Battery cell and secondary battery

Abstract

The utility model relates to the technical field of batteries, and discloses a battery cell and a secondary battery, the battery cell comprises a first pole piece, a second pole piece and a diaphragm, the first pole piece is provided with a first straight section and a first arc section, and the first straight section and the first arc section are sequentially and alternately arranged along the winding direction of the winding battery cell; the first pole piece comprises a first current collector and a first active material layer located on the first current collector, the first current collector is provided with a plurality of first coating areas arranged at intervals in the winding direction, first gap areas are formed between the adjacent first coating areas on the first current collector, and the first gap areas are located on a first arc section; the first active material layer forms a first inclined portion at at least one of both ends of the first coating region. The first gap area, not coated with the first active material layer, of the first pole piece is located on the first arc section, a physical gap is formed in the arc position of the winding battery cell, and a buffer space is reserved for expansion of the negative pole piece at the corresponding position, so that the fracture risk when the foil is stressed is reduced.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to battery cells and secondary batteries. Background Technology

[0002] In the field of battery manufacturing, lithium-ion batteries are a type of rechargeable battery widely used in portable electronic products (such as mobile phones and laptops) and electric vehicles. They are known for their high energy density, long lifespan, and low self-discharge rate.

[0003] Currently, the expansion of the negative electrode in lithium-ion batteries is one of the main reasons for the gradual deterioration of cycle and storage performance. The expansion of the negative electrode in silicon-doped cells is greater than that in pure graphite, and in severe cases, it may cause the copper and aluminum foils to break.

[0004] In response to the ever-increasing energy density requirements, once the silicon doping content of the negative electrode increases to a certain ratio, the copper or aluminum foil at the arc of the wound cell structure may break, forcing a shift to a laminated structure. However, the laminated cell structure also has problems such as lower efficiency than the wound structure, greater difficulty in controlling foreign matter, and higher cost. Utility Model Content

[0005] In view of this, the present invention provides a battery cell and a secondary battery to solve the problem of copper or aluminum foil breakage caused by severe expansion of the negative electrode in the wound battery cell structure.

[0006] In a first aspect, the present invention provides a battery cell, comprising: a first electrode, a second electrode, and a separator, wherein the first electrode, the separator, and the second electrode are stacked and wound to form a wound battery cell; the first electrode has a first straight section and a first arc section, the first straight section and the first arc section being alternately arranged in sequence along the winding direction of the wound battery cell; the first electrode includes a first current collector and a first active material layer located on the first current collector, the first current collector having a plurality of first coating areas spaced apart along the winding direction, a first void area being formed on the first current collector between adjacent first coating areas, the first void area being located on the first arc section, and the first active material layer forming a first inclined portion at at least one end of the coating of the first coating area.

[0007] Beneficial effects: The first active material layer is coated intermittently on the first electrode sheet. After the electrode sheet is wound into a battery cell, the first gap area on the first electrode sheet without the first active material layer is located in the first arc segment. The physical gap at the arc of the wound battery cell provides buffer space for the expansion of the corresponding negative electrode sheet, thereby reducing the risk of foil breakage under stress. It also avoids other risks associated with using a stacked structure, improving the battery cell manufacturing efficiency. The first active material layer avoids fold lines, thus preventing coating peeling due to folding. Continuous coating is not required on the first electrode sheet, reducing waste of active material.

[0008] In one optional embodiment, the second electrode has a second straight section and a second arc section, which are alternately arranged in sequence along the winding direction; the second electrode includes a second current collector and a second active material layer located on the second current collector, the second current collector has a plurality of second coating areas spaced apart along the winding direction, a second void area is formed on the second current collector between adjacent second coating areas, and the second void area is located on the second arc section.

[0009] Beneficial effects: Both the positive and negative electrodes of the battery cell employ spaced-apart active material layers. This allows for greater physical gaps at the arcs where the cell is wound, providing buffer space for the expansion of the corresponding negative electrode. This further reduces the risk of foil breakage under stress and avoids other risks associated with stacked structures, thus improving the cell manufacturing efficiency. The second active material layer avoids fold lines, preventing coating peeling due to folding. Continuous coating is unnecessary on both the first and second electrodes, reducing waste of active material.

