Secondary battery cells and secondary battery cell stacks

Abstract

The objective is to provide a secondary battery cell that can more reliably prevent moisture ingress. [Solution] The secondary battery cell comprises a battery element and an outer casing that houses the battery element. The outer casing comprises a housing portion, which houses the battery element, and a sealing portion, which is a portion where the inner surfaces of the outer casings are bonded together so that the inside of the housing portion becomes a sealed space. The sealing portion has a first folded portion, which is connected to one end of the housing portion and folded back so as to extend from one end toward the other end of the housing portion. The first folded portion overlaps the charge / discharge region of the battery element, and the other end of the first folded portion is located outside the other end of the charge / discharge region.

Description

Technical Field

[0001] The present invention relates to a secondary battery cell and a secondary battery cell laminate.

Background Art

[0002] A secondary battery is a rechargeable battery. A secondary battery may be provided as a cell (hereinafter referred to as a secondary battery cell). A secondary battery cell includes a battery element having an electrolyte layer and an electrode layer, and an exterior body that houses the battery element. As the exterior body, a film such as a metal laminate film may be used.

[0003] One of the functions required for the exterior body is to protect the battery element from moisture. Techniques related to the exterior body are described in, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 11-260327). Patent Document 1 discloses a thin battery having an exterior body with a specific configuration. In this thin battery, the exterior body includes an exterior body main body portion, a first sealing portion that seals the top of the exterior body main body portion, a second sealing portion that seals the bottom of the exterior body main body portion, and a third sealing portion that seals the side end portion of the exterior body main body portion, and at least one of the first to third sealing portions is bent, and the bent portion is regulated within the thickness range of the exterior body main body portion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, as a secondary battery, a battery (for example, an all-solid-state battery) in which an electrolyte layer containing a solid electrolyte is used is known. In a secondary battery containing a solid electrolyte, the battery element is particularly susceptible to the influence of moisture. Therefore, stronger prevention of moisture intrusion is required.

[0006] Therefore, the object of the present invention is to provide a secondary battery cell that can more reliably prevent moisture from entering. [Means for solving the problem]

[0007] In one embodiment, the secondary battery cell according to the present invention comprises a battery element and an outer casing for housing the battery element, the outer casing being made of a film. The battery element has a configuration in which an electrolyte layer containing a solid electrolyte, a positive electrode layer, and a negative electrode layer are stacked along the stacking direction. The battery element has a charge / discharge region, which is a region in which the electrolyte layer, positive electrode layer, and negative electrode layer all overlap when viewed along the stacking direction. The outer casing comprises a housing portion, which is a part that houses the battery element, and a sealing portion, which is a portion connected to the end of the housing portion, and in which the inner surfaces of the outer casings are bonded together so that the inside of the housing portion becomes a sealed space. The sealing portion has a first folded portion, which is connected to one end of the housing portion and is folded back so as to extend from one end toward the other end of the housing portion. When viewed along the stacking direction, the first folded portion overlaps the charge / discharge region, and the other end of the first folded portion is located outside the other end of the charge / discharge region. [Effects of the Invention]

[0008] The present invention provides a secondary battery cell that can more reliably prevent moisture from entering. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic plan view showing a secondary battery cell according to the first embodiment. [Figure 2] Figure 2 is a cross-sectional view showing section AA' of Figure 1. [Figure 3] Figure 3 shows a secondary battery cell with its outer casing fully extended. [Figure 4] Figure 4 is a cross-sectional view illustrating the folded structure of the exterior body. [Figure 5] Figure 5 is a schematic diagram showing a secondary battery cell according to Modification 1. [Figure 6] Figure 6 is a cross-sectional view showing a secondary battery cell according to Modification 2. [Figure 7] Figure 7 is a cross-sectional view showing a secondary battery cell according to Modification 3. [Figure 8] Figure 8 is a schematic cross-sectional view showing a secondary battery cell stack according to Modification 4. [Figure 9] Figure 9 is a schematic cross-sectional view showing a secondary battery cell according to the second embodiment. [Figure 10] Figure 10 is a schematic diagram showing the exterior body in an extended state in the second embodiment. [Figure 11] Figure 11 is a schematic cross-sectional view showing an example of a secondary battery cell stack according to the second embodiment. [Figure 12A] Figure 12 is a schematic cross-sectional view showing a secondary battery cell according to the third embodiment. [Figure 12B] Figure 12 is a schematic cross-sectional view showing a modified secondary battery cell according to the third embodiment. [Figure 13] Figure 13 is a schematic diagram showing the outer casing in an extended state in the third embodiment. [Figure 14] Figure 14 is a schematic diagram showing an example of a secondary battery cell stack including a secondary battery cell according to the third embodiment. [Figure 15] Figure 15 is a schematic diagram showing another example of a secondary battery cell stack. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings.

