CYLINDRICAL BATTERY CELL DESIGN WITH HIGH ENERGY DENSITY AND STACKED ELECTRODES

Abstract

A battery cell comprises a casing and an electrode stack arranged within the casing. The battery cell includes an anode with a first conductive tab, a cathode with a second conductive tab, and a separator. The battery cell further comprises two electrical connections, one attached to the first conductive tab and the other to the second conductive tab, and one to a negative and a positive terminal, respectively. The anode, cathode, and separator each share a common perimeter with a first section conforming to the shape of an inner surface of the casing and a second section having a cutout configured to recede from the inner surface. The second section of the anode, cathode, and separator is aligned with each other, forming a region between the stack and the inner surface. The tabs and electrical connections are located within this region.

Description

BACKGROUND

[0001] The disclosure generally relates to a cylindrical, high energy density, stacked electrode battery cell design.

[0002] Lithium-ion batteries and lithium-metal batteries are desirable candidates for powering electronic devices in the consumer, automotive, and aerospace industries due to their relatively high energy density, high power density, lack of memory effect, and long cycle life compared to other rechargeable battery technologies such as lead-acid, nickel-cadmium, and nickel-metal hydride batteries.

[0003] A battery cell contains at least one anode and one cathode pair. A battery cell contains a conventional polymer separator containing a liquid electrolyte between the anode and cathode electrodes. Alternatively, a solid-state battery cell contains a solid electrolyte film as a replacement for the conventional polymer separator. The solid electrolyte may have a first planar primary surface adjacent to and contacting a planar primary surface of an anode electrode. The solid electrolyte may have a second planar major surface adjacent to and contacting a planar major surface of a cathode electrode. DESCRIPTION

[0004] A battery cell is provided. The battery cell includes an outer casing having an inner surface. The battery cell further includes an electrode stack disposed within the outer casing. The electrode stack includes an anode having a first conductive tab, a cathode having a second conductive tab, and a separator. The battery cell further includes a positive terminal and a negative terminal. The battery cell further includes a first electrical connection attached to the first conductive tab and the negative terminal, and a second electrical connection attached to the second conductive tab and the positive terminal.The anode, the cathode, and the separator each have a common component perimeter including a first portion of the common component perimeter configured to conform to a shape of the inner surface and a second portion of the common component perimeter having a cutout configured to recede from the inner surface. The second portion of the anode common component perimeter, the second portion of the cathode common component perimeter, and the second portion of the separator common component perimeter are aligned and form a region between the electrode stack and the inner surface. The first conductive tab, the second conductive tab, the first electrical connection, and the second electrical connection are disposed within the region between the electrode stack and the inner surface.

[0005] In some embodiments, the battery cell further comprises a support plate disposed adjacent one end of the electrode stack. The battery cell further comprises a compression spring configured to exert a compressive force on the support plate and the electrode stack and to translate as the electrode stack expands volumetrically.

[0006] In some embodiments, the battery cell further includes a plurality of compression springs.

[0007] In some embodiments, the electrode stack comprises a first electrode stack, and the support plate is a first support plate. The battery cell further comprises a second electrode stack disposed within the external housing and a second support plate disposed at one end of the second electrode stack. The compression spring is further configured to exert a compressive force on the second support plate and the second electrode stack and to further translate as the second electrode stack expands volumetrically.

[0008] In some embodiments, the outer housing is a cylinder, and the inner surface has a first circular shape. The first portion of the common component perimeter has a second circular shape corresponding to the inner surface.

[0009] In some embodiments, the second part of the common component perimeter comprises a flat side.

[0010] In some embodiments, the battery cell further comprises a separator clip disposed in the region between the electrode stack and the inner surface and configured to separate the first conductive tab and the second conductive tab.

[0011] In some embodiments, the battery cell further includes a vent configured to allow gases to escape from the battery cell.

[0012] In some embodiments, the battery cell further includes a porous insulation slot disposed in the region between the electrode stack and the inner surface and configured to direct gases within the battery cell to the vent.

[0013] In some embodiments, the separator comprises a solid electrolyte separator.

[0014] In some embodiments, the separator comprises a polymerized separator configured to facilitate ion transfer between the anode and the cathode, and the battery cell further comprises a liquid electrolyte.

