Secondary battery, battery pack, and vehicle

Abstract

Embodiments of the present application relate to a secondary battery, a battery pack, and a vehicle. Provided is a secondary battery excellent in charge-discharge cycle performance, a battery pack including the secondary battery, and a vehicle including the battery pack. According to an embodiment, provided is a secondary battery including a positive electrode, a plurality of negative electrodes, and a separator. The negative electrode includes a negative electrode current collector, a negative electrode tab extending along a first direction, and a layer containing a negative electrode active material. The negative electrode has a second negative electrode end portion located at an end with respect to a second direction opposite to the first direction. The separator has a first separator end portion and a second separator end portion. The second separator end portion protrudes toward the second direction more than the second negative electrode end portion. When a distance between the second negative electrode end portion and the second separator end portion is set as Ln, a minimum value Lnmin of Ln is 1.5 mm or more. A maximum value Lnmax of Ln is 1.0 mm or more. A difference between Lnmax and Lnmin is 1.0 mm or more. min max min ​​​

Description

Technical Field

[0001] Embodiments of the present invention relate to secondary batteries, battery packs, and vehicles. Background Technology

[0002] Rechargeable batteries are used repeatedly by charging and discharging, which helps reduce waste and they are widely used as backup power sources for portable devices where AC power is unavailable and when AC power is cut off. In recent years, research has expanded their applications to include automotive use, backup power for solar cells, and power equalization, leading to increasing demands for improved performance in areas such as capacity, high-temperature operation, and safety.

[0003] Non-aqueous electrolyte secondary batteries are rechargeable batteries that utilize the movement of lithium ions between the positive and negative electrodes for charging and discharging. Because they use organic solvents in the electrolyte, non-aqueous electrolyte secondary batteries can achieve higher voltages compared to nickel-cadmium or nickel-metal hydride secondary batteries that use aqueous solutions. Currently, practically applicable non-aqueous electrolyte secondary batteries use transition metal oxides such as lithium-cobalt composite oxides and lithium-nickel composite oxides as the positive electrode active material. Furthermore, carbon-based materials and titanium-containing oxides are used as negative electrode active materials. As the electrolyte, a liquid non-aqueous electrolyte is used, for example, obtained by dissolving lithium salts such as LiPF6 and LiBF4 in organic solvents such as cyclic carbonates and chain carbonates. The above-mentioned positive electrode active materials, based on lithium metal, have an average operating potential of approximately 3.4V to 3.8V (vs. Li / Li). + The highest potential reached during charging is 4.1V to 4.3V (vs. Li / Li). + On the other hand, the operating potential range of the carbon-based materials in the above-mentioned negative electrode active materials, with lithium metal as a reference, is approximately 0.05V to 0.5V (vs. Li / Li). + Furthermore, lithium titanate (Li4Ti5O3), a representative compound of titanium-containing composite oxides and a negative electrode active material, is also mentioned. 12 The operating potential range is 1.55V (vs. Li / Li). + By combining these positive and negative electrode materials, the battery voltage becomes 2.2V to 3.8V, and the maximum charging voltage becomes 2.7V to 4.3V.

[0004] Secondary batteries using titanium-containing composite oxides in the negative electrode can improve charge-discharge cycle life, output performance, and safety, and are being put into practical use. Various titanium-containing composite oxides have been proposed, but spinel-type lithium titanate (e.g., Li₄Ti₅O₃) remains a popular choice. 12 There are many reports about lithium titanate (TLO), which has already been used in commercially available products. It should be noted that Li4Ti5O, as an example of spinel-type lithium titanate,12 The lowest potential reached during charging, based on lithium metal, is 1.0V to 1.45V (vs. Li / Li). + The highest potential reached during discharge is 1.6V to 2.0V (vs. Li / Li). + On the other hand, monoclinic titanium dioxide (TiO2, commonly known as TiO2(B)) and niobium-titanium composite oxides (e.g., monoclinic Nb2TiO7, orthorhombic niobium-titanium composite oxides) can achieve larger capacities than spinel-type lithium titanate. It should be noted that the lowest charging potential reached by monoclinic titanium dioxide, with lithium metal as a reference, is 0.9V–1.45V (vs. Li / Li). + The highest potential reached during discharge is 1.6V to 2.5V (vs. Li / Li). + As an example of a niobium-titanium composite oxide, the lowest charging potential reached by monoclinic Nb₂TiO₇ is 0.6V–1.40V (vs. Li / Li) as a reference for lithium metal. + The highest potential reached during discharge is 1.8V to 3.0V (vs. Li / Li). + ).

[0005] If the positive and negative electrodes of such a configuration are brought into electrical contact, a short circuit will occur. Therefore, in order to prevent contact between the positive and negative electrodes, a sheet-like diaphragm made of an electrically insulating material can be used. Summary of the Invention

[0006] The problem to be solved by the present invention is to provide a secondary battery with excellent charge-discharge cycle performance, a battery pack including the secondary battery, and a vehicle including the battery pack.

[0007] According to an embodiment, a secondary battery is provided. The secondary battery includes a positive electrode, a plurality of negative electrodes, and a separator disposed between the positive and negative electrodes. Each of the plurality of negative electrodes includes a negative current collector, a negative electrode tab, and a layer containing a negative electrode active material disposed on the negative current collector. The negative current collector includes aluminum or an aluminum alloy. The negative electrode tab is electrically connected to the negative current collector and extends along a first direction. The negative electrode has a second negative terminal portion located at an end with respect to a second direction opposite to the first direction. The separator has a first separator end portion located at an end with respect to the first direction and a second separator end portion located at an end with respect to the second direction. The second separator end portion protrudes toward the second direction compared to any of the second negative terminal portions included in each of the plurality of negative electrodes. When the distance between the second negative terminal portions included in each of the plurality of negative electrodes and the second separator end portion is set to Ln, the smallest value of Ln is Ln. min The maximum value is Ln max Ln min It is 1.5mm or more. Ln min With Lnmax The difference is greater than 1.0 mm.

[0008] The secondary battery constructed as described above can improve charge-discharge cycle performance. Attached Figure Description

[0009] Figure 1 This is a partial cutaway perspective view schematically illustrating an example of a secondary battery involved in an embodiment.

[0010] Figure 2 It is Figure 1 The cross-sectional view of part B of the secondary battery shown is magnified.

[0011] Figure 3 It means Figure 1 The diagram shows a plan view of the negative electrode contained in the secondary battery.

[0012] Figure 4 It means Figure 1 The diagram shows a plan view of the positive electrode contained in the secondary battery.

[0013] Figure 5 yes Figure 2 Enlarged image.

[0014] Figure 6 It means Figure 2 The electrode group shown is different from Figure 5 A magnified view of the part.

[0015] Figure 7 This is a three-dimensional diagram showing another example of an electrode assembly.

[0016] Figure 8 This is a perspective view that schematically illustrates an example of a battery pack involved in an embodiment.

[0017] Figure 9 This is an exploded perspective view that schematically illustrates an example of a battery pack involved in an embodiment.

[0018] Figure 10 It means Figure 8 The diagram shows a block diagram of an example of the circuitry for the battery pack.

[0019] Figure 11 This is a partial perspective view that schematically represents an example of a vehicle involved in the implementation.

[0020] Figure 12 This is a diagram that schematically illustrates an example of a control system for the electrical system in a vehicle according to the embodiment.

[0021] (Explanation of symbols) 1…Electrode assembly, 2…Outer packaging component, 3…Negative electrode, 4…Diaphragm, 5…Positive electrode, 6…Negative terminal, 7…Positive terminal, 21…Busbar, 22…Positive side lead, 23…Negative side lead, 24…Adhesive tape, 31…Container, 32…Lid, 33…Protective sheet, 34…Printed circuit board, 35…Wiring, 40…Vehicle body, 41…Vehicle power supply, 43…External terminal, 44…Converter, 45…Driver 200… battery pack, 300… battery pack, 342… positive side connector, 343… negative side connector, 345… thermistor, 346… protection circuit, 352… positive side terminal, 353… negative side terminal, 400… vehicle, 411… battery management device, 412… communication bus, 413… positive terminal, 414… negative terminal, 415… switching device, 417… negative input terminal, 418… positive input terminal. Detailed Implementation

[0022] As an electrode laminate, a laminate in which a positive electrode and a negative electrode are alternately laminated, sandwiching a separator between them, is sometimes used. In order to suppress short circuits between the positive and negative electrodes, the separator is arranged such that the ends of the separator are located on the outer side compared to the ends of the positive and negative electrodes.

[0023] However, in such an electrode stack, if all the ends of the negative electrodes are aligned in the thickness direction, it is easy to apply excessive force to the separator that contacts the ends of the negative electrodes. For example, in the manufacture of the electrode stack, sometimes after the positive electrode, negative electrode, and separator are stacked, they are pressed along the thickness direction. In such cases, the ends of the negative electrodes are pressed against a portion of the separator from both sides along the thickness direction, thus easily applying excessive force to the separator locally. As a result, short circuits become more likely to occur.

[0024] According to a first embodiment, a secondary battery is provided. The secondary battery includes a positive electrode, a plurality of negative electrodes, and a separator disposed between the positive and negative electrodes. Each of the plurality of negative electrodes includes a negative current collector, a negative electrode tab, and a layer containing a negative electrode active material disposed on the negative current collector. The negative current collector comprises aluminum or an aluminum alloy. The negative electrode tab is electrically connected to the negative current collector and extends along a first direction. The negative electrode has a second negative terminal portion located at an end with respect to a second direction opposite to the first direction. The separator has a first separator end portion located at an end with respect to the first direction and a second separator end portion located at an end with respect to the second direction. The second separator end portion protrudes toward the second direction compared to any of the second negative terminal portions included in each of the plurality of negative electrodes. When the distance between the second negative terminal portions included in each of the plurality of negative electrodes and the second separator end portion is set to Ln, the smallest value of Ln is Ln. min The maximum value is Ln max Ln min It is 1.5mm or more. Ln minWith Ln max The difference is greater than 1.0 mm.

[0025] Anode current collectors containing aluminum or aluminum alloys are highly flexible and easy to process.

[0026] The end of the second diaphragm protrudes in a second direction compared to any of the second negative terminals included in each of the plurality of negative terminals. Therefore, it is possible to suppress short circuits between the negative and positive terminals.

[0027] The minimum value Ln among the distances Ln between the second negative electrode end and the second diaphragm end of each of the multiple negative electrodes. min The distance is 1.5 mm or more. In other words, the distance between the second negative electrode portion included in each of the multiple negative electrodes and the end of the second diaphragm is 1.5 mm or more. Therefore, even if the negative electrode is displaced in the second direction due to external force, the outward protrusion of the negative electrode compared to the end of the second diaphragm can be suppressed. Therefore, short circuits can be suppressed, and thus charge-discharge cycle performance can be improved.

[0028] The largest value Ln among the distances Ln between the second negative electrode end and the second diaphragm end of each of the multiple negative electrodes. max With Ln min The difference is 1.0 mm or more. That is, the second negative electrode portion contained in each of the multiple negative electrodes is not aligned along the thickness direction. Therefore, it is possible to suppress diaphragm damage caused by locally applied strong force to the diaphragm. As a result, short circuits are less likely to occur, thus improving charge-discharge cycle performance.

[0029] The secondary battery involved in the implementation method is further explained with reference to the accompanying drawings.

[0030] The secondary battery according to the first embodiment includes a negative electrode, a positive electrode, and a separator. The negative electrode, positive electrode, and separator can constitute an electrode assembly. The secondary battery may further include an electrolyte. The electrolyte can be retained in the electrode assembly.

[0031] Furthermore, the secondary battery may further include an outer packaging component that houses the electrode assembly and electrolyte.

[0032] Furthermore, the secondary battery may further include a negative terminal electrically connected to the negative electrode and a positive terminal electrically connected to the positive electrode.

[0033] Figure 1 This is a partial cutaway perspective view schematically representing an example of a secondary battery. Figure 2 It is Figure 1 The cross-sectional view of part B of the secondary battery shown is magnified.

[0034] Figure 1 and Figure 2 The secondary battery 100 shown has Figure 1 and Figure 2 Electrode group 1 shown Figure 1 The outer packaging component 2 and the electrolyte (not shown) are shown. The electrode assembly 1 and the electrolyte are housed within the outer packaging component 2. The electrolyte is held within the electrode assembly 1.

[0035] The outer packaging component 2 is composed of a laminated film containing two resin layers and a metal layer sandwiched between them.

[0036] Electrode group 1 as follows Figure 2 The electrode assembly shown is a stacked type. The stacked type electrode assembly 1 has a structure in which a negative electrode 3 and a positive electrode 5 are sandwiched between a diaphragm 4 and stacked alternately.

[0037] It should be noted that, as shown later... Figures 2-6 In this diagram, the Y-axis is the axis along the stacking direction of the negative electrode, positive electrode, and separator. The X-axis is orthogonal to the Y-axis. The Z-axis is orthogonal to both the X-axis and Y-axis. The first direction d1 and the second direction d2 are along the X-axis.

[0038] The electrode assembly 1 includes multiple negative electrodes 3. Each negative electrode 3 has a negative current collector 3a and a layer 3b containing a negative active material supported on both sides of the negative current collector 3a. Furthermore, the electrode assembly 1 includes multiple positive electrodes 5. Each positive electrode 5 has a positive current collector 5a and a layer 5b containing a positive active material supported on both sides of the positive current collector 5a.

[0039] Each positive electrode 5's positive current collector 5a includes a portion on one side of which does not have a layer 5b containing the positive electrode active material on any surface. Figure 1 In the secondary battery shown, this part functions as the positive electrode tab 5c. The positive electrode tab 5c is electrically connected to the positive current collector 5a. Multiple positive electrode tabs 5c are electrically connected to the strip-shaped positive terminal 7. The front end of the strip-shaped positive terminal 7 is led out to the outside of the outer packaging component 2.

