A battery comprising bipolar battery cells having edge insulation devices supported by a support frame

Abstract

A battery includes a stacked arrangement of electrochemical cells. Each electrochemical cell is free of a cell housing and includes a bipolar plate having a substrate, a first active material layer formed on a first surface of the substrate, and a second active material layer formed on a second surface of the substrate. Each cell includes a solid electrolyte layer encapsulating at least one of the active material layers, and an edge insulation device disposed between the perimeter edges of the substrates of each pair of adjacent cells. A support frame encloses the cell stack and is configured to receive and support the outer perimeter edges of the edge insulation devices of each cell.

Description

BACKGROUND

[0001] Batteries provide power for a wide range of technologies, from portable electronic devices to renewable energy systems and environmentally friendly vehicles. For example, hybrid electric vehicles (HEVs) use batteries and electric motors in combination with combustion engines to improve fuel efficiency. Electric vehicles (EVs) are powered entirely by electric motors, which in turn are powered by one or more batteries. Batteries can include a number of electrochemical cells arranged in two- or three-dimensional arrays and electrically connected in series or in parallel. In a series connection, the positive and negative terminals of each of the two or more cells are electrically connected to one another, and the voltages of the cells are added to give the battery with the cells a greater voltage. For example, if n cells are electrically connected in series, the battery voltage is the voltage of a single cell multiplied by n, where n is a positive integer.

[0002] Typically, each cell is generally enclosed in a gas-impermeable housing. Often, the housing can be electrically connected to one pole of the cell. In applications where the cells are electrically connected to one another in series (e.g., by providing a connection between the positive terminal of one cell and the negative terminal of an adjacent cell), the cell voltages are added, and the housings must be insulated from one another to prevent a short circuit. Thus, within the battery, the space for housing the cell housings and corresponding insulation structures, as well as the materials used by the cell housings and corresponding insulation structures, reduce battery efficiency and increase manufacturing complexity and cost. SUMMARY

[0003] In some aspects, a battery includes a stacked arrangement of electrochemical cells, where each cell is centered on a stacking axis aligned with a stacking direction of the cells. Further, the battery includes a support frame that encloses the stacked arrangement of cells. Each cell includes a bipolar plate, a solid electrolyte layer, and an edge insulation device. The bipolar plate includes a substrate, a first active material layer disposed on a first surface of the substrate, and a second active material layer disposed on a second surface of the substrate. The second surface is opposite the first surface. The first active material layer has a first active material layer perimeter edge that is spaced apart from a substrate perimeter edge and disposed closer to a center of the substrate than the substrate perimeter edge. The second active material layer is of a different material than the material of the first active material layer. The second active material layer has a second active material layer perimeter edge that is spaced apart from the substrate perimeter edge. The solid electrolyte layer is disposed on the second surface so as to encapsulate the second active material layer including the second active material layer perimeter edge. The edge insulation device includes a sheet of electrically insulating material. The edge insulation device includes an outer perimeter edge and an inner perimeter edge. The edge insulation device is disposed between the perimeter edges of the substrates of a pair of adjacent cells such that the outer perimeter edge is disposed further from the center of the substrate than the substrate perimeter edge. Additionally, the edge insulation device physically contacts and is directly secured to the first surface of one of the pair of adjacent cells and is movable relative to the other of the pair of adjacent cells, or the edge insulation device physically contacts and is directly secured to the solid electrolyte layer of the other of the pair of adjacent cells and is movable relative to the one of the pair of adjacent cells. The support frame encloses the stacked arrangement of cells such that a gap exists between the support frame and the substrate perimeter edge. The support frame is configured to receive and support the outer perimeter edge of the edge insulation device of each cell and maintain a spaced apart relationship between the outer perimeter edge of the edge insulation device of one cell and the outer perimeter edge of the edge insulation device of an adjacent cell.

[0004] In some embodiments, the support frame is configured to maintain a spaced apart relationship between the outer perimeter edges of the edge insulation devices of adjacent cells while leaving unconstrained a portion of each edge insulation device residing between the outer perimeter edge and the inner perimeter edge.

[0005] In some embodiments, the unconstrained portion is curved when the battery is viewed in a cross-section parallel to the stacking axis.

[0006] In some embodiments, a length of the unconstrained portion of one cell of the battery is different than a length of the unconstrained portion of another cell of the battery, where the length of the unconstrained portion of a given cell is a distance between the perimeter edge of the substrate of the given cell and an inner surface of the support frame.

[0007] In some embodiments, the support frame is air and moisture impermeable, and encloses all sides of the stack of battery cells such that the battery cells are sealed from the environment of the battery.

[0008] In some embodiments, the outer perimeter edge of the edge insulation device of each battery cell is secured to the support frame, and the length of the edge insulation device is set such that the support frame and the edge insulation device cooperate to maintain a desired spacing between the inner perimeter edge of the edge insulation device and the first active material layer perimeter edge, wherein the length of the edge insulation device corresponds to the distance between the inner perimeter edge and the outer perimeter edge.

[0009] In some embodiments, the support frame includes a foam member that receives and supports the outer perimeter edge of the edge insulation device of each battery cell, is inelastic, and is disposed in a rigid outer frame member.

[0010] In some embodiments, the support frame includes a foam member that receives and supports the outer perimeter edge of the edge insulation device of each battery cell, is inelastic, and is disposed in a rigid outer frame member.

[0011] In some embodiments, the outer frame member includes an assembly of two rigid, overlapping outer frame halves.

[0012] In some aspects, the arrangement in which each battery cell is enclosed in a gas- impermeable housing is replaced by a number of individual electrochemical battery cells without housings that are stacked such that each battery cell forms a direct series connection with an adjacent battery cell of the stack of battery cells. Each battery cell has a planar shape and includes a planar anode and a planar cathode of nearly equal size separated by a separator (e.g., the anode and cathode are not wound into a jellyroll or folded into a z-fold configuration). In addition, each battery cell has a bipolar plate between the cathode of one battery cell and the connected anode of an adjacent battery cell. In the stack of battery cells, each cathode in the series arrangement is directly electrically connected to the next anode without an intervening housing. The bipolar plate replaces the cathode and anode current collectors and also prevents chemical reactions between the cathode active material and the anode active material. In the case of a lithium-ion battery cell, the bipolar plate may, for example, include a copper foil providing an anode on one side thereof, and an aluminum foil providing a cathode on its opposite side. The foils can be contiguous, or can provide outermost layers of an intervening electrically conductive substrate.