[0010] In one alternative implementation, the first electrode is a positive electrode and the second electrode is a negative electrode, and along the winding direction, the length of the first gap region is greater than the length of the second gap region.

[0011] Beneficial effects: The above settings can ensure that lithium ions can migrate smoothly between the positive and negative electrodes during charging and discharging, and will not accumulate too many lithium ions in a certain area, leading to local overcharging or over-discharging, which can improve the cycle life and safety of the battery.

[0012] In one alternative embodiment, a protective adhesive paper is affixed to the first gap area, and the projection area of ​​the protective adhesive paper on the diaphragm covers the projection area of ​​the second gap area on the diaphragm.

[0013] Beneficial effects: The protective film covers the first gap area of ​​the positive electrode, and the projection of the protective film covers the uncoated area of ​​the negative electrode. The use of non-ion-passing protective film reduces the waste of positive electrode active material caused by the positive electrode not being able to exert its capacity in the area below the protective film.

[0014] In one alternative implementation, the first void region is filled with a filling structure, and / or the second void region is filled with a filling structure.

[0015] Beneficial effects: The filling structure can increase the mechanical strength of the battery cell and reduce structural damage caused by the expansion and contraction of the active material during charging / discharging.

[0016] In one alternative embodiment, the filling structure is a mixture of one of ceramic alumina, boehmite, and lithium iron phosphate with adhesive.

[0017] Beneficial effects: Ceramic alumina, boehmite, and lithium iron phosphate all possess excellent high-temperature resistance, remaining stable in high-temperature environments and preventing thermal runaway caused by temperature increases. These materials also have good thermal insulation properties, forming a thermal insulation layer inside the battery, reducing the risk of localized overheating and improving the battery's thermal stability. Ceramic materials (such as alumina and boehmite) have high hardness, which enhances the mechanical strength of the coating, preventing it from cracking or peeling off when the battery is subjected to external impacts.

[0018] In one alternative implementation, the lengths of a plurality of first gap regions increase sequentially along the winding direction; and / or, the lengths of a plurality of second gap regions increase sequentially along the winding direction.

[0019] Beneficial effects: When winding the battery cell, the lengths of the first and second arc segments gradually increase from the inside to the outside along the winding direction. Correspondingly, the lengths of the first and second gap regions also gradually increase. The first and second active material layers can effectively avoid the crease positions, thereby effectively preventing the coating from peeling off due to the folding of the first and second active material layers. At the same time, it can further reduce the waste of active materials.

[0020] In one alternative implementation, the first inclined portion is located on the first arc segment.

[0021] Beneficial effects: The first arc segment can better disperse the stress generated during the winding process, reduce the risk of electrode material peeling or delamination at the edges, and enhance the mechanical stability of the battery cell.

[0022] In one alternative embodiment, along the winding direction, the ratio of the length L1 of the first inclined portion to the length L2 of the first gap region is 0.01-0.995; and / or, the slope angle α of the first inclined portion is 5°-89°.

[0023] Beneficial effects: By limiting the ratio of the length L1 of the first inclined portion to the length L2 of the first gap region to within the range of 0.01-0.995, the first fold of the battery cell can be easily wound, reducing damage to the cell during folding and improving its reliability and lifespan. It allows for winding into cells with a thickness of less than 20mm. Thinner cells better adapt to compact space requirements, making them suitable for applications such as portable electronic devices, wearable devices, and small energy storage systems. Thinner cells are typically lighter, contributing to higher overall system energy density. It is adaptable to various slurries with varying viscosities from low to high, and also to electrodes made of steel, offering a wide range of applications. The slope angle α of the first inclined portion, within the range of 5°-89°, reduces abrupt changes in the first active material layer at the edge, resulting in a smoother transition from no active material layer to its current state. This avoids significant stress concentration at the edge, reducing the risk of foil breakage. It is adaptable to various slurries with varying viscosities from low to high, and also to electrodes made of steel, offering a wide range of applications.

[0024] In one alternative embodiment, the second active material layer forms a second inclined portion at at least one end of the coating on both ends of the second coating area, the second inclined portion being located in the second arc segment.

[0025] Beneficial effects: The second inclined portion can reduce abrupt changes in the second active material layer at the edge, making the transition from no active material layer to active material layer smoother, avoiding abrupt changes in the thickness of the second active material layer at the edge, thereby reducing the edge effect.

