Secondary battery and electronic device

Abstract

Disclosed in the present application are a secondary battery and an electronic device. The secondary battery comprises a housing and an electrode assembly. In a first direction, the housing comprises a first wall portion and a second wall portion arranged opposite each other; and in a second direction, the housing comprises a third wall portion and a fourth wall portion arranged opposite each other, the third wall portion being connected between the first wall portion and the second wall portion to form a first corner. A first support member comprises a first portion and a second portion connected to each other. The second portion is arranged between the third wall portion and an electrode assembly, and the first portion is bent relative to the second portion, such that a first support point is formed at the bend between the first portion and the second portion. The included angle between the first portion and the second portion is α, where α≤90°. The first portion is arranged between the first wall portion and the electrode assembly, and the end of the first portion away from the second portion abuts against the electrode assembly; the first support point abuts against the first corner. The risk of deformation of the housing caused by expansion of the electrode assembly is reduced, improving the safety of the secondary battery.

Description

Secondary batteries and electronic devices Technical Field

[0001] This application relates to the field of battery technology, and in particular to a secondary battery and electronic device. Background Technology

[0002] With the rapid development of modern technology, the demand for high-performance energy storage devices is increasing in fields such as portable electronic devices and electric vehicles. Lithium-ion batteries, as a highly efficient and environmentally friendly energy storage device, have been widely used in many fields. However, during long-term charge-discharge cycles, the electrode components of lithium-ion batteries are prone to expansion, which can lead to irregular deformation of the casing. Summary of the Invention

[0003] This application proposes a secondary battery and electronic device, aiming to reduce the technical problem of the secondary battery casing being prone to deformation.

[0004] In a first aspect, this application proposes a secondary battery, including a housing and an electrode assembly disposed within the housing. Along a first direction, the housing includes a first wall portion and a second wall portion disposed opposite each other. Along a second direction, the housing includes a third wall portion and a fourth wall portion disposed opposite each other. The third wall portion connects the first wall portion and the second wall portion, such that the connection between the third wall portion and the first wall portion forms a first angle position. The secondary battery also includes a first support member, which includes a first part and a second part connected together. The second part is disposed between the third wall portion and the electrode assembly. The first part is bent relative to the second part, such that the bend between the first part and the second part forms a first support position; wherein the included angle between the first part and the second part is α, α ≤ 90°. The first part is disposed between the first wall portion and the electrode assembly, and the end of the first part away from the second part abuts against the electrode assembly, and the first support position abuts against the first angle position. The first direction is the thickness direction of the secondary battery, and the second direction is perpendicular to the first direction.

[0005] In the above technical solution, because the first support position and the first corner position abut against each other, part of the pressure generated by the expansion of the electrode assembly can be transferred to the stronger first corner position. The first corner position is formed by the connection of the first wall portion and the third wall portion, and its structure is stable. By transferring the expansion force to the first corner position, the special structure of the corner position can effectively disperse and bear the expansion force generated by the electrode assembly, reduce the deformation or damage caused by excessive force on the middle of the shell, and improve the safety performance of the secondary battery. Furthermore, the first part is bent relative to the second part, and the included angle α between the first part and the second part is limited to ≤90°, which helps to form a better elastic structure for the first support member, reduces the force transmitted to the shell, further enhances the buffering effect, reduces the risk of shell deformation caused by expansion force, and improves the safety of the secondary battery.

[0006] In some embodiments, 30°≤α≤60° allows the first support member to better function like a spring during deformation, effectively enhancing the cushioning effect. Furthermore, the 30°≤α≤60° angle range makes the elastic deformation of the first support member under stress more reasonable. When subjected to the expansion force of the electrode assembly, the first support member will undergo moderate elastic deformation at its bend and two other parts. This elastic deformation buffers the expansion force, reducing the impact on the housing and electrode assembly, effectively protecting them and further reducing housing deformation.

[0007] In some embodiments, the first part includes a first segment and a second segment connected together. The first segment is fitted onto the surface of the electrode assembly facing the first wall portion, and the second segment is connected between the second part and the first segment, with the second segment bent relative to the second part. This allows the first support member to better match the shape of the electrode assembly and fit tightly against its surface. This helps to more evenly receive and transmit the force generated by the expansion of the electrode assembly, reducing the possibility of excessive local stress due to poor contact, and improving the stability and reliability of the entire support structure.

[0008] In some embodiments, the first segment is bonded to the second wall portion. ， This allows for a tighter connection between the first section and the electrode assembly, effectively reducing the risk of the first support component detaching due to the expansion of the electrode assembly during the charging and discharging process of the secondary battery. This facilitates the continuous and stable performance of support and force transmission, thereby improving the stability of the entire support structure.

[0009] In some embodiments, the housing has a receiving cavity, which is formed by the first wall portion, the second wall portion, the third wall portion, and the fourth wall portion, and the electrode assembly is disposed within the receiving cavity. Along the second direction, the width of the receiving cavity is W, and the width of the first portion is W1, where 0.05×W≤W1≤0.4×W, ensuring that the first portion has sufficient width to contact and support the electrode assembly. When the electrode assembly expands, the first support member can withstand a certain pressure and reduce excessive deformation or damage, improving the stability of the support structure. Specifically, a width of 0.75mm≤W1≤6mm can be selected, allowing the first support member to undergo appropriate elastic deformation under stress, thereby enhancing the buffering effect.

[0010] In some embodiments, along the first direction, the height of the receiving cavity is H, and the height of the second part is H1, where 0.5 × H ≤ H1 ≤ 0.9 × H. This facilitates the installation of the first support member, and the second part can define the position of the first support member, making it easier for the first support position of the first support member to abut against the first corner position, thus improving the stability of the entire support structure. Optionally, 1.5 mm ≤ H1 ≤ 2.7 mm.