[0013] In some embodiments, each electrochemical battery cell can have approximately 3 mAh / cm 2The lithium metal anode expands in a direction perpendicular to the layer by, for example, about 13-15 micrometers (pm) by generating a deposited lithium metal layer on the anode as the battery cell is charged. Thus, the battery cell "breathes" (e.g., expands and contracts) about 13-15 pm between charging and discharging.

[0014] When connected in series, the battery cells are arranged such that their electrode layers are in close proximity with the bipolar plates. For example, the spacing of the layers can correspond to only the dimension of the battery cell thickness, which can be only between 40 pm to 120 pm. The bipolar plates of one battery cell and an adjacent battery cell in the battery cell stack are also similarly spaced. To avoid a short circuit occurring between adjacent battery cells of the battery cell stack, the bipolar plate of one battery cell is prevented from connecting with the bipolar plate of an adjacent battery cell by including an edge insulating device between the adjacent battery cells. More specifically, the edge insulating device is disposed between the peripheral edges of the bipolar plates of the adjacent battery cells. The edge insulating device is formed of an electrically insulating material and functions to electrically insulate each battery cell from the adjacent battery cell while still allowing the battery cells to expand or contract when cycled without the edge insulating device or the battery cells themselves being damaged.

[0015] In some aspects, the edge region of the edge insulating device can be secured to one of the anode side and the cathode side of the bipolar plate. The insulating function of the edge insulating device is imparted directly by mechanically interposing the device between the elements to be isolated. The edge insulating device prevents any external parts from making mechanical and electrical contact with the bipolar plate, the electrodes, and the electrolyte. The edge insulating device is secured to only one of the anode side and the cathode side of the bipolar plate and is free from the other of the anode side and the cathode side of the bipolar plate. For example, in some embodiments, the edge insulating device is secured to the cathode side (e.g., the same side of the bipolar plate as the cathode active material layer) and is not secured to any component of the adjacent battery cell. In other embodiments, the edge insulating device is secured to a peripheral portion of the solid electrolyte overlying the anode active material layer and thus is not directly secured to the bipolar plate between which it resides.

[0016] In some aspects, a support frame surrounds the battery cell stack such that there is a gap between the support frame and the base peripheral edge. The support frame is configured to receive and support the outer peripheral edge of the edge insulating device of each battery cell and maintain a spaced apart relationship between the outer peripheral edge of the edge insulating device of one battery cell and the outer peripheral edge of the edge insulating device of an adjacent battery cell.

[0017] The details of one or more features, aspects, implementations, and advantages of the disclosure are set forth in the detailed description, the drawings, and the claims that follow. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1is a schematic cross-sectional view of a battery including a battery housing and a battery cell stack disposed in the battery housing.

[0019] Figure 2 is Figure 1 a cross-sectional view of a peripheral portion of the battery cell stack of

[0020] Figure 2A is an enlarged view of a portion of the battery cell that is marked by the dashed line in Figure 2

[0021] Figure 3 is a cross-sectional view of the battery cell stack of Figure 2 as seen along line 3-3 of Figure 1

[0022] Figure 4 is an enlarged view of a portion of the battery cell stack that is marked by the dashed line in Figure 3

[0023] Figure 5 is a cross-sectional view of a peripheral portion of an alternative embodiment battery cell stack.

[0024] Figure 6 is a cross-sectional view of a peripheral portion of another alternative embodiment battery cell stack.

[0025] Figure 7 is a cross-sectional view of a peripheral portion of another alternative embodiment battery cell stack.

[0026] Figure 8 is a cross-sectional view of a peripheral portion of another alternative embodiment battery cell stack.

[0027] Figure 9 is a cross-sectional view of a peripheral portion of another alternative embodiment battery cell stack.

[0028] Figure 10 is a cross-sectional view of an enlarged portion of the battery cell stack of Figure 9 illustrating an embodiment of a base surface feature.

[0029] Figure 11 is a cross-sectional view of an enlarged portion of the battery cell stack of Figure 9 illustrating another embodiment of a base surface feature.

[0030] Figure 12 is a cross-sectional view of an enlarged portion of the battery cell stack of Figure 9 illustrating another embodiment of a base surface feature.

[0031] Figure 13 is a cross-sectional view of an enlarged portion of the battery cell stack of Figure 9 ​​​is a cross-sectional view of a magnified portion of the battery cell stack of

[0032] Figure 14 is another embodiment of a portion of the battery cell stack of Figure 9 Figure 9 is a cross-sectional view of a portion of the battery cell stack of

[0033] Figure 15 is a cross-sectional view of a portion of the battery cell stack of

[0034] Figure 16 is another embodiment of a portion of the battery cell stack of Figure 15 Figure 15 is a cross-sectional view of a portion of the battery cell stack of

[0035] Figure 17 is a cross-sectional view of an alternative embodiment of a portion of the battery cell stack of Figure 15

[0036] is a cross-sectional view of another alternative embodiment of a portion of the battery cell stack of Figure 18 Figure 15 is a cross-sectional view of another alternative embodiment of a portion of the battery cell stack of

[0037] Figure 19 Figure 15 is a cross-sectional view of another alternative embodiment of a portion of the battery cell stack of

[0038] Figure 20 is a cross-sectional view of a portion of the battery cell stack of Figure 1

[0039] is a cross-sectional view of a portion of the battery cell stack of Figure 21 Figure 20 is a cross-sectional view of a portion of the battery cell stack of

[0040] Figure 22 Figure 20 is a cross-sectional view of the support frame of

[0041] Figure 23 is a cross-sectional view of the support frame of Figure 20

[0042] Figure 24 is a schematic cross-sectional view of an alternative embodiment battery including a battery housing and a battery cell stack disposed in the battery housing. DETAILED DESCRIPTION

[0043] Referring to​​​​​​​Figure 1 The battery 1 is a power generation and storage device that includes a battery housing 2 that encloses a stacked arrangement of electrochemical battery cells 3. The battery housing 2 is configured so that air, moisture, and / or other contaminants are prevented from entering an interior space containing the battery cells 3. For example, in some embodiments, the battery housing 2 is formed from a flexible laminate material that includes a metal foil sandwiched between polymer layers and is provided in the form of a sealed pouch.