[0026] In one alternative embodiment, the length of the second inclined portion is 0.01-0.995 to the length of the second gap region along the winding direction; and / or, the slope angle α of the second inclined portion is 5°-89°.

[0027] Beneficial effects: By limiting the ratio of the length of the second inclined portion to the length of the second gap region to within the range of 0.01-0.995, the first fold of the battery cell can be easily wound, reducing damage to the cell during folding and improving its reliability and lifespan. It allows for winding into cells with a thickness of less than 20mm. Thinner cells better adapt to compact space requirements, making them suitable for applications such as portable electronic devices, wearable devices, and small energy storage systems. Thinner cells are typically lighter, contributing to higher overall system energy density. It is adaptable to various slurries with varying viscosities from low to high, and also to steel electrodes, offering a wide range of applications. The slope angle α of the second inclined portion, within the range of 5°-89°, reduces abrupt changes in the second active material layer at the edges, resulting in a smoother transition from no active material layer to its current state. This avoids significant stress concentration at the edges, reducing the risk of foil breakage. It is adaptable to various slurries with varying viscosities from low to high, and also to steel electrodes, offering a wide range of applications.

[0028] In one optional embodiment, the first current collector has a first single-sided region and a first double-sided region. One side surface of the first single-sided region is coated with a first active material layer, and both sides of the first double-sided region are coated with the first active material layer. The first single-sided region is located at the outer end of the first current collector along the winding direction. The second current collector has a second single-sided region and a second double-sided region. One side surface of the second single-sided region is coated with a second active material layer, and both sides of the second double-sided region are coated with the second active material layer. The second single-sided region is located at the inner end of the second current collector along the winding direction.

[0029] Beneficial effects: Setting single-sided sections in the outermost layer of the positive electrode and the innermost layer of the negative electrode can save active materials and reduce manufacturing costs.

[0030] Secondly, this utility model also provides a secondary battery, including the aforementioned battery cell. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a top view of the first type of positive electrode sheet according to an embodiment of the present utility model;

[0033] Figure 2 for Figure 1 A top view of the current collector of the positive electrode shown;

[0034] Figure 3 for Figure 1 The cross-sectional view of the positive electrode plate shown;

[0035] Figure 4 for Figure 1 The top view of the wound positive electrode sheet shown;

[0036] Figure 5 for Figure 1 The diagram shows a partial active material layer of the positive electrode plate with inclined portions at the beginning and end of the coating.

[0037] Figure 6 for Figure 5 A partial structural schematic diagram of the positive electrode plate is shown;

[0038] Figure 7 This is a cross-sectional view of the second type of positive electrode sheet according to an embodiment of the present utility model;

[0039] Figure 8 This is a cross-sectional view of the third type of positive electrode sheet according to an embodiment of the present invention.

[0040] Explanation of reference numerals in the attached figures:

[0041] 1. First electrode; 101. First current collector; 1011. First coating area; 1012. First void area; 102. First active material layer; 1021. First inclined portion; 103. Filling structure; 104. Protective adhesive paper. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0043] The following is combined with Figures 1 to 8 The following describes embodiments of the present invention.

[0044] According to an embodiment of the present invention, a battery cell is provided, comprising: a first electrode 1, a second electrode, and a separator, wherein the first electrode 1, the separator, and the second electrode are stacked and wound to form a wound battery cell; the first electrode 1 has a first straight section and a first arc section, the first straight section and the first arc section being alternately arranged sequentially along the winding direction of the wound battery cell; the first electrode 1 includes a first current collector 101 and a first active material layer 102 located on the first current collector 101, the first current collector 101 having a plurality of first coating areas 1011 spaced apart along the winding direction, a first void area 1012 being formed on the first current collector 101 between adjacent first coating areas 1011, the first void area 1012 being located in the first arc section, and the first active material layer 102 forming a first inclined portion 1021 at at least one end of the coating of the first coating area 1011.