[0011] In some embodiments, along a third direction, the length of the electrode assembly is L, and the length of the first portion is L1, where 0.1 × L ≤ L1 ≤ 0.8 × L ， This design provides stable support to the first part, effectively distributing the stress caused by volume changes in the electrode assembly during charging and discharging, thus improving the overall stability of the support structure. The first, second, and third directions are mutually perpendicular. Optionally, 2mm ≤ L1 ≤ 16mm. Preferably, 8mm ≤ L1 ≤ 13mm.

[0012] In some embodiments, the housing is a metal housing. ， The metal shell itself has a certain strength and rigidity, which can provide basic structural support. The first support component works in conjunction with the rigid metal shell to enhance the stability of the entire support structure, further disperse the expansion force of the electrode assembly, and reduce the risk of shell deformation.

[0013] In some embodiments, the electrode assembly includes a first electrode, a separator, and a second electrode. Along a first direction, a plurality of first electrodes and a plurality of second electrodes are alternately stacked, with a separator disposed between adjacent first and second electrodes. The expansion phenomenon of the stacked electrode assembly is more pronounced; therefore, the first support member is particularly effective in reducing the deformation of the stacked battery casing.

[0014] In some embodiments, a fourth wall portion is connected between the first wall portion and the third wall portion, such that the connection between the fourth wall portion and the first wall portion forms a second corner position. The secondary battery also includes a second support member, which comprises a third portion and a fourth portion connected together. The fourth portion is disposed between the fourth wall portion and the electrode assembly, and the third portion is bent relative to the fourth portion, such that the bend between the third and fourth portions forms a second support position; wherein the included angle between the third and fourth portions is β, β≤90°. The third portion is disposed between the first wall portion and the electrode assembly, and the end of the third portion away from the fourth portion abuts against the electrode assembly, with the second support position abutting against the second corner position. Through the combination of the first and second support members, both ends of the electrode assembly have supporting structures to buffer its expansion, effectively transferring the expansion force of the electrode assembly to the first and second corner positions with higher structural strength, reducing deformation of the casing, especially reducing deformation of the middle portion of the first wall portion.

[0015] Secondly, this application also proposes an electronic device including a secondary battery as described in any of the embodiments of the first aspect above.

[0016] Additional aspects and advantages of the embodiments of this application will be described, shown, or illustrated in part by way of implementation of the embodiments of this application in the following description. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, which are not intended to limit the embodiments, and elements having the same reference numerals in the drawings are designated as similar elements.

[0018] Figure 1 is a cross-sectional structural diagram of a secondary battery according to some embodiments of this application;

[0019] Figure 2 is a schematic diagram of the stacked structure of the first electrode, the separator, and the second electrode in some embodiments of this application;

[0020] Figure 3 is a structural schematic diagram of the first support member according to some embodiments of this application;

[0021] Figure 4 is a cross-sectional structural diagram of a secondary battery according to some embodiments of this application;

[0022] Figure 5 is a top view of the electrode assembly, the first support member, and the second support member according to some embodiments of this application;

[0023] Figure 6 is a schematic diagram of the structure of the second support member according to some embodiments of this application.

[0024] Explanation of reference numerals in the attached drawings: 100, secondary battery; 10, casing; 11, main body; 11a, first cavity; 111, second wall; 112, third wall; 113, fourth wall; 12, cover; 121, first wall; 20, electrode assembly; 21, first electrode; 211, first current collector; 212, first active material layer; 22, second electrode; 221, second current collector; 222, second active material layer; 23, separator; 30, first support; 31, first part; 311, first segment; 312, second segment; 32, second part; 30a, first support position; 40, second support; 41, third part; 42, fourth part; 40a, second support position; 50, first corner position; 60, second corner position; X, first direction; Y, second direction; Z, third direction. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0026] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0027] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0028] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0029] The technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0030] In a first aspect, this application proposes a secondary battery 100. Referring to Figure 1, the secondary battery 100 includes a housing 10 and an electrode assembly 20 and an electrolyte (not shown in the figure) housed within the housing 10. The electrolyte wets the electrode assembly 20 within the housing 10, thereby causing an electrochemical reaction.

[0031] The housing 10 described above can be made of metallic materials such as aluminum, aluminum alloy, steel, stainless steel, nickel, copper, or magnesium alloy, giving it a certain structural strength to protect the electrode assembly 20 inside the secondary battery 100. Furthermore, each material of the housing 10 has good thermal conductivity, which helps improve the heat dissipation performance of the secondary battery 100. Simultaneously, each material has good electrical conductivity, allowing the housing 10 to lead out a specific polarity of the secondary battery 100, for example, using the housing 10 itself as the positive or negative electrode of the secondary battery 100. In other embodiments, the housing 10 can also be made of a soft-pack material, such as an aluminum-plastic film or a copper-plastic film.

[0032] Referring to Figure 1, the housing 10 includes a main body 11 and a cover 12. The main body 11 has a first cavity (not shown in the figure), and the electrode assembly 20 can be disposed in the first cavity. The cover 12 does not have a cavity, or the cover 12 has a second cavity (not shown in the figure). By covering the first cavity with the cover 12 and connecting the cover 12 to the main body 11, the main body 11 and the cover 12 together form a complete housing 10. The connection method between the cover 12 and the main body 11 includes, but is not limited to, welding or bonding.

[0033] Referring to Figures 1 and 2, the electrode assembly 20 includes a first electrode 21, a second electrode 22, and a separator 23. Figure 2 shows the stacked structure of the first electrode 21, the separator 23, and the second electrode 22. The first electrode 21 and the second electrode 22 have opposite polarities; for example, the first electrode 21 is a positive electrode, and the second electrode 22 is a negative electrode. Alternatively, the first electrode 21 is a negative electrode, and the second electrode 22 is a positive electrode. The separator 23 is disposed between the first electrode 21 and the second electrode 22 to insulatingly separate them.

