Battery cell, battery pack and electric device

Abstract

Embodiments of the present disclosure provide a battery cell, a battery pack and an electric device. The battery cell has a thickness direction and an electrode assembly. The electrode assembly includes a negative electrode sheet, a plurality of positive electrode sheets and a pair of separators. The negative electrode sheet is folded in an arc shape along the thickness direction and has a first side and a second side opposite to each other, the first side encloses at least one first space, and the second side encloses at least one second space, wherein the at least one first space and the at least one second space are staggered in the thickness direction. The plurality of positive electrode sheets are each arranged in a corresponding space of the at least one first space and the at least one second space. The pair of separators are each folded in an arc shape, one of the pair of separators is arranged on the first side of the negative electrode sheet to separate the negative electrode sheet and the positive electrode sheets located in the at least one first space, and the other of the pair of separators is arranged on the second side of the negative electrode sheet to separate the negative electrode sheet and the positive electrode sheets located in the at least one second space.

Description

Technical Field

[0001] The embodiments of this disclosure generally relate to the field of battery technology, and more specifically, to battery cells, battery packs, and electrical devices. Background Technology

[0002] In the current battery manufacturing field, cell forming processes are mainly divided into two major technical routes: stacking and winding. These two processes fundamentally determine the internal physical morphology of the cell and directly affect the final performance limits of the battery.

[0003] The lamination process involves alternately stacking single-piece positive and negative electrode sheets with a separator to create a neat layered structure. This process makes full use of the corner space of the casing, improving space utilization and structural stability.

[0004] The winding process involves simultaneously winding continuous positive and negative electrode sheets with a separator to form a cylindrical or elliptical cell structure. During winding, the electrode sheets do not need to be cut, resulting in low manufacturing costs and high efficiency. Summary of the Invention

[0005] In a first aspect of this disclosure, a battery cell is provided having a thickness direction. The battery cell includes an electrode assembly comprising a negative electrode, a plurality of positive electrode plates, and a pair of separators. The negative electrode is folded in an arcuate manner along the thickness direction and has a first side and a second side opposite to each other, the first side enclosing at least one first space, and the second side enclosing at least one second space, wherein the at least one first space and the at least one second space are staggered in the thickness direction. The plurality of positive electrode plates are each disposed within a corresponding space in the at least one first space and the at least one second space. The pair of separators are each folded in an arcuate manner, one of the separators being disposed on the first side of the negative electrode to separate the negative electrode from the positive electrode located in the at least one first space, and the other separator being disposed on the second side of the negative electrode to separate the negative electrode from the positive electrode located in the at least one second space.

[0006] According to an embodiment of this disclosure, the negative electrode sheet includes a negative electrode current collector and a negative electrode slurry layer, wherein the negative electrode slurry layer is disposed on opposite sides of the negative electrode current collector in the thickness direction.

[0007] In some embodiments, the negative electrode slurry layer comprises a silicon-based material and graphite.

[0008] In some embodiments, the silicon-based material includes at least one of silicon carbide and silicon oxide.

[0009] In some embodiments, the positive electrode sheet includes a positive current collector and a positive electrode slurry layer, wherein the positive electrode slurry layer is disposed on opposite sides of the positive current collector in the thickness direction.

[0010] In some embodiments, the electrode assembly further has a length direction and a height direction, the thickness direction, the length direction and the height direction are perpendicular to each other, the negative electrode includes a plurality of extensions and a plurality of connecting portions, the plurality of extensions are arranged in the thickness direction, each extension extends along the length direction and the height direction, the connecting portions are disposed between adjacent extensions, and the shape of the connecting portions cut by a cross section perpendicular to the height direction includes an arc shape.

[0011] In some embodiments, the electrode assembly further has a length direction and a height direction, the thickness direction, the length direction and the height direction are perpendicular to each other, the negative electrode includes a plurality of extensions and a plurality of connecting portions, the plurality of extensions are arranged in the thickness direction, each extension extends along the length direction and the height direction, the connecting portions are disposed between adjacent extensions, and the shape of the connecting portions cut by a cross section perpendicular to the height direction includes a rectangle.

[0012] In some embodiments, the negative electrode sheet is folded in an arc shape along the thickness direction in 101 to 201 layers.

[0013] In a second aspect of this disclosure, a battery pack is provided, the battery pack comprising: a enclosure; a plurality of battery cells, each battery cell being any of the battery cells according to a first aspect of this disclosure; and a liquid cooling plate located on one side of the enclosure and thermally coupled to the plurality of battery cells.

