Electrochemical cells

Abstract

An electrochemical cell has: a first unit cell having a first power generation element and a first container that accommodates the first power generation element; a second unit cell having a second power generation element and a second container that accommodates the second power generation element; and an outer container that accommodates the first unit cell and the second unit cell. The electrochemical cell has a fused section in which the first unit cell and the second unit cell are layered and the first container and the second container are fused.

Description

Electrochemical cell

[0001] The present disclosure relates to an electrochemical cell.

[0002] As an electrochemical cell, for example, an electrochemical cell described in JP-A-2013-48042 (hereinafter referred to as Patent Document 1) has been proposed. The electrochemical cell described in Patent Document 1 includes a thin battery including a sheet-like electrode group, a non-aqueous electrolyte, and a first exterior body that hermetically houses the electrode group and the non-aqueous electrolyte, and a second exterior body that hermetically houses the thin battery.

[0003] The electrochemical cell of the present disclosure has a first single cell having a first power generation element and a first inner container that houses the first power generation element, a second single cell having a second power generation element and a second inner container that houses the second power generation element, and an outer container that houses the first single cell and the second single cell, and the first single cell and the second single cell are laminated, and is characterized by having a welded portion where the first inner container and the second inner container are welded.

[0004] A perspective view of the electrochemical cell X1 is shown. A cross-sectional view of the electrochemical cell X1 in FIG. 1 cut along line II-II is shown. A perspective view of the electrochemical cell X2 is shown. A cross-sectional view of the electrochemical cell X2 in FIG. 3 cut along line IV-IV is shown. The first single cell and the second single cell laminated from the outer container of the electrochemical cell X2 are taken out, and a top view when viewed from the lamination direction of the first single cell and the second single cell is shown. A perspective view of the electrochemical cell X3 is shown. A cross-sectional view of the electrochemical cell X3 in FIG. 6 cut along line VII-VII is shown. The first single cell and the second single cell laminated from the outer container of the electrochemical cell X3 are taken out, and a top view when viewed from the lamination direction of the first single cell and the second single cell is shown. A perspective view of the electrochemical cell X4 is shown. A cross-sectional view of the electrochemical cell X4 in FIG. 9 cut along line X-X is shown. The first single cell and the second single cell laminated from the outer container of the electrochemical cell X4 are taken out, and a top view when viewed from the lamination direction of the first single cell and the second single cell is shown. A perspective view of the electrochemical cell X5 is shown. A cross-sectional view of the electrochemical cell X5 in FIG. 12 cut along line XIII-XIII is shown.

[0005] The electrochemical cell X1 will be described in detail with reference to Figures 1 and 2. As shown in Figures 1 and 2, the electrochemical cell X1 comprises a first single cell 100, a second single cell 200, and an outer container 1 that houses the first single cell 100 and the second single cell 200. The first single cell 100 and the second single cell 200 are fixed together by a welded joint 4.

[0006] The first single cell 100 is the smallest unit component that functions as a battery within the electrochemical cell X1. The first single cell 100 is, for example, a lithium-ion battery. The first single cell 100 comprises a first power generation element 3, a first inner container 2, and a first terminal 8. The first single cell 100 is, for example, plate-shaped. The first single cell 100 can supply electricity to an external device by being electrically connected to the external device.

[0007] The first power generation element 3 is a component that stores and releases electricity using electrochemical reactions. The first power generation element 3 comprises, for example, a positive electrode 5, a negative electrode 6, and a separator 7 located between the positive electrode 5 and the negative electrode 6. The first power generation element 3 can exchange cations and anions between the positive electrode 5 and the negative electrode 6 through the separator 7. The first power generation element 3 can supply electricity to an external device by electrically connecting the positive electrode 5 and the negative electrode 6 to the external device.

[0008] The first power generation element 3 is, for example, a stack of a positive electrode 5, a separator 7, and a negative electrode 6. The first power generation element 3 is, for example, plate-shaped. The first power generation element 3 is, for example, plate-shaped with the positive electrode 5, separator 7, and negative electrode 6 stacked in the thickness direction.

[0009] The positive electrode 5 and the negative electrode 6 are, for example, electrochemically active substances. The positive electrode 5 and the negative electrode 6 may, for example, have an active material and an electrolyte. As the electrolyte, for example, a solvent or a solvent mixture to which a salt has been added can be used.

[0010] Specifically, for the positive electrode 5 and negative electrode 6, for example, the active substances and electrolytes described in U.S. Provisional Patent Application No. 61 / 787,382, titled "Semi-Solid Electrodes Having High Rate Capability," and U.S. Provisional Patent Application No. 61 / 787,372, titled "Asymmetric Battery Having a Semi-Solid Electrode and High Energy Density Anode," can be used. The positive electrode 5 and negative electrode 6 may, for example, have additives.