[0011] (1) First Embodiment Figure 1 is a schematic plan view showing a secondary battery cell 1 according to the first embodiment. Figure 2 is a cross-sectional view showing section AA' of Figure 1. For the sake of explanation, in this specification, the "first direction," "second direction," and "stacking direction" are defined for the secondary battery cell 1 as shown in Figures 1 and 2. These three directions are perpendicular to each other.

[0012] The secondary battery cell 1 according to this embodiment is a cell of a lithium-ion battery. As shown in FIGS. 1 and 2, the secondary battery cell 1 has a battery element 2 and an exterior body 3.

[0013] The battery element 2 is housed in the exterior body 3. Although not shown, the battery element 2 has an electrolyte layer, a positive electrode layer, and a negative electrode layer. These are laminated along the lamination direction. The battery element 2 is configured such that lithium ions conduct from the positive electrode layer through the electrolyte layer to the negative electrode layer during charging, and lithium ions conduct from the negative electrode layer through the electrolyte layer to the positive electrode layer during discharging.

[0014] The electrolyte layer contains a solid electrolyte. Typically, the secondary battery cell 1 is a cell of an all-solid-state battery.

[0015] The shape of the battery element 2 is not particularly limited. In this embodiment, as an example, the case where the battery element 2 is rectangular when viewed along the lamination direction will be described (see FIG. 1). In the example described below, the case where the short side of the battery element 2 is parallel to the first direction and the long side of the battery element 2 is parallel to the second direction will be described.

[0016] Note that a tab 4 is connected to the battery element 2 (see FIG. 1). The tab 4 is connected to one side (one short side in this embodiment) of the battery element 2 in the second direction. The tab 4 extends so as to protrude from the inside to the outside of the exterior body 3.

[0017] As shown in Figure 2, the battery element 2 has a charge / discharge region 9. The charge / discharge region 9 is the region where lithium ions are substantially conducted during charging and discharging. Although not shown in the figure, the charge / discharge region 9 is the region where the electrolyte layer, positive electrode layer, and negative electrode layer all overlap when viewed along the stacking direction. For example, if the edges of the electrolyte layer, positive electrode layer, and negative electrode layer are aligned when viewed along the stacking direction, then the entire region of the electrolyte layer, positive electrode layer, and negative electrode layer can be said to be the charge / discharge region 9. On the other hand, the edges of the electrolyte layer, positive electrode layer, and negative electrode layer may be misaligned for various reasons. In this case, the region of the battery element 2 where these three layers overlap becomes the charge / discharge region 9.

[0018] The outer casing 3 is provided to protect the battery element 2. The outer casing 3 is made of a film. The outer casing 3 is, for example, a metal laminate film. In this embodiment, the outer casing 3 is made of a single sheet.

[0019] In general terms, the outer casing 3 is folded at a portion corresponding to one side of the battery element 2 so as to enclose the battery element 2. The outer casing 3 is then sealed at the portions corresponding to the remaining three sides so that the space housing the battery element 2 becomes a sealed space. The outer casing 3 is further folded between the portion housing the battery element 2 and the sealed portion, with a portion of the sealed portion overlapping the portion housing the battery element 2 (see Figure 2).

[0020] Specifically, as shown in Figure 2, the outer casing 3 has a housing section 5 and a sealing section 6.

[0021] The housing section 5 is the part that houses the battery element 2.

[0022] On the other hand, the sealing portion 6 is the part where the inner surfaces of the outer casing 3 are bonded together so that the internal space of the housing portion 5 becomes a sealed space. The sealing portion 6 is connected to the end of the housing portion 5. The end of the housing portion 5 referred to here is the end in a direction perpendicular to the stacking direction. In the sealing portion 6, the inner surfaces of the outer casing 3 are pressed together by, for example, a heat-sealing resin. That is, in the sealing portion 6, the upper part of the outer casing 3 where the battery element 2 is located and the lower part where the battery element 2 is located are bonded together.

[0023] The sealing portion 6 has a first folded portion 7-1. The term "first" is used to distinguish it from the second folded portion 7-2 in other embodiments described later. In this embodiment, there is no "second" folded portion.

