Battery cell and electronic device

Abstract

The invention provides a battery cell and an electronic device. The battery cell comprises an electrode assembly and a supporting piece. The electrode assembly comprises a first pole piece, a second pole piece and an isolating membrane, wherein the isolating membrane is arranged between the first pole piece and the second pole piece. The electrode assembly has a winding center hole. And the first pole piece, the isolating membrane and the second pole piece are wound around the winding center hole. The supporting piece is arranged in the winding center hole. The supporting piece comprises a shell and a plurality of reinforcing pieces, the shell is provided with a containing cavity, at least part of the outer side face of the shell is attached to the hole wall of the winding center hole, the reinforcing pieces are connected to the inner side face of the shell, and the reinforcing pieces are arranged at intervals and divide the containing cavity into a plurality of sub-cavities. And a heat absorption piece or a flame-retardant piece is arranged in at least one sub-cavity.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a battery cell and an electronic device. Background Art

[0002] During the cycle, the winding core will be deformed due to the expansion of the pole piece. The deformation of the winding core is likely to cause the problem of poor battery interface and reduce the safety performance of the battery. Summary of the invention

[0003] In view of the above situation, the present application provides a battery cell, which is beneficial to improving the safety performance of the battery cell.

[0004] An embodiment of the present application provides a battery cell, which includes an electrode assembly and a support member. The electrode assembly includes a first pole piece, a second pole piece and a separator, and the separator is arranged between the first pole piece and the second pole piece. The electrode assembly has a winding center hole. The first pole piece, the separator and the second pole piece are wound around the winding center hole. The support member is arranged in the winding center hole. The support member includes an outer shell and a plurality of reinforcement members, the outer shell is provided with a accommodating cavity, at least part of the outer side surface of the outer shell is in contact with the hole wall of the winding center hole, a plurality of reinforcement members are connected to the inner side surface of the outer shell, and the plurality of reinforcement members are arranged at intervals and divide the accommodating cavity into a plurality of sub-cavities. At least one sub-cavity is provided with a heat absorbing member or a flame retardant member.

[0005] In the above-mentioned battery cell, multiple reinforcement members are arranged at intervals to improve the structural strength of the shell, and the shell fits the hole wall of the winding center hole to support the electrode assembly, reduce the risk of deformation of the electrode assembly, and thus improve the safety performance of the battery cell. At least one sub-cavity is provided with a heat absorber or a flame retardant. The heat absorber is configured to cool or dissipate heat inside the electrode assembly, and the flame retardant is configured to suppress the combustion of the battery cell when the battery cell is thermally runaway, so as to improve the safety performance of the battery cell.

[0006] In some embodiments of the present application, along the winding direction of the electrode assembly, the isolation film includes a first starting section that exceeds the starting end of the first pole piece and the starting end of the second pole piece. The first starting section is wound around the support member at least one circle to improve the tightness of the outer shell and the hole wall of the winding center hole.

[0007] In some embodiments of the present application, the housing includes two plane areas and two curved surface areas, the two plane areas are spaced apart along a first direction, the two curved surface areas are spaced apart along a second direction and are respectively connected to the two ends of the two plane areas, and the two plane areas and the two curved surface areas enclose a receiving cavity. The first direction is perpendicular to the second direction. A reinforcement member connects the two plane areas, a plurality of reinforcement members are arranged along the second direction, and a subcavity is formed between two adjacent reinforcement members or between a curved surface area and a reinforcement member adjacent to the curved surface area.

[0008] In some embodiments of the present application, the radius of the arc corresponding to the curved surface area is R1, 1mm≤R1≤3mm, so that the curved surface area is adapted to the bending curvature at the corner of the electrode assembly, thereby improving the stability of the curved surface area supporting the corner of the electrode assembly, reducing the risk of deformation of the electrode assembly, and thereby improving the safety performance of the battery cell.

[0009] In some embodiments of the present application, along the second direction, the spacing between two adjacent reinforcement members is W1, 10mm≤W1≤20mm, so that the space of the sub-cavity can accommodate the heat absorption member or the flame retardant member and can improve the supporting stability of the outer shell to the electrode assembly.

[0010] In some embodiments of the present application, the thickness of the planar area is T1, 0.3 mm ≤ T1 ≤ 2 mm, so as to improve the support stability of the planar area to the electrode assembly and improve the energy density of the battery cell.