[0011] The separator 7 is a component provided to exchange cations and anions between the positive electrode 5 and the negative electrode 6. The separator 7 may have, for example, fine holes through which cations and anions can pass. The separator 7 can be made of, for example, a porous insulating material. Specifically, for example, polyolefin or polyvinyl chloride can be used as the separator 7. The first power generation element 3 can electrically insulate the positive electrode 5 and the negative electrode 6 by having the separator 7.

[0012] If the first power generation element 3 is in the form of a plate, it can be set to, for example, a length of 50 to 500 mm, a width of 50 to 300 mm, and a thickness of 0.1 to 2 mm.

[0013] The first inner container 2 is a member having a space for enclosing the first power generation element 3 inside the first inner container 2. The first inner container 2 is provided to protect the first power generation element 3 from the external environment. More specifically, the first inner container 2 is provided to protect the first power generation element 3 from oxygen and water in the air. The first inner container 2 is provided so as to cover the entire first power generation element 3. The first inner container 2 is, for example, bag-shaped. The first inner container 2 is formed, for example, by making one member into a bag shape. Alternatively, the first inner container 2 may be formed, for example, by welding two members together. The first inner container 2 may be rectangular when viewed from the stacking direction of the positive electrode 5, separator 7, and negative electrode 6.

[0014] The first inner container 2 has, for example, an insulating material. This makes it difficult for the first power generation element 3 to short-circuit with the external environment through the first inner container 2. Therefore, the first inner container 2 can protect the first power generation element 3 from the external environment. The first inner container 2 has, for example, a resin material. More specifically, as the resin material, for example, polyethylene terephthalate or polyethylene can be used.

[0015] Furthermore, the first inner container 2 may have, for example, a multilayer structure. The first inner container 2 may have, for example, a two-layer structure. Specifically, the first inner container 2 may have, for example, a heat-adhesive resin material and a heat-resistant resin material. Specifically, the heat-adhesive resin material is a resin with a melting point less than 100°C. Specifically, the heat-resistant resin material is a resin with a melting point between 100°C and 300°C. As the heat-resistant resin material, for example, polyethylene terephthalate or polyethylene naphthalate can be used. As the heat-adhesive resin material, for example, polyethylene or polypropylene can be used.

[0016] If the first inner container 2 is rectangular when viewed from the stacking direction of the first single cell 100 and the second single cell 200, it can be set to, for example, a length of 55 to 550 mm, a width of 55 to 350 mm, and a thickness of 0.1 to 2.2 mm.

[0017] The first terminal 8 is provided to electrically connect the first power generation element 103 to an external device. The first terminal 8 is, for example, plate-shaped. Specifically, when viewed from the stacking direction of the first single cell 100 and the second single cell 200, the first terminal 8 is, for example, square-shaped. The first terminal 8 may also be, for example, rectangular. The rectangular shape may have, for example, a long side and a short side.

[0018] When viewed from the stacking direction of the first single cell 100 and the second single cell 200, the first terminal 8 is in contact with the first power generation element 103. When viewed from the stacking direction of the first single cell 100 and the second single cell 200, the first terminal 8 is located on one of the outer edges of the first power generation element 103. Furthermore, the first terminal 8 extends outward from the first inner container 102 in order to be electrically connected to an external device. In addition, the first terminal 8 is electrically connected to an external connection terminal outside the first inner container 102.

[0019] The first terminal 8 is, for example, a conductive member. The first terminal 8 may have, for example, a metallic material. More specifically, as the metallic material, for example, aluminum or copper can be used.

[0020] If the first terminal 8 is in the shape of a board, it can be set to, for example, 30 to 100 mm in length, 10 to 100 mm in width, and 0.1 to 0.5 mm in thickness.

[0021] The second cell 200, like the first cell 100, is provided to supply electricity to an external device. In the electrochemical cell X1, the first cell 100 and the second cell 200 are connected in parallel. This increases the capacity of the electrochemical cell X1. Alternatively, the first cell 100 and the second cell 200 may be connected in series. This increases the voltage of the electrochemical cell X1.

[0022] The second single cell 200 is stacked on top of the first single cell 100 inside the outer container 1. The second single cell 200 comprises a second power generation element 13 and a second inner container 12. In the electrochemical cell X1, the second single cell 200 has the same shape as the first single cell 100. However, the second single cell 200 may have a different shape from, for example, the first single cell 100. In the electrochemical cell X1, the second single cell 200 is stacked with the outer circumference aligned with the first single cell 100. However, the second single cell 200 may be stacked without the outer circumference aligned with the first single cell 100.