[0044] The battery cells 3 can be lithium-ion secondary battery cells, but are not limited to lithium-ion battery cell chemistry. The battery cells 3 have no cell housing, have a generally planar, low profile shape, and are stacked along a stacking axis 5 so that each battery cell 3a forms a direct series connection with an adjacent battery cell 3b of the battery cell stack 4. Each battery cell 3 includes a bipolar plate 12 having active material layers 30, 40 disposed on opposite surfaces thereof, a solid electrolyte layer 50 that permits ion exchange between adjacent battery cells 3a, 3b while preventing electrical contact between the active material layers 30, 40 of adjacent battery cells 3a, 3b, and an edge insulation device 60. In Figure 1 In the drawings and other figures, the components of the battery cells 3 are shown schematically due to the thinness of the material layers that make up the battery cells 3, and are not drawn to scale.

[0045] The edge insulation device 60 is disposed between the peripheral edges 15 of the bipolar plates 12 of adjacent battery cells 3a, 3b and functions to electrically insulate the bipolar plate 15a of one battery cell 3a from the bipolar plate 15b of an adjacent battery cell 3b, while still allowing the battery cells 3 to expand or contract upon cycling without the edge insulation device 60 or the battery cells 3 themselves being damaged. The edge insulation device 60 can be held in a desired position relative to the bipolar plate peripheral edges 15 by cooperation between surface features disposed on the bipolar plates and the edge insulation device, as discussed in further detail below. Each battery cell can further include a resilient sealing device 80 that is configured to seal a gap gl between the edge insulation device 60 and an adjacent battery cell 3b, thereby further preventing air and moisture from entering the battery cells 3, as discussed further below. Additionally, in some embodiments, the battery 1 can include an edge support frame 90 that receives and supports the outer peripheral edge 63 of each edge insulation device, as discussed further below.

[0046] Referring to Figure 2 A portion of the periphery of the battery cell stack 4 is shown. In this figure and other figures, only four complete battery cells 3 of the battery cell stack 4 are shown, and the ellipses above and / or below the illustrated battery cells 3 are used to indicate that additional battery cells reside on one or both sides of the illustrated battery cells. As discussed in further detail below, the battery cells 3 are stacked in a series configuration, with the positive and negative terminals of each battery cell 3 being connected to the positive and negative terminals of an adjacent battery cell 3.Figure 2 As seen in FIG. 1, bipolar plate 12 includes a plate-like substrate 20, a first active material layer 30 formed on a first surface 21 of substrate 20 and providing a cathode, and a second active material layer 40 formed on a second, opposite surface 22 of substrate 20 and providing an anode.

[0047] Substrate 20 is an electrical conductor and an ionic insulator, and can be a clad plate having a first metal foil providing first surface 21 on one side thereof and a second metal foil providing second surface 22 on an opposite side thereof. When battery cell 3 employs a lithium-ion battery cell chemistry, substrate 20 may, for example, include an aluminum foil providing a cathode substrate on one side and a copper foil providing an anode substrate on an opposite side. In some embodiments, these foils can be contiguous. Substrate 20 can be achieved, for example, by providing a copper foil on one side and evaporating or plating aluminum, or alternatively by providing an aluminum foil on one side and evaporating or plating copper. In other embodiments, substrate 20 can be a clad plate formed of other pairs of electrically conductive materials and / or via other suitable techniques.

[0048] In still other embodiments, substrate 20 can include metal foils forming opposite outermost layers of an intervening electrically conductive substrate.

[0049] In still other embodiments, substrate 20 can be a solid (e.g., unclad and formed of a single material) plate formed of an electrically conductive material. For example, in some embodiments, substrate 20 can be a solid nickel foil or a solid stainless steel foil.

[0050] First active material layer 30 is formed on substrate first surface 21. First active material layer 30 is formed of an active material. As used herein, the term "active material" refers to an electrochemically active material that participates in an electrochemical reaction within a battery cell that charges or discharges. First active material layer 30 has a first active material layer perimeter edge 31 that is spaced apart from and disposed closer to a center 24 of substrate 20 than a perimeter edge 23 of substrate 20. In embodiments in which first surface 21 is formed of aluminum, first active material layer 30 can be formed of, for example, lithiated metal oxide, where the metal portion of the lithiated metal oxide can be cobalt, manganese, nickel, or a composite of the three.

[0051] A second active material layer 40 is formed on the second surface 22 of the substrate. The second active material layer 40 is formed of a different active material than that used to form the first active material layer 30. The second active material layer 40 has a second active material layer perimeter edge 41 that is spaced apart from the substrate perimeter edge 23. In particular, the second active material layer perimeter edge 41 is not aligned with the first active material layer perimeter edge 31 along an axis parallel to the stacking axis 5 in order to avoid edge effects and current concentration at the edges of the anode. To this end, the second active material layer perimeter edge 41 is disposed closer to the center 24 of the substrate 20 than the substrate perimeter edge 23, and is disposed between the substrate perimeter edge 23 and the first active material layer perimeter edge 31. In embodiments in which the second surface 22 is formed of copper, the second active material layer 40 can be formed of, for example, lithium metal.

[0052] The solid electrolyte layer 50 is formed of a solid electrolyte (e.g., an ionically conductive and electrically insulating solid material), and can be provided as a film. The solid electrolyte layer 50 is disposed on the second surface 22 so as to encapsulate the second active material layer 40, including the second active material layer perimeter edge 41. As a result, the solid electrolyte layer 50 is configured to prevent the second active material layer 40 from contact with air and moisture, and from contact with cathode materials. In addition, the solid electrolyte layer 50 acts as an ion conductor between the first active material layer 30 of one cell 3a and the second active material layer 40 of an adjacent cell 3b. In some embodiments, the solid electrolyte layer 50 can be formed of, for example, a solid polymer electrolyte including a polymer similar to that used to form the active material layers 30, 40, a salt identical to that used to form the active material layers 30, 40, and an additive such as the additive sold under the name DryLyte® by Seeo Corporation of Hayward, California. In other embodiments, the solid polymer electrolyte layer 50 can be formed of other materials, including ceramics or a mixture of ceramic and polymer materials. TM

[0053] Referring again to Figure 1 , the battery 1 includes a negative end terminal 100 disposed at one end (e.g., the first end 6) of the cell stack 4 that is electrically connected to the outermost cell 3 at the first end 6 of the cell stack 4. In addition, the battery 1 includes a positive end terminal 110 disposed at the opposite end (e.g., the second end 8) of the cell stack 4. The positive end terminal 110 is electrically connected to the outermost cell 3 at the second end 8 of the cell stack 4.

