Secondary batteries

Abstract

To provide a technology that can suppress the lateral displacement of the negative electrode layer. [Solution] The secondary battery 1 comprises a first elastic member having a first bottom portion 2-1 and a first side wall portion 2-2 extending upward from the end of the first bottom portion, a negative electrode current collector 3 disposed on the first bottom portion 2-1, a negative electrode layer 4, an electrolyte layer 5 containing a solid electrolyte, a positive electrode layer 6, and a positive electrode current collector 7. The first side wall portion 2-2 is integral with the first bottom portion 2-1. The first side wall portion 2-2 is in contact with at least a portion of the side surface of the negative electrode layer 4.

Description

Technical Field

[0006] , , , ,

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

Background Art

[0002] Secondary batteries using an electrolyte layer containing a solid electrolyte are known. As such a secondary battery, a secondary battery having a configuration in which a negative electrode layer, an electrolyte layer, and a positive electrode layer are laminated in this order is known.

[0003] In the secondary battery as described above, the electrode layer may expand and contract during charge and discharge. In particular, the negative electrode layer is likely to expand and contract. Therefore, the secondary battery needs to have a configuration that allows the expansion and contraction of the negative electrode layer.

[0004] In relation to the above, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2022-074125) describes an invention related to a bipolar all-solid-state secondary battery including an electrode structure. Patent Document 1 discloses an electrode structure including a specific current collector having a folded structure, a specific positive electrode active material layer, a specific negative electrode active material layer, and a compression pad disposed inside the folded structure of the current collector. According to the description of Patent Document 1, this electrode structure can absorb the volume change of the negative electrode during charge and discharge and protect the negative electrode layer, so that the durability of the battery can be improved.

Prior Art Documents

Patent Documents

[0005] <00,00023>

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The negative electrode layer may expand and contract in a direction perpendicular to the stacking direction (hereinafter sometimes referred to as the lateral direction). If expansion and contraction in the lateral direction are repeated with charging and discharging, the position of the negative electrode layer may shift in the lateral direction. This lateral displacement may worsen the cycle characteristics.

[0007] Therefore, the object of the present invention is to provide a technology that can suppress the displacement of the negative electrode layer in the lateral direction. [Means for solving the problem]

[0008] In one embodiment, the secondary battery according to the present invention comprises a first elastic member having a first bottom and a first side wall portion extending upward from the end of the first bottom; a negative electrode current collector disposed on the first bottom; a negative electrode layer disposed on the negative electrode current collector; an electrolyte layer disposed on the negative electrode layer and containing a solid electrolyte; a positive electrode layer disposed on the electrolyte layer; and a positive electrode current collector disposed on the positive electrode layer. The first side wall portion is integral with the first bottom. The first side wall portion is in contact with at least a portion of the side surface of the negative electrode layer. [Effects of the Invention]

[0009] According to the present invention, a technique is provided that can suppress the displacement of the negative electrode layer in the lateral direction. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic cross-sectional view showing a secondary battery according to the first embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view showing a portion of a secondary battery related to a reference example. [Figure 3] Figure 3 is a schematic diagram showing a modified example of the first embodiment. [Figure 4] Figure 4 is a schematic cross-sectional view showing a part of a secondary battery according to the second embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view showing a part of a secondary battery according to the third embodiment. [Figure 6]FIG. 6 is a schematic cross-sectional view showing a part of a secondary battery according to the fourth embodiment. [Figure 7] FIG. 7 is a schematic cross-sectional view showing a modified example of the fourth embodiment. [Figure 8] FIG. 8 is a schematic cross-sectional view showing another modified example of the fourth embodiment. [Figure 9] FIG. 9 is a schematic cross-sectional view showing a part of a secondary battery according to the fifth embodiment. [Figure 10] FIG. 10 is a schematic cross-sectional view showing a part of a secondary battery according to the sixth embodiment. [Figure 11] FIG. 11 is a schematic view showing a modified example of the sixth embodiment. [Figure 12] FIG. 12 is a schematic cross-sectional view showing a part of a secondary battery according to the seventh embodiment. [Figure 13] FIG. 13 is a schematic view showing a part of a secondary battery according to the eighth embodiment. [Figure 14] FIG. 14 is a schematic cross-sectional view showing a modified example of the eighth embodiment. [Figure 15] FIG. 15 is a schematic cross-sectional view showing a part of a secondary battery according to the ninth embodiment. [Figure 16] FIG. 16 is a schematic cross-sectional view showing a part of a secondary battery according to the tenth embodiment. [Figure 17] FIG. 17 is a schematic cross-sectional view showing a part of a secondary battery according to the eleventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0012] (1) First Embodiment FIG. 1 is a schematic cross-sectional view showing a secondary battery 1 according to the first embodiment.

[0013] As shown in FIG. 1, the secondary battery 1 according to this embodiment has a first elastic member 2, a negative electrode current collector 3, a negative electrode layer 4, an electrolyte layer 5, a positive electrode layer 6, and a positive electrode current collector 7. These form a laminated structure. Specifically, on the first elastic member 2, the negative electrode current collector 3, the negative electrode layer 4, the electrolyte layer 5, the positive electrode layer 6, and the positive electrode current collector 7 are laminated in this order. In the example shown in FIG. 1, the secondary battery 1 has two units (a first unit and a second unit) arranged so as to sandwich the first elastic member 2 in the stacking direction. In each unit, the negative electrode current collector 3, the negative electrode layer 4, the electrolyte layer 5, the positive electrode layer 6, and the positive electrode current collector 7 are laminated in this order from the side of the first elastic member 2.