[0045] In this embodiment, the electrode sheet is coated with a first active material layer 102 at intervals on the first electrode sheet 1. After the electrode sheet is wound into a battery cell, the first gap area 1012 on the first electrode sheet 1 without the first active material layer 102 is located in the first arc segment. There is a physical gap at the arc of the wound battery cell, which provides buffer space for the expansion of the corresponding negative electrode sheet, thereby reducing the risk of foil breakage under stress and avoiding other risks brought about by the use of a stacked structure, thus improving the manufacturing efficiency of the battery cell. The first active material layer 102 avoids crease positions, thereby preventing the coating from falling off due to the first active material layer 102 being folded. Continuous coating is not required on the first electrode sheet 1, reducing the waste of active material.

[0046] The first active material layer 102 is coated on the first electrode 1 at intervals, and the stacking effect is achieved by winding. At the same time, it can also improve safety and increase the electrolyte retention.

[0047] The first active material layer 102 is formed by coating with slurry. Due to the flow characteristics of the slurry, the flowing slurry will inevitably produce an upward slope when it comes from nothing to something, and a downward slope when it comes from something to nothing. As a result, a first inclined portion 1021 will be formed at the beginning and end of the coating. The first inclined portion 1021 can reduce the abrupt change of the first active material layer 102 at the edge, making the transition of the first active material layer 102 from nothing to something smoother, avoiding the abrupt change in the thickness of the first active material layer 102 at the edge, thereby reducing the edge effect.

[0048] In one embodiment, the second electrode has a second straight segment and a second arc segment, which are alternately arranged sequentially along the winding direction. The second electrode includes a second current collector and a second active material layer located on the second current collector. The second current collector has a plurality of second coating regions spaced apart along the winding direction, and a second void region is formed on the second current collector between adjacent second coating regions. The second void region is located on the second arc segment. Wherein, the first electrode 1 is a positive electrode and the second electrode is a negative electrode, or the first electrode 1 is a negative electrode and the second electrode is a positive electrode.

[0049] Both the positive and negative electrodes of the battery cell employ spaced-apart active material layers. This allows for greater physical gaps at the arcs where the cell is wound, providing buffer space for the expansion of the corresponding negative electrode. This further reduces the risk of foil breakage under stress and avoids other risks associated with stacked structures, thus improving the cell's manufacturing efficiency. The second active material layer avoids fold lines, preventing coating peeling due to folding. Continuous coating is unnecessary on both the first and second electrodes, reducing waste of active material.

[0050] Understandably, in another embodiment, a second negative active material layer is continuously coated onto the second current collector. Continuous coating of the second active material layer maximizes the utilization of the negative electrode space, ensuring that each portion contains active material, thereby improving the overall energy density of the battery. Continuous coating reduces the amount of inactive materials (such as conductive agents, binders, etc.), increases the proportion of active material, and further improves energy density.

[0051] In lithium-ion battery cells, to ensure safety, the area with positive electrode active material must have a corresponding position with negative electrode active material. The area with negative electrode active material may not necessarily have a positive electrode active position, and the capacity of the negative electrode at the relative position must be higher than that of the positive electrode.

[0052] In one embodiment, the first electrode 1 is a positive electrode, and the second electrode is a negative electrode. Along the winding direction, the length of the first gap region 1012 is greater than the length of the second gap region. The uncoated area of ​​the positive electrode or the first gap region 1012 and the uncoated area of ​​the negative electrode or the second gap region are both located in the arc region of the wound cell. The projection of the uncoated area of ​​the positive electrode covers the projection of the uncoated area of ​​the negative electrode, that is, the projection area of ​​the first gap region 1012 of the positive electrode on the separator covers the projection area of ​​the second gap region of the negative electrode on the separator.

[0053] The projection area of ​​the second void region of the negative electrode sheet onto the separator is located within the projection area of ​​the first void region 1012 onto the separator. That is, the area of ​​the projection area of ​​the second void region of the negative electrode sheet onto the separator is smaller than the area of ​​the projection area of ​​the first void region 1012 of the positive electrode sheet onto the separator. This arrangement ensures that lithium ions can migrate smoothly between the positive and negative electrodes during charging and discharging, preventing excessive lithium ion accumulation in any one area, which could lead to localized overcharging or over-discharging. This improves the battery's cycle life and safety.