[0034] Referring to Figure 2, the first electrode 21 includes a first current collector 211 and a first active material layer 212. The first current collector 211 serves as the conductive substrate of the first electrode 21 and can be an integrally flat aluminum foil. Aluminum foil has high conductivity and low resistance, which can improve the charge / discharge rate of the secondary battery 100. The first active material layer 212 can be stacked on at least one surface of the first current collector 211 in the thickness direction. Taking the first electrode 21 as a positive electrode as an example, the first active material layer 212 includes a positive electrode active material, a conductive agent, and a binder, etc. These material components are mixed, stirred evenly, and coated onto the first current collector 211 to obtain the first active material layer 212. The positive electrode active material includes one or more of lithium nickel cobalt manganese oxide, lithium cobalt oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium manganese oxide, or lithium manganese iron phosphate.

[0035] The second electrode 22 includes a second current collector 221 and a second active material layer 222. The second current collector 221 serves as the conductive substrate of the second electrode 22 and can be an integrally flat copper foil. Copper foil has high conductivity and low resistance, which can improve the charge / discharge rate of the secondary battery 100. The second active material layer 222 can be disposed on at least one surface of the second current collector 221 in the thickness direction. Taking the second electrode 22 as a negative electrode as an example, the second active material layer 222 includes a negative electrode active material, a conductive agent, and a binder, etc. These materials are mixed, stirred evenly, and coated onto the second current collector 221 to obtain the second active material layer 222. The negative electrode active material includes one or more of graphite, soft carbon, hard carbon, carbon fiber, elemental silicon, silicon oxide, silicon alloy, etc.

[0036] Referring to Figure 1, along the first direction X (the thickness direction of the secondary battery 100), the housing 10 includes a first wall portion 121 and a second wall portion 111 disposed opposite to each other. When the cover 12 does not have a cavity, the cover 12 itself is the first wall portion 121. In some other embodiments, the first wall portion 121 may also be the bottom wall of the main body portion 11, in which case the second wall portion 111 is part of the cover 12.

[0037] During the charge-discharge cycle of the secondary battery 100, lithium ions are extracted and inserted into the positive and negative electrodes of the electrode assembly 20, causing the electrodes to expand and the volume of the electrode assembly 20 to increase. The electrode assembly 20 then exerts an expansion force on the casing 10. The inventors of this application have discovered that the structural characteristics of the casing 10 make the middle part of the cover 12 more prone to bulging under this expansion force, resulting in irregular deformation of the casing 10. The area where the main body 11 connects to the first wall 121 (denoted as the first corner 50) has greater strength and can better resist the expansion force, while the middle part is relatively independent and bears more concentrated pressure. However, the electrode assembly 20 usually deforms first in its middle, which easily leads to bulging in the middle of the first wall 121. This may have a certain impact on the performance and safety of the secondary battery 100. For example, the outer electrode of the electrode assembly 20 may deform and misalign due to compression, leading to a short circuit. In extreme cases, it may even damage the seal of the secondary battery 100, causing leakage and posing a safety hazard.

[0038] To mitigate the aforementioned problems, please refer to Figures 1 and 3. Along the second direction Y, the housing 10 further includes a third wall portion 112 and a fourth wall portion 113 disposed opposite to each other. The third wall portion 112 connects between the first wall portion 121 and the second wall portion 111, and the connection between the third wall portion 112 and the first wall portion 121 forms a first corner 50. In embodiments of this application, the secondary battery 100 further includes a first support member 30, which includes a first portion 31 and a second portion 32 connected to each other.

[0039] The second part 32 is disposed between the third wall portion 112 and the electrode assembly 20. The first part 31 is bent relative to the second part 32, such that the bend between the first part 31 and the second part 32 forms a first support position 30a, that is, the connection point of the bend between the first part 31 and the second part 32 forms the first support position 30a. The bending of the first part 31 and the second part 32 results in a certain angle between them, which is α, ≤ 90°, and can be any value from 0° to 90°, such as 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, or 90°. The first part 31 is disposed between the first wall portion 121 and the electrode assembly 20, and the end of the first part 31 away from the second part 32 abuts against the electrode assembly 20, and the first support position 30a abuts against the first corner position 50.

[0040] In the embodiments of this application, since the first support position 30a abuts against the first corner position 50, part of the pressure generated by the expansion of the electrode assembly 20 can be transmitted to the first corner position 50, which has greater strength. The first corner position 50 is formed by connecting the first wall portion 121 and the third wall portion 112, and its structure is more stable. By transmitting the expansion force to the first corner position 50, the special structure of the first corner position 50 can effectively disperse and bear the expansion force generated by the electrode assembly 20, reduce the deformation or damage caused by excessive force on the middle part of the shell 10, and improve the safety performance of the secondary battery 100.

[0041] Furthermore, the first part 31 is bent relative to the second part 32, and the included angle α between the first part 31 and the second part 32 is limited to 90°. For example, when α is 90°, the first part 31 can be directly attached between the electrode assembly 20 and the first wall 121. Since the first support position 30a and the first corner position 50 abut against each other, the first part 31 can also transfer part of the expansion force of the electrode assembly 20 to the first corner position 50, thereby reducing the deformation of the housing 10.

[0042] When α is chosen to be 0° < α < 90°, the first support member 30 can form a buffer structure, making it easier for the first support member 30 to undergo elastic deformation under stress. When the expansion force of the electrode assembly 20 acts on the first support member 30, its bending point and two parts will produce a certain degree of elastic deformation. This deformation can absorb some energy, reducing the energy transferred to the housing 10 and the electrode assembly 20, further enhancing the buffering effect and reducing the risk of deformation of the housing 10 due to expansion force.

[0043] When α is set to 0°, the first part 31 directly abuts between the electrode assembly 20 and the first corner position 50, which also allows the expansion force generated by the electrode assembly 20 to be transmitted to the first corner position 50, thereby reducing the deformation of the housing 10.

[0044] In the embodiments of this application, this force transmission method helps to improve the overall structural stability of the secondary battery 100. The first support member 30 and the first corner position 50 work together to form a stable support system, which can better adapt to the volume changes generated by the electrode assembly 20 during charging and discharging, reduce the risk of structural deformation of the secondary battery 100 due to internal pressure changes, and improve the safety of the secondary battery 100.