[0024] The first folded portion 7-1 is connected to one end (one end in the first direction) of the housing portion 5. The first folded portion 7-1 is folded back so as to extend from one end of the housing portion 5 toward the other end of the housing portion 5. That is, the outer casing 3 is folded back in the first direction so that the first folded portion 7-1 is positioned on the housing portion 5 in the stacking direction. Note that in Figure 2, a gap is shown between the first folded portion 7-1 and the housing portion 5 for clarity, but in reality, the two are in close contact. The same applies to the other drawings below.

[0025] The first folded portion 7-1 overlaps the charge / discharge region 9 when viewed along the stacking direction. As shown in Figure 2, the other end of the first folded portion 7-1 (see end b in Figure 2) is located outside the other end of the charge / discharge region 9 (see end a in Figure 2). Therefore, when viewed along the stacking direction, the charge / discharge region 9 is completely covered by the first folded portion 7-1.

[0026] For reference, Figure 3 shows the secondary battery cell 1 with the casing 3 fully unfolded. Figure 4 shows a cross-sectional view illustrating the folding structure of the casing 3. As shown in Figure 3, the housing portion 5 has a width of at least twice the size of the battery element 2 so that it can enclose the battery element 2 when folded. The sealing portion 6 is provided at the end of the casing 3 and surrounds the housing portion 5. Of the sealing portion 6, the portions located on both sides of the housing portion 5 in the first direction are the first folding portions 7-1.

[0027] Figures 3 and 4 show fold lines a and b for reference. As shown in Figure 4, the secondary battery cell 1 according to this embodiment is obtained by folding the outer casing 3 along fold line a, bonding the seal portion 6, and then folding it again along fold line b. In reality, the battery element 2 has a certain thickness, so there are two fold lines in the parts corresponding to each fold line. However, in Figures 3 and 4, for the sake of explanation, the thickness of the battery element 2 is ignored, and the folded structure is explained using a single fold line.

[0028] The above describes the configuration of the secondary battery cell 1 according to this embodiment. The above configuration provides the following effects.

[0029] First, according to this embodiment, moisture intrusion can be prevented more reliably. The main route for moisture intrusion into the secondary battery cell 1 is the seal portion 6 in the outer casing 3. If the width of the seal portion 6 (the path from the outside through the seal portion 6 to the internal space of the housing portion 5) is short, moisture can easily intrude. In this regard, according to this embodiment, a first folded portion 7-1 is provided in the seal portion 6. The width of the first folded portion 7-1 along the first direction is long enough to cover at least the charge / discharge area 9. Therefore, the intrusion of moisture passing through the seal portion 6 in the first direction is suppressed.

[0030] In this embodiment, the first folded portion 7-1 is located on the housing portion 5. Therefore, even though a sealing portion (first folded portion 7-1) with a long width in the first direction is provided, the area of ​​the secondary battery cell 1 does not increase significantly. Moisture ingress can be prevented without increasing the size of the cell.

[0031] Furthermore, as mentioned above, the main route for moisture to enter is the seal portion 6. Therefore, the longer the perimeter of the seal portion 6 (the length of the end portion of the seal portion 6 that is exposed to the outside), the easier it is for moisture to enter. In this embodiment, the outer casing 3 is a single sheet, and the battery element 2 is wrapped by a single sheet. Therefore, the perimeter of the seal portion 6 is not that long. That is, one side of the battery element 2 is covered by the folded outer casing 3, so there is no need to provide a seal portion 6. For example, compared to the case where two sheets are used and the seal portion 6 is provided to cover the entire circumference of the battery element 2, the perimeter of the seal portion 6 can be shortened. From the viewpoint of the perimeter of the seal portion 6, moisture is less likely to enter.

[0032] In addition, according to this embodiment, the secondary battery cell 1 can be uniformly pressurized. This point will be explained below.

[0033] Secondary batteries using solid electrolytes are typically pressurized in the stacking direction to achieve good charge-discharge characteristics. For example, a secondary battery cell 1 is constrained by a restraining member such as a rubber band via an end plate, thereby being pressurized to compress it. It is desirable that the pressure applied to the charge-discharge region 9 be as constant as possible. However, the battery elements 2 may expand and contract during charging and discharging; that is, their thickness may change. In particular, secondary battery cells 1 containing a solid electrolyte (typically all-solid-state batteries) have a large amount of expansion and contraction of the battery elements 2. This expansion and contraction causes changes in the pressure applied to the charge-discharge region 9.