[0023] For example, the second power generation element 13 can be made of the same material used for the first power generation element 3. More specifically, the second power generation element 13 may be made of the same material as the first power generation element 3. Alternatively, the second power generation element 13 may be made of a different material than the first power generation element 3.

[0024] The second inner container 12 has the same shape as the first inner container 2 in the electrochemical cell X1. However, the second inner container 12 may have a different shape from the first inner container 2, for example. For the second inner container 12, for example, the same material used for the first inner container 2 can be used. More specifically, the second inner container 12 may use the same material as the first inner container 2. Alternatively, the second inner container 12 may use a different material from the first inner container 2, for example.

[0025] The second single cell 200 can be set to the same dimensions as the first single cell 100, for example. Alternatively, the second single cell 200 may have different dimensions from the first single cell 100, for example.

[0026] The outer container 1 is a component having a space for enclosing the first single cell 100 and the second single cell 200 inside the outer container 1. The outer container 1 is a component for protecting the first single cell 100 and the second single cell 200 from the external environment. More specifically, the outer container 1 is a component for protecting the first single cell 100 and the second single cell 200 from oxygen and moisture in the air. The outer container 1 is, for example, bag-shaped. The outer container 1 is formed, for example, by making one component into a bag shape. Alternatively, the outer container 1 may be formed, for example, by welding two components together. The outer container 1 may be rectangular when viewed from the stacking direction of the first single cell 100 and the second single cell 200.

[0027] The outer container 1 has, for example, an insulating material. This makes it difficult for the outer container 1 to short-circuit with the external environment between the first single cell 100 and the second single cell 200. Therefore, the outer container 1 can protect the first single cell 100 and the second single cell 200 from the external environment. As the insulating material, for example, a resin material can be used. More specifically, as the resin material, for example, polyethylene terephthalate or polyethylene can be used.

[0028] The outer container 1 may have, for example, a multilayer structure. The outer container 1 may have, for example, a three-layer structure. Specifically, the outer container 1 may have, for example, a first insulating layer, a moisture-proof layer, and a second insulating layer. In this case, the moisture-proof layer is located, for example, between the first insulating layer and the second insulating layer. Specifically, the moisture-proof layer may be covered, for example, by the first insulating layer and the second insulating layer.

[0029] The first insulating layer has, for example, a resin material. Specifically, as the resin material, for example, polyethylene terephthalate or polyethylene naphthalate can be used.

[0030] The moisture barrier is provided to prevent oxygen and water that have penetrated the first resin layer from reaching the second resin layer. The moisture barrier has, for example, a metallic material. Specifically, as the metallic material, aluminum or copper can be used, for example.

[0031] The second resin layer has, for example, a resin material. Specifically, the resin material can be, for example, polyethylene or polypropylene.

[0032] The outer container 1 has a moisture-proof layer, which protects the first single cell 100 and the second single cell 200 from oxygen and water that have penetrated the first resin layer. As a result, the possibility of damage to the first single cell 100 and the second single cell 200 can be reduced.

[0033] If the outer container 1 is rectangular when viewed from the stacking direction of the first single cell 100 and the second single cell 200, it can be set to, for example, a length of 60 to 600 mm, a width of 60 to 400 mm, and a thickness of 1 to 20 mm.

[0034] The welded portion 4 is the part where the first inner container 2 and the second inner container 12 are welded together. The welded portion 4 is provided to fix the first single cell 100 and the second single cell 200. In the welded portion 4, for example, the material of the first inner container 2 and the material of the second inner container 12 may be diffused from each other. Also, in the welded portion 4, for example, the material of the first inner container 2 and the material of the second inner container 12 may be intertwined. Also, in the welded portion 4, for example, the material of the first inner container 2 and the material of the second inner container 12 may have a crystalline portion in which the molecules of the material of the first inner container 2 and the molecules of the material of the second inner container 12 are arranged in a certain order.

[0035] As shown in Figure 2, the first inner container 2 and the second inner container 12 are welded together, thereby fixing the first single cell 100 and the second single cell 200 within the outer container 1. Therefore, the possibility of misalignment between the first single cell 100 and the second single cell 200 can be reduced without increasing the size of the electrochemical cell X1. As a result, the possibility of partial thickness increase at the fixed portion can be reduced, while the possibility of compromising the reliability of the electrical connection of the electrochemical cell X1 can be reduced.