[0015] In some embodiments, the electrode stack includes a plurality of anodes, each having one of a plurality of first conductive tabs. The electrode stack further includes a plurality of cathodes, each including one of a plurality of second conductive tabs. The plurality of anodes and the plurality of cathodes are arranged in an alternating pattern. The electrode stack further includes a separator disposed between each of the plurality of anodes and each of the plurality of cathodes. Each of the plurality of first conductive tabs is connected to the first electrical connection, and each of the plurality of second conductive tabs is connected to the second electrical connection.

[0016] In some embodiments, the anode contains silicon or lithium metal.

[0017] According to an alternative embodiment, a cylindrical battery cell is provided. The cylindrical battery cell includes a cylindrical outer shell having an inner surface with a first circular shape. The cylindrical battery cell further includes an electrode stack disposed within the outer shell. The electrode stack includes a plurality of anodes, each including one of a plurality of first conductive tabs. The electrode stack further includes a plurality of cathodes, each including one of a plurality of second conductive tabs. The plurality of anodes and the plurality of cathodes are arranged in an alternating pattern. The electrode stack further includes a plurality of separators, one of the plurality of separators being disposed between each of the plurality of anodes and each of the plurality of cathodes. The cylindrical battery cell further includes a positive terminal and a negative terminal.The cylindrical battery cell further includes a first electrical connection attached to each of the plurality of first conductive tabs and to the negative terminal, and a second electrical connection attached to each of the plurality of second conductive tabs and to the positive terminal. The cylindrical battery cell further includes a support plate disposed adjacent one end of the electrode stack and a compression spring. The compression spring is configured to exert a compressive force on the support plate and the electrode stack and to translate as the electrode stack expands volumetrically. The plurality of anodes, the plurality of cathodes, and the plurality of separators each include a common component perimeter.The common component perimeter includes a first portion of the common component perimeter having a second rounded shape to conform to the inner surface and a second portion of the common component perimeter having a flat side configured to step back from the first rounded shape of the inner surface. The second portion of the common component perimeter of each of the plurality of anodes, the second portion of the common component perimeter of each of the plurality of cathodes, and the second portion of the common component perimeter of each of the plurality of separators are aligned and form a region between the electrode stack and the inner surface. The plurality of first conductive tabs, the plurality of second conductive tabs, the first electrical connection, and the second electrical connection are disposed within the region between the electrode stack and the inner surface.

[0018] In some embodiments, the cylindrical battery cell further comprises a separator clip disposed in the region between the electrode stack and the inner surface and configured to separate the plurality of first conductive tabs and the plurality of second conductive tabs.

[0019] In some embodiments, each of the plurality of separators comprises a solid electrolyte separator.

[0020] In some embodiments, each of the plurality of anodes includes silicon or lithium metal.

[0021] According to an alternative embodiment, an electrode stack is provided for use in a cylindrical battery cell. The electrode stack includes a plurality of anodes, each having one of a plurality of first conductive tabs. The electrode stack further includes a plurality of cathodes, each including one of a plurality of second conductive tabs. The plurality of anodes and the plurality of cathodes are arranged in an alternating pattern. The electrode stack further includes a plurality of separators, one of the plurality of separators being disposed between each of the plurality of anodes and each of the plurality of cathodes. The electrode stack further includes a first electrical connection attached to each of the plurality of first conductive tabs and a second electrical connection attached to each of the plurality of second conductive tabs.The plurality of anodes, the plurality of cathodes, and the plurality of separators each comprise a common component perimeter. The common component perimeter includes a first portion of the common component perimeter having a round shape configured to mate with a round inner surface of an outer shell of the cylindrical battery cell. The common component perimeter further includes a second portion of the common component perimeter having a flat side configured to step back from the round inner surface. The second portion of the common component perimeter of each of the plurality of anodes, the second portion of the common component perimeter of each of the plurality of cathodes, and the second portion of the common component perimeter of each of the plurality of separators are aligned and configured to form a region between the electrode stack and the round inner surface.

[0022] In some embodiments, each of the plurality of separators comprises a solid electrolyte separator.

[0023] In some embodiments, each of the plurality of anodes includes silicon or lithium metal.