[0014] In a third aspect of this disclosure, an electrical appliance is provided, comprising: a protective housing; and a battery pack according to a second aspect of this disclosure, the battery pack being disposed within the protective housing.

[0015] The embodiments disclosed herein can reduce the risk of powder shedding from the negative electrode, improve the yield of hi-pot, and maintain the interface flatness and uniform expansion stress of the electrode assembly.

[0016] It should be understood that the description in this section is not intended to limit the key or essential features of the embodiments of this disclosure, nor is it intended to restrict the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0017] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein: Figure 1 A cross-sectional view of an electrode assembly according to some embodiments of the present disclosure is shown; Figure 2 It shows Figure 1 An exploded view of the electrode assembly shown. Figure 3 and Figure 4 It shows Figure 1 A cross-sectional view of the negative electrode shown; Figure 5 It shows Figure 1 The cross-sectional view of the positive electrode shown; and Figure 6 A schematic diagram of a battery pack provided according to some embodiments of the present disclosure is shown.

[0018] Explanation of reference numerals in the attached figures: 100 is the electrode assembly, 101 is the first space, and 102 is the second space; 1 is the negative electrode sheet, 11 is the first side, 12 is the second side, 13 is the negative electrode current collector, 14 is the negative electrode slurry layer, 15 is the extension part, and 16 is the connecting part; 2 is the positive electrode plate, 21 is the positive electrode current collector, and 22 is the positive electrode slurry layer; 3 is an isolation component; X represents the length direction; Y represents the thickness direction; Z represents the height direction; 600 is the battery pack, 610 is the enclosure, 620 is the individual battery cell, and 630 is the liquid cooling plate. Detailed Implementation

[0019] Embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0020] The term "comprising" and its variations as used herein signify open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc., may refer to different or the same objects.

[0021] Traditional battery cells can be divided into two structures from the perspective of internal forming process: stacked structure and wound structure.

[0022] Stacked structures can fully utilize the corner space of the casing, resulting in high space utilization and good structural stability. However, stacked structures have the following technical problems: First, the stacking process is inefficient. Second, after the positive and negative electrodes are slit, they still need to be cut according to the design dimensions. Each electrode has cutting ends on both sides, and powder shedding is prone to occur at the cutting points. For negative electrodes, the powder shedding problem is particularly obvious, which is one of the main reasons for poor hi-pot (high potential test) results. Especially when using silicon-doped negative electrodes, due to the strong expansion force of silicon, silicon expands during cycling, leading to a decrease in the adhesion of the negative electrode and making it more prone to powder shedding.

[0023] Winded electrodes do not require cutting, resulting in lower cost and higher efficiency. However, winding structures also present the following technical challenges: First, they cannot fully utilize the corner space of the casing, leading to poor space utilization and reduced energy density. Second, winding structures exhibit poor interface stability; lithium plating easily occurs at the C-corners (corners) of the electrodes, resulting in uneven interfaces and uneven expansion stress, which reduces the cycle life of the cell and deteriorates gas generation performance.

[0024] Based on this, embodiments of the present disclosure provide a single battery cell to at least partially solve the above-mentioned problems.

[0025] The "bow-shaped folding" described in this disclosure refers to a folding method in which the negative electrode sheet 1 is alternately stacked in a bow-shaped pattern along the thickness direction Y to form a multi-layer structure. In bow-shaped folding, the negative electrode sheet 1 is repeatedly bent in the thickness direction Y, so that multiple layers of the negative electrode sheet 1 are arranged sequentially in the thickness direction Y, forming a stacking configuration similar to a bow shape. In this way, the negative electrode sheet 1 can form a continuous multi-layer structure without having to cut the negative electrode sheet 1 multiple times.

[0026] The “first space 101” described in this disclosure refers to the cavity formed by the first side 11 of the negative electrode 1 after the negative electrode 1 is folded in an arc shape, which is used to accommodate the positive electrode 2.

[0027] The "second space 102" described in this disclosure refers to the cavity formed by the second side 12 of the negative electrode 1 after the negative electrode 1 is folded in an arc shape, for accommodating the positive electrode 2. The first space 101 and the second space 102 are staggered in the thickness direction Y, so that the positive electrode 2 can be alternately inserted from the opposite sides of the negative electrode 1.