[0014] The first elastic member 2 has a first bottom portion 2-1 and a first side wall portion 2-2. The term "first" is used to distinguish it from the "second elastic member" used in other embodiments described later. In this embodiment, there is no second elastic member.

[0015] The first elastic member 2 is formed of one continuous member. That is, the first bottom portion 2-1 and the first side wall portion 2-2 are integral.

[0016] The first bottom portion 2-1 is a portion on which the negative electrode current collector 3, the negative electrode layer 4, the electrolyte layer 5, the positive electrode layer 6, and the positive electrode current collector 7 are arranged.

[0017] On the other hand, the first side wall portion 2-2 extends from the end of the first bottom portion 2-1 so as to rise along the stacking direction. The first side wall portion 2-2 is in contact with at least a part of the side surface of the negative electrode layer 4.

[0018] The negative electrode current collector 3 is provided to electrically connect the negative electrode layer 4 to an external device. As described above, the negative electrode current collector 3 is arranged on the first bottom portion 2-1. Further, the negative electrode current collector 3 penetrates the first elastic member 2 from the connection portion with the negative electrode layer 4 and extends in the lateral direction. Specifically, a gap (opening) for passing the negative electrode current collector 3 is provided in the first elastic member 2, and the negative electrode current collector 3 is drawn out to the outside through the gap.

[0019] For example, a SUS foil can be used as the negative electrode current collector 3.

[0020] The negative electrode layer 4 is located on the negative electrode current collector 3. The negative electrode layer 4 is a layer containing a negative electrode active material. The negative electrode active material is not particularly limited, but examples include silicon-based active materials. The negative electrode layer 4 is configured to take in lithium ions during charging and release lithium ions during discharging.

[0021] The electrolyte layer 5 is located on the negative electrode layer 4. The electrolyte layer 5 is configured to conduct lithium ions between the negative electrode layer 4 and the positive electrode layer 6 during charging and discharging. The electrolyte layer 5 contains a solid electrolyte. The electrolyte layer 5 as a whole is solid. The solid electrolyte is not particularly limited, but examples include argyrodite-type electrolytes.

[0022] The positive electrode layer 6 is located on the electrolyte layer 5. The positive electrode layer 6 contains a positive electrode active material. The positive electrode layer 6 may also contain a conductive additive, a solid electrolyte, and a resin binder. The positive electrode layer 6 is configured to release lithium ions during charging and to take in lithium ions during discharging.

[0023] The positive electrode current collector 7 is positioned on the positive electrode layer 6. The positive electrode current collector 7 is provided to electrically connect the positive electrode layer 6 to an external device. The positive electrode current collector 7 extends laterally from the connection point with the positive electrode layer 6. For example, aluminum foil can be used as the positive electrode current collector 7.

[0024] Next, we will explain how the secondary battery 1 operates.

[0025] During use of the secondary battery 1 according to this embodiment, charging and discharging are repeated. During charging, lithium ions move from the positive electrode layer 6 to the negative electrode layer 4. Conversely, during discharging, lithium ions move from the negative electrode layer 4 to the positive electrode layer 6. During charging and discharging, electrochemical reactions mediated by lithium ions proceed in each electrode layer. As a result of these electrochemical reactions, each electrode layer expands and contracts. The negative electrode layer 4, in particular, is prone to expansion and contraction.

[0026] In this embodiment, since the first elastic member 2 is provided, expansion and contraction of the negative electrode layer 4 in the stacking direction is permitted. Specifically, the thickness of the first bottom portion 2-1 changes with the expansion and contraction of the negative electrode layer 4 in the stacking direction. If the secondary battery 1 has a configuration that does not allow for expansion and contraction in the stacking direction, then large stresses may be generated in the components of the secondary battery 1 during charging and discharging. As a result, the components of the secondary battery 1 may be damaged. In contrast, in this embodiment, the expansion and contraction of the negative electrode layer 4 in the stacking direction is absorbed by the first bottom portion 2-1 of the first elastic member 2. Therefore, damage to the components of the secondary battery 1 is prevented.

[0027] Furthermore, according to this embodiment, since the first elastic member 2 is provided with the first side wall portion 2-2, displacement of the negative electrode layer 4 in the lateral direction is prevented. This point will be explained below with reference to a reference example.

[0028] Figure 2 is a schematic cross-sectional view showing a part of a secondary battery 1 according to a reference example. In Figure 2, the positive electrode layer 6 and positive electrode current collector 7 are not shown. Figure 2(i) shows the initial state, Figure 2(ii) shows the state after the first charge, and Figure 2(iii) shows the state after several cycles. In this reference example, the negative electrode current collector 3, the negative electrode layer 4, and the electrolyte layer 5 are laminated on the elastic member 2-A. In addition, an elastic member 2-B is positioned surrounding the negative electrode layer 4. However, elastic member 2-A and elastic member 2-B are not a single unit but separate components.