[0040] Furthermore, although not illustrated, each negative electrode 3's negative electrode current collector 3a includes a portion on one side of which does not have a layer 3b containing the negative electrode active material supported on any surface. Figure 1 In the secondary battery shown, this part functions as the negative electrode tab 3c. The negative electrode tab 3c is electrically connected to the negative current collector 3a. The negative electrode tab may not overlap with the positive electrode 5. Furthermore, the negative electrode tab is located on the opposite side of the electrode assembly 1 relative to the positive electrode tab 5c. The negative electrode tab is electrically connected to the strip-shaped negative terminal 6. The front end of the strip-shaped negative terminal 6 is located on the opposite side of the positive terminal 7 and is led out to the outside of the outer packaging member 2.

[0041] The negative electrode 3 has a second negative electrode portion 3e2 located at the end with respect to the second direction d2. The diaphragm 4 has a second diaphragm end portion 4e2 located at the end with respect to the second direction d2. The second diaphragm end portion 4e2 protrudes toward the second direction d2 compared to either the second negative electrode portion 3e2.

[0042] exist Figure 2 In the example shown, the second negative electrode portions 3e2 of each of the plurality of negative electrodes 3 do not overlap along the Y-axis direction. That is, the plurality of second negative electrode portions 3e2 are not aligned along the stacking direction. Compared with electrode groups in which the second negative electrode portions are aligned along the stacking direction, a secondary battery containing such an electrode group can suppress the localized stress on the separator, resulting in a lower likelihood of short circuits. It should be noted that in Figure 2 The illustration shows an example where all the second negative terminals are located at different positions along the stacking direction, but the configuration where multiple second negative terminals are not aligned along the stacking direction is not limited to this. For example, at least one of the multiple negative terminals may have its second negative terminal located at a different position along the stacking direction from the other second negative terminals. Preferably, more than half of the multiple negative terminals are in a state where they do not overlap with each other along the stacking direction.

[0043] Figure 3 It means Figure 1 The diagram shows a plan view of the negative electrode contained in the secondary battery. Figure 3 For illustration, a state is shown where the negative current collector 3a is exposed by cutting open a portion of the layer 3b containing the negative electrode active material. However, in Figure 3 In the illustrated negative electrode, layer 3b containing the negative electrode active material is disposed on the entire surface of the negative electrode current collector 3a along the X-axis and Z-axis. That is, in Figure 3 In the illustrated electrode, the surfaces of layer 3b containing the negative electrode active material and the negative electrode current collector 3a along the X-axis and Z-axis have the same rectangle.

[0044] The negative electrode 3 includes a negative electrode tab 3c that extends along a first direction d1. The negative electrode 3 has a second negative electrode portion 3e2 located at an end with respect to a second direction d2 opposite to the first direction d1. The diaphragm 4 has a first diaphragm end portion 4e1 located at an end with respect to the first direction d1 and a second diaphragm end portion 4e2 located at an end with respect to the second direction d2.

[0045] The second diaphragm end 4e2 protrudes in the second direction d2 compared to the second negative end portion 3e2. The distance between the second negative end portion 3e2 and the second diaphragm end 4e2 is denoted by the symbol Ln.

[0046] The first diaphragm end 4e1 protrudes toward the first direction d1 compared to the first negative end portion 3e1. The distance between the first negative end portion 3e1 and the first diaphragm end 4e1 is denoted by the symbol Ln'.

[0047] Figure 4 It means Figure 1 The diagram shows a plan view of the positive electrode contained in the secondary battery. Figure 4 For illustration, a state is shown where the positive current collector 5a is exposed by cutting open a portion of the layer 5b containing the positive electrode active material. However, in Figure 4 In the illustrated positive electrode, a layer 5b containing the positive electrode active material is disposed on the entire surface of the positive electrode current collector 5a along the X and Z axes. That is, in Figure 4 In the example of the positive electrode, the surfaces of the layer 5b containing the positive electrode active material and the positive electrode current collector 5a along the X-axis and Z-axis have the same rectangle.

[0048] The positive electrode tab 5c included in the positive electrode 5 extends along the second direction d2. The positive electrode 5 has a first positive electrode portion 5e1 located at the end with respect to the first direction d1 and a second positive electrode portion 5e2 located at the end with respect to the second direction d2.

[0049] The second diaphragm end 4e2 protrudes in the second direction d2 compared to the second positive end portion 5e2. The distance between the second positive end portion 5e2 and the second diaphragm end 4e2 is denoted by the symbol Lp.

[0050] The first diaphragm end 4e1 protrudes toward the first direction d1 compared to the first positive end portion 5e1. The distance between the first positive end portion 5e1 and the first diaphragm end 4e1 is denoted by the symbol Lp'.

[0051] Reference Figure 1 and Figure 2 The portion of the electrode assembly described, including the negative electrode where Ln is at its maximum and the negative electrode where Ln is at its minimum, is shown in magnification. Figure 5 and Figure 6 middle. Figure 5 This is a diagram representing the area near the positive terminal (positive electrode tab side) of this part. Figure 6 This is a diagram representing the area near the negative terminal (negative electrode tab side) of this part.

[0052] Figure 5 The three negative electrodes 3 shown each have a second negative end portion 3e2. The second diaphragm end portion 4e2 protrudes toward the second direction d2 compared to any of the second negative end portions 3e2.

[0053] It should be noted that, in Figure 5 In the example shown, the second membrane ends 4e2 of the plurality of membranes 4 included in the electrode assembly are aligned along the stacking direction (Y-axis direction). In this way, when the electrode assembly has a plurality of membranes 4, it can be said that any one of the second membrane ends 4e2 included in each of the plurality of membranes protrudes toward the second direction d2 compared to any one of the second negative terminal portions 3e2 included in the plurality of negative electrodes 3.

[0054] The smallest distance Ln among the distances Ln between the second negative end portion 3e2 and the second diaphragm end portion 4e2 of each of the plurality of negative electrodes 3 is denoted by Ln. min Represent the maximum distance in Ln. max express.

[0055] At a distance from Ln min When the distance is 1.5 mm or more, it can be said that the distance between the second negative electrode portion 3e2, the most prominent negative electrode portion along the second direction, and the end portion 4e2 of the second diaphragm in electrode assembly 1 is 1.5 mm or more. Therefore, even if the negative electrode deviates when an external force is applied to the electrode assembly, for example, short circuits can be suppressed. Furthermore, due to the distance Ln min and distance Ln max The difference is greater than 1.0 mm, thus suppressing the application of strong force to the diaphragm. Therefore, for example, it is possible to suppress short circuits between the negative electrode and the positive electrode tab due to the negative electrode penetrating the diaphragm.

[0056] From the perspective of ensuring battery capacity, distance Ln min and distance Ln max The difference is preferably set to 2.5 mm or less. Preferably, Ln min With Ln max The difference is 1.2 mm or more, and more preferably 1.5 mm or more. It should be noted that Ln min With Ln max The maximum value of the difference can be set to, for example, 2.0 mm, and more preferably 1.8 mm.

[0057] Ln min The value can also be 1.5 mm or more, preferably 2.0 mm or more, and more preferably 2.5 mm or more. Ln min The maximum value can also be 4.0 mm. Ln min Preferably, it is 3.5 mm or less, more preferably 3.0 mm or less. Ln min For example, it can be set to be above 1.5mm and below 3.5mm.

[0058] Ln max For example, it can be set to be above 2.5mm and below 4.5mm. It should be noted that... Figure 2 and Figure 5 The example illustrates electrode groups with three or more types of Ln, but Ln can also have two types. Specifically, the multiple negative electrodes included in an electrode group can also consist of one or more negative electrodes taking the larger of the two Ln values ​​and one or more negative electrodes taking the other (smaller) value of the two Ln values. When there are two types of Ln, the larger Ln value can be set as Ln. max Set the smaller of Ln to Ln min.

[0059] Figure 6 The three negative electrodes 3 shown each have a negative electrode tab 3c extending along the first direction d1.

[0060] exist Figure 6 In the example shown, the first positive terminal portion 5e1 of each of the plurality of positive electrodes 5 included in the electrode assembly is aligned along the stacking direction (Y-axis direction). Furthermore, the first negative terminal portion 3e1 of each of the plurality of negative electrodes 3 is aligned along the stacking direction. Each of the first negative terminal portions 3e1 protrudes toward the first direction d1 compared to each of the first positive terminal portions 5e1 included in the plurality of positive electrodes 5.

[0061] Here, refer again Figure 5 Each of the second negative electrode portions 3e2 contained in each of the plurality of negative electrodes 3 protrudes toward the second direction d2 compared to each of the second positive electrode portions 5e2 contained in each of the plurality of positive electrodes 5.

[0062] The smallest distance Lp between the second positive electrode portion 5e2 and the second diaphragm end portion 4e2 contained in each of the plurality of positive electrodes 5 is Lp. min The maximum value is Lp max .like Figure 5 As shown, the second positive electrode portions 5e2 of the plurality of positive electrodes 5 included in the electrode assembly 1 are aligned along the stacking direction. Therefore, it can be said that... Figure 5 The distance Lp shown is Lp min And for Lp max .

[0063] At a distance of Lp min and distance Ln min When the difference is 1.5 mm or more, it can be said that the second positive terminal portion 5e2, which is the most prominent positive terminal portion along the second direction d2, and the second negative terminal portion 3e2, which is the most prominent negative terminal portion along the second direction, are 1.5 mm or more apart. Therefore, even if the negative or positive terminal deviates when an external force is applied to the electrode assembly, it is possible to suppress the second positive terminal portion from protruding more than the second negative terminal portion. As a result, it is possible to suppress the deposition of metal caused by current concentration at the negative terminal, and thus it is less likely to cause a short circuit. Furthermore, in this electrode assembly, due to the distance Ln min and distance Ln max The difference is greater than 1.0 mm, so it can suppress the diaphragm damage caused by applying strong force to the diaphragm, and thus further suppress the generation of short circuits.

[0064] From the perspective of achieving a balance between positive and negative electrode capacity, the distance from Lp min and distance Ln minThe difference is preferably set to 5.0 mm or less. Lp min For example, it can be set to be above 3.5mm and below 6.5mm.

[0065] Refer again Figure 6 The negative electrode of the electrode assembly will be explained.

[0066] like Figure 6 As shown, each of the first negative terminal portions 3e1 protrudes in the first direction compared to each of the first positive terminal portions 5e1. Therefore, even if the negative or positive terminal deviates when an external force is applied to the electrode assembly, it is possible to suppress the first positive terminal portion from protruding more than the first negative terminal portion. Thus, it is possible to suppress short circuits caused by current concentration at the negative terminal.

[0067] Furthermore, each of the first diaphragm ends 4e1 protrudes in the first direction compared to each of the first negative end portions. Therefore, short circuits can be suppressed.

[0068] The smallest value among the distances Ln' between the first negative electrode portion 3e1 and the first diaphragm end portion 4e1 of each of the multiple negative electrodes 3 is Ln'. min The maximum value is Ln' max .exist Figure 6 In the example shown, the first negative electrode portions 3e1 of the plurality of negative electrodes 3 included in the electrode assembly 1 are aligned along the stacking direction. Therefore, it can be said that... Figure 6 The distance Ln shown is Ln' min , and for Ln' max .

[0069] The smallest value among the distances Lp' between the first positive electrode portion 5e1 and the first diaphragm end portion 4e1 contained in each of the plurality of positive electrodes 5 is Lp'. min The maximum value is Lp' max .exist Figure 6 In the example shown, the first positive electrode portions 5e1 of the plurality of positive electrodes 5 included in the electrode assembly 1 are aligned along the stacking direction. Therefore, it can be said that... Figure 6 The distance Lp' shown is Lp' min , and for Lp' max .

[0070] It should be noted that when the difference between the minimum and maximum distances between the first negative electrode portion and the end of the first diaphragm in each of the plurality of negative electrodes is 0.6 mm or less, it can be said that "the first negative electrode portions are aligned along the stacking direction." The same applies to the first positive electrode portion. Furthermore, when the difference between the minimum and maximum distances between the second negative electrode portion and the end of the second diaphragm in each of the plurality of negative electrodes is 0.6 mm or less, it can be said that "the second negative electrode portions are aligned along the stacking direction." The same applies to the second positive electrode portion.

[0071] It should be noted that, in Figure 1 In the battery shown in the diagram, the electrode assembly described earlier can also be used instead. Figure 7 The electrode assembly is illustrated in the image. Figure 7 The electrode assembly 1 shown is constructed by folding the diaphragm 4 in a zigzag manner, with negative electrodes 3 and positive electrodes 5 alternately arranged at the folded portions. Specifically, the negative electrodes 3, positive electrodes 5, negative electrodes 3, and positive electrodes 5 are arranged sequentially according to the arrangement of the diaphragms 4 sandwiched within the zigzag folded diaphragm 4. The negative electrode tab 3c protrudes from one long side of the zigzag folded diaphragm 4. The positive electrode tab 5c protrudes from the other long side of the zigzag folded diaphragm 4.

[0072] The order of negative electrode 3 and positive electrode 5 is not limited to Figure 7 The order shown can also be configured in the order of positive electrode 5, negative electrode 3, positive electrode 5, negative electrode 3.

[0073] The number of positive and negative electrode plates in the electrode assembly is not particularly limited and can be appropriately varied according to the desired capacity, battery size, etc. However, for example, the number of positive and negative electrode plates can be set to more than 40 and less than 70. Furthermore, the number of separator plates is not particularly limited and can be appropriately varied according to the shape of the separator. For example, multiple sheet-like separators can be used, with one separator sandwiched between the positive and negative electrodes respectively. Alternatively, a single separator can be folded and multiple negative and positive electrodes can be alternately arranged at the folded-in sections.

[0074] The secondary battery can be, for example, a secondary battery that uses alkali metal ions as charge carriers (carrier ions). Specifically, it can be a lithium-ion secondary battery that uses lithium (Li) as the carrier ion or a sodium secondary battery that uses sodium (Na) as the carrier ion. Furthermore, the secondary battery includes a non-aqueous electrolyte secondary battery containing a non-aqueous electrolyte.