[0034] In contrast, according to this embodiment, the first folded portion 7-1 is positioned to overlap with the charge / discharge region 9. Therefore, the first folded portion 7-1 functions as a cushion. That is, even when the battery element 2 expands and contracts, the pressure changes are absorbed by the first folded portion 7-1. The pressure applied to the charge / discharge region 9 becomes more uniform, resulting in better charge / discharge characteristics.

[0035] In addition, according to this embodiment, the other end of the first folded portion 7-1 is located outside the other end of the charge / discharge region 9. Therefore, there are no ends or seams of the outer casing 3 in the position overlapping the charge / discharge region 9 in the stacking direction. In other words, no steps are formed in the outer casing 3 in the position overlapping the charge / discharge region 9. If there were steps in the position overlapping the charge / discharge region 9, the magnitude of the pressure applied to the charge / discharge region 9 may change at that step. According to this embodiment, since no such steps exist, the charge / discharge region 9 can be pressurized uniformly regardless of position.

[0036] In this embodiment, the electrolyte layer contains a solid electrolyte. As previously described, secondary batteries in which a solid electrolyte is contained in the electrolyte layer are susceptible to the effects of moisture. Therefore, preventing the ingress of moisture is more strongly required. In addition, such secondary batteries expand and contract significantly with charging and discharging. Therefore, suppressing pressure changes due to expansion and contraction is also more strongly required. In contrast, the structure adopted in this embodiment is particularly valuable in secondary batteries using a solid electrolyte because it more reliably prevents the ingress of moisture and suppresses pressure changes due to expansion and contraction. From this viewpoint, the content of the solid electrolyte in the electrolyte layer is, for example, 50% by mass or more, more preferably 80% by mass or more.

[0037] In this embodiment, the case described is when the other end of the first folded portion 7-1 (see end b in Figure 2) is located outside the other end of the charge / discharge region 9 (see end a in Figure 2). However, in a preferred embodiment, when viewed along the stacking direction, it is preferable that the other end of the first folded portion 7-1 is located even further outside the outermost part of the ends of the positive electrode layer, electrolyte layer, and negative electrode layer of the battery element 2. With such a configuration, the ends of the outer casing 3 do not overlap the positive electrode layer, electrolyte layer, and negative electrode layer, so that pressure can be applied to the battery element 2 more uniformly. As a result, better charge / discharge characteristics can be obtained. Also, if the pressure applied to the battery element 2 is uneven, the battery element 2 may be destroyed. In contrast, by making the pressure applied to the battery element 2 uniform, the destruction of the battery element 2 is also prevented.

[0038] Next, a modified example of the secondary battery cell 1 according to this embodiment will be described.

[0039] (Variation 1) Figure 5 is a schematic diagram showing a secondary battery cell 1 according to Modification 1, and shows the outer casing 3 in a fully unfolded state. In Figure 5, the parts where the outer casing 3 is folded back are indicated as fold lines a to c.

[0040] In the first embodiment (see Figure 3), the case in which the outer casing 3 is folded twice in the first direction was described as an example. In contrast, in this modified example, the outer casing 3 is folded twice in the first direction and then folded again in the second direction.

[0041] Specifically, the sealing portion 6 of the outer casing 3 is formed to be long in the second direction as well, so that it can be folded back in the second direction and overlapped onto the housing portion 5. The outer casing 3 is folded back along folding lines a and b, and then again along folding line c. Therefore, when fully folded, the first folded portion 7-1 overlaps onto the housing portion 5, and the sealing portion 6 overlaps on top of the first folded portion 7-1. In other words, four more layers of the outer casing 3 overlap on top of the first folded portion 7-1.

[0042] According to this modified version, the width of the sealing portion 6 is increased not only in the first direction but also in the second direction, thus more reliably preventing moisture from entering through the sealing portion 6. Furthermore, since the sealing portion 6 is further superimposed on the first folded portion 7-1, pressure changes due to expansion and contraction are absorbed more reliably. In other words, the charging and discharging region 9 can be pressurized more uniformly.

[0043] (Modification 2) Next, we will describe Modification 2. Figure 6 is a cross-sectional view showing a secondary battery cell 1 according to Modification 2. In this modification, the first folded portion 7-1 is folded again. That is, the first folded portion 7-1 is folded again so that multiple overlapping regions are formed in the stacking direction.

[0044] According to this modified example, since multiple regions overlap in the stacking direction at the first folded portion 7-1, the first folded portion 7-1 is able to function more effectively as a cushion. In other words, pressure changes due to the expansion and contraction of the battery element 2 are more easily absorbed by the first folded portion 7-1. As a result, better charge and discharge characteristics can be achieved.