[0029] In the reference example shown in Figure 2, repeated charging and discharging can cause the negative electrode layer 4 to expand and contract not only in the stacking direction but also laterally. As a result, the position of the negative electrode layer 4 may shift laterally. Although the elastic member 2-B is arranged to surround the negative electrode layer 4, the elastic member 2-B itself may shift along with the negative electrode layer 4. Charging and discharging mainly occur in the region where the negative electrode layer 4 and the positive electrode layer 6 face each other via the electrolyte layer 5. If the negative electrode layer 4 shifts laterally, the region where the negative electrode layer 4 and the positive electrode layer 6 face each other decreases, thus degrading the cycle characteristics.

[0030] In contrast, as shown in Figure 1, according to this embodiment, the first elastic member 2 has a first bottom portion 2-1 and a first side wall portion 2-2. The first side wall portion 2-2 expands and contracts in accordance with the lateral expansion and contraction of the negative electrode layer 4. However, since the first side wall portion 2-2 is integral with the first bottom portion 2-1, it is less likely to shift laterally even after repeated charging and discharging. Therefore, the position of the negative electrode layer 4 in the lateral direction is also less likely to shift. That is, the position of the negative electrode layer 4 is less likely to shift laterally relative to the electrolyte layer 5 and the positive electrode layer 6. This prevents deterioration of cycle characteristics.

[0031] The above is an overview of this embodiment.

[0032] In this embodiment, the case in which the secondary battery 1 includes two units (a first unit and a second unit) has been described. However, the number of units included in the secondary battery 1 is not particularly limited. Figure 3 is a schematic diagram showing a modified example of this embodiment. In this modified example, the number of units included in the secondary battery 1 is one. That is, the negative electrode current collector 3, negative electrode layer 4, electrolyte layer 5, positive electrode layer 6, and positive electrode current collector 7 are each single. As shown in the example in Figure 3, the number of units may be one. Also, although not shown, the number of units may be three or more.

[0033] Furthermore, the first elastic member 2 may be any elastic material. Specifically, the first elastic member 2 may have a Young's modulus lower than that of the negative electrode layer 4, the electrolyte layer 5, and the positive electrode layer 6. The specific type of material used to make up the first elastic member 2 is not particularly limited. For example, rubber and elastomers can be used as the first elastic member 2.

[0034] Furthermore, the first side wall portion 2-2 only needs to be in contact with "at least a part" of the side surface of the negative electrode layer 4.

[0035] In a preferred embodiment, the first sidewall portion 2-2 is in contact with the "entire" area of ​​the side surface of the negative electrode layer 4. That is, the first sidewall portion 2-2 is arranged to cover the entire area of ​​the side surface of the negative electrode layer 4. With this configuration, displacement of the negative electrode layer 4 is suppressed in all lateral directions. Therefore, deterioration of cycle characteristics can be prevented more reliably.

[0036] However, the first sidewall portion 2-2 may only be in contact with a "part" of the side surface of the negative electrode layer 4. For example, if the negative electrode layer 4 is rectangular when viewed along the stacking direction, the first sidewall portion 2-2 may be provided along only one of the four sides of the negative electrode layer 4. Alternatively, the first sidewall portion 2-2 may only be in contact with a part of the negative electrode layer 4 in the stacking direction (thickness direction). Even in these cases, a certain effect can be obtained because the displacement of the negative electrode layer 4 is suppressed in the part where the first sidewall portion 2-2 is present.

[0037] Furthermore, the shape of the charge / discharge region (the region where the negative electrode layer 4, electrolyte layer 5, and positive electrode layer 6 overlap) is not particularly limited. For example, the shape of the charge / discharge region may be rectangular when viewed along the stacking direction. That is, the negative electrode layer 4, electrolyte layer 5, and positive electrode layer 6 may all be rectangular. On the other hand, the shape of the charge / discharge region does not necessarily have to be rectangular. For example, the shape of the charge / discharge region may be circular or triangular.

[0038] (2) Second embodiment Next, a second embodiment will be described. Detailed explanations will be omitted regarding aspects where the same configuration as the first embodiment can be adopted. Figure 4 is a schematic cross-sectional view showing a part of the secondary battery 1 according to the second embodiment.

[0039] As shown in Figure 4, in this embodiment, the first side wall portion 2-2 is in contact with the side surface of the negative electrode current collector 3. That is, in the example shown in Figure 1 (first embodiment), the first side wall portion 2-2 is separated from the side surface of the negative electrode current collector 3, and a space is formed between them. In contrast, as shown in Figure 4, in this embodiment, the first side wall portion 2-2 is in contact with the side surface of the negative electrode current collector 3, and there is no space between them.

[0040] According to this embodiment, since there is no space between the first side wall portion 2-2 and the negative electrode current collector 3, the position of the first elastic member 2 relative to the negative electrode current collector 3 is less likely to shift. As a result, the positional shift of the negative electrode layer 4 is more reliably prevented, and the cycle characteristics are improved.