[0028] The "extension 15" described in this disclosure refers to a planar region of the negative electrode 1 extending along the length direction X and the height direction Z. In an arc-shaped folded configuration, a plurality of extensions 15 are arranged in the thickness direction Y, and each extension 15 constitutes a layer of the negative electrode 1.

[0029] The "connecting portion 16" described in this disclosure refers to the bending transition region between adjacent extensions 15. The connecting portion 16 connects two adjacent extensions 15 in the thickness direction Y, so that the negative electrode sheet 1 forms a continuous arc-shaped folded structure. The shape of the connecting portion 16 as cut by a section perpendicular to the height direction Z may include an arc or a rectangle, etc.

[0030] Figure 1 A cross-sectional view of an electrode assembly 100 according to some embodiments of the present disclosure is shown. Figure 2 It shows Figure 1 An exploded view of the electrode assembly 100 shown.

[0031] Reference Figure 1 and Figure 2 The battery cell has a thickness direction Y, a length direction X, and a height direction Z, with each of these directions perpendicular to the others. The electrode assembly 100 includes a negative electrode 1, a positive electrode 2, and a separator 3. The negative electrode 1 is folded in an arc shape along the thickness direction Y and has a first side 11 and a second side 12 that are opposite to each other. The negative electrode 1 is repeatedly bent in the thickness direction Y, such that multiple layers of the negative electrode 1 are arranged sequentially in the thickness direction Y, forming a stacked configuration similar to an arc. In this way, the negative electrode 1 can form a continuous multilayer structure without having to cut the negative electrode 1 multiple times.

[0032] The first side 11 encloses at least one first space 101. The second side 12 encloses at least one second space 102. The at least one first space 101 and the at least one second space 102 are staggered in the thickness direction Y. It can be understood that the staggered arrangement of the first space 101 and the second space 102 in the thickness direction Y allows the positive electrode 2 to be alternately inserted from opposite sides of the negative electrode 1.

[0033] The positive electrode 2 is disposed within the space formed by folding the negative electrode 1. For example, multiple positive electrode sheets 2 are each disposed within a corresponding space in at least one first space 101 and at least one second space 102. Before assembly, the positive electrode sheets 2 need to be cut, while the negative electrode sheets 1 do not need to be cut. In this way, the positive electrode sheets 2 are interlaced in the arc-shaped structure formed by the negative electrode sheets 1 in a stacked manner, making the overall interface of the electrode assembly 100 smoother and the stress distribution more uniform. In addition, it is beneficial to increase the space utilization of the housing, enhance the structural stability of the electrode assembly 100, and improve the energy density of the electrode assembly 100.

[0034] Each pair of isolators 3 is folded in an arc shape. One of the isolators 3 is disposed on the first side 11 of the negative electrode 1 to isolate the negative electrode 1 from the positive electrode 2 located in the first space 101. The other isolator 3 is disposed on the second side 12 of the negative electrode 1 to isolate the negative electrode 1 from the positive electrode 2 located in the second space 102. The isolators 3 follow the arc shape folding of the negative electrode 1 to provide electrical isolation on both sides of the negative electrode 1.

[0035] The electrode assembly 100 combines the advantages of both lamination and winding processes. In traditional lamination structures, powder shedding is prone to occur at the cut edges of the electrodes, especially the negative electrode, which is one of the causes of hi-pot defects. In traditional winding structures, the electrodes do not need to be cut, but the winding structure cannot fully utilize the corner space of the casing, resulting in poor space utilization. Furthermore, lithium plating is prone to occur at the corners of the electrodes, leading to uneven interfaces and uneven expansion stress in the electrode assembly 100.

[0036] In the electrode assembly 100 disclosed herein, the negative electrode 1, which is prone to powder shedding, is manufactured using an arc-shaped folding process. The positive electrode 2, which has strong adhesion and is less prone to powder shedding, is interspersed in the space formed by the negative electrode 1 in a stacked manner. On the one hand, the negative electrode 1 only has cut ends at the beginning and end, simplifying the cutting process of the negative electrode 1 and reducing its powder shedding risk, thereby improving the high-pot yield. On the other hand, this manufacturing method retains the advantages of the stacking process and avoids the disadvantages of the winding process. There is no lithium plating on either the negative electrode 1 or the positive electrode 2, and neither the negative electrode 1 nor the positive electrode 2 has wrinkles, making the overall interface of the electrode assembly 100 smoother and the stress distribution more uniform.