[0036] As shown in Figure 2, the welded portion 4 is located, for example, between the first power generation element 3 and the second power generation element 13. The welded portion 4 is, for example, plate-shaped. Also, when viewed from the stacking direction of the first single cell 100 and the second single cell 200, the welded portion 4 is, for example, strip-shaped. The welded portion 4 may also be, for example, square-shaped. If the welded portion 4 is square-shaped, for example, the corners of the square shape may be rounded. This makes it less likely for external forces to concentrate at the corners of the square-shaped welded portion 4, and reduces the possibility of damage to the welded portion 4.

[0037] The welded portion 4 has, for example, an insulating material. As the insulating material, for example, a resin material can be used. Specifically, as the welded portion 4, for example, polyethylene terephthalate or polyethylene may be used.

[0038] Furthermore, for example, a material whose light transmittance changes when welded can be used as the welded portion 4. This makes it easier to visually confirm the welded portion 4. Alternatively, for example, a material that becomes hard when welded can be used as the welded portion 4. This reduces the possibility of the electrochemical cell X1 deforming under external force. As a result, the reliability of the electrical connection of the electrochemical cell X1 can be improved.

[0039] If the welded portion 4 is in the shape of a plate, it can be set to, for example, 1 to 100 mm in length, 1 to 20 mm in width, and 0.02 to 1 mm in thickness.

[0040] The welded portion 4 is formed, for example, by ultrasonic welding the first inner container 2 and the second inner container 12. The ultrasonic welding method will be described in more detail below. First, the first inner container 2 and the second inner container 12 are fixed on a table, and a horn is brought into contact with the position where the first inner container 2 and the second inner container 12 are to be welded together. The horn referred to here is, for example, a member that vibrates at a frequency of 20 to 40 kHz. The horn has a head portion that contacts the welding position and a connecting portion that transmits vibrations to the head portion. Specifically, the head portion is, for example, rectangular when viewed from the stacking direction of the first inner container 2 and the second inner container 12. Alternatively, the head portion may be, for example, square.

[0041] Next, the horn is vibrated, imparting vibrational energy to the first inner container 2 and the second inner container 12. The vibrational energy transmitted from the horn causes the interface where the first inner container 2 and the second inner container 12 come into contact to melt. Subsequently, the welded portion 4 is formed by applying pressure to the molten portion of the first inner container 2 and the second inner container 12 while cooling.

[0042] Furthermore, the welded portion 4 may be formed, for example, by heat sealing the first inner container 2 and the second inner container 12. The heat sealing method will be described in detail below. First, a heated metal plate is brought into contact with the position where the first inner container 2 and the second inner container 12 are to be welded together. Next, heat is applied to the first inner container 2 and the second inner container 12 to melt them. After that, the welded portion 4 is formed by cooling the molten parts of the first inner container 2 and the second inner container 12.

[0043] The metal plate is heated to, for example, 100 to 200°C. The metal plate is, for example, in a plate shape. Specifically, the metal plate is rectangular when viewed from the stacking direction of the first inner container 2 and the second inner container 12. Also, the metal plate may be, for example, square.

[0044] Also, the welded portion 4 is not limited to the methods of ultrasonic welding and heat sealing and may be formed by any method.

[0045] The electrochemical cell X2 will be described in detail using FIGS. 3 to 5. As shown in FIGS. 3 and 4, the electrochemical cell X2 includes a first single cell 100, a second single cell 200, and an outer container 1 that houses the first single cell 100 and the second single cell 200. Also, the first single cell 100 and the second single cell 200 are fixed by a welded portion 14.

[0046] The electrochemical cell X2 is different from the electrochemical cell X1 in the shape of the first power generation element 103, the shape of the first inner container 102, the shape of the second power generation element 113, and the shape of the second inner container 112. Further, the electrochemical cell X2 is different from the electrochemical cell X1 in the position and shape of the welded portion 14. Since the rest is the same as that of the electrochemical cell X1, the description thereof is omitted.

[0047] The first single cell 100 has a first power generation element 103 and a first inner container 102. The first power generation element 103 is, for example, rectangular when viewed from the stacking direction of the first single cell 100 and the second single cell 200. More specifically, the first power generation element 103 may be, for example, rectangular with a long side and a short side.

[0048] The first inner container 102 is, for example, rectangular when viewed from the stacking direction of the first single cell 100 and the second single cell 200. More specifically, the first inner container 102 may be, for example, rectangular with a long side and a short side. Further, the first inner container 102 has a first peripheral portion A1. The first peripheral portion A1 is a portion located around the first inner container 102. Specifically, the first peripheral portion A1 means the region from the outer periphery of the first inner container 102 to the outer periphery of the first power generation element 103 when viewed from the stacking direction of the first single cell 100 and the second single cell 200. That is, the first peripheral portion A1 is a region where the first power generation element 103 and the first inner container 102 do not overlap.