[0075] The following provides a detailed description of the negative electrode, positive electrode, electrolyte, separator, outer packaging components, negative terminal, and positive terminal that may be included in the secondary battery according to the embodiments.

[0076] 1) Negative electrode The negative electrode consists of a negative current collector, a layer containing negative active material, and a negative electrode tab.

[0077] The layer containing the negative electrode active material can be formed on one or both sides of the negative electrode current collector. The layer containing the negative electrode active material can include the negative electrode active material and optionally a conductive agent and a binder.

[0078] Examples of anode active materials include metals, nonmetals, alloys, oxides, sulfides, phosphides, oxysulfides, phosphoric acid, sulfuric acid compounds, and carbon materials. The number of anode active materials can be one or more.

[0079] Lithium is an example of a metal.

[0080] Silicon is an example of a nonmetal.

[0081] Examples of oxides include lithium titanate (e.g., Li) with an orthorhombic manganese oxide structure. 2+y Ti3O7, 0≤y≤3), lithium titanate with spinel structure (e.g., Li), 4+x Ti5O 12 The following are examples of anode materials containing niobium: 0≤x≤3), titanium dioxide (TiO2), anatase titanium dioxide, rutile titanium dioxide, niobium pentoxide (Nb2O5), alkali manganese oxide titanium composite oxide, orthorhombic titanium composite oxide, niobium-containing oxides, and monoclinic niobium-containing titanium oxides. Anodes containing these active materials can be used as anodes in lithium-ion secondary batteries.

[0082] As examples of the aforementioned histogram-type titanium-containing composite oxides, Li can be cited. 2+a M I 2-b Ti 6-c M II d O 14+σ The compound represented. Wherein, M I It is selected from at least one of the groups consisting of Sr, Ba, Ca, Mg, Na, Cs, Rb, and K. M II The composition is selected from at least one element in the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Y, Fe, Co, Cr, Mn, Ni, and Al. The subscripts in the composition formula are 0 ≤ a ≤ 6, 0 ≤ b < 2, 0 ≤ c < 6, 0 ≤ d < 6, and -0.5 ≤ σ ≤ 0.5. As a specific example of a histogram-type titanium-containing composite oxide, Li can be cited. 2+a Na2Ti6O 14 (0≤a≤6).

[0083] As examples of the aforementioned niobium-containing oxides, Nb can be cited. 16 W5O 55 、Nb18 W 16 O 93 , Nb 14 W3O 44 and the like.

[0084] Examples of the above-mentioned monoclinic niobium-titanium-containing oxide include Li x Ti 1-y M1 y Nb 2-z M2 z O 7+δ compounds represented by the formula. Herein, M1 is at least one selected from the group consisting of Zr, Si and Sn. M2 is at least one selected from the group consisting of V, Ta and Bi. The respective subscripts in the composition formula are 0≤x≤5, 0≤y<1, 0≤z<2, and -0.3≤δ≤0.3. Specific examples of the monoclinic niobium-titanium-containing oxide include Li x Nb2TiO7 (0≤x≤5).

[0085] Other examples of the monoclinic niobium-titanium-containing oxide include Li x Ti 1-y M3 y+z Nb 2-z O 7-δ compounds represented by the formula. Herein, M3 is at least one selected from Mg, Fe, Ni, Co, W, Ta and Mo. The respective subscripts in the composition formula are 0≤x≤5, 0≤y<1, 0≤z<2, and -0.3≤δ≤0.3.

[0086] Examples of the negative electrode active material further include carbon materials such as hard carbon and graphite, alloys containing tin (Sn), oxides, and sulfides. A negative electrode containing these negative electrode active materials can be used, for example, as a negative electrode of a sodium secondary battery. In the negative electrode of the sodium secondary battery, the type of the negative electrode active material may be set to one type or two or more types.

[0087] Examples of the above-mentioned oxides include Fe2O3, TiO2, and compounds represented by Li / Na x Ti 1-y Nb y O2, where x and y satisfy 0≤x≤1 and 0<y≤0.2, respectively.

[0088] Examples of the above-mentioned sulfides include FeS, CoS and MoS2.

[0089] Conductive agents are used to improve current collection performance and suppress contact resistance between the negative electrode active material and the negative electrode current collector. Examples of conductive agents include carbonaceous materials such as vapor-grown carbon fiber (VGCF), carbon black such as acetylene black, graphite, carbon nanotubes, and carbon nanofibers. One of these can be used as a conductive agent, or two or more can be combined. Alternatively, instead of using a conductive agent, carbon coating or electronically conductive inorganic material coating can be applied to the surface of the negative electrode active material particles.

[0090] The binder is used to fill the gaps between the dispersed negative electrode active material and to bond the negative electrode active material to the negative electrode current collector. Examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, styrene-butadiene rubber, polyacrylic acid compounds, imide compounds, carboxymethyl cellulose (CMC), and salts of CMC. One of these can be used as a binder, or a combination of two or more can be used as a binder.

[0091] The proportions of the negative electrode active material, conductive agent, and binder in the layer containing the negative electrode active material can be appropriately varied. For example, it is preferable to combine the negative electrode active material, conductive agent, and binder in proportions of 68% by mass or more and 97% by mass or less, 2% by mass or more and 30% by mass or less, and 1% by mass or more and 30% by mass or less, respectively. By setting the amount of conductive agent to 2% by mass or more, the current-collecting performance of the layer containing the negative electrode active material can be improved. Furthermore, by setting the amount of binder to 2% by mass or more, the adhesion between the layer containing the negative electrode active material and the negative electrode current collector becomes sufficient, and excellent cycle performance can be expected. On the other hand, setting the conductive agent and binder to 30% by mass or less is preferable in terms of pursuing high capacity.

[0092] The negative current collector contains aluminum or an aluminum alloy. As an aluminum alloy, for example, an alloy containing aluminum and one or more elements selected from Mg, Ti, Zn, Mn, Fe, Cu and Si can be used.

[0093] Anode current collectors containing aluminum or aluminum alloys are electrochemically stable at the potentials at which charge carriers are inserted and removed from the anode active material.

[0094] For example, in lithium-ion batteries, aluminum and aluminum alloys are electrochemically stable at the potentials at which lithium (Li) is inserted and extracted as a charge carrier. In sodium-ion batteries, aluminum and aluminum alloys are electrochemically stable at the potentials at which sodium (Na) is inserted and extracted as a charge carrier.

[0095] The thickness of the negative electrode current collector is preferably 7 μm or more and 20 μm or less. A negative electrode current collector with such a thickness can achieve a balance between the strength and lightweight of the negative electrode.

[0096] Furthermore, the negative current collector may include a portion of its surface where no layer containing the negative active material is formed. This portion can function as a negative electrode tab. Alternatively, the negative electrode tab, separate from the negative current collector, can be joined to the negative current collector by welding or the like. In either case, it can be said that the negative electrode tab and the negative current collector are electrically connected.

[0097] The density of the layer containing the negative electrode active material (excluding the current collector) is preferably 1.8 g / cm³. 3 Above and 2.8g / cm 3 The following describes the negative electrode with a layer density within this range, which exhibits excellent energy density and electrolyte retention. A more preferred layer density is 2.1 g / cm³. 3 Above and 2.6g / cm 3 the following.

[0098] The size of the negative electrode is not particularly limited and can be varied according to the desired capacity. However, for example, the distance from the first negative electrode to the second negative electrode can be set to be more than 15 cm and less than 100 cm. Within this range, it is easy to obtain a capacity from Ln. min For 1.5mm and above and Ln min With Ln max The difference of 1.0 mm or more results in a short-circuit suppression effect. The distance from the first negative terminal to the second negative terminal can be, for example, 150.0 mm or more and 1000.0 mm or less, or 190.0 mm or more and 210.0 mm or less.

[0099] The distance from the first negative electrode portion to the second negative electrode portion can be the length along the first direction of the layer containing the negative electrode active material. The width of the layer containing the negative electrode active material orthogonal to the first direction is not particularly limited, but can be 50.0 mm or more and 500.0 mm or less, or 90.0 mm or more and 110.0 mm or less.

[0100] The negative electrode can be produced, for example, by the following method. First, a negative electrode active material, a conductive agent and a binder are suspended in a solvent to prepare a slurry. This slurry is applied to one side or both sides of a negative electrode current collector. Next, the applied slurry is dried to obtain a laminate of the negative electrode active material-containing layer and the negative electrode current collector. Thereafter, the laminate is subjected to pressing. The negative electrode is produced in this manner.

[0101] Alternatively, the negative electrode can also be produced by the following method. First, a negative electrode active material, a conductive agent and a binder are mixed to obtain a mixture. Next, this mixture is formed into granules. Then, the negative electrode can be obtained by disposing these granules on a negative electrode current collector.

[0102] 2) Positive electrode The positive electrode can include a positive electrode current collector, a positive electrode active material-containing layer, and a positive electrode tab. The positive electrode active material-containing layer may be formed on one side or both sides of the positive electrode current collector. The positive electrode active material-containing layer may include a positive electrode active material and optional conductive agent and binder.

[0103] Examples of the positive electrode active material include compounds capable of intercalating and deintercalating Li or Li ions, and compounds capable of intercalating and deintercalating Na or Na ions. The compound capable of intercalating and deintercalating Li or Li ions may be, for example, an oxide or sulfide capable of intercalating and deintercalating Li or Li ions.

[0104] The positive electrode may contain one type of compound alone as the positive electrode active material, or may contain two or more types of compounds in combination.

[0105] The positive electrode containing a compound capable of intercalating and deintercalating Li or Li ions as the positive electrode active material can be used, for example, as the positive electrode of a lithium ion secondary battery.

[0106] Examples of the compound capable of intercalating and deintercalating Li or Li ions include manganese dioxide (MnO2), iron oxide, copper oxide, nickel oxide, lithium-manganese composite oxide (for example, Li x Mn2O4 or Li x MnO2; 0<x≤1), lithium-nickel composite oxide (for example, Li x NiO2; 0<x≤1), lithium-cobalt composite oxide (for example, Li x CoO2; 0<x≤1), lithium-nickel-cobalt composite oxide (for example, Li x Ni 1- y Co y O2; 0<x≤1, 0<y<1), lithium-manganese-cobalt composite oxide (for example, Li x Mn y Co 1-yO2; 0<x≤1, 0<y<1), spinel-structured lithium-manganese-nickel composite oxides (e.g., Li x Mn 2-y Ni y O4; 0<x≤1, 0<y<2), olivine-structured lithium phosphorus oxides (e.g., Li x FePO4; 0<x≤1, Li x Fe 1-y Mn y PO4; 0<x≤1, 0<y≤1, Li x CoPO4; 0<x≤1), iron sulfate (Fe2(SO4)3), vanadium oxides (e.g., V2O5) and lithium-nickel-cobalt-manganese composite oxides (Li x Ni 1-y-z Co y Mn z O2; 0<x≤1, 0<y<1, 0<z<1, y+z<1).

[0107] In the above, examples of more preferable compounds as the positive electrode active material include spinel-structured lithium-manganese composite oxides (e.g., Li x Mn2O4; 0<x≤1), lithium-nickel composite oxides (e.g., Li x NiO2; 0<x≤1), lithium-cobalt composite oxides (e.g., Li x CoO2; 0<x≤1), lithium-nickel-cobalt composite oxides (e.g., Li x Ni 1-y Co y O2; 0<x≤1, 0<y<1), spinel-structured lithium-manganese-nickel composite oxides (e.g., Li x Mn 2-y Ni y O4; 0<x≤1, 0<y<2), lithium-manganese-cobalt composite oxides (e.g., Li x Mn y Co 1-y O2; 0<x≤1, 0<y<1), lithium iron phosphate (e.g., Li x FePO4; 0<x≤1) and lithium-nickel-cobalt-manganese composite oxides (Li x Ni 1-y-z Co y Mn z O2; 0<x≤1, 0<y<1, 0<z<1, y+z<1). When these compounds are used as the positive electrode active material, the positive electrode potential can be increased.

[0108] When a room-temperature molten salt is used as the electrolyte of the battery, it is preferable to use a material containing lithium iron phosphate, Li xA positive electrode active material of VPO4F (0≤x≤1), a lithium-manganese composite oxide, a lithium-nickel composite oxide, a lithium-nickel-cobalt composite oxide, or a mixture thereof. These compounds have low reactivity with room-temperature molten salts, and thus can improve cycle life. Details of the room-temperature molten salts will be described later.

[0109] A positive electrode containing a compound capable of intercalating and deintercalating Na or Na ions as a positive electrode active material can be used, for example, as the positive electrode of a sodium secondary battery.

[0110] Examples of the compound capable of intercalating and deintercalating Na or Na ions include sodium transition metal oxides, sodium transition metal phosphate compounds, and Prussian blue analogs. In addition to the above, Na4Ti5O may also be mentioned. 12 , Na2NiMn3O8, Na2S, FeS, TiS2, NaFeO2, NaMn2O4, Na2TiS3, and the like.

[0111] Examples of the sodium transition metal oxide include the compound represented by Na n M I x M II y M III z O2. Here, M I , M II and M III are each at least one selected from the group consisting of Ni, Co, Mn, Fe, Cu, Al, V, Cr, Zn, Ti, and Mg. The respective subscripts in the compositional formula satisfy 0<n≤1.2, 0≤x≤1, 0≤y≤1, 0≤z≤1, and x+y+z=1. Examples of the compound represented by Na n M I x M II y M III z O2 include NaFe 0.33 Ni 0.33 Mn 0.33 O2.

[0112] Examples of the sodium transition metal phosphate compound include compounds represented by Na3M2(PO4)3 or Na a Fe b (PO4) c P2O7. Here, M is at least one selected from the group consisting of Ni, Co, Mn, V, and Cr. The respective subscripts in the compositional formula satisfy 3≤a≤4; a=c+2; b=c+1; and 1≤c≤2.