[0045] In some embodiments, 30°≤α≤60° allows the first support member 30 to better function like a spring during deformation, effectively enhancing the buffering effect. The 30°≤α≤60° angle range makes the elastic deformation of the first support member 30 under stress more reasonable. When subjected to the expansion force of the electrode assembly 20, the first support member 30 undergoes moderate elastic deformation at its bend and two other parts, buffering the expansion force through elastic deformation and reducing the impact on the housing 10 and electrode assembly 20, effectively protecting them and further reducing deformation of the housing 10. Furthermore, 30°≤α≤60° makes the transmission of expansion force more controllable, reducing the concentration of expansion force in one direction and thus better protecting the housing 10.

[0046] If α is small, for example, less than 30°, the small angle may make the shape of the first support member 30 too narrow and long. In the limited space inside the secondary battery 100, this is not conducive to installation and layout, and may interfere with other components. This will not only lead to the loss of energy density of the secondary battery 100, but also increase the assembly difficulty of the secondary battery 100. Furthermore, it may cause the force to be too concentrated in one direction, and also reduce the bearing area between the first part 31 and the electrode assembly 20, making it difficult to fully transmit the expansion force.

[0047] If α is large, for example, greater than 60°, the function of the first support member 30 as a buffer structure will be weakened. When the expansion force of the electrode assembly 20 is transmitted to the first corner 50, the first support member 30 has a small degree of bending and limited elastic deformation capacity, resulting in a smaller effect of absorbing and dissipating energy.

[0048] In some embodiments, referring to Figures 1 and 3, the first portion 31 includes a first segment 311 and a second segment 312 connected together. The first segment 311 is fitted onto the surface of the electrode assembly 20 facing the first wall portion 121. The second segment 312 is connected between the second portion 32 and the first segment 311, and the second segment 312 is bent relative to the second portion 32. The first segment 311 is fitted onto the surface of the electrode assembly 20 facing the first wall portion 121, which can better match the shape of the electrode assembly 20 and fit tightly against its surface. This helps to receive and transmit the force generated by the expansion of the electrode assembly 20 more evenly, reduce the situation of excessive local stress due to poor contact, and improve the stability and reliability of the entire support structure. Furthermore, this multi-segmented and bent structure allows force to be transmitted from the electrode assembly 20 through the first segment 311 to the second segment 312, and then through the second part 32 to the first corner 50 between the first wall portion 121 and the third wall portion 112. This facilitates a more reasonable and sufficient dispersion of the expansion force of the electrode assembly 20 to the first corner 50 with higher strength, thereby better protecting the structure of the casing 10 and improving the safety and service life of the secondary battery 100.

[0049] For the installation of the first support member 30, the first segment 311 can be bonded to the electrode assembly 20, forming a tighter connection between them. This effectively reduces the risk of the first support member 30 detaching due to the expansion of the electrode assembly 20 during the charging and discharging process of the secondary battery 100, thus facilitating continuous and stable support and force transmission, and improving the stability of the entire support structure. Furthermore, the bonding operation is relatively simple, requiring no additional tools or complex assembly processes, which helps improve production efficiency and reduce production costs. The adhesive used to bond the first segment 311 to the electrode assembly 20 can be one or more of the following: rubber-based adhesive, silicone-based adhesive, hot melt adhesive, water-based adhesive, polyurethane-based adhesive, epoxy-based adhesive, and polyimide-based adhesive, exhibiting good corrosion resistance and excellent bonding effect.

[0050] In some other embodiments, the second portion 32 may be bonded to the third wall portion 112, which may transfer part of the expansion force of the electrode assembly 20 to the third wall portion 112, further dispersing the expansion force and reducing the risk of deformation of the housing 10.

[0051] In some embodiments, referring to FIG4, the housing 10 is provided with a receiving cavity 11a, which is formed by the first wall portion 121, the second wall portion 111, the third wall portion 112, and the fourth wall portion 113. The electrode assembly 20 is disposed in the receiving cavity 11a. The housing 10 also includes a fifth wall portion (not shown) and a sixth wall portion (not shown). Along the third direction Z, the fifth wall portion and the sixth wall portion are disposed opposite to each other, and the fifth wall portion and the sixth wall portion are connected between the first wall portion 121 and the second wall portion 111, so that the first wall portion 121, the second wall portion 111, the third wall portion 112, the fourth wall portion 113, the fifth wall portion, and the sixth wall portion together form a closed receiving cavity 11a. Along the second direction Y, the width of the receiving cavity 11a is W, and the width of the first part 31 is W1, 0.05×W≤W1≤0.4×W. Any value from 0.05×W to 0.4×W can be selected, such as 0.05×W, 0.08×W, 0.1×W, 0.13×W, 0.15×W, 0.18×W, 0.2×W, 0.25×W, 0.28×W, 0.3×W, 0.35×W, 0.38×W, or 0.4×W, etc.

[0052] By limiting the width to 0.05×W ≤ W1 ≤ 0.4×W, the first part 31 has sufficient width to contact and support the electrode assembly 20. When the electrode assembly 20 expands, the first support 30 can withstand a certain amount of pressure, reducing excessive deformation or damage and improving the stability of the support structure. Furthermore, this width range allows the first support 30 to undergo appropriate elastic deformation under stress, thereby enhancing the buffering effect, reducing pressure on the electrode assembly 20 and the housing 10, and improving the reliability and safety of the secondary battery 100.

[0053] If W1 is too small, the contact area between the first support 30 and the electrode assembly 20 will be too small, making it difficult to effectively disperse the pressure generated by the expansion of the electrode assembly 20. Furthermore, a smaller width will result in a smaller connection area between the first part 31 and the electrode assembly 20, affecting the connection strength regardless of whether bonding or other connection methods are used, which is detrimental to improving the stability of the support structure. Simultaneously, when the first part 31 is subjected to the expansion force of the electrode assembly 20, its elastic deformation capacity is limited. It cannot absorb and dissipate energy through larger deformations as it would when the width is appropriate (e.g., 0.05×W≤W1≤0.4×W), resulting in decreased buffering performance and weakened protection for the electrode assembly 20 and the housing 10.