[0041] (3) Third Embodiment Next, a third embodiment will be described. Detailed explanations will be omitted for aspects where the same configuration as the previously described embodiments can be adopted. Figure 5 is a schematic cross-sectional view showing a part of the secondary battery 1 according to the third embodiment.

[0042] As shown in Figure 5, in this embodiment, the first sidewall portion 2-2 is in contact with at least a portion of the side surface of the electrolyte layer 5. That is, the first sidewall portion 2-2 extends from the end of the first bottom portion 2-1 along the stacking direction to a position that extends beyond the negative electrode layer 4 and contacts the electrolyte layer 5.

[0043] According to this embodiment, the side surface of the negative electrode layer 4 is covered by the first side wall portion 2-2 over its entire length in the stacking direction. Therefore, displacement of the negative electrode layer 4 in the lateral direction is more reliably prevented.

[0044] (4) Fourth Embodiment Next, a fourth embodiment will be described. Detailed explanations will be omitted for aspects where the same configuration as the previously described embodiments can be adopted. Figure 6 is a schematic cross-sectional view showing a part of the secondary battery 1 according to the fourth embodiment.

[0045] In this embodiment, a fixing portion 8 is added. The fixing portion 8 is positioned above and below the first side wall portion 2-2 in the stacking direction. The fixing portion 8 is configured to fix the first side wall portion 2-2 from above and below in the stacking direction.

[0046] In the example shown in Figure 6, the fixing portion 8 is realized by the edge of the electrolyte layer 5. That is, the outer peripheral edge of the electrolyte layer 5 is located outside the outer peripheral edge of the negative electrode layer 4 when viewed along the stacking direction. The edge of the first sidewall portion 2-2 in the stacking direction is in contact with the electrolyte layer 5 and is covered by the electrolyte layer 5. More specifically, the entire edge of the first sidewall portion 2-2 in the stacking direction is in contact with the electrolyte layer 5. With this configuration, the first sidewall portion 2-2 is sandwiched between the fixing portion 8 above and below in the stacking direction. As a result, the first sidewall portion 2-2 is pressed down and fixed by the fixing portion 8.

[0047] According to this embodiment, since the first side wall portion 2-2 is fixed by the fixing portion 8, displacement of the first elastic member 2 itself is suppressed. As a result, displacement of the negative electrode layer 4 is prevented more reliably. This makes it possible to more reliably prevent deterioration of cycle characteristics.

[0048] Figure 7 is a schematic cross-sectional view showing a modified example of the fourth embodiment. In this modified example, a step is formed at the end of the electrolyte layer 5. Also, a step corresponding to the shape of the end of the electrolyte layer 5 is formed at the end of the first side wall portion 2-2 in the stacking direction. The end of the first side wall portion 2-2 in the stacking direction is in contact with the electrolyte layer 5 in part and is fixed by the electrolyte layer 5. Even with this configuration, the end of the electrolyte layer 5 functions as a fixing portion 8, fixing the first elastic member 2. As a result, the first elastic member 2 is pressed down and fixed from above and below in the stacking direction. Consequently, displacement of the first elastic member 2 and the negative electrode layer 4 is prevented.

[0049] Figure 8 is a schematic cross-sectional view showing another modified example of the fourth embodiment. The secondary battery 1 according to this modified example further includes a second elastic member 9. The second elastic member 9 is an elastic member provided on the positive electrode layer 6 side. That is, the second elastic member 9 is positioned on the positive electrode current collector 7. The second elastic member 9, like the first elastic member 2, has a bottom portion (second bottom portion 9-1) and a side wall portion (second side wall portion 9-2). The second side wall portion 9-2 extends upward from the end of the second bottom portion 9-1 and covers at least a portion of the side surface of the positive electrode layer 6. Here, the end of the first side wall portion 2-2 in the stacking direction is in contact with the second side wall portion 9-2. In this modified example, the second side wall portion 9-2 functions as a fixing portion 8. That is, the first side wall portion 2-2 is fixed vertically in the stacking direction by the second side wall portion 9-2. Even with this configuration, the first elastic member 2 is fixed by the second elastic member 9, thus preventing displacement of the first elastic member 2 in the lateral direction.

[0050] In other words, in this embodiment, the fixing portion 8 does not necessarily have to be the electrolyte layer 5, but may be other components different from the electrolyte layer 5.

[0051] In the modified example shown in Figure 8, it is preferable that the end of the first side wall portion 2-2 in the stacking direction is bonded to the second side wall portion 9-2. With this configuration, displacement of the first elastic member 2 is more reliably suppressed.

[0052] (5) Fifth embodiment Next, a fifth embodiment will be described. Detailed explanations will be omitted for aspects where the same configuration as the previously described embodiments can be adopted. Figure 9 is a schematic cross-sectional view showing a part of the secondary battery 1 according to the fifth embodiment.

[0053] In this embodiment, the positional relationship between the end of the negative electrode current collector 3 and the end of the negative electrode layer 4 has been carefully designed. Specifically, when viewed along the stacking direction, the outer edge of the negative electrode layer 4 is located inside the outer edge of the negative electrode current collector 3 (see position "A" in Figure 9). More specifically, even when the negative electrode layer 4 is in a charge / discharge state that causes it to expand the most, the outer edge of the negative electrode layer 4 is located inside the outer edge of the negative electrode current collector 3.