[0113] Examples of Prussian blue analogs include Na n M I x [M II (CN)6] y ·zH2O. In the formula, M I and M II are at least one selected from the group consisting of Fe, Co, Ni, Cu, Zn, Ti, V, Cr and Mn. Each subscript in the composition formula satisfies 1<n≤2, 0<x≤1, 0<y≤1. Further, z satisfies 0<z≤16.

[0114] The primary particle diameter of the positive electrode active material is preferably 100 nm or more and 1 μm or less. The positive electrode active material with a primary particle diameter of 100 nm or more is easy to handle in industrial production. The positive electrode active material with a primary particle diameter of 1 μm or less allows the solid-state diffusion of lithium ions to proceed smoothly.

[0115] The specific surface area of the positive electrode active material is preferably 0.1 m 2 / g or more and 10 m 2 / g or less. The positive electrode active material with a specific surface area of 0.1 m 2 / g or more can sufficiently secure the intercalation / deintercalation sites for Li ions. The positive electrode active material with a specific surface area of 10 m 2 / g or less is easy to handle in industrial production and can ensure good charge-discharge cycle performance.

[0116] The binder is blended to fill the gaps between the dispersed positive electrode active materials and further bond the positive electrode active material to the positive electrode current collector. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, polyacrylic compounds, imide compounds, carboxymethyl cellulose (CMC) and salts of CMC. One of them may be used as the binder, or two or more thereof may be used in combination as the binder.

[0117] The conductive agent is blended to improve current collection performance and suppress the contact resistance between the positive electrode active material and the positive electrode current collector. Examples of the conductive agent include vapor grown carbon fiber (VGCF), carbon black such as acetylene black, and carbonaceous substances such as graphite. One of them may be used as the conductive agent, or two or more thereof may be used in combination as the conductive agent. In addition, the conductive agent may be omitted.

[0118] In the layer containing the positive electrode active material, the positive electrode active material and the binder are preferably mixed in proportions of 80% to 99% by mass and 1% to 20% by mass, respectively.

[0119] Sufficient electrode strength can be obtained by setting the amount of binder to 2% by mass or more. Furthermore, the binder functions as an insulator. Therefore, if the amount of binder is set to 20% by mass or less, the amount of insulator contained in the electrode is reduced, thereby reducing internal resistance.

[0120] When a conductive agent is added, the positive electrode active material, binder and conductive agent are preferably mixed in proportions of 77% or more and 96% or less by mass, 1% or more and 20% or less by mass, and 3% or more and 15% or less by mass, respectively.

[0121] The aforementioned effects can be achieved by setting the amount of the conductive agent to 3% by mass or more. Furthermore, by setting the amount of the conductive agent to 15% by mass or less, the proportion of the conductive agent in contact with the electrolyte can be reduced. At this low proportion, electrolyte decomposition can be reduced under high-temperature storage conditions.

[0122] The positive current collector is preferably aluminum foil or aluminum alloy foil containing one or more elements selected from Mg, Ti, Zn, Ni, Cr, Mn, Fe, Cu and Si.

[0123] The thickness of the aluminum foil or aluminum alloy foil is preferably 5 μm or more and 20 μm or less, more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% by mass or more. The content of transition metals such as iron, copper, nickel, and chromium contained in the aluminum foil or aluminum alloy foil is preferably 1% by mass or less.

[0124] Furthermore, the positive current collector may include a portion of its surface where no layer containing the positive active material is formed. This portion can function as a positive electrode tab. Alternatively, the positive electrode tab, separate from the positive current collector, can be joined to the positive current collector by welding or the like. In either case, it can be said that the positive electrode tab and the positive current collector are electrically connected.

[0125] The size of the positive electrode is not particularly limited and can be varied according to the desired capacity, but for example, the distance from the first positive terminal to the second positive terminal can be set to 15 cm or more and 100 cm or less. Furthermore, the distance from the first positive terminal to the second positive terminal is preferably 2.0 mm or more and 10.0 mm or less shorter than the distance from the first negative terminal to the second negative terminal. If it is within this range, short circuits can be effectively suppressed. The distance from the first positive terminal to the second positive terminal can also be, for example, 140.0 mm or more and 1000.0 mm or less, or 180.0 mm or more and 210.0 mm or less.

[0126] The distance from the first positive electrode portion to the second positive electrode portion can be the length of the layer containing the positive electrode active material along the first direction. The width of the layer containing the positive electrode active material orthogonal to the first direction is not particularly limited, but can be 50.0 mm or more and 500.0 mm or less, or 85.0 mm or more and 110.0 mm or less.

[0127] The positive electrode can be manufactured, for example, by the following method. First, a slurry is prepared by suspending the positive electrode active material, conductive agent, and binder in a solvent. This slurry is then coated onto one or both sides of the positive electrode current collector. Next, the coated slurry is dried to obtain a laminate containing the positive electrode active material and the positive electrode current collector. This laminate is then pressed. The positive electrode is manufactured by operating in this manner.

[0128] Alternatively, the positive electrode can be manufactured using the following method. First, the positive electrode active material, conductive agent, and binder are mixed to obtain a mixture. Next, this mixture is shaped into granules. Then, by placing these granules onto the positive electrode current collector, the positive electrode can be obtained.

[0129] 3) Electrolytes As an electrolyte, a non-aqueous electrolyte can be used, for example.

[0130] As a non-aqueous electrolyte, for example, a liquid non-aqueous electrolyte or a gel-like non-aqueous electrolyte can be used. A liquid non-aqueous electrolyte is prepared by dissolving an electrolyte salt, which is the solute, in an organic solvent. The concentration of the electrolyte salt is preferably 0.5 mol / L or higher and 2.5 mol / L or lower.

[0131] Examples of electrolyte salts include lithium salts such as lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), and lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3SO2)2), as well as mixtures thereof. The electrolyte salt is preferably a substance that is difficult to oxidize even at high potentials, and LiPF6 is most preferred.

[0132] Examples of organic solvents include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), and vinylene carbonate (VC); chain carbonates such as diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC); cyclic ethers such as tetrahydrofuran (THF), 2-methyl tetrahydrofuran (2Me THF), and dioxolane (DOX); chain ethers such as dimethoxyethane (DME) and diethoxyethane (DEE); γ-butyrolactone (GBL), acetonitrile (AN), and sulfolane (SL). These organic solvents can be used alone or as mixed solvents.

[0133] Gel-like nonaqueous electrolytes are prepared by compounding liquid nonaqueous electrolytes with polymeric materials. Examples of polymeric materials include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO), or mixtures thereof.

[0134] Alternatively, as a non-aqueous electrolyte, in addition to liquid non-aqueous electrolytes and gel non-aqueous electrolytes, room-temperature molten salts (ionic melts) containing lithium ions, polymeric solid electrolytes, and inorganic solid electrolytes can also be used.

[0135] Room-temperature molten salts (ionic melts) refer to compounds that exist as liquids at room temperature (above 15°C and below 25°C) in organic salts formed by the combination of organic cations and anions. Room-temperature molten salts include those existing as liquids in monomeric form, those that become liquids by mixing with electrolyte salts, those that become liquids by dissolving in organic solvents, or mixtures thereof. Generally, the melting point of room-temperature molten salts used in secondary batteries is below 25°C. Furthermore, the organic cations typically possess a quaternary ammonium framework.

[0136] Polymer solid electrolytes can be prepared by dissolving electrolyte salts in polymer materials and then solidifying them.

[0137] The inorganic solid electrolyte is a solid substance having Li ion conductivity. The term "having Li ion conductivity" as used herein means exhibiting 1×10 at 25°C -6 S / cm or more of lithium ion conductivity. Examples of the inorganic solid electrolyte include an oxide-based solid electrolyte or a sulfide-based solid electrolyte. Specific examples of the inorganic solid electrolyte are as follows.

[0138] As the oxide-based solid electrolyte, a lithium phosphate solid electrolyte having a NASICON (Sodium (Na) Super Ionic Conductor) type structure and represented by the general formula Li 1+x Mα2(PO4)3 is preferably used. Mα in the above general formula is, for example, one or more selected from the group consisting of titanium (Ti), germanium (Ge), strontium (Sr), zirconium (Zr), tin (Sn), aluminum (Al), and calcium (Ca). The subscript x is in the range of 0≤x≤2.

[0139] Specific examples of the lithium phosphate solid electrolyte having a NASICON type structure include those represented by Li 1+ x Al x Ti 2-x (PO4)3 and having 0.1≤x≤0.5, which is an LATP compound; a compound represented by Li 1+x Al y Mβ 2-y (PO4)3, in which Mβ is one or more selected from the group consisting of Ti, Ge, Sr, Zr, Sn and Ca, and 0≤x≤1 and 0≤y≤1; a compound represented by Li 1+x Al x Ge 2-x (PO4)3 and having 0≤x≤2; and a compound represented by Li 1+x Al x Zr 2-x (PO4)3 and having 0≤x≤2; a compound represented by Li 1+x+ y Al x Mγ 2-x Si y P 3-y O 12 , in which Mγ is one or more selected from the group consisting of Ti and Ge, and 0<x≤2 and 0≤y<3; a compound represented by Li 1+2x Zr 1-x Ca x (PO4)3 and having 0≤x<1.

[0140] In addition to the aforementioned lithium phosphate solid electrolyte, other oxide-based solid electrolytes, such as those based on Li... x PO y N z This refers to amorphous LIPON compounds (e.g., Li) where 2.6 ≤ x ≤ 3.5, 1.9 ≤ y ≤ 3.8, and 0.1 ≤ z ≤ 1.3. 2.9 PO 3.3 N 0.46 ); Garnet-type structure with La 5+x A x La 3-x Mδ2O 12 This indicates a compound in which A is selected from one or more of the group consisting of Ca, Sr, and Ba, and Mδ is selected from one or more of the group consisting of Nb and Ta, with 0 ≤ x ≤ 0.5; Li3Mδ 2-x L2O 12 This indicates that Mδ is a compound selected from one or more species in the group consisting of Nb and Ta, and L may contain Zr and 0 ≤ x ≤ 0.5; with Li 7-3x Al x La3Zr3O 12 Represents compounds in which 0 ≤ x ≤ 0.5; in Li 5+x La3Mδ 2-x Zr x O 12 Mδ represents an LLZ compound selected from the group consisting of Nb and Ta, where 0 ≤ x ≤ 2 (e.g., Li7La3Zr2O). 12 ); and those with a perovskite-type structure and La 2 / 3-x Li x TiO3 represents compounds in which 0.3 ≤ x ≤ 0.7.

[0141] One or more of the above-mentioned compounds may be used as a solid electrolyte. Two or more of the above-mentioned solid electrolytes may also be used.

[0142] The electrolytes described above can be used, for example, as electrolytes in lithium-ion secondary batteries. As the electrolyte material, materials from the electrolytes described above in which lithium (Li) is replaced by sodium (Na) can also be used. Electrolytes containing such materials can, for example, be used as electrolytes in sodium secondary batteries.

[0143] 4) Diaphragm The diaphragm may comprise, for example, a porous membrane containing polyethylene (PE), polypropylene (PP), cellulose, or polyvinylidene fluoride (PVdF), or a nonwoven fabric made of synthetic resin. From a safety perspective, the diaphragm preferably comprises a porous membrane formed of polyethylene or polypropylene, because these porous membranes melt at a certain temperature and can interrupt the current.

[0144] The diaphragm can be made solely of the aforementioned porous membrane or synthetic resin nonwoven fabric, or it can be combined with, for example, a solid electrolyte membrane or a ceramic membrane in addition to the aforementioned porous membrane or synthetic resin nonwoven fabric. For example, as a diaphragm, a solid electrolyte membrane or a ceramic membrane can be laminated on at least one surface of a porous sheet. Either a solid electrolyte membrane or a ceramic membrane can be used, or a combination of both can be used.

[0145] The diaphragm is preferably a composite solid electrolyte membrane having a solid electrolyte membrane on at least one side of a porous membrane or a nonwoven fabric made of synthetic resin. Examples of composite solid electrolyte membranes include coated diaphragms in which a dispersion containing solid electrolyte particles is coated on at least one side of a porous membrane or a nonwoven fabric made of synthetic resin to form a solid electrolyte layer.

[0146] Solid electrolyte membranes comprise solid electrolyte particles. For example, a solid electrolyte membrane may comprise solid electrolyte particles and a polymer material, wherein the solid electrolyte particles are formed into a membrane using the polymer material. Solid electrolyte membranes may also be formed solely of solid electrolyte particles. A solid electrolyte membrane may comprise one type of solid electrolyte particle or multiple types of solid electrolyte particles. A solid electrolyte membrane may also comprise at least one component selected from the group consisting of plasticizers and electrolyte salts. If the solid electrolyte membrane contains an electrolyte salt, the alkali metal ion conductivity of the solid electrolyte membrane can be further improved, for example.

[0147] As a solid electrolyte, the same solid electrolyte described above can be used.

[0148] It should be noted that polymer materials can be in the form of granules or fibers. Examples of polymer materials include polyether-based, polyester-based, polyamine-based, polyethylene-based, silicone-based, and polysulfide-based materials.

[0149] Ceramic membranes may or may not possess lithium-ion conductivity. For example, the lithium-ion conductivity of ceramic membranes is less than 2 × 10⁻⁶ at 25°C. -14S / cm. Examples of materials constituting ceramic membranes include zinc oxide (e.g., ZnO, ZnO2), aluminum oxide (e.g., Al2O3), boehmite, zirconium oxide (e.g., ZrO2), boron oxide (e.g., B2O3), and titanium oxides (e.g., TiO, TiO2). Ceramic membranes can also contain polymeric materials, similar to solid electrolyte membranes. In addition to the ceramics mentioned above, ceramic membranes can further contain solid electrolyte particles.

[0150] 5) Outer packaging components As outer packaging components, containers made of laminated film or metal containers can be used, for example.

[0151] The thickness of the laminate is, for example, 0.5 mm or less, preferably 0.2 mm or less.