[0054] If W1 is too large, the force transmission may become unbalanced, making it difficult to effectively transmit the expansion force to the first corner 50, and it will occupy a large space, resulting in a loss of energy density of the secondary battery 100.

[0055] Furthermore, a value of 0.75mm ≤ W1 ≤ 6mm can be selected, or any value from 0.75mm to 6mm can be chosen, such as 0.75mm, 1mm, 1.25mm, 1.5mm, 1.75mm, 2mm, 2.25mm, 2.5mm, 2.75mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, or 6mm. This allows the first support member 30 to produce appropriate elastic deformation under stress, thereby enhancing the buffering effect, reducing the compression on the electrode assembly 20 and the housing 10, and improving the reliability and safety of the secondary battery 100.

[0056] Taking the three-dimensional coordinate system defined by two perpendicular directions X, Y, and Z as an example, the first direction X is the thickness direction of the secondary battery 100, the second direction Y is the length or width direction of the secondary battery 100, and the third direction Z is the width or length direction of the secondary battery 100. For example, if the second direction Y is the length direction of the secondary battery 100, then the third direction Z is the width direction of the secondary battery 100; if the second direction Y is the width direction of the secondary battery 100, then the third direction Z is the length direction of the secondary battery 100.

[0057] In some embodiments, referring to Figure 4, along the first direction X, the height of the receiving cavity 11a is H, and the height of the second part 32 is H1, where 0.5×H≤H1≤0.9×H. Any value from 0.5×H to 0.9×H can be selected, such as 0.5×H, 0.6×H, 0.7×H, 0.8×H, or 0.9×H. The second part 32 is located between the electrode assembly 20 and the third wall portion 112. During installation, the first support position 30a and the first corner position 50 are directly abutted, and the second part 32 is attached to the third wall portion 112 (it can be glued or not). This allows the first support member 30 to be installed in the predetermined position, which is simple and convenient and helps improve the installation efficiency of the secondary battery 100. Furthermore, the second part 32 can limit the position of the first support member 30, making it easier for the first support position 30a of the first support member 30 to abut against the first corner position 50, thus improving the stability of the entire support structure. At the same time, the second part 32 can also transfer some of the expansion force to the third wall part 112, making the distribution of the expansion force more reasonable and further reducing the deformation of the shell 10.

[0058] If the height of the second part 32 is small, for example, less than 0.5 × H, it may be difficult to form a stable support structure. The first support 30 may be displaced due to the expansion of the electrode assembly 20, making it difficult to effectively disperse the expansion force of the electrode assembly 20. If the height of the second part 32 is large, for example, greater than 0.9 × H, it will occupy a large space, resulting in a loss of energy density in the secondary battery 100.

[0059] In some embodiments, 1.5mm ≤ H1 ≤ 2.7mm, and any value from 1.5mm to 2.7mm can be selected, such as 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, or 2.7mm. This facilitates the abutment between the first support position 30a of the first support member 30 and the first corner position 50, improving the stability of the entire support structure and thus reducing the risk of deformation of the shell 10.

[0060] In some embodiments, referring to Figures 4 and 5, along the third direction Z, the length of the electrode assembly 20 is L, and the length of the first part 31 is L1, where 0.1×L ≤ L1 ≤ 0.8×L. Any value from 0.1×L to 0.8×L can be selected, such as 0.1×L, 0.2×L, 0.3×L, 0.4×L, 0.5×L, 0.6×L, 0.7×L, or 0.8×L. This allows the first part 31 to provide stable support, effectively distributing the stress generated by the volume change of the electrode assembly 20 during charging and discharging, and improving the stability of the overall support structure. Furthermore, within this range, when the volume of the electrode assembly 20 changes, the first part 31 can deform accordingly within its elastic limit based on the force along its length. This prevents it from being too short to adapt to changes in the electrode assembly 20, and also prevents excessive and uncoordinated deformation due to excessive length, thereby effectively forming an elastic structure and protecting the electrode assembly 20 within the housing 10.

[0061] If L1 is small, the contact length between the first part 31 and the electrode assembly 20 will be too short, which may not be enough to provide sufficient support for the electrode assembly 20. Furthermore, when subjected to external force, the elastic deformation of the first part 31 is limited, making it difficult to form an effective elastic buffer structure. This will cause the electrode assembly 20 to be subjected to greater pressure when its volume changes. Simultaneously, the supporting force may be concentrated in a small area of ​​the electrode assembly 20, resulting in a much greater pressure on that area than other parts, causing severe stress concentration. Under this stress concentration state for a long time, the electrode assembly 20 is prone to cracks and damage in that area.

[0062] If L1 is too large, it may lead to a decrease in the structural stability of the first part 31. When subjected to external force, the first part 31 may undergo excessive bending or twisting and may not be able to return to its original shape, thus weakening the elastic buffering performance. In addition, it will occupy a large space, resulting in a loss of energy density of the secondary battery 100.

[0063] Furthermore, 2mm ≤ L1 ≤ 16mm can be any value from 2mm to 16mm, such as 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, or 16mm. This facilitates the formation of a stable support structure and an elastic structure, thereby protecting the electrode assembly 20 within the housing 10. Preferably, 8mm ≤ L1 ≤ 13mm can further enhance the support structure and elastic structure, and reduce the impact on the energy density of the secondary battery 100.

[0064] In some embodiments, the housing 10 is a metal housing 10. The metal housing 10 itself has a certain strength and rigidity, which can provide basic structural support. The first support member 30 cooperates with the hard metal housing 10 to enhance the stability of the entire support structure, further disperse the expansion force of the electrode assembly 20, and reduce the risk of deformation of the housing 10.

[0065] The electrode assembly 20 can adopt a wound structure, that is, the first electrode 21, the separator 23 and the second electrode 22 are stacked and wound together to form a flat wound electrode assembly 20.