[0054] According to this embodiment, even if the negative electrode layer 4 expands laterally, an electron conduction path in the stacking direction is ensured. If the outer edge of the negative electrode layer 4 is located outside the outer edge of the negative electrode current collector 3, that is, if the negative electrode layer 4 protrudes from the negative electrode current collector 3, then electrons and ions will not conduct easily in the "protruding portion" of the negative electrode layer 4 during charging and discharging. In other words, the charge-discharge reaction will not proceed easily. As a result, the cycle characteristics will deteriorate. In contrast, according to this embodiment, since there is no such "protruding portion," the cycle characteristics will be improved.

[0055] (6) Sixth Embodiment Next, a sixth embodiment will be described. Details regarding the ability to adopt the same configuration as in the previously described embodiments will be omitted. Figure 10 is a schematic cross-sectional view showing a part of the secondary battery 1 according to the sixth embodiment.

[0056] In this embodiment, the positional relationship between the outer edges of the negative electrode layer 4 and the electrolyte layer 5 has been carefully designed. Specifically, when viewed along the stacking direction, the outer edge of the negative electrode layer 4 is located inward from the outer edge of the electrolyte layer 5 (see position A in Figure 10).

[0057] According to this embodiment, even if the negative electrode layer 4 expands laterally, an electron conduction path in the stacking direction is ensured. If the outer edge of the negative electrode layer 4 is located outside the outer edge of the electrolyte layer 5, that is, if the negative electrode layer 4 protrudes from the electrolyte layer 5, then electrons and ions will not conduct easily in that "protruding portion" during charging and discharging. In other words, the charge-discharge reaction will not proceed easily. As a result, the cycle characteristics will deteriorate. In contrast, according to this embodiment, since there is no such "protruding portion," the cycle characteristics will be improved.

[0058] Figure 11 is a schematic diagram showing a modified version of this embodiment. In this modified version, when viewed along the stacking direction, the outer edge of the negative electrode layer 4 is located inward from the outer edge of the electrolyte layer 5 (see position A-1 in Figure 11) and the outer edge of the negative electrode current collector 3 (see position A-2 in Figure 11). Also, the ends (upper and lower ends) of the first side wall portion 2-2 in the stacking direction are in contact with the electrolyte layer 5 over their entire surface. With this configuration, since there is no portion of the negative electrode layer 4 that protrudes from the electrolyte layer 5 and the negative electrode current collector 3, the cycle characteristics are improved. In addition, since the first elastic member 2 is fixed by the electrolyte layer 5 above and below the first side wall portion 2-2, displacement of the first elastic member 2 is suppressed, and displacement of the negative electrode layer 4 is more reliably suppressed.

[0059] (7) Seventh Embodiment Next, a seventh embodiment will be described. Detailed explanations will be omitted for aspects where the same configuration as the previously described embodiments can be adopted. Figure 12 is a schematic cross-sectional view showing a part of the secondary battery 1 according to the seventh embodiment.

[0060] In this embodiment, when viewed along the stacking direction, the outer edge of the electrolyte layer 5 is located outside the outer edge of the first sidewall portion 2-2. Furthermore, the electrolyte layer 5 covers a portion of the outer surface of the first sidewall portion 2-2.

[0061] Specifically, the electrolyte layer 5 has an electrolyte layer base portion 5-1 and an outer covering portion 5-2.

[0062] The electrolyte layer base portion 5-1 is the portion positioned on the negative electrode layer 4 and the first sidewall portion 2-2. On the other hand, the outer covering portion 5-2 extends upward from the end of the electrolyte layer base portion 5-1 along the lamination direction and covers at least a portion of the outer surface of the first sidewall portion 2-2.

[0063] With this configuration, the lateral movement of the first elastic member 2 is hindered by the outer covering portion 5-2 of the electrolyte layer 5. In other words, the first elastic member 2 is fixed by the electrolyte layer 5. Since displacement of the first elastic member 2 in the lateral direction is prevented, displacement of the negative electrode layer 4 is also prevented, and deterioration of the cycle characteristics is more reliably prevented.

[0064] (8) Eighth embodiment Next, we will describe the eighth embodiment. Note that we will omit detailed explanations regarding aspects where the same configuration as the previously described embodiments can be adopted.

[0065] Figure 13 is a schematic diagram showing a part of the secondary battery 1 according to the eighth embodiment. Specifically, Figure 13 shows the positional relationship between the negative electrode current collector 3 and the first side wall portion 2-2 as a plan view.

[0066] Figure 13 defines a first direction and a second direction as directions perpendicular to the stacking direction. The first and second directions are perpendicular to each other.

[0067] The charge / discharge region 12 is rectangular in shape. That is, although not shown in the diagram, the negative electrode layer 4, the electrolyte layer 5, and the positive electrode layer 6 are all rectangular in shape.

[0068] The first side wall portion 2-2 is also rectangular in shape, corresponding to the shape of the charge / discharge region 12 (i.e., the shape of the negative electrode layer 4). In other words, the first side wall portion 2-2 is provided so as to surround the four sides of the negative electrode layer 4.