[0037] In this way, the solution combines the advantages of both stacking and winding processes, which improves production efficiency and reduces manufacturing costs, while reducing the risk of powder shedding from the negative electrode 1, improving the hi-pot yield, and maintaining the interface flatness and uniform expansion stress of the electrode assembly 100. This improves the electrochemical performance and safety performance of the electrode assembly 100, and also helps to improve the cycle life and gas generation performance of the electrode assembly 100.

[0038] Figure 3 and Figure 4 It shows Figure 1 The cross-sectional view of the negative electrode 1 shown. Figure 3 As shown, the negative electrode 1 may include a negative electrode current collector 13 and a negative electrode slurry layer 14. The negative electrode slurry layer 14 is disposed on opposite sides of the negative electrode current collector 13 in the thickness direction Y to form a double-sided coating design. In this way, the negative electrode 1 adopts a double-sided coating design, and both sides of the negative electrode 1 can undergo electrochemical reactions with the adjacent positive electrode 2, thereby improving the energy density of the electrode assembly 100.

[0039] Reference Figure 3 In some embodiments, the negative electrode current collector 13 may be made of copper foil. The thickness of the negative electrode current collector 13 is D1, satisfying 3μm≤D1≤12μm. In this way, the negative electrode current collector 13 maintains good conductivity while having appropriate mechanical strength to support the negative electrode slurry layer 14. Additionally or alternatively, the negative electrode current collector 13 may also be made of other materials.

[0040] In some embodiments, the negative electrode slurry layer 14 may include a silicon-based material and graphite. For example, the silicon-based material includes at least one of silicon carbide and silicon oxide. In some embodiments, the silicon-based material accounts for 3% to 7% of the content in the negative electrode slurry layer 14. In this way, the negative electrode slurry layer 14 can utilize the high specific capacity characteristics of the silicon-based material and the graphite material to improve the energy density of the electrode assembly 100, and can also maintain a high capacity retention rate, thereby extending the battery's lifespan.

[0041] Silicon-containing anodes undergo volume expansion during charge-discharge cycles. Due to the strong expansion force of silicon, it expands during cycling, leading to decreased adhesion of the anode sheet 1 and making it more prone to powder shedding. In traditional stacked structures, the anode sheet 1 needs to be cut to the design dimensions after slitting. Each anode sheet 1 has cutting ports on both ends, and powder shedding is prone to occur at the cutting points, which is one of the reasons for hi-pot defects.

[0042] In the electrode assembly 100 disclosed herein, the negative electrode 1 is manufactured using an arc-shaped folding process. The negative electrode 1 only has cut ends at the beginning and end, simplifying the negative electrode cutting process and reducing the risk of powder shedding. In this way, even if the negative electrode slurry layer 14 uses a silicon-containing material, the powder shedding problem caused by multiple cuttings can be avoided, thereby improving the hi-pot yield.

[0043] like Figure 4 As shown, the negative electrode 1 includes multiple extensions 15 and multiple connecting portions 16. The multiple extensions 15 are arranged in the thickness direction Y, and each extension 15 extends along the length direction X and the height direction Z. The extensions 15 constitute planar regions of the negative electrode 1 in the arcuate folded configuration, and each extension 15 forms a layer of the negative electrode 1. In this way, the multiple extensions 15 are arranged sequentially in the thickness direction Y to form a multilayer stacked structure of the negative electrode 1.

[0044] A connecting portion 16 is disposed between adjacent extension portions 15. The connecting portion 16 connects two adjacent extension portions 15 in the thickness direction Y, so that the negative electrode sheet 1 forms a continuous arc-shaped folded structure. In this way, the negative electrode sheet 1 can form a continuous multi-layer structure by alternating the extension portions 15 and the connecting portion 16, without having to cut the negative electrode sheet 1 multiple times, effectively avoiding the powder shedding problem caused by multiple cutting, thereby improving the hi-pot yield.

[0045] In some embodiments, the shape of the connecting portion 16 cut by a cross section perpendicular to the height direction Z may include an arc or a rectangle, etc., and the embodiments of this disclosure are not limited to the shape. When the cross-sectional shape of the connecting portion 16 is arc-shaped, the connecting portion 16 forms a smooth curved surface in the bending transition area, making the stress distribution of the negative electrode sheet 1 more uniform during the folding process. In this way, the arc-shaped connecting portion 16 can reduce the stress concentration of the negative electrode sheet 1 at the bending point, thereby reducing the risk of the negative electrode slurry layer 14 falling off at the connecting portion 16. Additionally or alternatively, the cross-sectional shape of the connecting portion 16 may also be rectangular to adapt to different electrode assembly 100 structural designs.