[0066] The electrode assembly 20 can also be stacked, for example, along the first direction X, a plurality of first electrode plates 21 and a plurality of second electrode plates 22 are alternately stacked, with a separator 23 disposed between adjacent first electrode plates 21 and second electrode plates 22. During charging and discharging, the stacked electrode assembly 20 experiences less binding force, resulting in more significant expansion. The first support member 30, tailored to the structural characteristics of the stacked electrode assembly 20, provides support inside the secondary battery 100, maintaining close contact with the electrode assembly 20 to effectively disperse the force generated by the electrode assembly 20, reducing direct impact on the first wall portion 121, especially the middle portion of the first wall portion 121, thereby reducing deformation of the casing 10. In this embodiment, the first support member 30 is particularly effective in reducing deformation of the stacked battery casing 10.

[0067] Referring to Figures 4 and 6, the secondary battery 100 also includes a second support member 40. A fourth wall portion 113 is connected between the first wall portion 121 and the third wall portion 112, forming a second angle position 60 at the connection between the fourth wall portion 113 and the first wall portion 121. The second support member 40 includes a connected third portion 41 and a fourth portion 42. The fourth portion 42 is disposed between the fourth wall portion 113 and the electrode assembly 20. The third portion 41 is bent relative to the fourth portion 42, forming a second support position 40a at the bend between the third portion 41 and the fourth portion 42. The included angle between the third portion 41 and the fourth portion 42 is β, where β ≤ 90°, and any value from 0° to 90° can be selected, such as 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, or 90°. The third part 41 is disposed between the first wall portion 121 and the electrode assembly 20, and the end of the third part 41 away from the fourth part 42 abuts against the electrode assembly 20, and the second support position 40a abuts against the second corner position 60.

[0068] In the embodiments of this application, since the second support position 40a abuts against the second corner position 60, part of the pressure generated by the expansion of the electrode assembly 20 can be transmitted to the stronger second corner position 60. The second corner position 60 is formed by connecting the second wall portion 111 and the fourth wall portion 113, and its structure is stable. By transmitting the expansion force to the second corner position 60, the special structure of the corner position can effectively disperse and bear the expansion force generated by the electrode assembly 20, reduce the deformation or damage caused by excessive force on the middle part of the housing 10, and improve the safety performance of the secondary battery 100.

[0069] Furthermore, the third part 41 is bent relative to the fourth part 42, and the included angle β between the third part 41 and the fourth part 42 is limited to ≤90°. For example, when β is 90°, the third part 41 can be directly fitted between the electrode assembly 20 and the first wall 121. Since the second support position 40a and the second corner position 60 abut against each other, the third part 41 can also transfer part of the expansion force of the electrode assembly 20 to the second corner position 60, thereby reducing the deformation of the housing 10. When β is selected as 0°<β<90°, the second support member 40 can form a buffer structure, and the second support member 40 is more likely to undergo elastic deformation when subjected to force. When the expansion force of the electrode assembly 20 acts on the second support member 40, its bend and the two parts will produce a certain degree of elastic deformation. This deformation can absorb some energy, reduce the energy transferred to the housing 10 and the electrode assembly 20, further enhance the buffering effect, and reduce the risk of deformation of the housing 10 caused by the expansion force. When β is set to 0°, the third part 41 directly abuts between the electrode assembly 20 and the second corner position 60, which is more conducive to the transmission of the expansion force generated by the electrode assembly 20 to the second corner position 60, thereby reducing the deformation of the housing 10.

[0070] In the embodiments of this application, the combination of the first support member 30 and the second support member 40 provides support structures at both ends of the electrode assembly 20 to buffer its expansion. This effectively transfers the expansion force of the electrode assembly 20 to the first corner 50 and the second corner 60, which have higher structural strength, reducing deformation of the housing 10, especially reducing deformation of the middle part of the first wall portion 121. The specific structure of the second support member 40 can be similar to that of the first support member 30, for example, the third part 41 may include a third segment 411 and a fourth segment 412 connected to each other, etc., which will not be described in detail in this application.

[0071] In some other embodiments, the connection between the third wall portion 112 and the second wall portion 111 forms a third corner (not shown in the figure), and the connection between the fourth wall portion 113 and the second wall portion 111 forms a fourth corner (not shown in the figure). The secondary battery 100 also includes a third support member (not shown in the figure) and a fourth support member (not shown in the figure). The third support member can transfer the expansion force of the electrode assembly 20 to the third corner, and the fourth support member can transfer the expansion force of the electrode assembly 20 to the fourth corner, thereby reducing the deformation of the second wall portion 111. The structures of the third support member and the fourth support member can be similar to those of the first support member 30, and will not be described in detail in this application.

[0072] Secondly, this application also proposes an electronic device, including a secondary battery 100 as described in any embodiment of the first aspect above. The electronic device in this application is not particularly limited and can be any electronic device known in the prior art. For example, electronic devices include, but are not limited to, Bluetooth headsets, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., while spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0073] Example 1:

[0074] <Preparation of the positive electrode>

[0075] The positive electrode active material is lithium cobalt oxide, the positive electrode conductive agent is acetylene black, and the positive electrode binder is polyvinylidene fluoride (PVDF, with a weight average molecular weight of 5×10⁻⁶). 5 The materials were mixed at a mass ratio of 94:3:3, with N-methylpyrrolidone (NMP) added as a solvent to prepare a positive electrode slurry with a solid content of 75 wt%, and stirred evenly under vacuum. An aluminum foil with a thickness of 10 μm, a length of 338.5 mm, and a width of 3.5 mm was used as the positive electrode current collector. The positive electrode slurry was uniformly coated onto one surface of the aluminum foil and dried at 110°C to obtain a positive electrode sheet with a single-sided coating of positive active material. The above steps were then repeated on the other surface of the aluminum foil to obtain a positive electrode sheet with a double-sided coating of positive active material. The coated electrode sheet was then cold-pressed to obtain a cold-pressed positive electrode sheet with a double-sided coating of positive active material. The single-sided coating weight of the positive electrode sheet was 21 mg / cm³. 2 The thickness of single-sided cold pressing is 62.25 μm, and the thickness of double-sided cold pressing is 112.5 μm.