[0069] On the other hand, the negative electrode current collector 3 extends from the charge / discharge region 12 toward both sides in the first direction through the gap 10 provided in the first elastic member 2.

[0070] In the second direction, the two sides (sides 11-1 and 11-2) of the negative electrode current collector 3 are each covered by the first side wall portion 2-2. That is, the first side wall portion 2-2 is positioned to cover the two sides (sides 11-1 and 11-2) of the negative electrode current collector 3.

[0071] With the configuration described above, the position of the negative electrode current collector 3 is fixed by the first side wall portion 2-2 on two sides (sides 11-1 and side 11-2). Therefore, the relative position of the first elastic member 2 and the negative electrode current collector 3 is easily fixed. As a result, misalignment of each component constituting the secondary battery 1 is more reliably suppressed, and the cycle characteristics are improved.

[0072] On the other hand, the first side wall portion 2-2 may cover three sides of the negative electrode current collector 3. Figure 14 is a schematic cross-sectional view showing a modified example of this embodiment. In this modified example, the negative electrode current collector 3 extends from the charge / discharge region 12 to one side in the first direction. That is, the negative electrode current collector 3 extends laterally from one of the four sides of the charge / discharge region 12. The first side wall portion 2-2 covers the sides of the negative electrode current collector 3 in the portions corresponding to the other three sides. That is, the first side wall portion 2-2 is provided so as to cover three sides (sides 11-1 to 11-3) of the negative electrode current collector. With this configuration, since the three sides of the negative electrode current collector 3 are covered by the first side wall portion 2-2, the relative positional relationship between the first elastic member 2 and the negative electrode current collector 3 is more reliably fixed. As a result, misalignment of each component constituting the secondary battery 1 is more reliably suppressed, and the cycle characteristics are improved.

[0073] (9) The ninth embodiment Next, we will describe the ninth embodiment. Note that we will omit detailed explanations regarding aspects where the same configuration as the previously described embodiments can be adopted.

[0074] Figure 15 is a schematic cross-sectional view showing a part of the secondary battery 1 according to the ninth embodiment. In this embodiment, the thickness of the first bottom portion 2-1 and the first side wall portion 2-2 has been modified.

[0075] Specifically, the thickness a of the first bottom portion 2-1 in the stacking direction is greater than the thickness b of the first sidewall portion 2-2 in the lateral direction (direction perpendicular to the stacking direction) in the portion located on the side of the negative electrode layer 4.

[0076] According to this embodiment, since the thickness b of the first elastic member 2 is small in the portion located on the side surface of the negative electrode layer 4, the size of the first elastic member 2 when viewed along the stacking direction can be reduced. As a result, the size of the secondary battery 1 can be reduced. Therefore, the energy density can be improved.

[0077] (10) Tenth Embodiment Next, we will describe the tenth embodiment. Note that we will omit detailed explanations regarding aspects where the same configuration as the previously described embodiments can be adopted.

[0078] Figure 16 is a schematic cross-sectional view showing a part of the secondary battery 1 according to the tenth embodiment. In this embodiment, a second elastic member 9 is arranged on the positive electrode current collector 7, similar to the example shown in Figure 8 (modified example of the fourth embodiment). The second elastic member 9 comprises a second bottom portion 9-1 and a second side wall portion 9-2. The second bottom portion 9-1 is the part arranged on the positive electrode current collector 7. On the other hand, the second side wall portion 9-2 extends upward from the end of the second bottom portion 9-1 and covers at least a part of the side surface of the positive electrode layer 6.

[0079] In this embodiment, the thicknesses of the first elastic member 2 and the second elastic member 9 are different. Specifically, in the lamination direction, the thickness a of the first bottom portion 2-1 is greater than the thickness c of the second bottom portion 9-1.

[0080] According to this embodiment, since the second elastic member 9 is provided, the expansion and contraction of the positive electrode layer 6, as well as the negative electrode layer 4, are addressed. Expansion and contraction during charging and discharging can occur not only in the negative electrode layer 4 but also in the positive electrode layer 6. According to this embodiment, since the second elastic member 9 is provided, expansion and contraction of the positive electrode layer 6 in the stacking direction is permitted, and displacement of the positive electrode layer 6 in the lateral direction is prevented.

[0081] In addition, according to this embodiment, the energy density can be improved because the thickness c of the second bottom portion 9-1 is small. Although the positive electrode layer 6 expands and contracts with charging and discharging, the amount of expansion and contraction is less than that of the negative electrode layer 4. Therefore, from the viewpoint of allowing expansion and contraction in the stacking direction, it is not a problem if the thickness c of the second elastic member 9 is smaller than the thickness a of the first elastic member 2. On the other hand, by reducing the thickness c, the overall thickness of the secondary battery 1 in the stacking direction can be reduced. As a result, the energy density can be improved.

[0082] In this embodiment, preferably, the thickness c is equal to or greater than the thickness b (the thickness in the direction perpendicular to the lamination direction of the first sidewall portion 2-2 in the portion located on the side surface of the negative electrode layer 4).

[0083] (11) Eleventh Embodiment Next, we will describe the eleventh embodiment. Note that we will omit detailed explanations regarding aspects where the same configuration as the previously described embodiments can be adopted.