[0045] In this modified example 2, the ends of the first folded portion 7-1 (see ends b-1 and b-2 in the figure) are located outside the ends of the charge / discharge region 9 (see end a in the figure) so as not to overlap with the charge / discharge region 9. Here, the ends of the first folded portion 7-1 include both the folded portion of the first folded portion 7-1 (end b-1 in the figure) and the tip of the first folded portion 7-1 (the end when the outer casing is unfolded: end b-2 in the figure). In other words, no step is formed by the ends of the outer casing 3 in the area overlapping with the charge / discharge region 9. Therefore, the charge / discharge region 9 is uniformly pressurized regardless of its position.

[0046] (Variation 3) Next, we will describe Modification 3. Figure 7 is a cross-sectional view showing the secondary battery cell 1 according to Modification 3. In this modification, an elastic member 11 is further added. The elastic member 11 is positioned between the housing portion 5 and the first folded portion 7-1 in the stacking direction.

[0047] According to this modified example, since the elastic member 11 is provided, the pressure changes due to the expansion and contraction of the battery element 2 are also absorbed by the elastic member 11. This allows the charge and discharge region 9 to be pressurized more uniformly.

[0048] Figure 7 shows a preferred example, similar to Modification 2, where the first folded portion 7-1 is further folded so that multiple regions overlap. Elastic members 11 are also placed between these multiple regions. If elastic members 11 are also placed in such portions, pressure changes due to expansion and contraction are more easily absorbed.

[0049] Furthermore, as the elastic member 11, for example, a material with a lower elastic modulus (Young's modulus) than the outer casing 3 can be used.

[0050] (Modification 4) Next, we will explain Modification 4. In this modification, we will explain the secondary battery cell stack 10. A secondary battery cell stack refers to a stack made up of multiple secondary battery cells.

[0051] Figure 8 is a schematic cross-sectional view showing a secondary battery cell stack 10 according to this modified example. The secondary battery cell stack 10 according to this modified example is formed by stacking multiple secondary battery cells 1 as described above along the stacking direction.

[0052] In this modified example, as shown in Figure 8, the direction in which the first folded portion 7-1 extends from the end of the housing portion 5 (the direction in the first direction) is reversed between two adjacent secondary battery cells (1-1 and 1-2) in the stacking direction. With this configuration, variations in thickness are less likely to occur. This makes it possible to pressurize each secondary battery cell 1 more uniformly.

[0053] Furthermore, the multiple secondary battery cells 1 are stacked such that the side on which the first folded portion 7-1 is folded is the same side in the stacking direction. In the example shown in Figure 8, the multiple secondary battery cells 1 are all stacked such that the side on which the first folded portion 7-1 is folded is the upper side in the stacking direction.

[0054] (2) Second embodiment Next, a second embodiment will be described. Note that detailed explanations will be omitted regarding aspects where the same configuration as the first embodiment and its modified examples can be adopted.

[0055] Figure 9 is a schematic cross-sectional view showing the secondary battery cell 1 according to this embodiment. Figure 10 is a schematic diagram showing the outer casing 3 in an unfolded state in this embodiment.

[0056] In the first embodiment, a case was described in which the outer casing 3 consists of a single sheet. In contrast, in the second embodiment, the outer casing 3 includes two sheets. That is, the outer casing 3 includes a first sheet 8-1 and a second sheet 8-2. The first sheet 8-1 and the second sheet 8-2 are arranged so as to sandwich the battery element 2 in the stacking direction.

[0057] In this embodiment, the sealing portion 6 is the portion on the outside of the housing portion 5 where the first sheet 8-1 and the second sheet 8-2 are bonded together on their inner surfaces.

[0058] The sealing portion 6 has a first folded portion 7-1, similar to the first embodiment. The configuration of the first folded portion 7-1 is the same as in the first embodiment. That is, the first folded portion 7-1 is connected to one end of the housing portion 5 and is folded back from that end toward the other end.

[0059] On the other hand, in this embodiment, the sealing portion 6 further has a second folded portion 7-2. The second folded portion 7-2 is connected to the other end of the housing portion 5 and is folded back so as to extend from the other end toward the one end. As shown in Figure 9, similar to the first folded portion 7-1, the second folded portion 7-2 also overlaps the charge / discharge region 9 when viewed along the stacking direction. Furthermore, the end of the second folded portion 7-2 on one end is located outside the end of the charge / discharge region 9 on one end. In other words, no step is formed by the end of the second folded portion 7-2 in a position that overlaps with the charge / discharge region 9.