[0054] In one embodiment, such as Figure 7 As shown, a protective adhesive paper 104 is affixed to the first void region 1012. The projection area of ​​the protective adhesive paper 104 on the separator covers the projection area of ​​the second void region on the separator. The protective adhesive paper 104 covers the first void region 1012 of the positive electrode, and the projection of the protective adhesive paper 104 covers the uncoated area of ​​the negative electrode. By using a non-ion-passing protective adhesive paper 104, the waste of positive electrode active material caused by the positive electrode below the protective adhesive paper 104 not being able to exert its capacity is reduced.

[0055] Furthermore, the thickness is increased after the protective adhesive paper 104 is applied to the first gap region 1012 of the positive electrode, which can increase the mechanical strength of the cell and reduce structural damage caused by the expansion and contraction of the active material during charging or discharging.

[0056] In one embodiment, such as Figure 8As shown, the first void region 1012 is filled with a filling structure 103, and the second void region is filled with a filling structure 103. The filling structure 103 can increase the mechanical strength of the battery cell and reduce structural damage caused by the expansion and contraction of the active material during charging / discharging.

[0057] In one embodiment, such as Figure 1 , Figure 3 and Figure 8 As shown, the filling structure 103 is made of a liquid-absorbing material that can absorb electrolyte. This liquid-absorbing material can adsorb electrolyte, improving the safety performance of the battery cell. Preferably, the liquid-absorbing material is a sponge-like substance or similar material.

[0058] It is understood that, in another embodiment, the filling structure 103 is made of a heat-absorbing material. This heat-absorbing material can absorb the heat generated during battery cell operation, facilitating heat dissipation and reducing the risk of thermal runaway. Preferably, the heat-absorbing material is a hydrogel, aerogel, or the like.

[0059] Understandably, in another embodiment, the filling structure 103 can be a safety coating to improve the safety performance of the battery cell in scenarios such as drops. Preferably, the safety coating is a mixture of one of ceramic alumina, boehmite, and lithium iron phosphate with a binder. Ceramic alumina, boehmite, and lithium iron phosphate all have excellent high-temperature resistance and can remain stable in high-temperature environments, preventing thermal runaway caused by temperature rise. These materials have good thermal insulation properties and can form a thermal insulation layer inside the battery, reducing the risk of local overheating and improving the thermal stability of the battery. Ceramic materials (such as alumina and boehmite) have high hardness, which can enhance the mechanical strength of the coating and prevent the coating from cracking or peeling off when the battery is subjected to external impact.

[0060] It should be noted that the materials used for liquid-absorbing materials, heat-absorbing materials, and safety coatings are not limited to these.

[0061] In one embodiment, such as Figure 4 As shown, along the winding direction, the lengths of multiple first gap regions 1012 increase sequentially; along the winding direction, the lengths of multiple second gap regions also increase sequentially. When winding the battery cell, along the winding direction, the lengths of the first and second arc segments from the inside out gradually increase, correspondingly increasing the lengths of the first and second gap regions 1012. This allows the first and second active material layers 102 to effectively avoid creases, thus effectively preventing coating peeling due to folding of the first and second active material layers, and further reducing waste of active materials.

[0062] In one embodiment, the first inclined portion 1021 is located on the first arc segment. The first arc segment can better disperse the stress generated during the winding process, reduce the risk of electrode material peeling or delamination at the edges, and enhance the mechanical stability of the battery cell.

[0063] It is understood that, in another embodiment, the first inclined portion 1021 may also be located at the first straight section.

[0064] In one embodiment, such as Figure 6 As shown, along the winding direction, the ratio of the length L1 of the first inclined portion 1021 to the length L2 of the first gap region 1012 is 0.01-0.995. By limiting the ratio of the length L1 of the first inclined portion 1021 to the length L2 of the first gap region 1012 to the range of 0.01-0.995, the first fold of the battery cell can be easily wound, reducing damage to the battery cell during the folding process and improving the reliability and lifespan of the battery cell. It can be wound into battery cells with a thickness of less than 20mm. The thinner battery cell can better adapt to the compact space requirements and is suitable for applications such as portable electronic devices, wearable devices, and small energy storage systems. The thinner battery cell is usually lighter, which helps to improve the energy density of the overall system. It can be adapted to different slurries with viscosities from low to high and can also be adapted to electrodes made of steel, with a wide range of applications.