[0054] ​The negative end terminal 100 includes a conductive sheet material (e.g., a copper sheet) that serves as a negative current collector 102, and a negative current collector active material layer 104 that is formed on a surface of the negative current collector 102 that faces the cell stack. The negative current collector active material layer 104 employs the same active material layer that is used to form the anode of the battery cell 3. In the illustrated embodiment, which involves lithium-ion battery cell chemistry, the negative current collector active material layer 104 can be, for example, lithium metal that is encapsulated in a solid electrolyte material. In use, the negative end terminal 100 is stacked onto the first end 6 of the cell stack 4 so that the negative current collector active material layer 104 is in direct contact with and forms an electrical connection with the first active material layer 30 of the outermost battery cell of the first end 6 of the cell stack 4.

[0055] The positive end terminal 110 includes a conductive sheet material (e.g., an aluminum sheet) that serves as a positive current collector 112, and a positive current collector active material layer 114 that is formed on a surface of the positive current collector 112 that faces the cell stack. The positive current collector active material layer 114 employs the same active material layer that is used to form the cathode of the battery cell 3. In the illustrated embodiment, which involves lithium-ion battery cell chemistry, the positive current collector active material layer 114 can be, for example, lithiated metal oxide. In use, the positive end terminal 110 is stacked onto the second end 8 of the cell stack 4 so that the positive current collector active material layer 114 is in direct contact with the solid electrolyte layer 50 of the outermost battery cell 3 of the second end of the cell stack 4. The positive current collector active material layer 114 forms an electrical connection with the second active material layer 40 (e.g., lithium metal anode) of the outermost battery cell 3 of the second end of the cell stack 4 via the solid electrolyte layer 50.

[0056] With reference to Figures 2-5 The edge insulation device 60 is formed from a sheet of electrically insulating material, and includes an outer peripheral edge 63 and an inner peripheral edge 64 that is surrounded by and spaced apart from the outer peripheral edge 63. As a result, the edge insulation device 60 has the shape of a frame when viewed in a direction that is parallel to the stacking direction of the battery cells 3.

[0057] An edge insulation device 60 is provided for each cell 3 and is disposed between the perimeter edges 23a, 23b of the bipolar plate base 20 of adjacent cells 3a, 3b. Within each cell 3, an outer perimeter edge 63 is spaced apart from the base perimeter edge 23 and is disposed further from the center 24 of the base 20 than the base perimeter edge 23. An inner perimeter edge 64 is spaced apart from the base perimeter edge 23 and the second active material layer perimeter edge 41 and is disposed closer to the center 24 of the base 20 than the base perimeter edge 23 and the second active material layer perimeter edge 41. Additionally, the inner perimeter edge 64 is disposed further from the center 24 of the base 20 than the first active material layer perimeter edge 31, whereby the inner perimeter edge 64 is spaced apart from the first active material layer perimeter edge 31 and faces the first active material layer perimeter edge 31.

[0058] While disposed between the bases 20a, 20b of each pair of adjacent cells 3a, 3b, the edge insulation device 60 physically contacts and is directly secured to either the first surface 21a of one cell (e.g., cell 3a) or the solid electrolyte layer 50b of the adjacent cell (e.g., cell 3b), while being free to move relative to the other of the first surface 21a of the one cell 3a and the solid electrolyte layer 50b of the adjacent cell 3b.

[0059] For example, in some embodiments, the edge insulation device 60 physically contacts and is directly secured to the first surface 21a of one cell 3a, while being free to move relative to the adjacent cell 3b, and more particularly, free to move relative to the solid electrolyte layer 50b of the adjacent cell 3b. Figure 2 The edge insulation device 60 is secured to the first surface 21a of the cell 3a using any suitable method, such as by providing a layer of adhesive between the elements.

[0060] In other embodiments, the edge insulation device 60 physically contacts and is directly secured to the solid electrolyte layer 50b of the adjacent cell 3b, while being free to move relative to the first surface 21a of the one cell 3a. Figure 5 The edge insulation device 60 can be secured to the solid electrolyte layer 50b of the adjacent cell 3b via the mechanical properties (e.g., adhesion or tackiness) of the outer surface of the solid electrolyte layer 50b, or can be secured to the solid electrolyte layer 50b of the adjacent cell 3b via other methods, such as by providing a layer of adhesive between the elements.

[0061] Since the edge insulation device 60 (in this case 60a) is fixed to one cell and is movable relative to the other cell, the cells 3a, 3b are allowed to freely expand and contract in a direction parallel to the stacking axis 5 (e.g., due to charge cycling), and the edge insulation device 60 and the cells 3a, 3b remain undamaged despite the relative motion of one cell relative to the other cell and the relative motion of the edge insulation device relative to the adjacent cells 3a, 3b.

[0062] The edge insulation device 60 overlaps the perimeter edge 23 of the base 20 of the bipolar plate 12, with the outer perimeter edge 63 disposed outside the cell 3. The outer perimeter edge 63 is sufficiently distanced from the base perimeter edge 23 so that the bipolar plates of different cells can never touch each other and form a short circuit, even under some deformation forces, thus avoiding the large current and heat generation associated with a short circuit. In some embodiments, the outer perimeter edge 63 can be 3 to 20 times or more the thickness of the cell distanced from the base perimeter edge 23. As used herein, the term "thickness" corresponds to the dimension in a direction parallel to the stacking direction of the cell.

[0063] The edge insulation device 60 overlaps the perimeter edge 23 of the base 20 of the bipolar plate 12, with the inner perimeter edge 66 disposed inside the cell 3. The inner perimeter edge 66 is sufficiently distanced from the base perimeter edge 23 to place the inner perimeter edge 66 as close as possible to the first active material layer perimeter edge 31 while preventing contact between the edge insulation device 60 and the first active material layer perimeter edge 31. The spacing or gap g2 between the inner perimeter edge 66 of the edge insulation device 60 and the first active material layer perimeter edge 31 depends on the edge tolerance resulting from the method of forming the first active material layer 30 on the base first side 21, which can be, for example, a patch process. In some embodiments, the distance of the inner perimeter edge 66 from the first active material layer perimeter edge 31 (gap g2) is set to be about twice the edge tolerance. For example, if the tolerance of the patch process is about 0.15 mm, the distance of the inner perimeter edge 66 from the first active material layer perimeter edge 31 is set to be about 0.3 mm.