[0060] In this embodiment, the first folded portion 7-1 and the second folded portion 7-2 are folded to the same side in the stacking direction.

[0061] Even with the configuration of this embodiment, the width of the sealing portion 6 is ensured to be wide, just as in the first embodiment, so that moisture intrusion can be prevented more reliably.

[0062] Furthermore, according to this embodiment, the pressure changes associated with expansion and contraction are absorbed not only by the first folded portion 7-1 but also by the second folded portion 7-2. Therefore, the charge and discharge region 9 can be pressurized more uniformly.

[0063] Furthermore, in this embodiment as well, since a large area of ​​the sealing portion 6 is secured, the intrusion of moisture can be prevented more reliably.

[0064] Furthermore, multiple secondary battery cells 1 according to this embodiment can be stacked and used as a secondary battery cell stack 10. Figure 11 is a schematic cross-sectional view showing an example of the configuration of a secondary battery cell stack 10 according to this embodiment. In this secondary battery cell stack 10, multiple secondary battery cells 1 are stacked such that the folding directions of the first folded portion 7-1 and the second folded portion 7-2 in the stacking direction are on the same side.

[0065] (3) Third Embodiment Next, a third embodiment will be described. This embodiment can also be considered a modified version of the second embodiment. Detailed explanations of aspects that can be adopted in the same way as the second embodiment will be omitted.

[0066] Figure 12A is a schematic cross-sectional view showing the secondary battery cell 1 according to this embodiment. Figure 13 is a schematic diagram showing the outer casing 3 in an unfolded state in this embodiment.

[0067] In the second embodiment, the case was described in which the first folded portion 7-1 and the second folded portion 7-2 are folded to the same side in the stacking direction. In contrast, in this embodiment, the first folded portion 7-1 and the second folded portion 7-2 are folded to opposite sides in the stacking direction.

[0068] Even if the configuration according to this embodiment is adopted, the same effects as those of the previously described embodiment can be achieved. That is, since a larger area of ​​the sealing portion 6 is secured, the intrusion of moisture can be prevented more reliably. In addition, since the pressure changes due to expansion and contraction caused by charging and discharging are absorbed by the first folded portion 7-1 and the second folded portion 7-2, the charging and discharging region 9 can be pressurized more uniformly.

[0069] Figure 12B is a schematic cross-sectional view showing a modified example of this embodiment. In the example shown in Figure 12A, both opposing sides of the battery element 2 are covered by the second sheet 8-2. In contrast, in the modified example shown in Figure 12B, one side of the battery element is covered by the first sheet 8-1, and the other side is covered by the second sheet 8-2. The same effects as in this embodiment can be obtained by adopting the configuration shown in Figure 12B.

[0070] In this embodiment as well, multiple secondary battery cells 1 may be stacked and used as a secondary battery cell stack 10. Figure 14 is a schematic diagram showing an example of a secondary battery cell stack 10 including secondary battery cells 1 according to this embodiment. In the example shown in Figure 14, multiple secondary battery cells 1 are simply stacked in the stacking direction. By adopting such a configuration, a secondary battery can be provided as a secondary battery cell stack 10.

[0071] On the other hand, Figure 15 is a schematic diagram showing another example of the secondary battery cell stack 10. In the example shown in Figure 15, in two secondary battery cells (1-1 and 1-1) adjacent in the stacking direction, the first folded portion 7-1 of one secondary battery cell 1-2 is inserted between the housing portion 5 and the second folded portion 7-2 of the other secondary battery cell 1-1.

[0072] With the configuration shown in Figure 15, variations in the thickness of the secondary battery cell stack 10 in the stacking direction are reduced. This makes it possible to apply pressure to each secondary battery cell 1 more uniformly.

[0073] The present invention has been described above with reference to the first to third embodiments. These embodiments and modifications are not independent of each other and can be combined and used within a non-contradictory scope.

[0074] [Note] The following is a summary of typical configurations included in the present invention and their effects, as an appendix.