[0065] Furthermore, the ratio of the length L1 of the first inclined portion 1021 to the length L2 of the first gap region 1012 is in the range of 0.01-0.995, which makes the first current collector 101 have a gap, which can also ensure the capacity of the battery. The gap can disperse stress, reduce stress concentration points, improve the mechanical strength of the positive electrode, and reduce the risk of breakage during coating and subsequent processing.

[0066] In order to minimize the loss of battery capacity, the ratio of the length L1 of the first inclined portion 1021 to the length L2 of the first gap region 1012 is set to be relatively high, thereby ensuring the battery capacity.

[0067] In one embodiment, such as Figure 5 and Figure 6 As shown, the slope angle α of the first inclined part 1021 is 5°-89°.

[0068] If the slope angle of the first inclined portion 1021 is too small, it may cause a large change in coating thickness at the edge, increasing the edge effect; it may also generate a large stress concentration at the edge, increasing the risk of foil breakage during coating and subsequent processing.

[0069] Therefore, the slope angle α of the first inclined portion 1021 is in the range of 5°-89°, which can reduce the abrupt change of the first active material layer 102 at the edge, making the transition of the first active material layer 102 from nothing to something smoother; it can avoid the risk of large stress concentration at the edge, thus preventing foil breakage; it can be adapted to different slurries with viscosity from low to high, and can also be adapted to electrodes made of steel, with a wide range of applications.

[0070] In one embodiment, the second active material layer forms a second inclined portion at at least one end of the two ends of the second coating area, and the second inclined portion is located in the second arc segment.

[0071] The second active material layer is formed by coating with slurry. Due to the flow characteristics of the slurry, the flowing slurry will inevitably create an upward slope when it comes to being, and a downward slope when it comes to being gone. This will create a second inclined section at the beginning and end of the coating. The second inclined section can reduce the abrupt changes of the second active material layer at the edge, making the transition of the second active material layer from nothing to being something smoother, avoiding abrupt changes in the thickness of the second active material layer at the edge, and thus reducing the edge effect.

[0072] In one embodiment, the ratio of the length of the second inclined portion to the length of the second gap region along the winding direction is 0.01-0.995. By limiting the ratio of the length of the second inclined portion to the length of the second gap region to the range of 0.01-0.995, the first fold of the battery cell can be easily wound, reducing damage to the battery cell during the folding process and improving the reliability and lifespan of the battery cell. It can be wound into a battery cell with a thickness of less than 20mm. The thinner battery cell can better adapt to compact space requirements and is suitable for applications such as portable electronic devices, wearable devices, and small energy storage systems. The thinner battery cell is usually lighter, which helps to improve the energy density of the overall system. It can be adapted to different slurries with viscosities from low to high and can also be adapted to electrodes made of steel, with a wide range of applications.

[0073] In one embodiment, the slope angle α of the second inclined portion is 5°-89°. If the slope angle of the second inclined portion is too small, it may cause a large change in coating thickness at the edge, increasing the edge effect; it may also generate a large stress concentration at the edge, increasing the risk of foil breakage during coating and subsequent processing.

[0074] Therefore, the slope angle α of the second inclined part is in the range of 5°-89°, which can reduce the abrupt change of the second active material layer at the edge, making the transition from the absence of the second active material layer to its presence smoother; it can avoid the risk of large stress concentration at the edge, thus preventing foil breakage; it can be adapted to different slurries with viscosity from low to high, and can also be adapted to electrodes made of steel, with a wide range of applications.

[0075] In one embodiment, such as Figure 3 , Figure 5 , Figure 7 and Figure 8 As shown, the first current collector 101 has a first single-sided region and a first double-sided region. One surface of the first single-sided region is coated with a first active material layer 102, and both surfaces of the first double-sided region are coated with the first active material layer 102. The first single-sided region is located at the outer end of the first current collector 101 along the winding direction. The second current collector has a second single-sided region and a second double-sided region. One surface of the second single-sided region is coated with the second active material layer, and both surfaces of the second double-sided region are coated with the second active material layer. The second single-sided region is located at the inner end of the second current collector along the winding direction. The first electrode 1 is a positive electrode, and the second electrode is a negative electrode. After the positive and negative electrodes are wound into a battery cell, the first single-sided region is located at the outer end of the first current collector along the winding direction, and the second single-sided region is located at the inner end of the second current collector along the winding direction. Thus, along the winding direction, the first single-sided region of the positive electrode is located on the outer side, and the second single-sided region of the negative electrode is located on the inner side. Providing single-sided sections in the outermost layer of the positive electrode and the innermost layer of the negative electrode can save active material and reduce manufacturing costs.