[0064] Generally, the thickness of the edge insulation device 60 is less than the thickness of the battery cell 3, regardless of the state of charge of the battery cell. In some embodiments, the thickness of the edge insulation device 60 is less than the sum of the thicknesses of the first active material layer 30, the solid electrolyte layer 50, and the second active material layer 40, regardless of the state of charge of the battery cell 3. This is the case for embodiments in which the edge insulation device 60 is fixed to the first surface 21 of the bipolar plate 12, as well as for embodiments in which the edge insulation device 60 is fixed to the solid electrolyte layer 50. For example, if a charged battery cell has a thickness of 80 pm without a bipolar plate, and a discharged battery cell has a thickness of 65 pm, the edge insulation device 60 should have a thickness that is 3-10 pm less than the thinnest (here 65 pm) thickness. Thus, in this example, the edge insulation device 60 should have a thickness that is less than 62 pm, in particular less than 55 pm. It is to be understood that the thickness of the edge insulation device includes the adhesive layer or any other fixing components required.

[0065] In some embodiments, the edge insulation device 60 is provided as a tape or strip. The tape can be applied first along two parallel edges of the battery cell and then along the transversely parallel edges. This method of application results in a doubling of the thickness of the tape at each corner of the battery cell. In other embodiments, and when the profile of the battery cell is rectangular, the edge insulation device is merely folded 90° to accommodate the rectangular circumferential edges. This also results in a doubling of the thickness of the edge insulation device at the corners of the battery cell. When determining the thickness requirement of the edge insulation device 60, the thickness dimension at the corners of the battery cell is taken into account, as the doubled thickness portion of the edge insulation device 60 should also be thinner than the battery cell at any state of charge.

[0066] During the manufacturing of the battery cell stack 4, it can be difficult to insert the edge insulation device 60 into the gap between the battery cells 3 if the battery cells are laminated. For this reason, in some embodiments, the edge insulation device 60 is previously glued on the bipolar plate or otherwise assembled with the bipolar plate prior to stacking the battery cells 3.

[0067] The edge insulation device 60 functions to electrically insulate the circumferential edges of the battery cells from each other. To this end, the material used to form the edge insulation device 60 can be an inelastic insulating polymer film. Such a material can include, for example, a polyalkylene film or any other known highly insulating and non-hygroscopic sealing material. Other exemplary materials include a fluoroalkylene type polymer, a polystyrene type polymer, a polyphenylene sulfide, a polyethylene terephthalate, a polyimide, a polyacrylate, a polyetherimide, a polytetrafluoroethylene, a silicone, or a combination thereof.

[0068] Reference Figures 6-8As previously discussed, the edge insulation device 60 physically contacts and is directly secured to either the first surface 21a of one cell (e.g., cell 3a) or the solid electrolyte layer 50b of an adjacent cell (e.g., cell 3b) while being free to move relative to the other of the first surface 21a of cell 3a and the solid electrolyte layer 50b of adjacent cell 3b. In some embodiments, a gap g1 is provided between the edge insulation device 60 and the structure to which it is free to move opposite. For example, when the edge insulation device 60 physically contacts and is directly secured to the first surface 21a of one cell 3a while being free to move relative to the solid electrolyte layer 50b of adjacent cell 3b, a gap g1 can be provided between the edge insulation device 60 and the solid electrolyte layer 50b.

[0069] In some embodiments, in addition to the edge insulation device 60, each cell further includes a resilient sealing device 80. The sealing device 80 provides a moisture-tight seal around the perimeter of the cell 3. In embodiments in which the edge insulation device 60 physically contacts and is directly secured to the first surface 21a of one cell 3a while being free to move relative to the solid electrolyte layer 50b of adjacent cell 3b, the sealing device 80 is disposed in the gap g1 between the edge insulation device 60 and the solid electrolyte layer 50b of adjacent cell 3b. Figure 6 More particularly, the sealing device 80 is disposed between the edge insulation device 60 and the solid electrolyte layer 50b and directly physically contacts the edge insulation device 60 and the solid electrolyte layer 50b. In this configuration, the sealing device 80 can cover a portion of the solid electrolyte layer 50b (e.g., its perimeter edge 51) as well as the edge insulation device 60 and form a seal with each of the solid electrolyte layer 50b and the edge insulation device 60. As a result, the sealing device 80 provides a barrier that prevents moisture and other contaminants from contacting the solid electrolyte layer 50b and the electrochemically active materials. Additionally, due to the resilience of the sealing device 80 and because the sealing device 80 abuts the solid electrolyte layer perimeter edge 51, the sealing device 80 can exert an outward force that compresses the perimeter edge 51 and acts to prevent the electrolyte layer 50b from peeling away from its substrate 20b.

[0070] In embodiments in which the edge insulation device 60 physically contacts and is directly secured to the solid electrolyte layer 50b of adjacent cell 3b while being free to move relative to the first surface 21a of cell 3a, the sealing device 80 is disposed in the gap g1(a) between the edge insulation device 60 and the first surface 21a of cell 3a. Figure 7). More specifically, the sealing device 80 forms a seal with each of the edge insulation device 60 and the first surface 21a of the battery cell 3a. In some embodiments, a second sealing device 82 can be disposed in the gap gl(b) between the edge insulation device 60 and the second surface 22b of the adjacent battery cell 3b Figure 8 ) The second seal 82 directly physically contacts and forms a seal with both the opposite side of the edge insulation device 60 and the second surface 22b of the base 20b of the adjacent battery cell 3b. This configuration can advantageously effectively glue together adjacent battery cells 3a, 3b via the two sealing devices 80, 82.

[0071] The sealing devices 80, 82 provide impermeability by closing the gap gl between the edge insulation device 60 and the bipolar plate 12b of the adjacent battery cell 3b. The sealing device 80 can for example be provided in the form of a strip of elastic material, or in the form of a closed-cell elastic foam or polymer printed or glued on the edge insulation device. The sealing devices 80, 82 can extend around the perimeter of the battery cell 3, whereby the sealing devices 80, 82 can have the shape of a frame when viewed in a direction parallel to the stacking direction of the battery cell 3.

[0072] The sealing devices 80, 82 have elastic properties that allow them to compensate for battery cell dimensional changes in a direction parallel to the stacking axis 5, including swelling and shrinking associated with charge cycling. Since the amount of swelling or shrinking can correspond to up to 10% or more of the battery cell thickness, the sealing devices 80, 82 must have sufficient elasticity in order to maintain the seal regardless of the battery cell dimensional changes.