[0011] In some embodiments of the present application, the thickness of the arc surface area is T2, 0.3mm≤T2≤2mm, so as to improve the supporting stability of the arc surface area to the electrode assembly and improve the energy density of the battery cell.

[0012] In some embodiments of the present application, the sub-cavity provided with the heat absorption component and the sub-cavity provided with the flame retardant component are arranged at intervals to improve the balance between the heat absorption capacity and the flame retardant capacity.

[0013] In some embodiments of the present application, the material of the heat absorber includes paraffin wax, which has a wide phase change temperature range. The phase change temperature of the heat absorber can be adjusted by adjusting the content and type of paraffin wax in the heat absorber. Paraffin wax has a high latent heat of phase change and can store more heat. Paraffin wax has good chemical stability and can repeatedly undergo endothermic phase change and exothermic phase change, with low leakage risk and high safety. In addition, paraffin wax has viscosity, which facilitates contact with the inner wall of the sub-cavity.

[0014] In some embodiments of the present application, the flame retardant includes a shell and a flame retardant, the shell is provided with a receiving cavity, the flame retardant is arranged in the receiving cavity, and the melting point of the shell is 100°C to 130°C. When the temperature inside the battery cell reaches the melting point of the shell, the shell melts, and the flame retardant is released, dissolved and dispersed into the battery cell to inhibit the combustion of the battery cell when the battery cell thermally runs away. The shell seals the flame retardant when the inside of the battery cell does not reach the melting point of the shell, reducing the risk of the flame retardant affecting the normal use of the battery cell.

[0015] In some embodiments of the present application, the material of the shell includes polymethyl methacrylate, and the weight percentage of the shell in the flame retardant component is 3% to 10%, so that the shell can wrap the flame retardant and improve the flame retardant effect.

[0016] In some embodiments of the present application, the material of the flame retardant includes at least one of alkyl phosphate esters, fluoroalkyl phosphate esters, aromatic phosphate esters, fluorine-containing flame retardants, and carbonates to enhance the flame retardant effect.

[0017] In some embodiments of the present application, the material of the support member includes at least one of aluminum, nickel, copper, and ceramic to improve the structural strength of the support member and facilitate the outer shell to act as a heat conductor to conduct heat between the heat absorption member and the electrode assembly.

[0018] An embodiment of the present application further provides an electronic device, which includes any one of the battery cells in the above embodiments.

[0019] In the above-mentioned battery cell and electronic device, the multiple reinforcement members are arranged at intervals to improve the structural strength of the shell, and the shell fits the hole wall of the winding center hole to support the electrode assembly, reduce the risk of deformation of the electrode assembly, and thus improve the safety performance of the battery cell. At least one sub-cavity is provided with a heat absorber or a flame retardant. The heat absorber is configured to cool or dissipate heat inside the electrode assembly, and the flame retardant is configured to suppress the combustion of the battery cell when the battery cell is thermally runaway, so as to improve the safety performance of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of a battery cell in one embodiment of the present application.

[0021] Figure 2 It is a schematic structural diagram of the assembly of an electrode assembly and a support member of a battery cell in one embodiment of the present application.

[0022] Figure 3 It is a schematic structural diagram of a support member of a battery cell in an embodiment of the present application, wherein a heat absorbing member and a flame retardant member are filled in corresponding sub-cavities.

[0023] Figure 4 It is a schematic structural diagram of a support member of a battery cell in another embodiment of the present application, wherein a heat absorbing member and a flame retardant member are coated on the cavity wall of a corresponding sub-cavity.

[0024] Figure 5 It is a schematic diagram of the structure of an electronic device in one embodiment of the present application.

[0025] Main component symbols Battery Cell 100 Electronic device 200 Electrode assembly 10 Winding center hole 10A The first pole piece 11 The first pole ear 111 The second pole piece 12 Second sub-electrode 121 Isolation film 13 First starting section 131 Support member 20 Housing 21 Accommodation chamber 21A Sub-chamber 21A1 Opening 21B Sub-opening 21B1 First gap 21C Second gap 21D Plane Area 211 Curved area 212 Heat absorbing element 30 Flame retardant 40 Packaging bag 50 Main body 51 Top wall 511 Bottom wall 512 Top seal 52 First tab 60 Second pole ear 70 First direction X Second direction Y Axis Z The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0027] It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be a centrally disposed element at the same time. When an element is considered to be "disposed" on another element, it may be directly disposed on the other element or there may be a centrally disposed element at the same time.