[0152] As a laminated film, a multilayer film comprising multiple resin layers and a metal layer sandwiched between these resin layers is used. The resin layers include, for example, polymeric materials such as polypropylene (PP), polyethylene (PE), nylon, and polyethylene terephthalate (PET). For weight reduction, the metal layer is preferably made of aluminum foil or aluminum alloy foil. The laminated film is sealed using hot-melt bonding and can be shaped into an outer packaging component.

[0153] The thickness of the wall of the metal container is, for example, 1 mm or less, more preferably 0.5 mm or less, and even more preferably 0.2 mm or less.

[0154] Metal containers are made of materials such as aluminum or aluminum alloys. The aluminum alloy preferably contains elements such as magnesium, zinc, and silicon. When the aluminum alloy contains transition metals such as iron, copper, nickel, and chromium, their content is preferably less than 100 ppm by mass.

[0155] There are no particular limitations on the shape of the outer packaging components. The outer packaging components can be, for example, flat (thin), square, cylindrical, coin-shaped, or button-shaped. The outer packaging components can be appropriately selected based on the battery size or intended use.

[0156] 6) Negative extremes The negative terminal can be formed from a material that is electrochemically stable and conductive at the Li insertion / deintercalation potential of the aforementioned negative electrode active material. Specifically, examples of materials for the negative terminal include copper, nickel, stainless steel, or aluminum, or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. Aluminum or aluminum alloys are preferred as the material for the negative terminal. When the negative terminal is connected to the negative electrode tab, the negative terminal is preferably made of the same material as the negative electrode tab to reduce contact resistance. The negative terminal can also be made of the same material as the negative current collector.

[0157] The negative electrode described above can be used, for example, as the negative electrode in lithium-ion secondary batteries. Furthermore, it can also be used as the negative electrode in sodium secondary batteries. This is because the materials described above are electrochemically stable at the Na intercalation / deintercalation potential of the negative electrode active material used in sodium batteries.

[0158] 7) Positive extreme The positive terminal can be located in a potential range of 3V or higher and 4.5V or lower relative to the redox potential of lithium (vs. Li / Li). + The positive terminal is formed of a material that is electrically stable and conductive. Examples of materials for the positive terminal include aluminum, or aluminum alloys containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. When the positive terminal is connected to the positive electrode tab, it is preferable that the positive terminal is made of the same material as the positive electrode tab to reduce contact resistance. The positive terminal may also be made of the same material as the positive current collector.

[0159] The positive terminal described above can be used, for example, as the positive terminal of a lithium-ion secondary battery. Furthermore, it can also be used as the positive terminal of a sodium secondary battery. This is because the materials described above are electrochemically stable at the Na intercalation / deintercalation potential of the positive electrode active material used in sodium batteries.

[0160] (Manufacturing method) The secondary battery involved in the implementation method can be manufactured, for example, by the following method. First, after manufacturing a positive electrode and multiple negative electrodes using the previously described method, the negative electrodes and / or the positive electrodes are adjusted to the desired size. At this time, the sizes of the multiple negative electrodes are made inconsistent. The specific method is described below.

[0161] First, the direction in which the negative electrode tab is drawn out relative to the negative electrode current collector is set as the first direction, and the opposite direction is set as the second direction.

[0162] The end of the layer containing the negative electrode active material in the first direction is designated as the first negative electrode end, and the end of the negative electrode in the second direction is designated as the second negative electrode end.

[0163] The dimensions of each of the multiple negative electrodes are adjusted such that the distance (length) from the first negative electrode to the second negative electrode is a different value. More specifically, the dimensions are adjusted such that the total length of the multiple negative electrodes is not a single value.

[0164] The difference between the length of the shortest negative electrode and the length of the longest negative electrode among multiple negative electrodes can be set to, for example, 1.0 mm or more.

[0165] Next, the positive electrode and the separator are adjusted to the desired dimensions.

[0166] For example, the direction in which the positive electrode tab is drawn out relative to the positive current collector can be designated as the second direction, and the opposite direction as the first direction. The end of the layer containing the positive electrode active material in the positive electrode with respect to the second direction can be designated as the second positive electrode portion, and the end of the positive electrode with respect to the first direction can be designated as the first positive electrode portion. In this case, the distance (length) from the first positive electrode portion to the second positive electrode portion can be adjusted to be smaller than the length of any of the multiple negative electrodes. Furthermore, when there are multiple positive electrodes, the size of all the positive electrodes can be set to be the same. More specifically, the size of the multiple positive electrodes can be adjusted so that the distance (length) from the first positive electrode portion to the second positive electrode portion is all the same value.

[0167] The end of the diaphragm located in the first direction is designated as the first diaphragm end, and the end located in the second direction is designated as the second diaphragm end. The distance (length) from the first diaphragm end to the second diaphragm end is adjusted to be longer than the length of any of the plurality of negative and positive electrodes. When there are multiple diaphragms, for example, the size of all the diaphragms can be set to be the same.

[0168] Next, the negative and positive electrodes are alternately stacked, with a diaphragm sandwiched between them. At this point, the negative and positive electrodes are stacked in opposite directions. That is, the positive electrode is stacked with the positive electrode extending in the second direction.

[0169] Multiple negative electrodes are stacked such that their respective first negative terminals overlap each other along the stacking direction. Multiple positive electrodes are stacked such that their respective second positive terminals overlap each other along the stacking direction.

[0170] The end of the diaphragm located in the first direction is designated as the first diaphragm end, and the end located in the second direction is designated as the second diaphragm end. The diaphragms are stacked such that the second diaphragm ends protrude in the second direction compared to any of the second negative electrode portions included in each of the plurality of negative electrodes. Furthermore, the distance between the second negative electrode portion of the longest negative electrode among the plurality of negative electrodes and the second diaphragm end is 1.5 mm or more.

[0171] This process is used to create the electrode assembly.

[0172] Terminals can also be connected to the negative and positive electrodes using methods such as ultrasonic welding. Then, by housing the electrode assembly in an outer packaging member and injecting electrolyte, the electrolyte can be retained within the electrode assembly. Finally, by sealing the opening of the outer packaging member, a battery can be manufactured. The manufactured battery can also be used as a secondary battery according to the embodiment, but it is preferable to use it as a secondary battery according to the embodiment after performing a first charge and discharge cycle. The first charge and discharge cycle can be performed, for example, by charging with constant current and constant voltage (CCCV) followed by constant current discharge. During the first charge and discharge cycle, the electrode assembly may slightly expand or contract. Specifically, the negative electrode included in the electrode assembly may expand during charging. Furthermore, the negative electrode may contract to near its pre-charging size during discharging. As a result, the negative electrode may be in a slightly expanded state after the first charge and discharge cycle.

[0173] Therefore, the dimensions of the components included in the electrode assembly can be different before and after the first charge and discharge. In the secondary battery after the first charge and discharge, Ln is preferred. min For thicknesses of 1.5mm or more, Ln min With Ln max The difference is greater than 1.0 mm.

[0174] During the first charge and discharge, it is preferable to constrain the secondary battery. The form of constraint is not particularly limited, but it can be achieved, for example, by clamping the secondary battery with a pair of plates. The constraint pressure can be set, for example, to be between 0.05 MPa and 0.20 MPa. Within this range, it is possible to suppress significant changes in the dimensions of the components included in the electrode assembly from their dimensions at the time of assembly. Therefore, even after the first charge and discharge, Ln is easily obtained. min For 1.5mm or more, and Ln min With Ln max The difference between the two secondary batteries is 1.0 mm or more. For example, the surface pressure when the secondary battery is clamped by a pair of plates can be set to 0.05 MPa or more and 0.2 MPa or less. The pressure during constraint can be set to 0.1 MPa, for example.

[0175] (Determination Method) (Method for measuring the distance between the electrode tip and the diaphragm tip) First, set the battery to be tested to a discharged state. Then, open the outer packaging component in a manner that prevents deformation of the electrode assembly's stacked structure or damage to the positive electrode, negative electrode, and separator. Afterward, remove the electrode assembly from the outer packaging component.

[0176] For example, if the outer packaging is made of laminated sheet material, the outer packaging is opened to remove the electrode assembly. If necessary, the portion connecting the negative electrode tab to the negative terminal and the portion connecting the positive electrode tab to the positive terminal are cut off.

[0177] The outermost diaphragm of the extracted electrode assembly is peeled off and removed to expose the electrode (e.g., the negative electrode). For the exposed electrode, the distance from the end of the electrode to the end of the diaphragm is measured. After measurement, the measured electrode and diaphragm are removed to expose the underlying electrode for further measurement. This operation is repeated to measure all electrodes included in the electrode assembly.

[0178] For example, if the electrode assembly is a structure in which positive and negative electrodes are alternately stacked by a folded diaphragm, the folds in the diaphragm can be removed to expose the electrodes alternately, and measurements can be performed simultaneously. If the electrode assembly is a structure in which materials containing electrodes are stacked within a bag-shaped diaphragm, the bag of the diaphragm can be cut open to expose the electrodes.

[0179] For example, when measuring the negative electrode, the direction in which the negative electrode tab extends relative to the negative electrode current collector is set as the first direction, and the opposite direction is set as the second direction.

[0180] The end of the negative electrode located in the second direction is designated as the second negative electrode portion. The end of the layer containing the negative electrode active material located in the first direction is designated as the first negative electrode portion. Furthermore, the end of the membrane located in the first direction is designated as the first membrane end, and the end located in the second direction is designated as the second membrane end.

[0181] Using a ruler, measure the distance Ln between the second negative end and the end of the second diaphragm. Also, measure the distance Ln' between the first negative end and the end of the first diaphragm.

[0182] When measuring the positive electrode, the end of the positive electrode located in the first direction is designated as the first positive electrode portion. The end of the layer containing the positive electrode active material located in the second direction is designated as the second positive electrode portion.

[0183] The distance Lp between the first positive terminal and the end of the first diaphragm was measured. Furthermore, the distance Lp' between the second positive terminal and the end of the second diaphragm was measured.

[0184] It should be noted that when the ruler is placed with the end of the diaphragm of the object being measured as the starting point and in a manner that becomes perpendicular to the end of the diaphragm, the measurement is performed at the position where the distance to the end of the electrode of the object being measured is the shortest.

[0185] (Method for determining the composition of the current collector) When determining the composition of the current collector, firstly, the electrode (e.g., the negative electrode) of the object to be measured is removed from the battery that has been decomposed as described above. After immersing the electrode in water, the layer containing the active material is separated from the current collector. Separation can be carried out, for example, by ultrasonic treatment or heat treatment such as firing at 400°C in the atmosphere for 2 hours.

[0186] The element can be determined by fluorescence X-ray analysis of the current collector separated using the methods described above. For example, the Fundamental Parameter method (FP) can be used to determine the element.

[0187] (Compositional analysis of active substances) The composition of the active substances contained in the layer containing the active substances can be determined by the following operation.

[0188] First, the layer containing the active substance is separated from the electrode of the test object using the method described above.

[0189] X-ray diffraction was performed on the separated layers containing the active substance. The crystalline phase in the active substance layer was determined using quantitative analysis methods such as RIR (Reference Intensity Ratio). When the active substance is an amorphous phase and the crystalline phase is difficult to observe by X-ray diffraction, the composition of the active substance can be determined by simultaneously performing compositional analysis using fluorescence X-ray analysis and ICP-based luminescence spectrophotometry.

[0190] (Method for measuring the thickness of the current collector) The thickness of the current collector contained in the electrode can be measured as follows.

[0191] First, the layer containing the active material on the electrode of the object being measured is removed by the method described earlier or by dissolution. The thickness of the current collector after removing the active material layer is measured using a thickness gauge. The average thickness of the current collector is taken as the average thickness obtained by randomly measuring five locations with a size of 5 cm square.

[0192] The secondary battery according to the first embodiment includes a positive electrode, a plurality of negative electrodes, and a separator disposed between the positive and negative electrodes. Each of the plurality of negative electrodes includes a negative current collector, a negative electrode tab, and a layer containing a negative active material disposed on the negative current collector. The negative current collector includes aluminum or an aluminum alloy. The negative electrode tab is electrically connected to the negative current collector and extends along a first direction. The negative electrode has a second negative terminal portion located at an end with respect to a second direction opposite to the first direction. The separator has a first separator end portion located at an end with respect to the first direction and a second separator end portion located at an end with respect to the second direction. The second separator end portion protrudes toward the second direction compared to any of the second negative terminal portions included in each of the plurality of negative electrodes. When the distance between the second negative terminal portions included in each of the plurality of negative electrodes and the second separator end portion is set to Ln, the smallest value of Ln is Ln. min The maximum value is Ln max Ln min It is 1.5mm or more. Ln min With Ln max The difference is greater than 1.0 mm. Therefore, the secondary battery can improve charge-discharge cycle performance.

[0193] (Second Implementation) According to a second embodiment, a battery pack is provided. The battery pack includes a plurality of secondary batteries as described in the first embodiment.

[0194] In the battery pack, the individual cells can be electrically connected in series or in parallel, or a combination of series and parallel connections can be configured.

[0195] Next, an example of a battery pack involved in the embodiment will be described with reference to the accompanying drawings.

[0196] Figure 8 This is a three-dimensional diagram that roughly represents an example of a battery pack. Figure 8 The battery pack 200 shown includes five individual cells 100a to 100e, four busbars 21, a positive electrode lead 22, and a negative electrode lead 23. Each of the five individual cells 100a to 100e is a secondary battery according to the first embodiment.

[0197] Bus 21 connects, for example, the negative terminal 6 of a single cell 100a to the positive terminal 7 of the adjacent single cell 100b. In this manner, five single cells 100 are connected in series via four buses 21. That is, Figure 8 The battery pack 200 consists of five batteries connected in series. Although no example is shown, in a battery pack containing multiple individual cells electrically connected in parallel, for example, multiple negative terminals are connected to each other via a busbar, and multiple positive terminals are connected to each other via a busbar, so that multiple individual cells can be electrically connected.