[0046] Figure 5 It shows Figure 1 The cross-sectional view of the positive electrode 2 shown. Figure 5 As shown, the positive electrode 2 includes a positive current collector 21 and a positive electrode slurry layer 22. The positive electrode slurry layer 22 is disposed on opposite sides of the positive current collector 21 in the thickness direction Y, forming a double-sided coating design. In this way, the positive electrode 2 adopts a double-sided coating design, and both sides of the positive electrode 2 can undergo electrochemical reactions with the adjacent negative electrode 1, thereby improving the energy density of the electrode assembly 100.

[0047] Reference Figure 5 In some embodiments, the positive current collector 21 may be made of aluminum foil. The thickness, D2, of the positive current collector 21 satisfies 6μm ≤ D2 ≤ 16μm. In this way, the positive current collector 21 maintains good conductivity while having appropriate mechanical strength to support the positive electrode slurry layer 22. Additionally or alternatively, the positive current collector 21 may also be made of other materials.

[0048] In some embodiments, the positive electrode slurry layer 22 may include a positive electrode active material, a conductive agent, and a binder. The positive electrode active material is Ni65 material. In this way, the positive electrode slurry layer 22 can utilize the high energy density characteristics of Ni65 material to improve the electrochemical performance of the electrode assembly 100.

[0049] In the electrode assembly 100 of this disclosure, the positive electrode 2 is interlaced in a stacked manner within the first space 101 and the second space 102 formed by the bow-shaped folded negative electrode 1. Because the positive electrode 2 has strong adhesion and is not prone to powder shedding, cutting the positive electrode 2 using a stacked manner does not cause powder shedding. Furthermore, the stacked interlacing of the positive electrode 2 retains the advantages of a smooth interface and uniform expansion stress in the electrode assembly 100, while avoiding the hi-pot defects caused by powder shedding in traditional stacked structures.

[0050] In some embodiments, the separator 3 may employ a base film structure. The thickness of the base film of the separator 3 may be from 4 μm to 20 μm. In this way, the separator 3 provides electrical isolation between the negative electrode 1 and the positive electrode 2 while having appropriate mechanical strength to support the bow-shaped folded structure and allowing lithium ions to be transported smoothly during charging and discharging.

[0051] As previously described, the electrode assembly 100 has a length direction X, a thickness direction Y, and a height direction Z, with the thickness direction Y, length direction X, and height direction Z being mutually perpendicular. In some embodiments, the electrode assembly 100 has a thickness T in the thickness direction Y, a length L in the length direction X, and a height H in the height direction Z, satisfying at least one of the following: (1) 2 mm ≤ T ≤ 200 mm; (2) 100 mm ≤ L ≤ 1200 mm; (3) 30 mm ≤ H ≤ 600 mm.

[0052] This size range allows the electrode assembly 100 to be suitable for a variety of applications, such as prismatic power batteries. In this way, the electrode assembly 100 can be flexibly configured to meet diverse needs, from small power batteries to large energy storage batteries, according to different battery capacity and energy density requirements. Additionally or alternatively, the dimensional parameters of the electrode assembly 100 can also be adjusted according to specific battery casing dimensions and space utilization requirements.

[0053] Before assembling the electrode assembly 100, both the positive electrode 2 and the negative electrode 1 employ a double-sided coating design. The negative electrode 1 is die-cut to form tabs before assembly. The position of the tabs can be configured according to the design requirements of the battery cell; the tabs of the positive electrode 2 and the negative electrode 1 can be located on the same side or on different sides. In this way, the tab position configuration can adapt to different battery cell structures and welding assembly requirements.

[0054] Before assembly, the positive electrode 2 is cut, while the negative electrode 1 is not cut. In this way, the negative electrode 1 only has cut ends at the beginning and end, which simplifies the cutting process of the negative electrode 1 and reduces the risk of powder shedding.

[0055] During assembly, the negative electrode 1 and the separator 3 are stacked in an arc shape to form an electrode assembly 100 with a set number of layers. During the arc-shaped stacking process, a positive electrode 2 is inserted each time the negative electrode 1 and the separator 3 are folded. In this way, the positive electrode 2 is interspersed in the arc-shaped structure formed by the negative electrode 1 in a stacked manner, making the overall interface of the electrode assembly 100 smoother and the stress distribution more uniform.

