0078] wherein it further comprises: [0079] spreading a tow
comprising carbon fibers for obtaining a thin carbon fiber ply,
[0080] integrating at least part of the thin carbon fiber ply in at
least one of the anode or the cathode for forming the anode or the
cathode.
[0081] Spreading a tow of fibers allow creating a particularly thin
layer of fibers, which may also be named a spread tow tape.
Besides, spreading a tow of fibers allow the fibers to have a high
degree of orientation along one predetermined direction. Moreover
spreading a tow of fibers allow the fibers to be close to each
other with a low variance of the distances between two neighboring
fibers; thereby the maximal distance between two consecutive fibers
is low, thus improving the mechanical resistance of a composite
material comprising such fiber ply.
[0082] An electrode of the battery cell is formed with at least one
thin carbon fiber ply. The fibers may be coated by an electrode
coating, such as a ferritic oxide coating for example on the carbon
fibers of the cathode.
[0083] The carbon fiber ply may be impregnated with a polymer. The
impregnating polymer may be any resin, such as a thermoset or
thermoplastic resin. Such resin may be treated with ionic liquid,
such as Li-ionic liquid, before curing in order to ensure a good
transportation of Lithium ions in the electrode.
[0084] The method may comprise a step of stacking a plurality of
thin carbon fiber plies together In particular, the method may
comprise a step of laminating a plurality of thin carbon fiber
plies together, so as to obtain a carbon fiber laminate. Such
carbon fiber laminate may have a high mechanical resistance,
combined to a very small thickness. In particular at least four
carbon fiber plies, or more particularly at least eight carbon
fiber plies, may be laminated together.
[0085] The laminate may thereafter be impregnated by a resin.
Alternatively each ply may be pre-impregnated before the laminating
step.
[0086] An electrode (anode or cathode) may comprise one or more
layers (or plies) of material. Each ply of an electrode may be of
the same or of different materials. In particular, an electrode may
comprise at least a first carbon fiber ply and at least a second
ply comprising a different material such as fibers of a different
material and/or a different matrix material.
[0087] A method according to the disclosure herein may beneficially
comprise spreading the tow comprising carbon fibers so as to obtain
a thin carbon fiber ply with a thickness of less than 90
micrometers.
[0088] The carbon fibers may be selected to have a predetermined
diameter adapted to obtain a carbon fiber ply of less than 90
micrometers. The carbon fiber ply may beneficially have a thickness
of less than 50 micrometers, more particularly of less than 40
micrometers, for example of about or less than 30 micrometers. The
carbon fibers may have an average diameter of between 1 and 10
micrometers.
[0089] The separator may be obtained by a process similar to the
process for the forming of an electrode. For the forming of the
separator, glass fibers instead of carbon fibers may be used.
[0090] The disclosure herein also extends to other possible
combinations of features described in the above description and in
the following description relative to the figures. In particular,
the disclosure herein extends to batteries comprising features
described in relation to the battery cell and/or the method for
manufacturing a battery cell; the disclosure herein extends to a
battery cell comprising features described in relation to the
battery and/or the method for manufacturing a battery cell; and,
the disclosure herein extends to methods for manufacturing a
battery cell comprising features described in relation to the
battery and/or the battery cell.
BRIEF DESCRIPTION OF THE DRAWINGS
[0091] Some specific example embodiments and aspects of the
disclosure herein are described in the following description in
reference to the accompanying figures.
[0092] FIG. 1 is a schematic representation of a cross-section of a
battery cell embodiment according to the disclosure herein.
[0093] FIG. 2 is a schematic representation of a battery comprising
a plurality of battery cells according to the disclosure
herein.
[0094] FIG. 3 is a schematic representation of a laminate of a
battery electrode according to the disclosure herein.
[0095] FIG. 4 is a schematic representation of a step for spreading
a tow of a method according to the disclosure herein.
DETAILED DESCRIPTION
[0096] In FIG. 1 a battery cell 1 is represented which comprises a
cathode 3, an anode 4, and a separator 5. The separator is
separated from the anode and the cathode respectively by two
electrolytes 6.
[0097] The anode 4 and the cathode 3 have each been obtained by the
lamination of eight plies of carbon fiber spread tow tapes,
impregnated with a matrix such as for example a resin of
HexFlow.RTM. RTM6 commercialized by Hexcel.RTM..
[0098] The carbon fiber laminate may be of the type described with
FIG. 3. After impregnation, the laminated may be cured by
application of heat and/or pressure for example.
[0099] Previous to the impregnation of the carbon fiber plies of
the cathode 3, these may be coated with a ferritic oxide, for
example by bathing the carbon fiber plies in a liquid solution
comprising ferritic oxide.
[0100] The total thickness of the anode 4 may be of about 650
micrometers. The total thickness of the battery cell shown on FIG.
1 may be less than 4.0 mm, for example of about 2.0 mm.
[0101] Similarly the separator 5 may have been obtained by the
lamination of eight plies of glass fiber spread tow tapes,
impregnated with a matrix such as for example a resin of
HexFlow.RTM. RTM6 commercialized by Hexcel.RTM..
[0102] Other elements of the battery cell such as charge collectors
and electrical connectors are not represented.