[0049] The second single cell 200 has a second power generation element 113 and a second inner container 112. The second power generation element 113 has the same shape as the first power generation element 103 in the electrochemical cell X2. However, the first power generation element 103 and the second power generation element 113 may have different shapes. Also, the second power generation element 113 can use the material used in the first power generation element 103. More specifically, the second power generation element 113 may be formed of, for example, the same material as the first power generation element 103.

[0050] The second inner container 112 has the same shape as the first inner container 102 in the electrochemical cell X2. However, the second inner container 112 and the first inner container 102 may have different shapes, for example. Also, the second inner container 112 can use the material used in the first inner container 102. Specifically, the second inner container 112 may be formed of, for example, the same material as the first inner container 102. Further, the second inner container 112 has a second peripheral portion A2. The second peripheral portion A2 is a portion around the second inner container 112. Specifically, the second peripheral portion A2 means the region from the outer periphery of the second inner container 112 to the outer periphery of the second power generation element 113 when viewed from the stacking direction of the first single cell 100 and the second single cell 200. That is, the second peripheral portion A2 is a region where the second power generation element 113 and the second inner container 112 do not overlap.

[0051] The first power generation element 103 and the second power generation element 113 are stacked so that their long sides and short sides are aligned when viewed from the stacking direction of the first single cell 100 and the second single cell 200. Similarly, the first inner container 102 and the second inner container 112 are stacked so that their long sides and short sides are aligned when viewed from the stacking direction of the first single cell 100 and the second single cell 200.

[0052] Note that in Figure 4, the positive electrode 5, separator 7, and negative electrode 6 of the first power generation element 103 and the second power generation element 113 are omitted.

[0053] As shown in Figure 4, the welded portion 14 is welded to a first peripheral portion A1 and a second peripheral portion A2. This allows for a gap between the welded portion 14 and the first and second power generation elements 103 and 113 compared to when the welded portion 14 is located in the overlapping area of ​​the first and second inner containers 102 and 112 and the first and second power generation elements 103 and 113. Therefore, the influence of thermal stress caused by heat generated from the first and second power generation elements 103 and 113 can be reduced in the welded portion 14. As a result, the possibility of damage to the welded portion 14 can be reduced.

[0054] Figure 5 shows a top view of the electrochemical cell X2, with the first single cell 100 and the second single cell 200 stacked together, removed from the outer container 1, as seen from the stacking direction of the first single cell 100 and the second single cell 200. The outer circumferences of the first power generation element 103 and the second power generation element 113, as seen from the stacking direction through the first inner container 102 and the second inner container 112, are shown by dotted lines. The extensions of the long sides of the first power generation element 103 and the second power generation element 113 are shown as dashed lines as imaginary lines.

[0055] As shown in Figures 4 and 5, there may be multiple welded joints 14. This allows the external force to be distributed among multiple welded joints 14. Therefore, it is less likely that the external force will be concentrated on a single welded joint 14. As a result, the possibility of damage to the welded joint 14 can be reduced.

[0056] Furthermore, as shown in Figure 5, the welded portion 14 may be located along the respective long sides of the first power generation element 103 and the second power generation element 113. Alternatively, the welded portion 14 may be located along the extension of the respective long sides of the first power generation element 103 and the second power generation element 113. By positioning the welded portion along the long side, which is more susceptible to external forces, the possibility of the first single cell 100 or the second single cell 200 shifting in the direction of the short side can be reduced. As a result, the reliability of the electrical connection of the electrochemical cell can be improved.

[0057] Furthermore, when viewed from the stacking direction of the first single cell 100 and the second single cell 200, the welded portion 14 is, for example, rectangular in shape. Specifically, the welded portion 14 may be, for example, a rectangle with a long side. In this case, the long side of the welded portion 14 may be aligned with the respective long sides of the first power generation element 103. This allows the welded portion to be positioned along the long side that is more susceptible to external forces. Therefore, the possibility of the first single cell 100 or the second single cell 200 shifting in the direction of the short side can be reduced. As a result, the reliability of the electrical connection of the electrochemical cell can be improved.

[0058] The electrochemical cell X3 will be described in detail using Figures 6 to 8. As shown in Figures 6 and 7, the electrochemical cell X3 comprises a first single cell 100, a second single cell 200, and an outer container 1 that houses the first single cell 100 and the second single cell 200. Furthermore, the first single cell 100 and the second single cell 200 are fixed together by a welded portion 24. The electrochemical cell X3 differs from the electrochemical cell X2 in that the position of the welded portion 24 is different and the welded portion 24 has a protrusion 9. Other than that, it is the same as the electrochemical cell X2, so the explanation will be omitted.