[0024] The above features and advantages, as well as other features and advantages of the present disclosure, will be apparent from the following detailed description of the best modes for carrying out the disclosure when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 schematically shows in plan view an exemplary cathode having a perimeter including a circular outer perimeter and a flat side, according to the present disclosure; Fig. 2 schematically shows in plan view an exemplary anode having a perimeter including a circular outer perimeter and the flat side, according to the present disclosure; Fig. 3 schematically shows in plan view an exemplary separator having a perimeter including a circular outer perimeter and the flat side, according to the present disclosure; Fig. Figure 4 shows schematically in a side view a monocell with the cathode of Fig. 1 and the anode of Fig. 2, between which the separator of Fig. 3 is arranged, according to the present disclosure; Fig. 5 schematically shows a plurality of monocells arranged in an electrode stack according to the present disclosure; Fig. 6 schematically illustrates an exemplary support plate and a plurality of compression springs according to the present disclosure; Fig. 7 shows a schematic side section of a cylindrical battery cell according to the present disclosure; and Fig. Figure 8 shows schematically the cylindrical battery cell of Fig. 7 in a plan view according to the present disclosure. DETAILED DESCRIPTION

[0025] A battery system may contain one or more solid-state battery cells. A solid-state battery cell may contain an anode electrode, a cathode electrode, and a solid electrolyte.

[0026] A solid-state battery contains a solid electrolyte that enables or facilitates ion transfer between the anode and cathode electrodes. The solid electrolyte also acts as a physical separator between the anode and cathode electrodes, preventing internal short circuits within the battery.

[0027] A jelly-roll electrode comprises a flexible anode, a flexible separator, and a flexible cathode wound around a core, giving the electrode a spiral shape. A cylindrical battery cell with a tabless jelly-roll electrode used in the art may utilize lithium metal and / or high silicon content in the anodes to increase the energy density within the battery cell. Such a configuration can cause an overpressure problem due to the significant expansion of the lithium metal or high silicon content anodes during lithium formation. As the layers of the jelly-roll electrode thicken due to expansion, the electrode may press against a cylindrical outer casing, leading to the overpressure problem.

[0028] A cylindrical battery cell design with high energy density and stacked electrodes with a high coating ratio is provided. The battery cell comprises at least one electrode stack containing a plurality of monocells. A monocell comprises an anode, a cathode, and two separators, with a separator between each anode and each cathode.

[0029] A monocell may have a common component perimeter. In one example, a monocell may include a first portion of the common component perimeter including a circular outer perimeter, configured, for example, to correspond to an inner surface of a cylindrical outer casing of the battery cell. The monocell may include a second portion of the common component perimeter including a flat side of the common component perimeter. The anode, cathode, and separator(s) of the monocell may each have the same common component perimeter, including the first portion having the circular outer perimeter and the second portion having the flat side.When stacked together to form a monocell, the second sections, including the flat sides of the anode, cathode, and separator(s), can be aligned so that the monocell as a whole has the common component perimeter, with the circular outer perimeters aligned and the flat sides aligned. When inserted into the cylindrical outer casing of the battery cell, the circular outer perimeter of the monocell is flush with the inner surface of the outer casing, and the flat side of the monocell forms an open area with the outer casing.A first tab may be attached to the anode along the flat side of the anode, and a second tab may be attached to the cathode along the flat side of the cathode such that electrical connections can be made to the first tab and the second tab within the open area of ​​the outer casing. The electrical connections may include a first electrical connection connecting the first tab attached to the anode to a negative terminal of the battery cell, and a second electrical connection connecting the second tab attached to the cathode to a positive terminal of the battery cell. A plurality of monocells or a repeating pattern of monocells may be stacked within the battery cell to form an electrode stack within the battery cell.

[0030] The electrode design, with the anode containing the first tab along the flat side of the anode, and the cathode containing the second tab along the flat side of the cathode electrode, aligns the tabs and the space required for electrical connections along one side of the electrode stack. This flat side and the tabs allow a majority of the flat, planar surfaces of the anode and cathode to contain electrode coatings with the respective anode and cathode active materials. The resulting electrodes exhibit excellent energy density. Because the flat electrodes are stacked in the battery cell, a support plate can be used in combination with one or more springs to accommodate the volumetric expansion of the anodes in the electrode stack during lithium formation.This ability to accommodate significant volumetric expansion allows the use of lithium metal and / or silicon in relatively high concentrations, which in turn enables excellent energy density. The resulting battery cell configuration exhibits excellent energy density and excellent resistance to volumetric expansion of the anodes.