[0084] Figure 17 is a schematic cross-sectional view showing a part of the secondary battery 1 according to the eleventh embodiment. In this embodiment, the direction in which the negative electrode current collector 3 and the positive electrode current collector 7 extend from the charge / discharge region has been devised. Specifically, as shown in Figure 17, the negative electrode current collector 3 and the positive electrode current collector 7 extend from the charge / discharge region in opposite directions to each other.

[0085] According to this embodiment, since the negative electrode current collector 3 and the positive electrode current collector 7 extend in opposite directions, the thickness of the secondary battery 1 is easily averaged. This makes it easier for the pressure distribution applied to the electrode layer and electrolyte layer to become uniform. As a result, the short-circuit rate can be reduced and the cycle characteristics can be improved.

[0086] In this embodiment, the case where the negative electrode current collector 3 and the positive electrode current collector 7 extend in opposite directions has been described. However, the direction in which each current collector extends may be offset in the stacking direction so as to complete a full circle. For example, the direction in which the current collectors extend may be offset by 90° between adjacent current collectors in the stacking direction. Even with such a configuration, variations in the thickness of the secondary battery 1 can be reduced, and the cycle characteristics can be improved.

[0087] [Note] The present invention has been described above with reference to embodiments and their modifications. A representative configuration and its effects included in the present invention are summarized below as an appendix.

[0088] (Note 1) A secondary battery comprising: a first elastic member 2 having a first bottom portion 2-1 and a first side wall portion 2-2 extending upward from the end of the first bottom portion; a negative electrode current collector 3 disposed on the first bottom portion 2-1; a negative electrode layer 4 disposed on the negative electrode current collector; an electrolyte layer 5 disposed on the negative electrode layer and containing a solid electrolyte; a positive electrode layer 6 disposed on the electrolyte layer; and a positive electrode current collector 7 disposed on the positive electrode layer, wherein the first side wall portion 2-2 is integral with the first bottom portion 2-1 and the first side wall portion 2-2 is in contact with at least a portion of the side surface of the negative electrode layer 4.

[0089] According to the above configuration, the first side wall portion 2-2 suppresses lateral displacement of the negative electrode layer 4.

[0090] (Note 2) A secondary battery as described in Appendix 1, wherein the first side wall portion 2-2 is in contact with the side surface of the negative electrode current collector 3.

[0091] With the above configuration, no space is formed between the first side wall portion 2-2 and the negative electrode current collector 3, thus preventing misalignment between the first elastic member 2 and the negative electrode current collector 3. As a result, misalignment of the negative electrode layer 4 is more reliably prevented.

[0092] (Note 3) A secondary battery as described in Appendix 1 or 2, wherein the first side wall portion 2-2 is in contact with at least a part of the side surface of the electrolyte layer 5.

[0093] According to the above configuration, the first sidewall portion 2-2 covers the entire side surface of the negative electrode layer 4 in the stacking direction. Therefore, displacement of the negative electrode layer 4 in the lateral direction is more reliably prevented.

[0094] (Note 4) A secondary battery as described in any of Appendix 1 to 3, further comprising a fixing portion 8 positioned above and below the first side wall portion 2-2 in the stacking direction and configured to press down on the first side wall portion 2-2 in the stacking direction.

[0095] According to the above configuration, the first sidewalls 2-2 are fixed from both sides in the stacking direction, so the displacement of the first elastic member 2 is more reliably suppressed. As a result, the displacement of the negative electrode layer 4 is also more reliably suppressed.

[0096] (Note 5) A secondary battery as described in any of the appendices 1 to 4, wherein, when viewed along the stacking direction, the outer edge of the negative electrode layer 4 is located inward from the outer edge of the negative electrode current collector 3.

[0097] According to the above configuration, since there is no portion of the negative electrode layer 4 that protrudes laterally from the negative electrode current collector 3, an electron conduction path is secured in the stacking direction. As a result, the cycle characteristics are improved.

[0098] (Note 6) A secondary battery as described in any of Appendix 1 to 5, wherein, when viewed along the stacking direction, the outer edge of the negative electrode layer 4 is located inward from the outer edge of the electrolyte layer 5.

[0099] According to the above configuration, since there is no portion of the negative electrode layer 4 that protrudes laterally from the electrolyte layer 5, an electron conduction path is secured in the stacking direction. As a result, the cycle characteristics are improved.

[0100] (Note 7) A secondary battery as described in Appendix 6, wherein the end of the first side wall portion 2-2 in the stacking direction is in contact with the electrolyte layer 5 over its entire surface.

[0101] According to the above configuration, in the stacking direction, the first sidewall portion 2-2 is pressed down and fixed by the electrolyte layer 5. As a result, displacement of the first elastic member 2 is suppressed, and displacement of the negative electrode layer 4 is more reliably suppressed.

[0102] (Note 8) A secondary battery as described in Appendix 6 or 7, wherein, when viewed along the stacking direction, the outer peripheral edge of the electrolyte layer 5 is located outside the outer peripheral edge of the first side wall portion 2-2, and the electrolyte layer 5 has an outer covering portion 5-2 that covers at least a part of the outer surface of the first side wall portion 2-2.