[0059] In Figure 8, similar to Figure 5, the first single cell 100 and the second single cell 200 are removed from the outer container 1 of the electrochemical cell X3, with their long sides and short sides aligned, and the figure shows a top view of the stacked first single cell 100 and the second single cell 200. The extensions of the long sides and short sides of the first power generation element 103 and the second power generation element 113 are shown as dashed lines.

[0060] As shown in Figure 8, when viewed from the stacking direction of the first single cell 100 and the second single cell 200, the welded portion 24 may be located at the four corners of the first peripheral portion A1 and the second peripheral portion A2. More specifically, the four corners of the first peripheral portion A1 and the second peripheral portion A2 refer to the region enclosed by the extensions of the long sides of the first power generation element 103 and the second power generation element 113, the extensions of the short sides of the first power generation element 103 and the second power generation element 113, and the outer circumference of the first inner container 102 and the second inner container 112. This makes it possible to make the first single cell 100 and the second single cell 200 less susceptible to deformation in the region of the four corners of the first single cell 100 and the second single cell 200, where external forces tend to concentrate. As a result, the reliability of the electrical connection of the electrochemical cell can be improved.

[0061] Furthermore, as shown in Figures 7 and 8, the welded portion 24 has a protrusion 9. The protrusion 9 is provided to distribute the external force applied to the welded portion 24 to itself. This reduces the possibility of damage to the welded portion 24. The protrusion 9 is provided, for example, at a position adjacent to the welded portion 24. Specifically, the protrusion 9 may be located, for example, along the outer circumference of the welded portion 24.

[0062] In the electrochemical cell X3, the protrusion 9 is linear. More specifically, when viewed from the stacking direction of the first single cell 100 and the second single cell 200, the protrusion 9 is frame-shaped. Also, as shown in Figure 7, the cross-section of the protrusion 9 is semicircular.

[0063] The protrusion 9 has, for example, an insulating material. As the insulating material, for example, a resin material may be used. More specifically, as the resin material, for example, polyethylene terephthalate or polyethylene may be used.

[0064] Furthermore, the protrusion 9 can be formed from the same material as the welded portion 24. Therefore, the thermal expansion coefficients of the protrusion 9 and the welded portion 24 can be made the same. As a result, the possibility of the protrusion 9 and the welded portion 24 separating due to differences in thermal expansion coefficients can be reduced. The protrusion 9 may, for example, be formed simultaneously with the formation of the welded portion 24.

[0065] Furthermore, the protrusion 9 may be formed from a different material than the welded portion 24, for example. More specifically, the protrusion 9 may have a higher elastic modulus than the welded portion 24. This allows the protrusion 9 to deform when an external force is applied, making it more difficult for the external force to be transmitted to the welded portion 24. As a result, the possibility of the welded portion 24 being damaged can be reduced.

[0066] Furthermore, there may be multiple protrusions 9 for each welded portion 24. This allows external forces to be distributed among multiple protrusions 9, making it less likely for external forces to concentrate on a single protrusion 9. Therefore, the possibility of damage to a protrusion 9 can be reduced.

[0067] If the protrusion 9 is linear when viewed from the stacking direction of the first single cell 100 and the second single cell 200, it can be set to, for example, 1 to 50 mm in length, 1 to 10 mm in width, and 0.1 to 5 mm in thickness.

[0068] The electrochemical cell X4 will be described in detail using Figures 9 to 11. The electrochemical cell X4 differs from the electrochemical cell X3 in that the first single cell 100 has a first terminal 8 and the second single cell 200 has a second terminal 18. Furthermore, the electrochemical cell X4 differs from the electrochemical cell X3 in that the position of the welded portion 34 is different. Other than that, it is the same as the electrochemical cell X3, so the explanation will be omitted.

[0069] In Figure 11, similar to Figure 8, the first single cell 100 and the second single cell 200 are removed from the outer container 1 of the electrochemical cell X4, with their long sides and short sides aligned, and the figure shows a top view of the stacked first single cell 100 and the second single cell 200 as seen from the stacking direction.

[0070] When viewed from the stacking direction of the first single cell 100 and the second single cell 200, the first power generation element 103 has a first terminal 8 extending outward from one of its sides. The first terminal 8 is provided for electrically connecting the first power generation element 103 to an external device. The first terminal 8 is, for example, plate-shaped. Specifically, the first terminal 8 is, for example, rectangular when viewed from the stacking direction of the first single cell 100 and the second single cell 200. The first terminal 8 may also be, for example, rectangular. Specifically, the rectangular shape may have, for example, a long side and a short side.