[0031] The disclosed anodes and cathodes, useful for forming electrode stacks in a cylindrical cell, provide a high active material coating ratio by placing both tabs on the notched flat edge of the round electrodes, which increases the energy density of the cell.

[0032] The conductive tab connection has high space utilization efficiency by folding the electrode tabs in a vertical direction perpendicular to the stacked electrode planes, flattening them, and welding them to an electrical connector.

[0033] The disclosed electrodes can be manufactured using the same electrode coating with some minor modifications. Therefore, they can be manufactured on a large scale and with a relatively rapid process, reducing processing costs and overcoming the difficulties of mass production compared to electrodes requiring more complex shapes.

[0034] A separator clamp or insulating slot can be placed between the conductive cathode tabs and the conductive anode tabs to prevent cell short circuits. The separator clamp can also serve as an alignment aid during battery cell assembly.

[0035] The resulting battery cell design has a relatively short current path and offers excellent low cell resistance.

[0036] The disclosed battery cell design can be applied to cylindrical cells with various chemistries, including conventional liquid electrolyte lithium-ion cells and solid-state batteries with solid electrolyte separators or cells with high-expansion anodes, including relatively high silicon content and / or lithium metal. The cylindrical stacked cell design is particularly useful for solid-state batteries with rigid and brittle solid electrolyte films, as the flat layers of the electrode stack embodiments in the disclosed battery cell configuration are not bent or deformed into a curved shape.

[0037] The disclosed battery cell design allows for the venting of gases through the area where the electrical connectors are routed. In one embodiment, the separator clip or insulation slot may have pores through which gases can pass during venting through the clip or slot.

[0038] The battery cell design can be applied to cylindrical cells with different dimensions and aspect ratios.

[0039] The Fig. 1 to 3 schematically show the components of an electrode stack, each having a common component perimeter 12 such that the flat sides 26, 36, and 46, respectively, are aligned with one another when the cathode 20, the anode 30, and the separator 40 are stacked and aligned. Fig. 1 schematically shows, in plan view, an exemplary cathode 20 having a circumference including a circular outer perimeter 24 and a flat side 26. The cathode 20 includes a flat plate surface 22 that may be covered with a cathode electrode containing an active cathode material, a binder, and a conductive material. The cathode 20 further includes a current collector electrically connected to or integrally formed with the conductive tab 29. The cathode 20 further includes an insulator 28 surrounding the cathode 20 so that the cathode 20 and its active materials do not come into electrically conductive contact with other parts of the battery cell, e.g., the outer casing.

[0040] Fig. Figure 2 schematically shows, in plan view, an exemplary anode 30 having a perimeter including a circular outer perimeter 34 and the flat side 36. The anode 30 includes a flat plate surface 32, which may be covered with an anode electrode comprising an active anode material, a binder, and a conductive material. The anode 30 further includes a current collector electrically connected to or integrally formed with the conductive tab 39.

[0041] Fig. Figure 3 schematically shows in plan view an exemplary separator 40 having a circumference including a circular outer circumference 44 and the flat side 46. The separator 40 includes a flat plate surface 42 configured to be adjacent to the flat plate surface 22 of Fig. 1 or the flat plate surface 32 of Fig. 2. The separator 40 is constructed of a material configured to facilitate ion transfer between the cathode 20 and the anode 30 and to facilitate the electrochemical reaction of the battery cell. In one embodiment, the separator 40 may be made of a polymerized separator material and configured for use with a liquid electrolyte within the battery cell. In another embodiment, the separator 40 may be made of a solid electrolyte separator material.

[0042] Fig. Figure 4 shows schematically in a side view a monocell 10 with the cathode 20 of Fig. 1 and the anode 30 of Fig. 2, between which the separator 40 of Fig. 3. Within a battery cell and in the presence of an electrolyte, the monocell 10 can function as a battery cell, wherein an electrochemical reaction within the monocell 10 generates electrical energy. The cathode 20 shown comprises a current collector 21, which can be made of aluminum. On a first flat plate surface 22 of Fig. 1 on the current collector 21, a first cathode electrode 23 is formed. In a second flat plate surface 22 of Fig. 1, a second cathode electrode 23 is formed on the underside of the current collector 21. The insulator 28 is shown surrounding the cathode electrode 23.