[0076] <Preparation of Negative Electrode Sheets>

[0077] A mixture of graphite powder (negative electrode active material), silicon powder, conductive carbon black (Super P) as a conductive agent, and styrene-butadiene rubber (SBR) as a binder was prepared in a weight ratio of 87.5:10:1:1.5. Deionized water was then added as a solvent to prepare a negative electrode slurry with a solid content of 50 wt%, and the mixture was stirred thoroughly. A copper foil with a thickness of 8 μm, a length of 374 mm, and a width of 4.1 mm was selected as the negative electrode current collector. The negative electrode slurry was uniformly coated onto one surface of the copper foil and dried at 90°C to obtain a single-sided negative electrode sheet. This completes the single-sided coating of the negative electrode sheet. The above steps were then repeated on the other surface of the negative electrode sheet to obtain a double-sided coated negative electrode sheet. The coated electrode sheet was then cold-pressed to obtain a cold-pressed negative electrode sheet with a double-sided negative electrode active material layer. The single-sided coating weight of the negative electrode sheet was 8.6 mg / cm³. 2 The thickness of single-sided cold pressing is 61.4 μm, and the thickness of double-sided cold pressing is 112.8 μm.

[0078] <Preparation of the separating membrane>

[0079] A porous polyethylene film with a thickness of 7 μm was used as the separator.

[0080] <Electrolyte Preparation>

[0081] In a dry argon atmosphere, ethylene carbonate, methyl ethyl carbonate and diethyl carbonate were mixed in a mass ratio of 30:50:20 to obtain an organic solution. Then, lithium hexafluorophosphate was added to the organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0082] <Preparation of Lithium-ion Batteries>

[0083] Several positive and negative electrode sheets prepared above are alternately stacked, with a separator film placed between adjacent positive and negative electrode sheets to obtain an electrode assembly. The electrode assembly is placed in the first cavity of the main body, and the first cavity is covered by a cover. A first support member is placed between the cover (the cover does not have a cavity; the cover itself is the first wall portion, hereinafter referred to as the first wall portion) and the electrode assembly. The angle between the first part and the second part of the first support member is 90°. The first part is placed between the electrode assembly and the first wall portion, and the second part is placed between the side wall (third wall portion) of the main body, such that the first support position and the first corner position between the first part and the second part abut against each other. The width W1 of the first part is 3 mm, the height H1 of the second part is 2 mm, and the length L1 of the first part is 10 mm. A second support member is similarly arranged, abutting against the second corner position, forming a structure similar to Figure 1. After the positive and negative electrodes are welded together, the water is removed at 80°C, electrolyte is injected, and processes such as formation, capacity testing, and voltage and internal resistance testing are performed to obtain a lithium-ion secondary battery. The distance H3 between the first wall and the electrode assembly is 1 mm. The secondary battery is 22 mm long (electrode assembly length L is 20 mm), 17 mm wide (electrode assembly width W is 15 mm), and 3.2 mm thick. The thickness S of each wall of the casing is 0.1 mm, and the height H of the internal cavity is 3 mm.

[0084] Unlike Example 1, the relevant parameters in Examples 2 to 34 and Comparative Examples 1 to 2 are shown in Table 1 below. In Comparative Example 1, the first support member was not provided.

[0085] Test method for battery swelling:

[0086] A: Place the battery under test on the test platform and ensure that the battery surface makes good contact with the movable plate of the capacitance sensor.

[0087] B: Initial measurement: Record the battery's capacitance value in its initial state as a reference value.

[0088] C: Charge and discharge process: At 25℃, the secondary battery, which has reached a constant temperature, is charged at a constant current of 0.2C until the voltage is the cutoff voltage. Then, it is charged at a constant voltage of the cutoff voltage until the current is 0.02C, and discharged at 0.2C until the voltage is 3.0V. One charge and discharge cycle is one cycle. Record the change in capacitance value after 1000 cycles.

[0089] D: Data Recording and Analysis: Record the changes in capacitance during charging and discharging, and convert the capacitance value into changes in battery thickness through calculation.

[0090] The following benchmarks were used for evaluation: after 1000 charge-discharge cycles at 25°C, the thickness increase should not exceed 10%; that is, for the selected battery, the upper limit of thickness is 3.52mm. Exceeding the upper limit is considered a failure. Each group of 20 batteries was tested, the number of failures was N, and the failure rate was N / 20.

[0091] Table 1

[0092] According to Table 1 above, and in conjunction with Examples 1 to 34 and Comparative Examples 1 to 2, when a first support is provided and the included angle between the first part and the second part is selected as α, where α ≤ 90°, the test failure rate can be effectively reduced. Because the first support abuts against the first corner, some of the pressure generated by the expansion of the electrode assembly can be transferred to the stronger first corner. The first corner is formed by the connection of the first wall and the third wall, and its structure is stable. By transferring the expansion force to the first corner, the special structure of the corner can effectively disperse and bear the expansion force generated by the electrode assembly, reducing excessive force on the middle of the casing and thus preventing deformation or damage, thereby improving the safety performance of the secondary battery. Furthermore, the first part is bent relative to the second part, and the included angle between the first part and the second part is limited to α ≤ 90°, which helps the first support to form a better elastic structure, reducing the force transmitted to the casing, further enhancing the buffering effect, reducing the risk of casing deformation due to expansion force, and improving the safety of the secondary battery. In Comparative Example 1, the absence of a first support component makes it difficult to transfer the expansion force to the first corner. In Comparative Example 2, the included angle α is relatively large, which may cause the expansion force to be directly concentrated and transferred to the center of the first wall, thereby increasing the risk of shell deformation.