[0103] According to the above configuration, the external coating portion 5-2 suppresses the displacement of the first elastic member 2. As a result, the displacement of the negative electrode layer 4 is more reliably suppressed.

[0104] (Note 9) A secondary battery as described in any of the appendices 1 to 8, wherein the first side wall portion 2-2 is provided so as to cover two or three sides of the negative electrode current collector 3.

[0105] According to the above configuration, since multiple surfaces of the negative electrode current collector 3 are covered by the first side wall portion 2-2, displacement of the first elastic member 2 relative to the negative electrode current collector 3 is suppressed. As a result, displacement of the negative electrode layer 4 is more reliably suppressed.

[0106] (Note 10) A secondary battery as described in any of the appendices 1 to 9, wherein the thickness of the first bottom portion 2-1 in the stacking direction is greater than the thickness of the first side wall portion 2-2 in the direction perpendicular to the stacking direction in the portion located on the side surface of the negative electrode layer 4.

[0107] According to the above configuration, the size of the first elastic member 2 when viewed along the stacking direction can be reduced. Therefore, the energy density can be improved.

[0108] (Note 11) A secondary battery as described in any of Appendix 1 to 10, further comprising a second elastic member 9 disposed on a positive electrode current collector 7, wherein the second elastic member 9 comprises a second bottom portion 9-1 and a second side wall portion 9-2 extending upward from the end of the second bottom portion 9-1 and covering at least a portion of the side surface of the positive electrode layer 6, and in the stacking direction, the first bottom portion 2-1 is thicker than the second bottom portion 9-1.

[0109] According to the above configuration, the presence of the second elastic member 9 allows for expansion and contraction of the positive electrode layer 6 in the stacking direction. Furthermore, displacement of the positive electrode layer 6 in the lateral direction is prevented. On the other hand, since the second bottom portion 9-1 is thinner than the first bottom portion 2-1, the increase in the thickness of the secondary battery 1 due to the provision of the second elastic member 9 is minimized. Therefore, the energy density is improved. [Explanation of Symbols]

[0110] 1...Secondary battery, 2...First elastic member, 2-1...First bottom, 2-2...First side wall, 3...Negative electrode current collector, 4...Negative electrode layer, 5...Electrolyte layer, 5-1...Electrolyte layer base, 5-2...Outer coating, 6...Positive electrode layer, 7...Positive electrode current collector, 8...Fixing part, 9...Second elastic member, 9-1...Second bottom, 9-2...Second side wall, 10...Gap, 11-1~11-2...Side, 12...Charge / discharge region

Claims

1. A first elastic member comprising a first bottom portion and a first side wall portion extending upward from the end of the first bottom portion, A negative electrode current collector is positioned on the first bottom portion, A negative electrode layer is disposed on the negative electrode current collector, An electrolyte layer, which is disposed on the negative electrode layer and contains a solid electrolyte, A positive electrode layer is disposed on the electrolyte layer, A positive electrode current collector is disposed on the positive electrode layer, Equipped with, The first side wall portion is integral with the first bottom portion, The first side wall portion is in contact with at least a part of the side surface of the negative electrode layer. Secondary battery.

2. A secondary battery according to claim 1, The first side wall portion is in contact with the side surface of the negative electrode current collector. Secondary battery.

3. A secondary battery according to claim 1 or 2, The first side wall portion is in contact with at least a part of the side surface of the electrolyte layer. Secondary battery.

4. A secondary battery according to claim 1 or 2, Furthermore, A fixing portion is positioned above and below the first side wall in the stacking direction and is configured to press down on the first side wall in the stacking direction. Equipped with, Secondary battery.

5. A secondary battery according to claim 1 or 2, When viewed along the stacking direction, the outer edge of the negative electrode layer is located inward from the outer edge of the negative electrode current collector. Secondary battery.

6. A secondary battery according to claim 1 or 2, When viewed along the stacking direction, the outer edge of the negative electrode layer is located inward from the outer edge of the electrolyte layer. Secondary battery.

7. A secondary battery according to claim 6, The end of the first sidewall in the stacking direction is in contact with the electrolyte layer over its entire surface. Secondary battery.

8. A secondary battery according to claim 6, When viewed along the stacking direction, the outer peripheral edge of the electrolyte layer is located outside the outer peripheral edge of the first side wall portion. The electrolyte layer has an outer covering portion that covers at least a part of the outer surface of the first side wall portion. Secondary battery.

9. A secondary battery according to claim 1 or 2, The first side wall portion is provided so as to cover two or three sides of the negative electrode current collector. Secondary battery.

10. A secondary battery according to claim 1 or 2, The thickness of the first bottom portion in the stacking direction is greater than the thickness of the first sidewall portion in the portion located on the side of the negative electrode layer in the direction perpendicular to the stacking direction. Secondary battery.

11. A secondary battery according to claim 1 or 2, Furthermore, A second elastic member is disposed on the positive electrode current collector. Equipped with, The second elastic member is The second bottom and, It comprises a second side wall portion that extends upward from the end of the second bottom portion and covers at least a portion of the side surface of the positive electrode layer, In the stacking direction, the first bottom is thicker than the second bottom. Secondary battery.

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