[0075] (Note 1) A secondary battery cell comprising: a battery element 2; an outer casing 3 for housing the battery element 2, the outer casing being made of film, wherein the battery element 2 has a configuration in which an electrolyte layer containing a solid electrolyte, a positive electrode layer, and a negative electrode layer are laminated along the lamination direction, and the battery element 2 has a charge / discharge region 9 which is a region in which the electrolyte layer, the positive electrode layer, and the negative electrode layer all overlap when viewed along the lamination direction, and the outer casing 3 comprises a housing portion 5 which is a portion for housing the battery element 2; and a sealing portion 6 which is connected to the end of the housing portion 5 and is a portion in which the inner surfaces of the outer casing 3 are bonded together so as to form a sealed space inside the housing portion, wherein the sealing portion 6 has a first folded portion 7-1 which is connected to one end of the housing portion 5 and is folded back so as to extend from one end toward the other end of the housing portion, and when viewed along the lamination direction, the first folded portion 7-1 overlaps with the charge / discharge region 9, and the other end of the first folded portion 7-1 is located outside the other end of the charge / discharge region 9.

[0076] According to the above configuration, the seal portion 6 has a width long enough to cover at least the charge / discharge region 9, making it difficult for moisture to penetrate. In addition, since the first folded portion 7-1 of the outer casing 3 overlaps the charge / discharge region 9, the first folded portion 7-1 functions as a buffer, suppressing changes in pressure applied to the charge / discharge region 9 during expansion and contraction.

[0077] (Note 2) A secondary battery cell as described in Appendix 1, wherein the first folded portion 7-1 is further folded so as to form multiple overlapping regions in the stacking direction.

[0078] According to the above configuration, since the first folded portion 7-1 is superimposed in multiple layers on the housing portion 5, changes in pressure due to expansion and contraction are further suppressed.

[0079] (Note 3) A secondary battery cell as described in Appendix 1 or 2, further comprising an elastic member 11 disposed between the housing portion 5 and the first folded portion 7-1 in the stacking direction.

[0080] According to the above configuration, the pressure changes in the charge / discharge region 9 due to expansion and contraction are also absorbed by the elastic member 11.

[0081] (Note 4) A secondary battery cell as described in any of the appendices 1 to 3, wherein the outer casing 3 consists of a single sheet.

[0082] According to the above configuration, the battery element 2 can be housed by enclosing it in a single sheet. As a result, compared to the case where the sealing portion 6 surrounds the entire circumference of the battery element 2, the perimeter length of the sealing portion 6 can be reduced, and moisture intrusion can be more reliably suppressed.

[0083] (Note 5) A secondary battery cell stack 10 comprising a plurality of secondary battery cells 1, wherein each of the plurality of secondary battery cells 1 is a secondary battery cell described in any of appendices 1 to 4, the plurality of secondary battery cells are stacked along the stacking direction, and the plurality of secondary battery cells are stacked such that, between two adjacent secondary battery cells in the stacking direction, the direction in which the first folded portion 7-1 extends from the housing portion 5 is opposite to that of the other secondary battery cells.

[0084] According to the above configuration, variations in the thickness of the secondary battery cell stack 10 are less likely to occur, and the charge / discharge region 9 can be pressurized more uniformly.

[0085] (Note 6) A secondary battery cell 1 as described in any of Appendix 1 to 5, wherein the outer casing 3 comprises a first sheet 8-1 and a second sheet 8-2 arranged to sandwich the battery element 2 in the stacking direction, the sealing portion 6 is the portion where the first sheet 8-1 and the second sheet 8-2 are bonded together on their inner surfaces, the sealing portion 6 has a second folding portion 7-2 in addition to a first folding portion 7-1, the second folding portion 7-2 is connected to the other end of the housing portion 5 and is folded back so as to extend from the other end toward one end of the housing portion, and when viewed along the stacking direction, the second folding portion 7-2 overlaps the charge / discharge region 9, and the end of the second folding portion 7-2 on one end side is located outside the end of the charge / discharge region 9 on one end side.

[0086] With the above configuration, since the second folded portion 7-2 overlaps the charge / discharge region 9 in addition to the first folded portion 7-1, pressure changes due to expansion and contraction are absorbed more reliably. As a result, the pressure changes applied to the charge / discharge region 9 can be made more uniform.

[0087] (Note 7) A secondary battery cell as described in Appendix 6, wherein the first folded portion 7-1 and the second folded portion 7-2 are folded to the same side in the stacking direction.

[0088] (Note 8) A secondary battery cell as described in Appendix 6, wherein the first folded portion 7-1 and the second folded portion 7-2 are folded to opposite sides in the stacking direction.

[0089] (Note 9) A secondary battery cell stack 10 comprising a plurality of secondary battery cells 1, wherein each of the plurality of secondary battery cells is a secondary battery cell as described in claim 8, the plurality of secondary battery cells 1 are stacked along the stacking direction, and in two secondary battery cells adjacent in the stacking direction, the first folded portion 7-1 of one secondary battery cell is inserted between the housing portion 5 and the second folded portion 7-2 of the other secondary battery cell.