[0198] The positive terminal 7 of at least one of the five individual cells 100a to 100e is electrically connected to the positive side lead 22 for external connection. In addition, the negative terminal 6 of at least one of the five individual cells 100a to 100e is electrically connected to the negative side lead 23 for external connection.

[0199] The battery pack according to the second embodiment includes the secondary battery according to the first embodiment. Therefore, it is possible to improve charge-discharge cycles.

[0200] (Third implementation) According to a third embodiment, a battery pack is provided. This battery pack includes the battery pack according to the second embodiment. Alternatively, the battery pack may include a single secondary battery according to the first embodiment instead of the battery pack according to the second embodiment.

[0201] The battery pack may further include a protection circuit. This protection circuit controls the charging and discharging of the secondary battery. Alternatively, a circuit included in a device that uses the battery pack as a power source (e.g., electronic equipment, automobiles, etc.) may be used as the protection circuit for the battery pack.

[0202] Furthermore, the battery pack may also include external terminals for power supply. These external terminals are components used to output current from the secondary battery to the outside and / or to input current from the outside to the secondary battery. In other words, when the battery pack is used as a power source, current is supplied to the outside via the external terminals for power supply. Furthermore, when the battery pack is being charged, charging current (including regenerative energy from the power source of an automobile, etc.) is supplied to the battery pack via the external terminals for power supply.

[0203] Next, an example of the battery pack involved in the embodiment will be described with reference to the accompanying drawings.

[0204] Figure 9 This is an exploded perspective view that roughly represents an example of a battery pack. Figure 10 It means Figure 9 The diagram shows a block diagram of an example of the circuitry for the battery pack.

[0205] Figure 9 and Figure 10 The battery pack 300 shown includes a container 31, a cover 32, a protective sheet 33, a battery pack 200, a printed circuit board 34, wiring 35, and an insulating plate (not shown).

[0206] Figure 9The container 31 shown is a square container with a rectangular base. The container 31 is configured to house the protective sheet 33, the battery pack 200, the printed circuit board 34, and the wiring 35. The cover 32 has a rectangular shape. The cover 32 houses the battery pack 200 and the like by covering the container 31. Although not shown, the container 31 and the cover 32 are provided with openings or connection terminals for connecting to external devices.

[0207] The battery pack 200 includes multiple individual cells 100, positive electrode side lead 22, negative electrode side lead 23, and adhesive tape 24.

[0208] At least one of the plurality of individual cells 100 is a secondary battery according to the first embodiment. Each of the plurality of individual cells 100 is as follows: Figure 10 As shown, the individual cells 100 are electrically connected in series. Multiple individual cells 100 can also be connected in parallel, or a combination of series and parallel connections can be used. If multiple individual cells 100 are connected in parallel, the battery capacity increases compared to a series connection.

[0209] Adhesive tape 24 is used to bundle multiple individual cells 100 together. Alternatively, heat-shrinkable tape can be used to secure the multiple individual cells 100 instead of adhesive tape 24. In this case, protective sheets 33 are placed on both sides of the battery pack 200, and the heat-shrinkable tape is wrapped around the pack and then heat-shrinked to bundle the multiple individual cells 100 together.

[0210] One end of the positive electrode lead 22 is connected to the battery pack 200. One end of the positive electrode lead 22 is electrically connected to the positive electrode of one or more individual cells 100. One end of the negative electrode lead 23 is connected to the battery pack 200. One end of the negative electrode lead 23 is electrically connected to the negative electrode of one or more individual cells 100.

[0211] The printed circuit board 34 is disposed along one of the shorter sides of the inner surface of the receiving container 31. The printed circuit board 34 includes a positive-side connector 342, a negative-side connector 343, a thermistor 345, a protection circuit 346, wirings 342a and 343a, an external terminal 350 for power supply, positive-side wiring 348a, and negative-side wiring 348b. One main surface of the printed circuit board 34 faces one side of the battery pack 200. An insulating plate (not shown) is sandwiched between the printed circuit board 34 and the battery pack 200.

[0212] The other end 22a of the positive lead 22 is electrically connected to the positive connector 342. The other end 23a of the negative lead 23 is electrically connected to the negative connector 343.

[0213] A thermistor 345 is fixed to a main surface of the printed circuit board 34. The thermistor 345 detects the temperature of each individual cell 100 and sends its detection signal to the protection circuit 346.

[0214] An external terminal 350 for power supply is fixed to another main surface of the printed circuit board 34. The external terminal 350 for power supply is electrically connected to a device located outside the battery pack 300. The external terminal 350 for power supply includes a positive terminal 352 and a negative terminal 353.

[0215] The protection circuit 346 is fixed to another main surface of the printed circuit board 34. The protection circuit 346 is connected to the positive terminal 352 via a positive side wiring 348a. The protection circuit 346 is connected to the negative terminal 353 via a negative side wiring 348b. Furthermore, the protection circuit 346 is electrically connected to the positive connector 342 via wiring 342a. The protection circuit 346 is electrically connected to the negative connector 343 via wiring 343a. Moreover, the protection circuit 346 is electrically connected to each of the plurality of individual cells 100 via wiring 35.

[0216] The protective sheet 33 is disposed on the two inner sides of the receiving container 31 along the long side and on the inner side of the battery pack 200 opposite to the printed circuit board 34 along the short side. The protective sheet 33 is formed, for example, from resin or rubber.

[0217] The protection circuit 346 controls the charging and discharging of multiple individual batteries 100. In addition, based on the detection signal sent by the thermistor 345, or the detection signal sent by each individual battery 100 or battery pack 200, the protection circuit 346 disconnects the electrical connection between the protection circuit 346 and the external terminals 350 (positive terminal 352, negative terminal 353) for powering on external devices.

[0218] As a detection signal sent by the thermistor 345, examples include signals indicating that the temperature of a single cell 100 is above a predetermined temperature. As a detection signal sent by each single cell 100 or the battery pack 200, examples include signals indicating overcharging, over-discharging, and overcurrent of a single cell 100. In the case of detecting overcharging in each single cell 100, the battery voltage, or the positive or negative electrode potential, can be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each single cell 100.

[0219] It should be noted that the protection circuit 346 can also be a circuit included in a device that uses the battery pack 300 as a power source (e.g., electronic equipment, automobiles, etc.).

[0220] Furthermore, the battery pack 300, as described above, includes an external terminal 350 for power supply. Therefore, the battery pack 300 can output current from the battery pack 200 to an external device and input current from an external device into the battery pack 200 via the external terminal 350. In other words, when the battery pack 300 is used as a power source, current from the battery pack 200 is supplied to the external device via the external terminal 350. Furthermore, when the battery pack 300 is being charged, charging current from the external device is supplied to the battery pack 300 via the external terminal 350. When the battery pack 300 is used as a vehicle battery, the regenerative energy from the vehicle's power source can be utilized as the charging current from the external device.

[0221] It should be noted that the battery pack 300 may also include multiple battery groups 200. In this case, the multiple battery groups 200 may be connected in series, in parallel, or a combination of series and parallel connections. Furthermore, the printed circuit board 34 and wiring 35 may be omitted. In this case, the positive terminal lead 22 and the negative terminal lead 23 may be used as the positive terminal 352 and negative terminal 353 of the external terminal 350 for power supply, respectively.

[0222] Such battery packs are used, for example, in applications requiring excellent cycle performance when drawing high currents. Specifically, they are used as power sources for electronic devices, stationary batteries, and in-vehicle batteries for various vehicles. Examples of electronic devices include digital cameras. This battery pack is particularly suitable for use as an in-vehicle battery.

[0223] The battery pack according to the third embodiment includes either the secondary battery according to the first embodiment or the battery pack according to the second embodiment. Therefore, charge-discharge cycle performance can be improved.

[0224] (Fourth implementation) According to a fourth embodiment, a vehicle is provided. This vehicle is equipped with the battery pack described in the third embodiment.

[0225] In the vehicle, the battery pack, for example, recovers regenerative energy from the vehicle's kinetic energy. The vehicle may also include a mechanism (Regenerator) that converts the vehicle's kinetic energy into regenerative energy.

[0226] Examples of vehicles include two- to four-wheeled hybrid electric vehicles, two- to four-wheeled electric vehicles, electric bicycles, and railway vehicles.

[0227] There are no particular restrictions on the location of the battery pack in a vehicle. For example, when mounting the battery pack in a car, it can be installed in the engine compartment, at the rear of the vehicle body, or under the seats.

[0228] The vehicle can also be equipped with multiple battery packs. In this case, the batteries in each battery pack can be electrically connected in series, in parallel, or a combination of series and parallel connections. For example, if each battery pack contains battery groups, the battery groups can be electrically connected in series, in parallel, or a combination of series and parallel connections. Alternatively, if each battery pack contains a single battery, the individual batteries can be electrically connected in series, in parallel, or a combination of series and parallel connections.

[0229] Next, an example of a vehicle involved in the implementation method will be described with reference to the accompanying drawings.

[0230] Figure 11 This is a partial perspective view that roughly represents an example of a vehicle.

[0231] Figure 11 The vehicle 400 shown includes a vehicle body 40 and a battery pack 300 as described in the third embodiment. Figure 11 In the example shown, vehicle 400 is a four-wheeled car.

[0232] The vehicle 400 can also be equipped with multiple battery packs 300. In this case, the batteries (e.g., single cells or battery packs) contained in the battery pack 300 can be connected in series, in parallel, or a combination of series and parallel connections.

[0233] exist Figure 11 The diagram illustrates an example where the battery pack 300 is mounted in the engine compartment located at the front of the vehicle body 40. As mentioned above, the battery pack 300 can also be mounted, for example, at the rear of the vehicle body 40 or under the seats. The battery pack 300 can be used as a power source for the vehicle 400. Furthermore, the battery pack 300 can recover regenerative energy from the power source of the vehicle 400.

[0234] Next, refer to Figure 12 The implementation method of the vehicle involved in the implementation method will be described.

[0235] Figure 12 This is a diagram that roughly represents an example of a control system for the electrical system in a vehicle. Figure 12 The vehicle 400 shown is an electric vehicle.

[0236] Figure 12 The vehicle 400 shown includes a vehicle body 40, a vehicle power supply 41, a vehicle ECU (Electric Control Unit) 42 which is a higher-level control device for the vehicle power supply 41, an external terminal (a terminal for connecting to an external power supply) 43, a converter 44, and a drive motor 45.

[0237] Vehicle 400 uses a power supply 41, for example, mounted in the engine compartment, at the rear of the vehicle body, or under the seats. It should be noted that... Figure 12 In the vehicle 400 shown, the mounting location of the vehicle power supply 41 is roughly indicated.

[0238] The vehicle power supply 41 includes multiple (e.g., three) battery packs 300a, 300b and 300c, a battery management unit (BMU) 411 and a communication bus 412.

[0239] Battery pack 300a includes battery pack 200a and battery pack monitoring device 301a (e.g., VTM: Voltage Temperature Monitoring). Battery pack 300b includes battery pack 200b and battery pack monitoring device 301b. Battery pack 300c includes battery pack 200c and battery pack monitoring device 301c. Battery packs 300a to 300c are the same type of battery pack as battery pack 300 described above, and battery packs 200a to 200c are the same type of battery pack as battery pack 200 described above. Battery packs 200a to 200c are electrically connected in series. Battery packs 300a, 300b, and 300c can be removed independently and can be exchanged with other battery packs 300.

[0240] Each of the battery packs 200a to 200c comprises a plurality of individual cells connected in series. At least one of the plurality of individual cells is a secondary battery according to the first embodiment. The battery packs 200a to 200c are charged and discharged via the positive terminal 413 and the negative terminal 414, respectively.

[0241] The battery management device 411 communicates with the battery pack monitoring devices 301a-301c, and collects information about voltage, temperature, etc., for each individual cell 100 included in the battery packs 200a-200c contained in the vehicle power supply 41. Thus, the battery management device 411 collects information regarding the maintenance of the vehicle power supply 41.

[0242] The battery management device 411 is connected to the battery monitoring devices 301a to 301c via a communication bus 412. In the communication bus 412, one communication line has multiple nodes (the battery management device 411 and one or more battery monitoring devices 301a to 301c). The communication bus 412 is, for example, a communication bus based on the CAN (Control Area Network) standard.

[0243] The battery monitoring devices 301a to 301c measure the voltage and temperature of each individual cell constituting the battery packs 200a to 200c based on instructions received via communication from the battery management device 411. However, the temperature can be measured at multiple locations for only one battery pack, or the temperature of all individual cells can be measured.

[0244] The vehicle power supply 41 may also have an electromagnetic contactor (e.g., to switch the electrical connection between the positive terminal 413 and the negative terminal 414) to enable or disable the connection. Figure 12 The switching device 415 shown is included. The switching device 415 includes a pre-charge switch (not shown) that is turned on when charging the battery packs 200a-200c, and a main switch (not shown) that is turned on when supplying output from the battery packs 200a-200c to a load. Both the pre-charge switch and the main switch have relay circuits (not shown) that are switched on or off by signals supplied to coils located near the switching elements. The electromagnetic contactors, such as the switching device 415, are controlled based on control signals from the vehicle ECU 42 that control the operation of the battery management device 411 or the vehicle 400 as a whole.

[0245] Converter 44 converts the input DC voltage into a high-voltage 3-phase AC voltage for motor drive. The 3-phase output terminals of converter 44 are connected to the 3-phase input terminals of each of the drive motors 45. Converter 44 is controlled based on control signals from the vehicle ECU 42 used to control the operation of the battery management device 411 or the vehicle as a whole. By controlling converter 44, the output voltage from converter 44 is adjusted.

[0246] The drive motor 45 rotates by electricity supplied by the converter 44. The driving force generated by the rotation of the drive motor 45 is transmitted to the axle and drive wheel W, for example, through a differential gear unit.