[0071] In the electrochemical cell X4, when viewed from the stacking direction of the first single cell 100 and the second single cell 200, the first terminal 8 is in contact with the first power generation element 103. When viewed from the stacking direction of the first single cell 100 and the second single cell 200, the first terminal 8 is located on one of the outer edges of the first power generation element 103. In addition, the first terminal 8 extends outside the first inner container 102 in order to be electrically connected to an external device.

[0072] The first terminal 8 is, for example, a conductive member. The first terminal 8 may have, for example, a metallic material. More specifically, as the metallic material, for example, aluminum or copper can be used.

[0073] If the first terminal 8 is in the shape of a board, it can be set to, for example, 30 to 100 mm in length, 10 to 100 mm in width, and 0.1 to 0.5 mm in thickness.

[0074] When viewed from the stacking direction of the first single cell 100 and the second single cell 200, the second power generation element 113 has a second terminal 18 extending outward from one of its sides. In the electrochemical cell X4, the second terminal 18 has the same shape as the first terminal 8. However, the second terminal 18 may have a different shape from, for example, the first terminal 8. Furthermore, the second terminal 18 can be made of the same material as the first terminal 8. Specifically, the second terminal 18 may be made of the same material as the first terminal 8.

[0075] In the electrochemical cell X4, when viewed from the stacking direction of the first single cell 100 and the second single cell 200, the second terminal 18 is located on one of the outer edges of the first power generation element 103. The second terminal 18 also extends outside the second inner container 112 in order to be electrically connected to an external device. Furthermore, in the electrochemical cell X4, when viewed from the stacking direction of the first single cell 100 and the second single cell 200, the second terminal 18 overlaps with the first terminal 8, with their outer edges aligned. In Figure 11, the overlapping portion of the first terminal 8 and the second terminal 18 with the first inner container 102 and the second inner container 112 when viewed from the stacking direction of the first single cell 100 and the second single cell 200 is indicated by a dotted line.

[0076] When viewed from the stacking direction, the first power generation element 103 and the second power generation element 113 each have terminals extending outward from one of their sides. The welded portion 34 may be located along the side where no terminals are located. This reduces the influence of external forces applied to the electrochemical cell X4 at a position away from the terminals fixed to the external device when vibrations are transmitted to the electrochemical cell X4 from the outside.

[0077] In the electrochemical cell X4, as shown in Figure 11, when viewed from the stacking direction of the first single cell 100 and the second single cell 200, the welded portion 34 is located along the outer edges of the first power generation element 103 and the second power generation element 113 where the first terminal 8 and the second terminal 18 are not located. More specifically, the outer edges of the first power generation element 103 and the second power generation element 113 where the first terminal 8 and the second terminal 18 are not located refer to the edges where the outer edges of the first power generation element 103 and the second power generation element 113 do not overlap with the first terminal 8 and the second terminal 18. Therefore, by positioning the welded portion 34 along the edges where the first terminal 8 and the second terminal 18 are not located, the first single cell 100 and the second single cell 200 can be fixed at a position at a distance from the first terminal 8 and the second terminal 18. As a result, the influence of external forces applied to the first single cell 100 and the second single cell 200 can be reduced. As a result, the reliability of the electrical connections in the electrochemical cell X4 can be improved.

[0078] Furthermore, as shown in Figure 10, in the electrochemical cell X4, the welded portion 34 welds the first inner container 102 and the second inner container 112 via the separator 7. At this time, the separator 7, which is part of the first power generation element 103, and the first inner container 102 are fixed by the welded portion 34. Also, the separator 7, which is part of the second power generation element 113, and the second inner container 112 are fixed by the welded portion 34. Therefore, the possibility of misalignment between the first power generation element 103 and the first inner container 102 can be reduced. Also, the possibility of misalignment between the second power generation element 113 and the second inner container 112 can be reduced. As a result, the reliability of the electrical connection between the first single cell 100 and the second single cell 200 can be improved.

[0079] An electrochemical cell is not limited to having two single cells. An electrochemical cell may have three or more single cells. In that case, the welded portion only needs to fix at least two of the three or more single cells. Electrochemical cell X5 has three single cells. Electrochemical cell X5 will be described in detail using Figures 12 and 13. In electrochemical cell X5, the welded portion 44 fixes the three single cells together.

[0080] As shown in Figures 12 and 13, the electrochemical cell X5 comprises a first single cell 100, a second single cell 200, a third single cell 300, and an outer container 1 that houses the first single cell 100, the second single cell 200, and the third single cell 300. Furthermore, the first single cell 100, the second single cell 200, and the third single cell 300 are fixed together by a welded joint 44.

[0081] Electrochemical cell X5 differs from electrochemical cell X4 in that it has a third single cell 300. Electrochemical cell X5 is otherwise identical to electrochemical cell X4, so details are omitted.