[0043] The illustrated anode 30 comprises a current collector 31, which may be made of copper. On a first flat plate surface 32 of Fig. 2 on the top side of the current collector 31, a first anode electrode 33 is formed. In a second flat plate surface 32 of Fig. 2 A second anode electrode 33 is formed on the underside of the current collector 31. A first separator 40 is arranged between the cathode 20 and the anode 30. A second optional separator 40 is arranged next to and below the anode 30.

[0044] Fig. 5 schematically shows a plurality of monocells 10A, 10B, 10C arranged in an electrode stack 50.

[0045] Fig. 6 schematically shows an exemplary carrier plate 60 and a plurality of compression springs 70. The carrier plate 60 and the compression springs 70 are configured to exert a compressive force on the electrode stack 50 of Fig. 5. The compression springs 70 are configured to allow displacement of the support plate 60 as the electrode stack 50 expands due to lithium formation of the anode(s) 30 of the electrode stack 50. The support plate 60 may encompass the common component perimeter 12 such that a circular outer perimeter 64 and a flat side 66 of the support plate 60 may be aligned with the components of the electrode stack 50. The support plate 60 includes a flat plate surface 62 configured to be attached to the compression springs 70 and / or configured to be disposed adjacent to a flat component of the electrode stack 50.

[0046] Fig. Figure 7 schematically shows a cylindrical battery cell 100 in side section. The cylindrical battery cell 100 comprises a cylindrical outer housing 105, a positive terminal 110, and a negative terminal 120. A first electrode stack 50A and a second electrode stack 50B are arranged within the cylindrical outer housing 105. Support plates 60 are arranged on each side of the electrode stacks 50A, 50B. Compression springs 70 are arranged between the two inner support plates 60, so that when the volume of the electrode stacks 50A, 50B expands, the compression springs 70 can be compressed and provide the electrode stacks 50A, 50B in the cylindrical battery cell 100 with additional volume. The components of the electrode stacks 50A, 50B and the support plates 60 can each form the common component circumference 12 of the Fig. 1-3 and 6, wherein flat sides 52 of the electrode stacks 50A, 50B and corresponding flat sides of the carrier plates 60 are aligned such that a region 108 is provided within the cylindrical battery cell 100. A first electrical connection 130 within the region 108 is connected to the conductive tabs 39 of the anodes 30 of Fig. 2, which are arranged within the electrode stacks 50A, 50B. The first electrical connector 130 is conductively connected to the negative terminal 120. A second electrical connection 140 within the region 108 is connected to the conductive tabs 29 of the cathodes 20 of Fig. 1 within the electrode stacks 50A, 50B. The second electrical terminal 140 is conductively connected to the positive terminal 110. A cap 150 is attached to the top of the cylindrical outer casing 105 and secures the contents therein. A vent 160 may be arranged within the cap 150, through which gases can escape from the cylindrical battery cell 100.

[0047] Fig. 8 schematically shows the cylindrical battery cell 100 from Fig. 7 in a top view. The cylindrical battery cell 100 is shown with the cap 150 removed. The outer casing 105 is shown, including an inner surface 107. The electrode stack 50A is shown with the perimeter, except for the flat side of the electrode stack 50A, conforming to the inner surface 107. The conductive tabs 29, 39 are shown extending from the electrode stack 50A and in direct communication with the second electrical connection 140 and the first electrical connection 130. An optional tab separator clip 170 is shown between the conductive tab 29 and the conductive tab 39. The separator clip 170 is configured to prevent inadvertent contact between the conductive tab 29 and the conductive tab 39. The separator clip 170 can assist in the alignment of the electrode stack during assembly.The separator clamp 170 can also direct gases to the vent 160 from . Fig. 7 facilitate.

[0048] The cylindrical battery cell 100 is shown as a cylinder. In other forms, a battery cell may have the shape of a cube, a rectangular outer casing, a casing with a hexagonal cross-section, or another shape. The electrode stack 50 of Fig.5 and the other components of the cylindrical battery cell 100 can be adapted to other shapes. In an embodiment where the housing has a hexagonal cross-section, the anodes, cathodes, separators, and support plates can have a common component perimeter that substantially corresponds to a hexagonal inner surface of the housing. A cutout can be created on the common component perimeter so that the conductive anode and cathode tabs can each be connected to the corresponding electrical connections. The cutout can include a flat side of the common component perimeter that is recessed from the inner surface of the housing. The cutout can include a concave depression formed in one of the flat sides of the hexagonal shape. The recess can have other shapes or an irregular shape.