[0056] After stacking, adhesive is applied to the beginning and end positions of the electrode assembly 100 to fix the electrode assembly 100. In some embodiments, at the beginning and end stages of stacking, the electrode assembly 100 can be initially fixed by wrapping the spacer 3 along the length direction X. This method helps to maintain the structural stability of the electrode assembly 100 in subsequent processes.

[0057] After stacking and fixing, the electrode assembly 100 undergoes hot or cold pressing shaping. Through hot or cold pressing, the layers of the electrode assembly 100 are tightly bonded together, resulting in an electrode assembly 100 suitable for welding assembly. In this way, the electrode assembly 100 can proceed to subsequent welding and assembly processes to complete the manufacturing of the battery cell.

[0058] Embodiments of this disclosure also provide a battery cell. The battery cell includes at least one electrode assembly 100, each electrode assembly 100 being as described above. In some embodiments, the battery cell may be encapsulated in an aluminum case. The battery cell has a capacity of up to 155 Ah. In this way, the battery cell can meet the high energy density requirements of power batteries.

[0059] In some embodiments, the dimensions of the battery cell are 50.5mm × 205mm × 95mm (thickness × length × height). This size configuration allows the battery cell to be suitable for various application scenarios of prismatic power batteries.

[0060] In some embodiments, a single battery housing may contain one electrode assembly 100. Alternatively or additionally, a single battery housing may also contain two electrode assemblies 100. When a battery housing contains two electrode assemblies 100, the two electrode assemblies 100 are configured in parallel. In this way, the battery cells can be flexibly configured according to different capacity and energy density requirements.

[0061] Embodiments of this disclosure also provide a battery pack. Figure 6 A schematic diagram of a battery pack provided according to some embodiments of the present disclosure is shown. For example... Figure 6 As shown, the battery pack 600 includes a enclosure 610, a plurality of battery cells 620, and a liquid cooling plate 630. Each battery cell 620 is based on the battery cell described above and is disposed within the enclosure 610. The liquid cooling plate 630 is located on one side of the enclosure 610 and is thermally coupled to the plurality of battery cells 620. Heat in the battery cells 620 can be transferred to the liquid cooling plate 630 to efficiently remove heat from the battery cells 620, thereby helping to ensure the cycle life of the battery pack 600 and improving the safety of the battery pack 600.

[0062] Embodiments of this disclosure also provide an electrical device. The electrical device includes a protective housing and a battery pack. Each battery pack is configured as described above and is housed within the protective housing. The protective housing protects the battery pack, preventing risks such as short circuits caused by impacts, punctures, or compression, thus ensuring the long-term reliability of the battery pack.

[0063] The following describes several specific comparative configurations and several specific embodiment configurations.

[0064] In Comparative Example 1, a single electrode assembly 100 comprises 100 layers of positive electrode sheets 2 and 101 layers of negative electrode sheets 1. In this configuration, both the positive electrode sheets 2 and the negative electrode sheets 1 employ a double-sided coating design. The positive electrode slurry layer 22 uses Ni65 material as the positive electrode active material. The negative electrode slurry layer 14 uses graphite-doped silicon-based material, with the silicon-based material content in the negative electrode slurry layer 14 ranging from 3% to 7%. During assembly, the positive electrode sheets 2 and the negative electrode sheets 1 are stacked after being cut. The battery cell includes two electrode assemblies 100. The dimensions of the battery cell are 50.5mm × 205mm × 95mm (thickness × length × height), and the dimensions of the electrode assembly 100 are 24mm × 201mm × 88mm (thickness × length × height). A buffer space needs to be reserved between the electrode assembly 100 and the battery casing to accommodate the expansion of the electrode assembly 100 during charge-discharge cycles.

[0065] In Comparative Example 2, a single electrode assembly 100 comprises 100 layers of positive electrode 2 and 101 layers of negative electrode 1. In this configuration, both the positive electrode 2 and the negative electrode 1 employ a double-sided coating design. The positive electrode slurry layer 22 uses Ni65 material as the positive electrode active material. The negative electrode slurry layer 14 uses graphite-doped silicon-based material, with the silicon-based material content in the negative electrode slurry layer 14 ranging from 3% to 7%. During assembly, the positive electrode 2 and the negative electrode 1 do not require cutting and are assembled using a winding method. The battery cell includes two electrode assemblies 100. The dimensions of the battery cell are 50.5mm × 205mm × 95mm (thickness × length × height), and the dimensions of the electrode assembly 100 are 24mm × 201mm × 88mm (thickness × length × height).