[0073] In addition to having sufficient elasticity to accommodate battery cell swelling and shrinking due to charge cycling, the material used to form the sealing devices 80, 82 must also be moisture vapor impermeable. In some embodiments, the sealing devices 80, 82 can be a closed-cell elastic foam rubber, where the pore fraction of the closed-cell elastic foam is sufficient to compensate for swelling and shrinking of the battery cell 3 of up to 10% or more of the battery cell thickness. In other embodiments, the sealing devices 80, 82 can be formed of other materials that address the requirements of a particular application, including but not limited to open-cell foam rubber.

[0074] The use of the sealing devices 80, 82 is also advantageous in battery cell stacks with liquid electrolytes or gel-type electrolytes. In some embodiments, it is sufficient to provide the edge insulation device with an additional seal on the top side of the edge insulation device in the form of an elastic or closed-cell elastic foam or rubber-type polymer film.

[0075] Reference is made to Figures 9-13As previously discussed, the inner perimeter edge 64 of the edge insulating device is spaced apart from the first active material layer perimeter edge 31 in a direction transverse to the stacking axis 5 so as to avoid any collision between these components, as such a collision could possibly damage the first active material layer 30. In some embodiments, the base 20 of the bipolar plate 12 can include surface features that engage the edge insulating device 60 so as to position the edge insulating device 60 relative to the base 20, thereby ensuring that a spacing is maintained between the inner perimeter edge 64 of the edge insulating device and the first active material layer perimeter edge 31.

[0076] For example, the first surface 21 of the base 20 can include a protrusion 25 that protrudes outward from the first surface 21 in a direction perpendicular to the first surface 21. Figure 9 ) When viewed in a direction parallel to the stacking axis 5, the protrusion 25 can have a circular or elliptical profile. Additionally, the protrusion 25 can include an end face 26 and a sidewall 27 that extends between the end face 26 and the base first surface 21. The protrusion 25 is positioned along the first surface 21 at a location between the base perimeter edge 23 and the inner perimeter edge 64 of the edge insulating device 60. The edge insulating device 60 can include a corresponding feature, such as a through hole 66 Figure 10 and Figure 11 ) or a recess 68 Figure 12 and Figure 13 ) that is shaped and sized to receive the protrusion 25. The through hole 66 extends between opposing broad surfaces of the edge insulating device 60 and is disposed at a location spaced apart from the outer perimeter edge 63 and the inner perimeter edge 64. When the protrusion 25 and the through hole 66 are engaged, the edge insulating device 60 is positioned and retained relative to the base 20 such that a spacing is maintained between the edge insulating device inner perimeter edge 64 and the first active material layer perimeter edge 31. In the case where the recess 68 is substituted for the through hole 66, it is understood that the recess 68 is similar in form and function to the through hole 66, but extends only partially through the thickness of the edge insulating device 60.

[0077] In some embodiments, the protrusion 25 can be received within the through hole 66 or the recess 68 with a tolerance fit. Alternatively, the protrusion 25 can be received within the through hole 66 or the recess 68 with a press fit. In these embodiments, the protrusion sidewall 27 is linear and perpendicular to the base first surface 21. The edge insulating device through hole 66 or recess 68 includes an inner surface 67 that can be linear and perpendicular to the opposing broad surfaces of the edge insulating device 60 Figure 10 ), or alternatively can include a surface feature 66a Figure 11 ) that engages the protrusion sidewall 27.

[0078] In some embodiments, the shape and / or size of the protrusions 25 and / or the through-holes 66 or recesses 68 are adapted to provide a "snap-in" or "click-in" mechanical connection therebetween. In these embodiments, the protrusion sidewalls 27 can have a non-linear profile, the inner surfaces 67 of the recesses 68 or through-holes 66 can have a non-linear profile complementary to the non-linear profile of the protrusion sidewalls 27, and the protrusions 25 engage with the through-holes 66 via a snap-fit engagement between the protrusion sidewalls 27 and the through-hole inner surfaces 67. In Figure 12 the example illustrated in FIG. 22, the protrusion sidewalls 27 and the recess inner surfaces 67 have complementary shapes and sizes that are each angled relative to the base first surface 21. Additionally, the recess opening is smaller in size than the widest dimension of the protrusions 25, whereby the protrusions 25 are snapped or clicked into engagement with the recess inner surfaces 67. In Figure 13 the example illustrated in FIG. 23, the protrusion sidewalls 27 and the recess inner surfaces 67 have complementary shapes in a manner similar to Figure 12 , but are sized to permit some movement of the protrusions 25 within the cavities 68 while still serving to retain the protrusions 25 within the cavities 68.

[0079] Referring to Figure 14 , the base 20 of each cell 3 can include a number of protrusions 25 spaced apart along lines extending parallel to the base perimeter edge 23 to enclose the perimeter of the base 20.

[0080] Referring to Figure 15 and Figure 16 , in some embodiments, the edge insulator 60 is free of through-holes 66 and / or recesses 68. In these embodiments, the base 20 of the bipolar plate 12 can include surface features (e.g., protrusions 125) that engage the edge insulator inner perimeter edge 64 to position the edge insulator 60 relative to the base 20. Like the previous embodiments, a number of protrusions 125 are arranged spaced apart along lines extending parallel to the base perimeter edge 23 to enclose the perimeter of the base 20. The protrusions 125 are positioned between the edge insulator inner perimeter edge 64 and the first active material layer perimeter edge 31 to prevent contact between the edge insulator 60 and the first active material layer 30, and in particular, to position the edge insulator 60 and maintain the spacing between the edge insulator 60 inner perimeter edge 64 and the first active material layer perimeter edge 31, as discussed above.

[0081] Referring to Figure 17In some embodiments, the inner perimeter edge 64 of the edge insulator device cooperates with alternative embodiment surface features 225 formed on the base first surface 21. For example, the alternative embodiment surface features 225 can be frame-shaped rims that protrude from the base first surface 21 and are positioned to maintain a spacing between the inner perimeter edge 66 of the edge insulator device 60 and the first active material layer perimeter edge 31, as discussed above. The rims 225 can extend continuously (shown) or discontinuously (not shown) along the perimeter of the edge insulator device 60.