[0049] While the best modes for carrying out the disclosure have been described in detail, those skilled in the art to which this disclosure relates will recognize various alternative designs and embodiments for carrying out the disclosure within the scope of the appended claims.

Claims

[1] Battery cell, comprising: an outer casing having an inner surface; an electrode stack arranged within the external housing and comprising: an anode having a first conductive tab; a cathode with a second conductive tab; and a separator; a positive pole; a negative pole; a first electrical connection attached to the first conductive tab and to the negative terminal; and a second electrical connection attached to the second conductive tab and to the positive terminal; and wherein the anode, the cathode and the separator each have a common component scope comprising: a first portion of the common component perimeter configured to conform to a shape of the inner surface; and a second portion of the common component perimeter having a cutout configured to step back from the inner surface; wherein the second portion of the common component circumference of the anode, the second portion of the common component perimeter of the cathode and the second portion of the common component perimeter of the separator are aligned and form a region between the electrode stack and the inner surface; and wherein the first conductive tab, the second conductive tab, the first electrical connection and the second electrical connection are arranged within the area between the electrode stack and the inner surface. [2] Battery cell according to claim 1, further comprising: a support plate disposed adjacent one end of the electrode stack; and a compression spring configured to: Providing a compressive force to the carrier plate and the electrode stack; and Move when the electrode stack expands volumetrically. [3] The battery cell of claim 2, further comprising a plurality of compression springs. [4] Battery cell according to claim 2, wherein the electrode stack comprises a first electrode stack; wherein the carrier plate is a first carrier plate; further comprising: a second electrode stack disposed within the external housing; and a second carrier plate which is arranged at one end of the second electrode stack is arranged; and wherein the compression spring is further configured to: Providing the compressive force to the second carrier plate and the second electrode stack; and continue to move as the second electrode stack expands volumetrically. [5] The battery cell of claim 1, wherein the outer casing is a cylinder; wherein the inner surface has a first round shape; wherein the first part of the common component circumference has a second circular shape configured to conform to the inner surface. [6] The battery cell of claim 5, wherein the second portion of the common component perimeter has a flat side. [7] The battery cell of claim 1, further comprising a separator clip disposed in the region between the electrode stack and the inner surface and configured to separate the first conductive tab and the second conductive tab. [8] The battery cell of claim 1, further comprising a vent configured to allow gases to exit the battery cell. [9] The battery cell according to claim 1, wherein the separator comprises a solid electrolyte separator. [10] Cylindrical battery cell, comprising: a cylindrical external housing having an inner surface with a first circular shape; an electrode stack arranged within the external housing and comprising: a plurality of anodes, each of which includes one of a plurality of first conductive tabs; a plurality of cathodes, each including one of a plurality of second conductive tabs, the plurality of anodes and the plurality of cathodes being arranged in an alternating pattern; and a plurality of separators, one of the plurality of separators being disposed between each of the plurality of anodes and each of the plurality of cathodes; and a positive pole; a negative pole; a first electrical connection attached to each of the plurality of first conductive tabs and to the negative terminal; a second electrical connection attached to each of the plurality of second conductive tabs and to the positive terminal; a support plate disposed adjacent one end of the electrode stack; and a compression spring configured to: Providing a compressive force to the carrier plate and the electrode stack; and Shift when the electrode stack expands volumetrically; and wherein the plurality of anodes, the plurality of cathodes and the plurality of Separators each have a common component perimeter, comprising: a first portion of the common component perimeter having a second round shape corresponding to the inner surface; and a second portion of the common component perimeter having a flat side configured to step back from the first circular shape of the inner surface; wherein the second portion of the common component perimeter of each of the plurality of anodes, the second portion of the common component perimeter of each of the plurality of cathodes, and the second portion of the common component perimeter of each of the plurality of separators are aligned and form a region between the electrode stack and the inner surface; and wherein the plurality of first conductive tabs, the plurality of second conductive tabs, the first electrical connection, and the second electrical connection are disposed within the region between the electrode stack and the inner surface.

Images