[0082] The third single cell 300 includes a third power generation element 23 and a third inner container 22. In the electrochemical cell X5, the third power generation element 23 has the same shape as the first power generation element 103 and the second power generation element 113. However, the third power generation element 23 may have a different shape from the first power generation element 103 and the second power generation element 113. Furthermore, the third power generation element 23 can use the same material as the first power generation element 103 and the second power generation element 113. More specifically, the third power generation element 23 may be formed from the same material as the first power generation element 103 and the second power generation element 113. When viewed from the stacking direction of the first power generation element 103, the second power generation element 113 and the third power generation element 23, they have a rectangular shape with a long side and a short side. The first power generation element 103, the second power generation element 113, and the third power generation element 23 are stacked with their respective long sides and short sides aligned.

[0083] In the electrochemical cell X5, the third inner container 22 has the same shape as the first inner container 102 and the second inner container 112. However, the third inner container 22 may have a different shape from, for example, the first inner container 102 and the second inner container 112. Furthermore, the third inner container 22 can be made of the same material used for the first inner container 102 and the second inner container 112. Specifically, the third inner container 22 may be made of the same material as, for example, the first inner container 102 and the second inner container 112.

[0084] The electrochemical cell X5 has a welded portion 44 where a first single cell 100, a second single cell 200, and a third single cell 300 are welded together. The welded portion 44 is provided to fix the first single cell 100, the second single cell 200, and the third single cell 300 together. More specifically, as shown in Figure 13, the welded portion 44 fixes the first single cell 100, the second single cell 200, and the third single cell 300 together. This allows the first single cell 100, the second single cell 200, and the third single cell 300 to be fixed more securely compared to fixing at least two single cells. Therefore, the reliability of the electrical connection of the electrochemical cell X5 can be improved.

[0085] For the sake of simplicity, Figures 1 to 13 show each single cell, each power generation element, each inner container, and each terminal as having the same shape and aligned outer circumference. However, they do not need to be exactly the same shape and have aligned outer circumferences. For example, the first power generation element 103 and the second power generation element 113 can be considered to have the same shape and to be overlapping with aligned outer circumferences, provided that the error is within 5 mm. The same applies to each single cell, each inner container, and each terminal.

[0086] X1-X5 Electrochemical Cell 1 Outer container 2, 102 First inner container 3, 103 First power generation element 4, 14, 24, 34, 44 Welded part 5 Positive electrode 6 Negative electrode 7 Separator 8 First terminal 9 Protrusion 12, 112 Second inner container 13, 113 Second power generation element 18 Second terminal 22 Third inner container 23 Third power generation element 28 Third terminal 100 First single cell 200 Second single cell 300 Third single cell A1 First periphery A2 Second periphery

Claims

1. An electrochemical cell comprising: a first single cell comprising the first power-generating element and a first inner vessel holding the first power-generating element; a second single cell comprising the second power-generating element and a second inner vessel holding the second power-generating element; and an outer vessel holding the first and second single cells, where the first and second single cells are stacked on top of each other, and the electrochemical cell comprising at least one fused part in which the first and second inner vessels are fused together.

2. An electrochemical cell according to claim 1 where at least one fused part is comprising multiple fused parts. 3.An electrochemical cell according to claim 1 or 2 such that when viewed from the orientation of the first and second single cells, all of the first power-generating element is within the outer circumference of the first inner container, and the first inner container is comprised of the first lateral boundary which does not overlap with the first power-generating element; all of the second power-generating element is within the outer circumference of the second inner container, and the second inner container is comprised of the second lateral boundary which does not overlap with the first power-generating element; and the first and second lateral boundary are fused together in at least one of the fused parts.4.An electrochemical cell according to claim 3 where, when viewed from the stacking direction, the first and second power generating elements are identical rectangular prisms and are stacked such that their relative long and short sides coincide, and at least one connecting part is a rectangle along each relative long side or an extension line of each relative long side.

5. An electrochemical cell according to claim 3 or 4 where, when viewed from the stacking direction, the first and second power generating elements are identical rectangular prisms and are stacked such that their relative long and short sides coincide, and at least one connecting part is a rectangle along each relative long side or an extension line of each relative long side. 6.An electrochemical cell according to claim 4 or 5 such that, when viewed from the superposition direction, at least one of the fused parts is located within the boundary of the long side extensions of the first power element, the short side extensions of the first power element, and the outer circumference of the inner vessel.

7. An electrochemical cell according to any of claim 1 to 3 such that, when viewed from the superposition direction, the first power element has a terminal protruding outwards from one side of it, and the second power element has a terminal protruding outwards from one side of it, and at least one of the fused parts is located along the sides of the first and second power elements where each of the related terminals is not located there;