[0082] Referring to Figure 18 If desired for a particular application, the base 20 can include both the positioning surface features 25 that engage the corresponding surface features 66 of the edge insulator device 60 and the positioning surface features 125 that engage the inner perimeter edge 64 of the edge insulator device 60.

[0083] Although the positioning surface features 25, 125 have been described herein as being provided on the first surface 21 (i.e., the first surface 21a) of the battery cell 3 (the battery cell 3a) with which the edge insulator device 60 is associated, it should be understood that the positioning surface features 25, 125 can alternatively be formed on the base 20b (i.e., the second surface 22b) of the adjacent battery cell 3b.

[0084] The protrusions 25, 125 can be an integral part of the base surface or can be formed thereon. For example, in some embodiments, the protrusions 25, 125 can be formed on the base surface during a silk screening process.

[0085] Referring to Figure 19 In some embodiments, the positioning features 25, 66 can be combined with a resilient additional pad 86, which can be formed of a closed cell foam rubber or a resilient circumferential strip (not shown). The pad 86 functions to resiliently secure and seal the edge insulator device 60, and thus the edges of the battery cell 3a and / or the base 20b of the adjacent battery cell 3b, in combination.

[0086] Referring to Figure 20 In some embodiments, a support frame 90 is provided that receives and supports the outer perimeter edge 63 of each edge insulator device 60, maintains each outer perimeter edge 63 in a spaced apart relationship relative to the edge insulator outer perimeter edge 63 of the adjacent battery cell along a direction parallel to the stacking axis 5, and provides a seal at the perimeter of the edge insulator device 60. The support frame 90 is disposed inside the battery housing 2 and encloses the battery cell stack 4 such that a gap g3 exists between the support frame 90 and the base perimeter edge 23.

[0087] The support frame 90 can be implemented as an edge seal tape (not shown) or a thick foam member 91 Figure 20). The foam member 91 is air and moisture impervious and extends around the perimeter of the cell stack 4 and can also enclose both ends of the cell stack 4, whereby the cells 3 are sealed from the environment of the battery 1.

[0088] The support frame 90 receives and supports the outer perimeter edges 63 of each edge insulator 60 of the cell stack 4. In some embodiments, the foam member 91 is elastic. In particular, the foam member 91 is sufficiently elastic to compensate for expansion and contraction of the cell stack 4 in a direction parallel to the stack axis 5 (e.g., due to charge cycling). The support frame 90 is configured to maintain a spaced apart relationship between the respective outer perimeter edges 63 of the edge insulators 60 of adjacent cells 3 while leaving the portions 69 of the edge insulators 60 unconstrained. The unconstrained portions 69 of the edge insulators 60 are portions that reside outside of the cells 3, e.g., beyond the perimeter edges 23 of the base 20 and inwardly relative to the support frame 90.

[0089] With reference to Figure 21 In embodiments where the edge insulators 60 extend outwardly beyond the base perimeter edges 23 a distance that is about 100 to 1000 times or more the thickness of the cells, the foam member 91 can be formed of a material that is less or not elastic and can include an insulating material consisting of a rubber, polymer or ceramic polymer hybrid mass. Additionally, the unconstrained portions 69 of the edge insulators 60 can be curved when the battery 1 is viewed in a cross section parallel to the stack axis 5. Thus, the edge insulators 60 can have a folding wave. The excess material used to form the curve or wave is used to compensate for expansion and contraction of the cells 3 relative to the support frame 90 in a direction parallel to the stack axis 5, thus avoiding the generation of tensile forces that would be generated if the foam member 91 were not elastic and preventing movement of the edge insulator outer perimeter edges 63 in a direction parallel to the stack axis 5.

[0090] In other embodiments, the unconstrained portion 69 of the edge insulation device 60 of one battery cell 3 of the battery cell stack 4 may have a different length than the unconstrained portion 69 of the edge insulation device 60 of another battery cell 3 of the battery cell stack 4. As used herein, the length of the unconstrained portion 69 is the distance between the inner surface of the support frame 90 and the peripheral edge 23 of the corresponding substrate 20. For example, the unconstrained portion 69 of the battery cell 3 positioned at the center of the battery cell stack 4 (e.g., midway between the first end 6 and the second end 8 of the battery cell stack) may have a shorter length than the unconstrained portion 69 of the battery cell 3 positioned at either the first end 6 or the second end 8 of the battery cell stack 4. By providing the edge insulation devices 60 with different lengths of unconstrained portions 69, the battery cell stack 4 (which experiences greater displacement at the ends 6, 8 of the battery cell stack 4 than at the center of the battery cell stack 4) can easily accommodate expansion and contraction of the battery cell stack in a direction parallel to the stack axis 5 due to battery cell charge cycling.

[0091] In some embodiments, the outer peripheral edge 63 of the edge insulation device 60 of each battery cell 3 is fixed to the support frame 90. In addition, the length of the edge insulation device 60 (e.g., the distance between the outer peripheral edge 63 and the inner peripheral edge 64) is set so that the support frame 90 and the edge insulation device 60 cooperate to maintain the desired spacing between the edge insulation device inner peripheral edge 64 and the first active material layer peripheral edge 31. Since the edge insulation device 60 is fixed to the support frame 90, the edge insulation device 60 is prevented from colliding with the first active material layer 30. Therefore, it is optional to Figure 9 and Figure 15 The battery 1 is formed using the support frame 90 with the described locating features 25 , 125 .

[0092] refer to Figure 22 and Figure 23 , the support frame 90 may optionally include an outer frame member 92 that is rigid and encloses the foam member 91. The outer frame member 92 serves to prevent the foam member 91 from being compressed by the battery housing 2. In some embodiments, such as those in which the foam member 91 is formed of an elastic material, the outer frame member 92 may have features that allow the outer frame member 92 to expand in a direction parallel to the stacking axis 5. Such features may include providing the outer frame member 92 as an assembly of two rigid, overlapping outer frame halves 93, 94 ( Figure 23 In other embodiments, such as those in which the foam member 91 is formed of an inelastic material, the outer frame member 92 may be a unitary structure that is rigid and cannot expand in a direction parallel to the stacking axis 5 ( Figure 22 ).

[0093] refer to Figure 24 , alternative embodiment battery 200 and above about Figure 1 The battery 1 described is similar, and common reference numerals are used to refer to common elements. Battery 200 encloses a stacked arrangement of electrochemical cells 203. Cell 203 is identical to cell 3 described above, except that cell 203 does not include edge insulation 60. Instead, an insulating tape 260 is applied to the peripheral edge 23 of each substrate 20 and each current collector 102, 112, extending along the entire perimeter of these structures.