[0093] In conjunction with embodiments 4 to 7, the test failure rate is further reduced. In the embodiments of this application, 30°≤α≤60° can be further selected so that the first support member can better play a spring-like role during deformation, which can effectively enhance the buffering effect.

[0094] In conjunction with Embodiments 11 to 19, in Embodiment 11, a smaller W1 results in a small contact area between the first support and the electrode assembly, making it difficult to effectively disperse the pressure generated by the expansion of the electrode assembly. In Embodiment 19, a larger W1 occupies more space, leading to energy density loss in the secondary battery and potentially causing uneven force transmission; its test failure rate is similar to that of Embodiment 18. In the embodiments of this application, considering both increasing energy density and reducing casing deformation, a value of 0.05×W≤W1≤0.4×W can be selected; further, a value of 0.75mm≤W1≤6mm can be selected.

[0095] In conjunction with Examples 20 to 25, in Example 20, H1 is relatively small, which may make it difficult to form a stable support structure. The first support member may shift due to the expansion of the electrode assembly, making it difficult to effectively disperse the expansion force of the electrode assembly. In Example 25, H1 is relatively large, which will occupy more space, leading to a loss of energy density in the secondary battery. Furthermore, the test failure rate of Example 25 is similar to that of Example 24. In the embodiments of this application, considering improving energy density while reducing shell deformation, 0.5×H≤H1≤0.9×H can be selected, and further, 1.5mm≤H1≤2.7mm can be selected.

[0096] In conjunction with embodiments 26 to 34, in embodiment 26, L1 is relatively small, and the contact length between the first part and the electrode assembly is too short, which may make it difficult to provide sufficient support for the electrode assembly. In embodiment 34, L1 is relatively large, occupying a large space, resulting in energy density loss of the secondary battery, and may also lead to a decrease in the structural stability of the first part. When subjected to external force, the first part may undergo excessive bending or twisting, thereby weakening the elastic buffering performance. Therefore, in the embodiments of this application, 0.1×L≤L1≤0.8×L can be selected, and further, 2mm≤L1≤13mm can be selected. In embodiments 31 to 32, the failure rate is further reduced, and the impact on energy density is reduced. In the embodiments of this application, 8mm≤L1≤13mm is preferably selected.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this application as described above, which are not provided in detail for the sake of brevity; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A secondary battery, comprising a housing and an electrode assembly, the electrode assembly being disposed within the housing; the housing comprising, along a first direction, a first wall portion and a second wall portion disposed opposite to each other; and, along a second direction, the housing comprising a third wall portion and a fourth wall portion disposed opposite to each other, the third wall portion being connected between the first wall portion and the second wall portion, such that the connection between the third wall portion and the first wall portion forms a first angular position, characterized in that: The secondary battery also includes a first support member, which includes a first part and a second part connected to each other. The second part is disposed between the third wall portion and the electrode assembly, and the first part is bent relative to the second part, such that the bend of the first part and the second part forms a first support position; wherein, the included angle between the first part and the second part is α, and α≤90°; The first part is disposed between the first wall portion and the electrode assembly, and the end of the first part away from the second part abuts against the electrode assembly, and the first support position abuts against the first corner position; Wherein, the first direction is the thickness direction of the secondary battery, and the second direction is perpendicular to the first direction.

2. The secondary battery according to claim 1, characterized in that, 30°≤α≤60°。 3. The secondary battery according to claim 1 or 2, characterized in that, The first part includes a first segment and a second segment connected to each other. The first segment is attached to the surface of the electrode assembly facing the first wall portion. The second segment is connected between the second part and the first segment, and the second segment is bent relative to the second part.

4. The secondary battery according to claim 3, characterized in that, The first segment is bonded to the second wall portion.

5. The secondary battery according to any one of claims 1 to 4, characterized in that, The housing is provided with a receiving cavity, which is formed by the first wall portion, the second wall portion, the third wall portion and the fourth wall portion, and the electrode assembly is disposed within the receiving cavity; Along the second direction, the width of the receiving cavity is W, and the width of the first portion is W1, where 0.05×W≤W1≤0.4×W.

6. The secondary battery according to claim 5, characterized in that, 0.75mm≤W1≤6mm.

7. The secondary battery according to claim 5, characterized in that, Along the first direction, the height of the receiving cavity is H, and the height of the second part is H1, where 0.5×H≤H1≤0.9×H.

8. The secondary battery according to claim 7, characterized in that, 1.5mm≤H1≤2.7mm.

9. The secondary battery according to any one of claims 1 to 8, characterized in that, Along a third direction, the length of the electrode assembly is L, and the length of the first part is L1, where 0.1×L≤L1≤0.8×L; Wherein, the first direction, the second direction, and the third direction are all perpendicular to each other.

10. The secondary battery according to claim 9, characterized in that, 2mm≤L1≤16mm.

11. The secondary battery according to claim 10, characterized in that, 8mm≤L1≤13mm.

12. The secondary battery according to any one of claims 1 to 11, characterized in that, The casing is a metal casing.

13. The secondary battery according to any one of claims 1 to 12, characterized in that, The electrode assembly includes a first electrode, a separator, and a second electrode. Along the first direction, a plurality of first electrodes and a plurality of second electrodes are alternately stacked, and the separator is disposed between two adjacent first electrodes and second electrodes.

14. The secondary battery according to any one of claims 1 to 13, characterized in that, The fourth wall portion is connected between the first wall portion and the third wall portion, and the connection between the fourth wall portion and the first wall portion forms a second corner position; The secondary battery also includes a second support member, which includes a third part and a fourth part connected to each other. The fourth part is disposed between the fourth wall portion and the electrode assembly, and the third part is bent relative to the fourth part, such that the bend between the third part and the fourth part forms a second support position; wherein, the included angle between the third part and the fourth part is β, and β≤90°; The third part is disposed between the first wall portion and the electrode assembly, and the end of the third part away from the fourth part abuts against the electrode assembly, and the second support position abuts against the second corner position.

15. An electronic device, characterized in that, Includes the secondary battery as described in any one of claims 1 to 14.

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