[0090] According to the above configuration, variations in the thickness of the secondary battery cell stack 10 are suppressed, and the charge / discharge region 9 can be pressurized more uniformly.

[0091] (Note 10) A secondary battery cell as described in any of the appendices 1-4 and 6-8, wherein, when viewed along the stacking direction, the other end of the first folded portion 7-1 is located outside the outermost portion of the ends of the positive electrode layer, electrolyte layer, and negative electrode layer.

[0092] This configuration allows for more uniform pressure distribution across the battery elements. Therefore, better charge-discharge characteristics can be achieved, and damage to the battery elements can be prevented. [Explanation of Symbols]

[0093] 1...Secondary battery cell, 2...Battery element, 3...Outsole, 4...Tab, 5...Housing section, 6...Seal section, 7-1...First folded section, 7-2...Second folded section, 8-1...First sheet, 8-2...Second sheet, 9...Charge / discharge area, 10...Secondary battery cell laminate, 11...Elastic member

Claims

1. Battery elements, An outer casing for housing the aforementioned battery element, comprising an outer casing made of film, Equipped with, The aforementioned battery element has a configuration in which an electrolyte layer containing a solid electrolyte, a positive electrode layer, and a negative electrode layer are stacked along the stacking direction. The aforementioned battery element has a charge / discharge region in which the electrolyte layer, the positive electrode layer, and the negative electrode layer all overlap when viewed along the stacking direction. The exterior body is, The housing portion is the part that houses the aforementioned battery element, A sealing portion is provided, which is connected to the end of the housing portion and is a portion where the inner surfaces of the outer casings are bonded together so that the inside of the housing portion becomes a sealed space, The sealing portion has a first folded portion which is connected to one end of the housing portion and is folded back so as to extend from the one end toward the other end of the housing portion. When viewed along the stacking direction, the first folded portion overlaps the charge / discharge region, and the other end of the first folded portion is located outside the other end of the charge / discharge region. Secondary battery cell.

2. A secondary battery cell as described in claim 1, The first folded portion is further folded so that multiple overlapping regions are formed in the stacking direction. Secondary battery cell.

3. A secondary battery cell according to claim 1 or 2, Furthermore, The system includes an elastic member disposed between the housing portion and the first folded portion in the stacking direction, Secondary battery cell.

4. A secondary battery cell according to claim 1 or 2, The exterior body consists of a single sheet, Secondary battery cell.

5. A secondary battery cell stack comprising multiple secondary battery cells, Each of the plurality of secondary battery cells is a secondary battery cell as described in claim 4, The plurality of secondary battery cells are stacked along the stacking direction, The plurality of secondary battery cells are stacked such that, in the stacking direction, the direction in which the first folded portion extends from the housing portion is opposite to that of two adjacent secondary battery cells. A stack of secondary battery cells.

6. A secondary battery cell according to claim 1 or 2, The exterior body is, The stacking direction comprises a first sheet and a second sheet arranged to sandwich the battery element, The sealing portion is the part where the first sheet and the second sheet are bonded together on their inner surfaces. The sealing portion has a second folded portion in addition to the first folded portion. The second folded portion is connected to the other end of the housing portion and is folded back so as to extend from the other end toward one end of the housing portion. When viewed along the stacking direction, the second folded portion overlaps the charge / discharge region, and the end of the second folded portion on one side is located outside the end of the charge / discharge region on one side. Secondary battery cell.

7. A secondary battery cell according to claim 6, The first folded portion and the second folded portion are folded to the same side in the stacking direction. Secondary battery cell.

8. A secondary battery cell according to claim 6, The first folded portion and the second folded portion are folded to opposite sides in the stacking direction. Secondary battery cell.

9. A secondary battery cell stack comprising multiple secondary battery cells, Each of the plurality of secondary battery cells is a secondary battery cell as described in claim 8, The plurality of secondary battery cells are stacked along the stacking direction, In two secondary battery cells adjacent to each other in the stacking direction, the first folded portion of one secondary battery cell is inserted between the housing portion and the second folded portion of the other secondary battery cell. A stack of secondary battery cells.

10. A secondary battery cell as described in claim 1, When viewed along the stacking direction, the other end of the first folded portion is located further out than the outermost portion of the ends of the positive electrode layer, the electrolyte layer, and the negative electrode layer. Secondary battery cell.

Images