[0076] According to an embodiment of the present invention, in another aspect, a secondary battery is also provided, comprising: the above-mentioned battery cell.

[0077] In one embodiment, the secondary battery further includes a casing, the casing having a receiving cavity, and the battery cell being disposed within the receiving cavity of the casing. The casing protects the battery cell from physical damage and chemical corrosion. Secondary batteries offer advantages such as high energy density, long cycle life, no memory effect, and low self-discharge rate.

[0078] It should be noted that, Figure 1 , Figures 3 to 8 The black area in the figure refers to the first active material layer 102, and the blank area refers to the first void area 1012 on the electrode where the first active material layer 102 is not coated.

[0079] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, include: A first electrode (1), a second electrode, and a separator are stacked and wound together to form a wound battery cell. The first electrode (1) has a first straight section and a first arc section, and the first straight section and the first arc section are alternately arranged along the winding direction of the wound cell. The first electrode (1) includes a first current collector (101) and a first active material layer (102) located on the first current collector (101). The first current collector (101) has a plurality of first coating regions (1011) spaced apart along the winding direction. A first void region (1012) is formed on the first current collector (101) between adjacent first coating regions (1011). The first void region (1012) is located in the first arc segment. The first active material layer (102) forms a first inclined portion (1021) at at least one end of the first coating region (1011).

2. The battery cell according to claim 1, characterized in that, The second electrode has a second straight section and a second arc section, and the second straight section and the second arc section are alternately arranged along the winding direction; The second electrode includes a second current collector and a second active material layer on the second current collector. The second current collector has a plurality of second coating regions spaced apart along the winding direction. A second void region is formed on the second current collector between adjacent second coating regions. The second void region is located in the second arc segment.

3. The battery cell according to claim 2, characterized in that, The first electrode (1) is a positive electrode, and the second electrode is a negative electrode. Along the winding direction, the length of the first gap region (1012) is greater than the length of the second gap region.

4. The battery cell according to claim 2, characterized in that, A protective adhesive paper (104) is affixed to the first gap area (1012), and the projection area of ​​the protective adhesive paper (104) on the diaphragm covers the projection area of ​​the second gap area on the diaphragm.

5. The battery cell according to any one of claims 2 to 4, characterized in that, The first void region (1012) is filled with a filling structure (103), and / or the second void region is filled with a filling structure (103).

6. The battery cell according to any one of claims 2 to 4, characterized in that, Along the winding direction, the lengths of the plurality of first gap regions (1012) increase sequentially; And / or, along the winding direction, the lengths of the plurality of second gap regions increase sequentially.

7. The battery cell according to any one of claims 1 to 4, characterized in that, The first inclined portion (1021) is located in the first arc segment.

8. The battery cell according to any one of claims 1 to 4, characterized in that, Along the winding direction, the ratio of the length L1 of the first inclined portion (1021) to the length L2 of the first gap region (1012) is 0.01-0.995; And / or, the slope angle α of the first inclined portion (1021) is 5°-89°.

9. The battery cell according to any one of claims 2 to 4, characterized in that, The second active material layer forms a second inclined portion at at least one end of the coating on the second coating area, and the second inclined portion is located in the second arc segment.

10. The battery cell according to claim 9, characterized in that, Along the winding direction, the ratio of the length of the second inclined portion to the length of the second gap region is 0.01-0.995; And / or, the slope angle α of the second inclined portion is 5°-89°.

11. The battery cell according to any one of claims 2 to 4, characterized in that, The first current collector (101) has a first single-sided area and a first double-sided area. One side surface of the first single-sided area is coated with the first active material layer (102), and both sides of the first double-sided area are coated with the first active material layer (102). The first single-sided area is located at the outer end of the first current collector (101) along the winding direction. The second current collector has a second single-sided area and a second double-sided area. One side surface of the second single-sided area is coated with the second active material layer, and both sides of the second double-sided area are coated with the second active material layer. The second single-sided area is located at the inner end of the second current collector along the winding direction.

12. A secondary battery, characterized in that, include: The battery cell according to any one of claims 1 to 11.

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