[0094] For example, in some embodiments, the tape 260 is a thin and flexible electrical insulator and has an adhesive supplied on one surface of the tape. For example, the tape 260 can be an adhesive-backed polyamide tape such as Kapton. TM Kapton TM is a registered trademark of EI du Pont de Nemours and Company. An adhesive surface is used to secure the tape 260 to the electrical conductor (e.g., substrate 20 and current collectors 102, 112). Although the tape 260 can be applied to only one surface of the electrical conductor, it is more effective when the tape 260 is wrapped around the edge of the electrical conductor so that it covers the periphery of the first surface 21 and the second surface 22 and the cut or edge surface of the electrical conductor, as shown. In addition, although the tape 260 is illustrated as covering only the electrical conductor and not the solid electrolyte layer 50 or the active material layers 30, 40, it is contemplated that the solid electrolyte layer 50 or the active material layers 30, 40 can also be partially covered by the tape 260 if desired.

[0095] Although edge insulation 60 has been described herein as being part of a battery cell having a solid electrolyte 50, edge insulation 60 is not limited to this type of battery cell. For example, edge insulation 60 can be advantageously used in semi-solid battery cells, such as battery cells having a gel electrolyte with higher viscosity and lower flow properties. Edge insulation 60 can also be used in battery cells having a liquid electrolyte, along with an additional liquid-sealing elastic membrane on the top side of the edge seal. Silicone gels and polymers are suitable as elastic liquid electrolyte sealing layers.

[0096] In the embodiments described herein, the solid electrolyte layer 50 is disposed on the second surface 22 so as to encapsulate the second active material layer 40, which is accordingly described as providing the anode of the electrochemical cell 3. However, in other embodiments, the solid electrolyte layer 50 can be configured to encapsulate the first active material layer 30, which provides the cathode of the electrochemical cell 3.

[0097] exist Figure 5 In the embodiment illustrated in FIG, the solid electrolyte 50 overlies the anode active material layer 40, and the edge insulation device 60 is directly fixed to the peripheral portion of the solid electrolyte 50. However, the battery cell 3 is not limited to this configuration. For example, in other embodiments, the solid electrolyte 50 may overlie the cathode active material layer 30, and the edge insulation device 60 may be directly fixed to the peripheral portion of the solid electrolyte 50. In any case, the cathode active material layer 30 does not contact the edge insulation device 60, so as to prevent forces from acting on the active material layer 30 and thus prevent damage (e.g., by causing it to separate from the corresponding substrate).

[0098] The embodiments described above have been shown by way of example, and it should be understood that these embodiments are susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the specific forms disclosed, but to cover all modifications, equivalents, and alternatives that fall within the spirit and scope of the present disclosure.

Claims

1. A battery comprising a stacked arrangement of electrochemical cells, wherein each cell is centered on a stacking axis aligned with a stacking direction of the cells, and each cell comprises A bipolar plate comprising a substrate, a first active material layer disposed on a first surface of the substrate, and a second active material layer disposed on a second surface of the substrate, the second surface being opposite the first surface, the first active material layer having a first active material layer peripheral edge, the first active material layer peripheral edge being spaced apart from a substrate peripheral edge and disposed closer to a center of the substrate than the substrate peripheral edge, the second active material layer being a material different from that of the first active material layer, the second active material layer having a second active material layer peripheral edge, the second active material layer peripheral edge being spaced apart from the substrate peripheral edge, a solid electrolyte layer disposed on the second surface so as to encapsulate the second active material layer including a peripheral edge of the second active material layer, and An edge insulation device comprising a sheet of electrically insulating material, the edge insulation device including an outer peripheral edge and an inner peripheral edge, the edge insulation device being positioned between the peripheral edges of the bases of a pair of adjacent battery cells such that The outer peripheral edge is positioned further away from the center of the base than the base peripheral edge, and The edge insulation device physically contacts and is directly fixed to the first surface of one of the pair of adjacent battery cells and is movable relative to the other of the pair of adjacent battery cells, or the edge insulation device physically contacts and is directly fixed to the solid electrolyte layer of the other of the pair of adjacent battery cells and is movable relative to the one of the pair of adjacent battery cells, the battery including a support frame surrounding the stacked arrangement of battery cells such that a gap exists between the support frame and the base peripheral edge, the support frame being configured to receive and support an outer peripheral edge of an edge insulation device of each battery cell and to maintain a spaced-apart relationship between the outer peripheral edge of the edge insulation device of one battery cell and the outer peripheral edge of the edge insulation device of an adjacent battery cell; in, the support frame being configured to maintain a spaced-apart relationship between outer peripheral edges of edge insulation devices of adjacent battery cells while leaving unconstrained a portion of each edge insulation device residing between the outer peripheral edge and the inner peripheral edge; The length of the unconstrained portion of one cell of the battery is different from the length of the unconstrained portion of another cell of the battery, wherein the length of the unconstrained portion of a given cell is the distance between the peripheral edge of the base of the given cell and the inner surface of the support frame.

2. The battery according to claim 1, wherein When the cell is viewed in cross-section parallel to the stacking axis, the unconstrained portion is curved.

3. The battery according to claim 1, wherein The support frame is impermeable to air and moisture and encloses all sides of the battery cell stack so that the battery cells are sealed from the battery's environment.

4. The battery according to claim 1, wherein An outer peripheral edge of an edge insulation device of each battery cell is fixed to a support frame, and a length of the edge insulation device is set so that the support frame and the edge insulation device cooperate to maintain a desired spacing between an inner peripheral edge of the edge insulation device and a peripheral edge of the first active material layer, wherein the length of the edge insulation device corresponds to the distance between the inner peripheral edge and the outer peripheral edge.

5. The battery according to claim 1, wherein The support frame includes a foam member that receives and supports the outer peripheral edge of the edge insulation of each battery cell, the foam member being inelastic and positioned within a rigid outer frame member.

6. The battery according to claim 1, wherein The support frame includes a foam member that receives and supports the outer peripheral edge of the edge insulation of each battery cell, the foam member being resilient and housed within an expandable outer frame member.

7. The battery according to claim 6, wherein The outer frame member comprises an assembly of two rigid, overlapping outer frame halves.

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