[0103] In FIG. 2 a battery 2 comprising a plurality of anodes 4 and
cathodes 3 is represented. Each pair of cathode and anode is
separated by a separator 5 and two layers of electrolytes 6. The
anodes 4 and cathodes 3 situated between two successive separators
5 are part of two battery cells (one on each of their faces)
simultaneously.
[0104] The total thickness of the battery shown on FIG. 2 may be
less than 10 mm, in particular less than 2 mm, for example of about
0.65 mm. This very low thickness of a battery may allow to ingrate
such battery in many different places of a vehicle, in particular
of an aircraft. Besides such battery has high mechanical
resistance, due to the high mechanical resistance of each of its
layer, and in particular due to the high mechanical resistance of
the carbon fiber laminate integrated in the electrodes 3, 4 of the
battery cells. Such battery may thus for example form a portion of
a wing skin, of a fuselage, of a cabin floor or of a frame of an
aircraft.
[0105] The compactness, alignment and low thickness of fiber plies
also allows a higher energy density. The energy density of the
battery cell is thus higher than the energy density of conventional
battery cells. The energy density of such battery is estimated to
be multiplied by up to 2 compared to batteries using conventional
thick carbon fiber plies.
[0106] In FIG. 3, a laminate 7 for an anode or a cathode of a
battery cell according to the disclosure herein is represented.
[0107] The laminate 7 comprises a plurality of carbon fiber plies
8, 9, 10, 11, 12, 13, 14, 15. Each carbon fiber ply is made of a
plurality of carbon fibers 17, the carbon fibers being for the most
part generally oriented along a predetermined direction in the
ply.
[0108] In the example of FIG. 3 each ply comprises about 2 carbon
fibers in its thickness. Each carbon fiber may have an average
diameter of about 6 micrometer, such that the total thickness of
each carbon fiber ply may be of about 12 micrometer. The total
thickness of the carbon fiber laminate 7 may thus be of less than
100 micrometer, for example of about 96 micrometer.
[0109] Each carbon fiber ply may be pre-impregnated with a
HexFlow.RTM. RTM6 resin commercialized by Hexcel.RTM.. Eight carbon
fiber plies may then be stacked and laminated together.
[0110] A carbon fiber laminate may be obtained for example by a
process in which resin is impregnated into the carbon fiber plies
under pressure. To do so, the preform is enclosed to a vacuum bag
or laid into a closed tool. The textile preform comprising carbon
fiber plies and the resin are preheated to 120.degree. C. A
pressure differential is applied between the resin pod and the
preform (vacuum or pressure) so as to obtain an impregnation of the
fiber plies by the resin. After impregnation, the impregnated
laminate is heated up to 180 degrees Celsius, and cured for 90
minutes. It is afterwards cooled down to less than 70 degrees
Celsius and de-molded.
[0111] The carbon fiber plies may be arranged so as to increase the
mechanical resistance of the laminate. In particular, if a first
carbon fiber ply 15 is disposed with its carbon fiber in a
predetermined direction of reference at zero degrees, a second
carbon fiber ply 14 may be placed on it with fibers oriented at 90
degrees, a third carbon fiber ply 13 may be placed on it with
fibers oriented at 45 degrees, a fourth carbon fiber ply 12 with
fibers oriented at 135 degrees, a fifth carbon fiber ply 11 with
fibers oriented at 45 degrees, a sixth carbon fiber ply 10 with
fibers oriented at 135 degrees, a seventh carbon fiber ply 9 with
fibers oriented at 90 degrees, an eighth carbon fiber ply 8 with
fibers oriented at zero degrees. Thereby the mechanical resistance
of the laminate is increased in multiple directions.
[0112] In FIG. 4 a step of spreading a carbon fiber tow is
represented. In this step a carbon fiber tow 16 is submitted to an
air flow 18 in an orthogonal direction compared to the longitudinal
direction of the carbon fiber tow 16. The suction of the air flow
18 on the sides of the carbon fiber tow 16 leads to the detachment
of some carbon fibers 17 on each side of the carbon fiber tow 16,
towards directions orthogonal to the air flow 18 and orthogonal to
the longitudinal direction of the carbon fiber tow 16. During the
process the carbon fibers 17 of the carbon fiber tow 16 are
separated from each other in a flat configuration leading to the
formation of a spread tow tape of carbon fibers 17. Such spread tow
tape may then be used to form a carbon fiber ply.
[0113] The disclosure herein is not limited to the specific
embodiments herein disclosed as examples. The disclosure herein
also encompasses other embodiments not herein explicitly described,
which may comprise various combinations of the features herein
described.
[0114] While at least one exemplary embodiment of the present
invention(s) is disclosed herein, it should be understood that
modifications, substitutions and alternatives may be apparent to
one of ordinary skill in the art and can be made without departing
from the scope of this disclosure. This disclosure is intended to
cover any adaptations or variations of the exemplary embodiment(s).
In addition, in this disclosure, the terms "comprise" or
"comprising" do not exclude other elements or steps, the terms "a",
"an" or "one" do not exclude a plural number, and the term "or"
means either or both. Furthermore, characteristics or steps which
have been described may also be used in combination with other
characteristics or steps and in any order unless the disclosure or
context suggests otherwise. This disclosure hereby incorporates by
reference the complete disclosure of any patent or application from
which it claims benefit or priority.
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