[0066] In Example 1, a single electrode assembly 100 comprises 100 layers of positive electrode sheets 2 and 101 layers of negative electrode sheets 1. In this configuration, both the positive electrode sheets 2 and the negative electrode sheets 1 employ a double-sided coating design. The positive electrode slurry layer 22 uses Ni65 material as the positive electrode active material. The negative electrode slurry layer 14 uses graphite-doped silicon-based material, with the silicon-based material content in the negative electrode slurry layer 14 ranging from 3% to 7%. During assembly, the positive electrode sheet 2 is cut in the same manner as in Comparative Example 1, while the negative electrode sheet 1 does not require cutting. Each time the negative electrode sheet 1 and the separator 3 are folded, a layer of positive electrode sheet 2 is inserted. The battery cell includes two electrode assemblies 100. The dimensions of the battery cell are 50.5mm × 205mm × 95mm (thickness × length × height), and the dimensions of the electrode assembly 100 are 24mm × 201mm × 88mm (thickness × length × height).

[0067] In Example 2, a single electrode assembly 100 comprises 106 layers of positive electrode 2 and 107 layers of negative electrode 1. In this configuration, both the positive electrode 2 and the negative electrode 1 employ a double-sided coating design. The positive electrode slurry layer 22 uses Ni65 material as the positive electrode active material. The negative electrode slurry layer 14 uses graphite-doped silicon-based material, with the silicon-based material content in the negative electrode slurry layer 14 ranging from 3% to 7%. During assembly, the positive electrode 2 is cut in the same manner as in Comparative Example 1, while the negative electrode 1 does not require cutting. Each time the negative electrode 1 and the separator 3 are folded, a layer of positive electrode 2 is inserted. The battery cell includes two electrode assemblies 100. The dimensions of the battery cell are 50.5mm × 205mm × 95mm (thickness × length × height), and the dimensions of the electrode assembly 100 are 24mm × 201mm × 88mm (thickness × length × height).

[0068] In Example 3, a single electrode assembly 100 comprises 200 layers of positive electrode sheets 2 and 201 layers of negative electrode sheets 1. In this configuration, both the positive electrode sheets 2 and the negative electrode sheets 1 employ a double-sided coating design. The positive electrode slurry layer 22 uses Ni65 material as the positive electrode active material. The negative electrode slurry layer 14 uses graphite-doped silicon-based material, with the silicon-based material content in the negative electrode slurry layer 14 ranging from 3% to 7%. During assembly, the positive electrode sheet 2 is cut in the same manner as in Comparative Example 1, while the negative electrode sheet 1 does not require cutting. Each time the negative electrode sheet 1 and the separator 3 are folded, a layer of positive electrode sheet 2 is inserted. The battery cell includes one electrode assembly 100, with the battery cell dimensions being 50.5mm × 205mm × 95mm (thickness × length × height), and the electrode assembly 100 dimensions being 47.8mm × 201mm × 88mm (thickness × length × height).

[0069] After the battery cell is manufactured, it is tested and verified as follows: (1) Hi-pot defect rate is calculated; (2) 1C / 1C charge and discharge cycle performance test is performed in a constant temperature room at room temperature, and the capacity retention rate and the disassembly interface of negative electrode 1 are tested after 1500 cycles.

[0070] The following describes the performance data of several specific comparative configurations and several specific embodiments in conjunction with Table 1.

[0071]

[0072] As shown in Table 1, in Examples 1-3, the negative electrode 1 only has cut ends at the beginning and end, simplifying the cutting process and reducing the risk of powder shedding. Compared to the stacked electrode assembly in Comparative Example 1, the hi-pot defect rate decreased from 7.8% to about 3%, effectively improving the hi-pot yield. Meanwhile, in Examples 1-3, only the positive electrode 2, which is less prone to powder shedding, is interspersed in the space formed by the negative electrode 1 in a stacked manner. There is no lithium plating on the negative electrode 1, and the negative electrode 1 is wrinkle-free. Compared to the wound electrode assembly in Comparative Example 2, the overall interface is smoother and the stress distribution is more uniform.