[0247] Furthermore, although not shown, vehicle 400 is equipped with a regenerative braking mechanism (regenerator). When braking vehicle 400, the regenerative braking mechanism causes drive motor 45 to rotate, converting kinetic energy into regenerative energy as electrical energy. The regenerative energy recovered by the regenerative braking mechanism is input to converter 44, where it is converted into direct current. The converted direct current is input to vehicle power supply 41.

[0248] One terminal of the connecting line L1 is connected to the negative terminal 414 of the vehicle power supply 41. The other terminal of the connecting line L1 is connected to the negative input terminal 417 of the converter 44. A current detection unit (current detection circuit) 416 of the battery management device 411 is provided on the connecting line L1 between the negative terminal 414 and the negative input terminal 417.

[0249] A terminal of a connecting line L2 is connected to the positive terminal 413 of the vehicle power supply 41. The other terminal of the connecting line L2 is connected to the positive input terminal 418 of the converter 44. A switching device 415 is provided on the connecting line L2 between the positive terminal 413 and the positive input terminal 418.

[0250] External terminal 43 is connected to battery management device 411. External terminal 43 can be connected to an external power source, for example.

[0251] The vehicle ECU 42 responds to input from the driver and other operators, and coordinates with other management and control devices, including the battery management device 411, to control the vehicle power supply 41, switching device 415, and converter 44. Through the coordinated control of the vehicle ECU 42 and others, it controls the output of power from the vehicle power supply 41 and the charging of the vehicle power supply 41, thus managing the overall vehicle 400. Data related to the maintenance of the vehicle power supply 41, such as the remaining capacity of the vehicle power supply 41, is transmitted between the battery management device 411 and the vehicle ECU 42 via a communication line.

[0252] The vehicle according to the fourth embodiment is equipped with the battery pack according to the third embodiment. Because the battery pack has high charge-discharge cycle performance, the reliability of the vehicle can be improved.

[0253] (Example) The following describes the embodiments, but the implementation is not limited to the embodiments described below.

[0254] (Example 1) (Making the negative electrode) An aluminum foil with a thickness of 15 μm is prepared as the negative electrode current collector.

[0255] A slurry, obtained by dispersing TiNb₂O₇ (as the negative electrode active material), acetylene black (as the conductive agent), carboxymethyl cellulose (as the binder), and styrene-butadiene rubber (as the binder) in a solvent, is coated onto a negative electrode current collector to form a layer containing the negative electrode active material. In this case, the ratios of the negative electrode active material, conductive agent, carboxymethyl cellulose, and styrene-butadiene rubber in the layer containing the negative electrode active material are 100 parts by mass, 4 parts by mass, 1 part by mass, and 2 parts by mass, respectively. Furthermore, the coating weight of the layer containing the negative electrode active material is 100 g / m². 2The density is 2.5 g / cm³. 3 The layer containing the negative electrode active material is formed as a strip with a pair of long sides and a short side. Furthermore, a portion of the negative electrode current collector does not have a layer containing the negative electrode active material. This portion serves as the negative electrode tab.

[0256] The negative electrode is fabricated as described above. It should be noted that there are two types of negative electrodes: negative electrode S and negative electrode L, where the longer side of the layer containing the negative electrode active material is longer than that of negative electrode S. In Example 1, as negative electrode S, eight layers containing the negative electrode active material with an area (length of the longer side × length of the shorter side) of 200.0 mm × 95.0 mm are fabricated; and as negative electrode L, eight layers containing the negative electrode active material with an area of ​​201.5 mm × 95.0 mm are fabricated.

[0257] (The production of the positive electrode) Prepare aluminum foil with a thickness of 15μm.

[0258] This will make LiNi, as the positive electrode active material, 0.8 Co 0.1 Mn 0.1 O2, acetylene black (as a conductive agent), and PVdF (as a binder) are dispersed in a solvent to form a slurry, which is then coated onto the positive current collector to form a layer containing positive electrode active material. At this point, the ratio of positive electrode active material, conductive agent, and binder in the layer containing positive electrode active material is 100 parts by mass, 3 parts by mass, and 2 parts by mass, respectively. Furthermore, the coating weight of the layer containing positive electrode active material is 115 g / m². 2 The density is 3.3 g / cm³. 3 The layer containing the positive electrode active material is formed as a strip with a pair of long sides and a short side. Furthermore, a portion of the positive electrode current collector does not have a layer containing the positive electrode active material. This portion is designated as the positive electrode tab. The area (length of the long side × length of the short side) of the layer containing the positive electrode active material is set to 195.0 mm × 90.0 mm.

[0259] (Battery assembly) Prepare a polyethylene film with a thickness of 15 μm and a width of 208.0 mm as the separator. Repeatedly fold the separator in a mountain and valley pattern to make it curved. At this time, each fold line is folded along the width direction. Negative and positive electrodes are alternately arranged in the spaces between the folded separators. The negative electrodes S and L are randomly arranged within the negative electrode. During stacking, the positive and negative electrode tabs are stacked in opposite directions.

[0260] That is, the direction in which the negative electrode tab extends relative to the negative electrode current collector is set as the first direction, and the positive electrode tabs are stacked in a manner in which they extend in a second direction opposite to the first direction. The end of each negative electrode located in the second direction is designated as the second negative electrode portion. Furthermore, the end of the layer containing the negative electrode active material located in the first direction is designated as the first negative electrode portion. The end of each positive electrode located in the first direction is designated as the first positive electrode portion. Furthermore, the end of the layer containing the positive electrode active material located in the second direction is designated as the second positive electrode portion. Additionally, the end of the separator located in the first direction is designated as the first separator end, and the end located in the second direction is designated as the second separator end.

[0261] The negative and positive electrodes are stacked as follows.

[0262] The negative electrode S is arranged such that the distance between the first negative terminal portion and the first diaphragm end portion of the negative electrode S is equal to the distance between the second negative terminal portion and the second diaphragm end portion. That is, it is arranged such that the first diaphragm end portion protrudes 4.0 mm compared to the first negative terminal portion of the negative electrode S, and the second diaphragm end portion protrudes 4.0 mm compared to the second negative terminal portion of the negative electrode S.

[0263] The negative electrode L is arranged such that its first negative terminal portion overlaps with the first negative terminal portion of the negative electrode S along the thickness direction. In other words, all the negative electrodes are stacked in such a way that their first negative terminal portions are aligned. That is, the electrodes are arranged such that the first diaphragm end protrudes 4.0 mm from the first negative terminal portion of the negative electrode L and the second diaphragm end protrudes 2.5 mm from the second negative terminal portion of the negative electrode L.

[0264] The positive electrode is arranged such that the distance between the first positive electrode and the first negative electrode of the negative electrode S is equal to the distance between the second positive electrode and the second negative electrode of the negative electrode S. That is, the first negative electrode of the negative electrode S protrudes 2.5 mm compared to the first positive electrode, and the second negative electrode of the negative electrode S protrudes 2.5 mm compared to the second positive electrode. The electrodes are stacked such that the distance between the first positive electrode and the end of the first diaphragm is 6.5 mm for each positive electrode.

[0265] As described above, the positive electrode, negative electrode, and separator are stacked to obtain the electrode assembly.

[0266] Aluminum tabs were ultrasonically welded to the positive and negative current collectors of the resulting electrode assembly. The electrode assembly was then placed in a laminated film package as the outer packaging and vacuum-dried at 80°C for 12 hours. Subsequently, a liquid non-aqueous electrolyte was injected into the laminated film package in an argon-atmospheric glove box, and the battery was completely sealed by heat sealing. The liquid non-aqueous electrolyte was obtained by dissolving LiPF6 at a concentration of 1M in a solvent consisting of a 1:2 volume ratio of PC and MEC.

[0267] The obtained battery was subjected to its first charge and discharge under the following conditions: Charged in a constant current and constant voltage mode in a thermostatic bath at 25°C. Charged at 0.2C to 2.95V, then switched to constant voltage charging until a current of 0.05C was reached. After a 10-minute rest, discharged in constant current mode. Discharged at 0.2C until a voltage of 1.5V was reached. During the first charge and discharge, the battery was further constrained by clamping it from the outside with a pair of aluminum plates, with the bakelite board in contact with both sides. The surface pressure was adjusted to 0.1 MPa. This process was used to produce a secondary battery.

[0268] (Example 2) In the fabrication of the negative electrode, the area of ​​the layer containing the negative electrode active material of the negative electrode L was changed to 202.0 mm × 95.0 mm. In the stacking, the second separator end protrudes 2.0 mm beyond the second negative electrode portion of the negative electrode L. Apart from the above, the secondary battery was fabricated in the same manner as in Example 1.

[0269] (Example 3) In the fabrication of the negative electrode, the area of ​​the layer containing the negative electrode active material of the negative electrode S is changed to 198.0 mm × 95.0 mm, and the area of ​​the layer containing the negative electrode active material of the negative electrode L is changed to 199.0 mm × 95.0 mm.

[0270] In the stacking process, the negative electrode S is arranged such that the first separator end protrudes 5.0 mm from the first negative electrode end of the negative electrode S, and the second separator end protrudes 5.0 mm from the second negative electrode end of the negative electrode S. Similarly, the negative electrode L is arranged such that the first separator end protrudes 5.0 mm from the first negative electrode end of the negative electrode L, and the second separator end protrudes 4.0 mm from the second negative electrode end of the negative electrode L. Except for the above, the secondary battery is manufactured in the same manner as in Example 1.

[0271] (Example 4) In the fabrication of the negative electrode, the area of ​​the layer containing the negative electrode active material of the negative electrode S is changed to 198.0mm × 95.0mm, and the area of ​​the layer containing the negative electrode active material of the negative electrode L is changed to 201.0mm × 95.0mm.

[0272] In the stacking process, the negative electrode S is arranged such that the first separator end protrudes 5.0 mm from the first negative electrode end of the negative electrode S, and the second separator end protrudes 5.0 mm from the second negative electrode end of the negative electrode S. Similarly, the negative electrode L is arranged such that the first separator end protrudes 5.0 mm from the first negative electrode end of the negative electrode L, and the second separator end protrudes 2.0 mm from the second negative electrode end of the negative electrode L. Except for the above, the secondary battery is manufactured in the same manner as in Example 1.

[0273] (Example 5) In the fabrication of the negative electrode, the area of ​​the layer containing the negative electrode active material of the negative electrode S is changed to 201.0mm × 95.0mm, and the area of ​​the layer containing the negative electrode active material of the negative electrode L is changed to 202.0mm × 95.0mm.

[0274] In the fabrication of the positive electrode, the area of ​​the layer containing the positive electrode active material is changed to 200.0 mm × 90.0 mm.

[0275] In the stacking process, the negative electrode S is arranged such that its first diaphragm end protrudes 3.5 mm from the first negative electrode end of the negative electrode S, and its second diaphragm end protrudes 3.5 mm from the second negative electrode end of the negative electrode S. Furthermore, its first diaphragm end protrudes 3.5 mm from the first negative electrode end of the negative electrode L.

[0276] The first negative electrode portion of the negative electrode S protrudes 0.5 mm more than the first positive electrode portion, and the second negative electrode portion of the negative electrode S protrudes 0.5 mm more than the second positive electrode portion. The electrodes are stacked such that the distance between the first positive electrode portion and the end of the first separator is 4.0 mm for each positive electrode. Except as described above, the secondary battery is manufactured in the same manner as in Example 1.

[0277] (Example 6) The type of negative electrode active material was changed to Nb. 16 W5O 55 Otherwise, the secondary battery is manufactured in the same manner as in Example 1.

[0278] (Example 7) (Making the negative electrode) An aluminum foil with a thickness of 15 μm is prepared as the negative electrode current collector.

[0279] A slurry, obtained by dispersing hard carbon (as the negative electrode active material), acetylene black (as the conductive agent), carboxymethyl cellulose (as the binder), and styrene-butadiene rubber (as the binder) in a solvent, is coated onto a negative electrode current collector to form a layer containing the negative electrode active material. In this case, the ratios of the negative electrode active material, conductive agent, carboxymethyl cellulose, and styrene-butadiene rubber in the layer containing the negative electrode active material are 100 parts by mass, 4 parts by mass, 1 part by mass, and 2 parts by mass, respectively. Furthermore, the coating weight of the layer containing the negative electrode active material is 100 g / m². 2 The density is 2.5 g / cm³. 3 .

[0280] Furthermore, a portion of the negative current collector lacks a layer containing the negative electrode active material. This portion is used as the negative electrode tab.

[0281] Produce the negative electrode as described above. Produce two types of negative electrodes: one with a coating area of ​​200.0mm × 95.0mm (negative electrode S) and the other with a coating area of ​​202.0mm × 95.0mm (negative electrode L).

[0282] (The production of the positive electrode) Prepare aluminum foil with a thickness of 15μm.

[0283] This will make NaFe, as the positive electrode active material, 0.33 Ni 0.33 Mn 0.33 O2, acetylene black (as a conductive agent), and PVdF (as a binder) are dispersed in a solvent to form a slurry, which is then coated onto the positive current collector to form a layer containing positive electrode active material. At this point, the ratio of positive electrode active material, conductive agent, and binder in the layer containing positive electrode active material is 100 parts by mass, 3 parts by mass, and 2 parts by mass, respectively. Furthermore, the coating weight of the layer containing positive electrode active material is 125 g / m². 2 The density is 2.9 g / cm³. 3 .

[0284] Furthermore, a portion of the positive current collector lacks a layer containing the positive active material. This portion is designated as the positive electrode tab. The area of ​​the coated portion is set to 195.0 mm × 90.0 mm.

[0285] (Battery assembly) Aluminum tabs are ultrasonically welded to the positive and negative current collectors of the resulting electrode assembly. As a liquid non-aqueous electrolyte, it is used in a solvent prepared by dissolving NaPF6 at a concentration of 1M in a 1:2 volume ratio mixture of PC and MEC.

[0286] Apart from the above, the battery was manufactured in the same manner as in Example 1. It should be noted that the secondary battery involved in Example 7 is a sodium secondary battery.