[0073] Furthermore, there is a correlation between the number of layers and the risk of powder shedding. Since fewer layers result in fewer corners in the negative electrode 1, the risk of powder shedding is lower, and the hi-pot defect rate is lower. For example, the hi-pot defect rates in Examples 3, 2, and 1 gradually decrease.

[0074] Furthermore, there is also a correlation between the number of layers and capacity retention. With a constant total thickness, increasing the total number of layers results in a corresponding decrease in the thickness of each coating layer; conversely, decreasing the total number of layers results in a corresponding increase in the thickness of each coating layer. Coating thickness refers to the thickness of the active material, conductive agent, and binder applied to the negative electrode slurry layer 14 and the positive electrode slurry layer 22. Since a smaller total number of layers results in a thicker coating, the ion migration path becomes longer, leading to a lower capacity retention after 1500 cycles. For example, the capacity retention gradually decreases in Examples 3, 2, and 1.

[0075] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A battery cell having a thickness direction (Y), characterized in that, The battery cell includes an electrode assembly (100), the electrode assembly (100) comprising: A negative electrode (1) is folded in an arc shape along the thickness direction (Y) and has a first side (11) and a second side (12) opposite to each other. The first side (11) encloses at least one first space (101), and the second side (12) encloses at least one second space (102). The at least one first space (101) and the at least one second space (102) are staggered in the thickness direction (Y). Multiple positive electrode plates (2) are each disposed in a corresponding space within the at least one first space (101) and the at least one second space (102); and A pair of separators (3) are each folded in an arc shape. One of the separators (3) is disposed on the first side (11) of the negative electrode (1) to isolate the negative electrode (1) from the positive electrode (2) located in the at least one first space (101), and the other separator (3) is disposed on the second side (12) of the negative electrode (1) to isolate the negative electrode (1) from the positive electrode (2) located in the at least one second space (102).

2. The battery cell according to claim 1, characterized in that, The negative electrode sheet (1) includes a negative electrode current collector (13) and a negative electrode slurry layer (14), wherein the negative electrode slurry layer (14) is disposed on opposite sides of the negative electrode current collector (13) in the thickness direction (Y).

3. The battery cell according to claim 2, characterized in that, The negative electrode slurry layer (14) includes silicon-based materials and graphite.

4. The battery cell according to claim 3, characterized in that, The silicon-based material includes at least one of silicon carbide and silicon oxide.

5. The battery cell according to claim 1, characterized in that, The positive electrode sheet (2) includes a positive current collector (21) and a positive slurry layer (22), which is disposed on opposite sides of the positive current collector (21) in the thickness direction (Y).

6. The battery cell according to claim 1, characterized in that, The electrode assembly (100) also has a length direction (X) and a height direction (Z), the thickness direction (Y), the length direction (X) and the height direction (Z) are perpendicular to each other, the negative electrode (1) includes a plurality of extensions (15) and a plurality of connecting portions (16), the plurality of extensions (15) are arranged in the thickness direction (Y), each extension (15) extends along the length direction (X) and the height direction (Z), the connecting portions (16) are disposed between adjacent extensions (15), and the shape of the connecting portions (16) cut by a cross section perpendicular to the height direction (Z) includes an arc shape.

7. The battery cell according to claim 1, characterized in that, The electrode assembly (100) also has a length direction (X) and a height direction (Z), the thickness direction (Y), the length direction (X) and the height direction (Z) are perpendicular to each other, the negative electrode (1) includes a plurality of extensions (15) and a plurality of connecting portions (16), the plurality of extensions (15) are arranged in the thickness direction (Y), each extension (15) extends along the length direction (X) and the height direction (Z), the connecting portions (16) are disposed between adjacent extensions (15), and the shape of the connecting portions (16) cut by a cross section perpendicular to the height direction (Z) includes a rectangle.

8. The battery cell according to claim 1, characterized in that, The negative electrode sheet (1) is folded in an arc shape along the thickness direction (Y) with 101 to 201 layers.

9. A battery pack, characterized in that, The battery pack includes: Enclosure (610); A plurality of battery cells (620), each battery cell (620) being a battery cell according to any one of claims 1 to 8, and disposed within the enclosure (610); and A liquid cooling plate (630) is located on one side of the enclosure (610) and thermally coupled to the plurality of battery cells (620).

10. An electrical appliance, characterized in that, The electrical equipment includes: Protective casing; and The battery pack according to claim 9 is disposed within the protective housing.

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