[0287] (Examples 8-11) The thickness of the current collector is set as described in Table 1, and the secondary battery is manufactured in the same manner as in Example 1.

[0288] (Comparative Example 1) In the fabrication of the negative electrode, the area of ​​the layer containing the negative electrode active material of the negative electrode S is changed to 201.0mm × 95.0mm, and the area of ​​the layer containing the negative electrode active material of the negative electrode L is changed to 203.0mm × 95.0mm.

[0289] In the stacking process, the negative electrode S is arranged such that the first separator end protrudes 3.5 mm from the first negative electrode end of the negative electrode S, and the second separator end protrudes 3.5 mm from the second negative electrode end of the negative electrode S. Furthermore, the negative electrode L is arranged such that the first separator end protrudes 3.5 mm from the first negative electrode end of the negative electrode L, and the second separator end protrudes 1.5 mm from the second negative electrode end of the negative electrode L. Moreover, the surface pressure is adjusted to be 0.3 MPa during the initial charge and discharge cycle. Except for the above, the secondary battery is manufactured in the same manner as in Example 1.

[0290] (Comparative Example 2) In the fabrication of the negative electrode, the area of ​​the layer containing the negative electrode active material of the negative electrode S is changed to 201.0mm × 95.0mm, and the area of ​​the layer containing the negative electrode active material of the negative electrode L is changed to 203.0mm × 95.0mm.

[0291] In the stacking process, the negative electrode S is arranged such that the first separator end protrudes 3.5 mm from the first negative electrode end of the negative electrode S, and the second separator end protrudes 3.5 mm from the second negative electrode end of the negative electrode S. Similarly, the negative electrode L is arranged such that the first separator end protrudes 3.5 mm from the first negative electrode end of the negative electrode L, and the second separator end protrudes 1.5 mm from the second negative electrode end of the negative electrode L. Except for the above, the secondary battery is manufactured in the same manner as in Example 7.

[0292] (Measurement) For the secondary batteries of each embodiment and comparative example, an initial charge-discharge cycle was performed. Afterward, the secondary battery was fully discharged, and Ln was measured using the method described previously. min 、Ln max Lp min In addition, Ln was calculated. max With Ln min The difference, Lp min With Ln minThe difference is then determined. Furthermore, the type of negative electrode active material and the thickness of the current collector are determined using the methods described above. The measurement results are shown in Table 1.

[0293] (evaluate) For the batteries of the examples and comparative examples, the capacity retention rate was measured for 500 cycles as follows.

[0294] The battery under test was charged at 2C at 25°C, and then discharged at 2C. This charge-discharge cycle was considered as one cycle, and the cycle was repeated 500 times. The discharge capacity was measured during the first and 500th cycles. The capacity retention rate (%) over 500 cycles was obtained by dividing the discharge capacity of the 500th cycle by the discharge capacity of the first cycle and multiplying by 100. The capacity retention rate over 500 cycles is used as an indicator of charge-discharge cycle performance.

[0295] The minimum value of Ln among the distances Ln between the second negative terminal portion and the end of the second separator in each of the plurality of negative electrodes in the secondary batteries of Examples 1 to 11. min All are above 1.5mm, and the largest value in Ln is Ln. max With Ln min The difference is 1.0 mm or more. Therefore, compared with the secondary batteries of Comparative Examples 1 and 2, the capacity retention rate of Examples 1 to 11 is higher after 500 cycles. That is, the charge-discharge cycle performance is good.

[0296] It should be noted that in the secondary batteries of the various embodiments and comparative examples, the measured values ​​shown in Table 1 regarding the distance between the end of each electrode and the end of the separator sometimes differ from the values ​​at the time of assembly. Specifically, Ln min 、Ln max and Lp min With Ln min The difference is attributed to the slight expansion and contraction of the negative electrode within the electrode assembly during the initial charge and discharge of the secondary battery.

[0297] Ln in Comparative Example 1 and Comparative Example 2 min The value is as small as 1.0 mm. Therefore, it is believed that because the distance between the second negative terminal and the end of the second diaphragm is too small, a short circuit is easily generated, resulting in difficulty in charging. As a result, the capacity retention rate is low after 500 cycles.

[0298] The results from Examples 1-3 show that even if Ln is changed min The value of Ln can also improve charge-discharge cycle performance. Furthermore, Ln minExample 3, with its larger value, exhibits particularly good charge-discharge cycle performance. This is believed to be because, throughout the entire negative electrode, the distance between the second negative electrode end and the second diaphragm end is adequately ensured, thus effectively suppressing short circuits.

[0299] The results from Examples 1 and 4 show that even if Ln is changed max With Ln min Even with a slight difference, excellent charge-discharge cycle performance can still be obtained. Furthermore, the results of Examples 1 and 5 show that even with changes in Lp... min and Lp min With Ln min Even with a small difference, excellent charge-discharge cycle performance can still be obtained.

[0300] The results of Examples 1, 6, and 7 demonstrate that excellent charge-discharge cycle performance can be obtained even when the type of negative electrode active material is changed. Furthermore, the results of Example 7 show that excellent charge-discharge cycle performance can be obtained even when the secondary battery is a sodium secondary battery.

[0301] The results from Examples 1, 8-11 demonstrate that excellent charge-discharge cycle performance can be obtained even with various modifications to the thickness of the negative electrode current collector. In particular, a thicker negative electrode current collector increases electrode strength, thus tending towards superior charge-discharge cycle performance. However, from the viewpoint of battery capacity density, Examples 1 and 9, with their thinner current collectors, are superior to Example 11.

[0302] According to at least one embodiment or example described above, a secondary battery is provided. The secondary battery includes a positive electrode, a plurality of negative electrodes, and a separator disposed between the positive and negative electrodes. Each of the plurality of negative electrodes includes a negative current collector, a negative electrode tab, and a layer containing a negative electrode active material disposed on the negative current collector. The negative current collector comprises aluminum or an aluminum alloy. The negative electrode tab is electrically connected to the negative current collector and extends along a first direction. The negative electrode has a second negative terminal portion located at an end with respect to a second direction opposite to the first direction. The separator has a first separator end portion located at an end with respect to the first direction and a second separator end portion located at an end with respect to the second direction. The second separator end portion protrudes toward the second direction compared to any of the second negative terminal portions included in each of the plurality of negative electrodes. When the distance between the second negative terminal portions included in each of the plurality of negative electrodes and the second separator end portion is set to Ln, the smallest value of Ln is Ln. min The maximum value is Ln max Ln min It is 1.5mm or more. Ln min With Ln max The difference is greater than 1.0 mm. Therefore, the secondary battery can improve charge-discharge cycle performance.

[0303] It should be noted that the above-described implementation methods can be summarized into the following technical solutions.

[0304] (Technical Solution 1) A secondary battery comprising a positive electrode, a plurality of negative electrodes, and a separator disposed between the positive electrode and the negative electrodes. Each of the aforementioned plurality of negative electrodes comprises a negative electrode current collector containing aluminum or an aluminum alloy, a negative electrode tab electrically connected to the aforementioned negative electrode current collector and extending along a first direction, and a layer containing a negative electrode active material disposed on the aforementioned negative electrode current collector. The aforementioned negative electrode has a second negative terminal portion located at the end in a second direction opposite to the aforementioned first direction. The aforementioned diaphragm has a first diaphragm end located at the end with respect to the first direction and a second diaphragm end located at the end with respect to the second direction. The end of the second diaphragm protrudes toward the second direction compared to any of the second negative electrode portions included in each of the plurality of negative electrodes. When the distance between the second negative electrode portion and the end of the second diaphragm in each of the plurality of negative electrodes is set to Ln, The smallest value among the above Ln is Ln min The maximum value is Ln max , The above Ln min For 1.5mm or more, The above Ln min With the above Ln max The difference is greater than 1.0 mm.

[0305] (Technical Solution 2) According to the secondary battery of Technical Solution 1, the negative electrode has a first negative end portion located at the end of the layer containing the negative electrode active material about the first direction. There are multiple positive electrodes mentioned above. Each of the aforementioned positive electrodes includes a positive current collector, a positive electrode tab electrically connected to the positive current collector and extending along the second direction, and a layer containing a positive active material disposed on the positive current collector. The aforementioned positive electrode has a first positive terminal portion and a second positive terminal portion. The first positive terminal portion is located at the end of the positive electrode with respect to the first direction. The second positive electrode portion is located at the end of the layer containing the positive electrode active material about the second direction. Each of the aforementioned first negative electrode portions included in the plurality of negative electrodes protrudes in the first direction compared to each of the aforementioned first positive electrode portions included in the plurality of positive electrodes, and each of the aforementioned second negative electrode portions included in the plurality of negative electrodes protrudes in the second direction compared to each of the aforementioned second positive electrode portions included in the plurality of positive electrodes. When the distance between the second positive electrode portion and the end of the second diaphragm in each of the plurality of positive electrodes is set to Lp, The smallest value among the above Lp is Lp min , The above Lp min With the above Ln min The difference is more than 1.5mm.

[0306] (Technical Solution 3) The secondary battery according to Technical Solution 1 or Technical Solution 2 is a lithium-ion secondary battery.

[0307] (Technical Solution 4) The secondary battery according to any one of Technical Solution 1 to Technical Solution 3, wherein the layer containing the negative electrode active material comprises an oxide containing niobium and titanium.

[0308] (Technical Solution 5) The secondary battery according to any one of Technical Solution 1 to Technical Solution 4, wherein the layer containing the negative electrode active material comprises hard carbon.

[0309] (Technical Solution 6) The secondary battery according to any one of Technical Solution 1 to Technical Solution 5, wherein the thickness of the negative electrode current collector is 7 μm or more and 20 μm or less.

[0310] (Technical Solution 7) The secondary battery according to any one of Technical Solution 1 to Technical Solution 6 includes a plurality of the above-mentioned separators.

[0311] (Technical Solution 8) The secondary battery according to any one of Technical Solution 1 to Technical Solution 7 includes the above-mentioned separator that is folded in a tortuous manner.

[0312] (Technical Solution 9) A battery pack comprising a secondary battery as described in any one of Technical Solutions 1 to 8.

[0313] (Technical Solution 10) The battery pack according to Technical Solution 9 further comprises: External terminals for power supply, and Protection circuit.

[0314] (Technical Solution 11) The battery pack according to Technical Solution 9 or Technical Solution 10 includes multiple of the aforementioned secondary batteries. The aforementioned secondary batteries are electrically connected in series, in parallel, or in a combination of series and parallel connections.

[0315] (Technical Solution 12) A vehicle equipped with a battery pack as described in any one of Technical Solutions 9 to 11.

[0316] (Technical Solution 13) The vehicle according to Technical Solution 12 includes a mechanism for converting the kinetic energy of the vehicle into regenerative energy.

[0317] Several embodiments of the present invention have been described, but these embodiments are provided by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the invention described in the claims and its equivalents.

Claims

1. A secondary battery comprising a positive electrode, a plurality of negative electrodes, and a separator disposed between the positive electrode and the negative electrodes. Each of the plurality of negative electrodes comprises a negative electrode current collector containing aluminum or an aluminum alloy, a negative electrode tab electrically connected to the negative electrode current collector and extending along a first direction, and a layer containing a negative electrode active material disposed on the negative electrode current collector. The negative electrode has a second negative end portion located at the end with respect to a second direction opposite to the first direction. The diaphragm has a first diaphragm end located at an end about the first direction and a second diaphragm end located at an end about the second direction. The end of the second diaphragm protrudes toward the second direction compared to any of the second negative end portions included in each of the plurality of negative electrodes. When the distance between the second negative electrode portion and the end of the second diaphragm in each of the plurality of negative electrodes is set to Ln, The smallest value in Ln is Ln min The maximum value is Ln max , The Ln min For 1.5mm or more, The Ln min With the Ln max The difference is greater than 1.0 mm.

2. The secondary battery according to claim 1, wherein, The negative electrode has a first negative end portion located at the end of the layer containing the negative electrode active material about the first direction. The number of positive electrodes is multiple. Each of the plurality of positive electrodes includes a positive current collector, a positive electrode tab electrically connected to the positive current collector and extending along the second direction, and a layer containing a positive active material disposed on the positive current collector. The positive electrode has a first positive terminal portion and a second positive terminal portion. The first positive terminal is located at the end of the positive electrode with respect to the first direction. The second positive electrode portion is located at the end of the layer containing the positive electrode active material about the second direction. Each of the plurality of negative electrodes includes a first negative terminal portion that protrudes in a first direction compared to each of the plurality of positive electrodes includes a first positive terminal portion, and each of the plurality of negative electrodes includes a second negative terminal portion that protrudes in a second direction compared to each of the plurality of positive electrodes includes a second negative terminal portion. When the distance between the second positive terminal portion of each of the plurality of positive electrodes and the end of the second diaphragm is set to Lp, The smallest value in Lp is Lp min , The Lp min With the Ln min The difference is more than 1.5mm.

3. The secondary battery according to claim 1 or 2, wherein, The secondary battery is a lithium-ion secondary battery.

4. The secondary battery according to any one of claims 1 to 3, wherein, The layer containing the negative electrode active material comprises niobium-titanium oxide.

5. The secondary battery according to any one of claims 1 to 4, wherein, The layer containing the negative electrode active material comprises hard carbon.

6. The secondary battery according to any one of claims 1 to 5, wherein, The thickness of the negative electrode current collector is greater than 7 μm and less than 20 μm.

7. A battery pack comprising the secondary battery according to any one of claims 1 to 6.

8. The battery pack according to claim 7, wherein, Further features include: External terminals for power supply, and Protection circuit.

9. The battery pack according to claim 7 or 8, wherein, Equipped with multiple of the aforementioned secondary batteries, The secondary batteries are electrically connected in series, in parallel, or in a combination of series and parallel connections.

10. A vehicle equipped with a battery pack according to any one of claims 7 to 9.

11. The vehicle according to claim 10, wherein, It includes a mechanism for converting the kinetic energy of the vehicle into regenerative energy.

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