[0028] When a value is considered to be "equal" to another value, it means that the two are equal within the set deviation, and the set deviation range is within 5%. In other words, when at least one of the two values ​​fluctuates within the set deviation range, even if their values ​​are not equal, they are still judged to be roughly equal. When a value is considered to have a ratio of "1:1" to another value, it means that the two are equal within the set deviation, and the set deviation range is within 5%. In other words, when at least one of the two values ​​fluctuates within the set deviation range, even if their values ​​are not equal, they are still judged to be equal in ratio.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items. The term "overlap" used herein refers to the overlap of the projections of two parts or the overlap of the projections of two parts.

[0030] An embodiment of the present application provides a battery cell, which includes an electrode assembly and a support member. The electrode assembly includes a first pole piece, a second pole piece and a separator, and the separator is arranged between the first pole piece and the second pole piece. The electrode assembly has a winding center hole. The first pole piece, the separator and the second pole piece are wound around the winding center hole. The support member is arranged in the winding center hole. The support member includes an outer shell and a plurality of reinforcement members, the outer shell is provided with a accommodating cavity, at least part of the outer side surface of the outer shell is in contact with the hole wall of the winding center hole, a plurality of reinforcement members are connected to the inner side surface of the outer shell, and the plurality of reinforcement members are arranged at intervals and divide the accommodating cavity into a plurality of sub-cavities. A heat absorbing member or a flame retardant member is provided in at least one sub-cavity.

[0031] In the above-mentioned battery cell, multiple reinforcement members are arranged at intervals to improve the structural strength of the shell, and the shell fits the hole wall of the winding center hole to support the electrode assembly, reduce the risk of deformation of the electrode assembly, and thus improve the safety performance of the battery cell. At least one sub-cavity is provided with a heat absorber or a flame retardant. The heat absorber is configured to cool or dissipate heat inside the electrode assembly, and the flame retardant is configured to suppress the combustion of the battery cell when the battery cell is thermally runaway, so as to improve the safety performance of the battery cell.

[0032] The embodiments of the present application are further described below in conjunction with the accompanying drawings.

[0033] Please also read Figure 1 and Figure 2 An embodiment of the present application provides a battery cell 100 , which can be continuously used by activating active materials through charging after discharge.

[0034] The battery cell 100 includes an electrode assembly 10 and a support member 20. The electrode assembly 10 is used to convert chemical energy into electrical energy. The electrode assembly 10 includes a first pole piece 11, a second pole piece 12 and a separator 13, and the separator 13 is arranged between the first pole piece 11 and the second pole piece 12. The polarity of the first pole piece 11 is opposite to the polarity of the second pole piece 12.

[0035] The electrode assembly 10 has a winding center hole 10A. The first pole piece 11, the separator 13, and the second pole piece 12 are wound around the winding center hole 10A. Specifically, the separator 13, the first pole piece 11, the separator 13, and the second pole piece 12 are wound around the winding center hole 10A, or the first pole piece 11, the separator 13, the second pole piece 12, and the separator 13 are wound around the winding center hole 10A. There are two winding directions, namely clockwise and counterclockwise winding. This application takes counterclockwise winding as an example for explanation.

[0036] The support member 20 is arranged at the winding center hole 10A, and the support member 20 includes a shell 21 and a plurality of reinforcement members 22. The shell 21 is provided with a receiving cavity 21A, and at least part of the outer side surface of the shell 21 is in contact with the hole wall of the winding center hole 10A. The plurality of reinforcement members 22 are connected to the inner side surface of the shell 21, and the plurality of reinforcement members 22 are arranged at intervals and divide the receiving cavity 21A into a plurality of sub-cavities 21A1. The plurality of reinforcement members 22 are arranged at intervals to improve the structural strength of the shell 21, and the shell 21 is in contact with the hole wall of the winding center hole 10A to support the electrode assembly 10, reduce the risk of deformation of the electrode assembly 10, and thus improve the safety performance of the battery cell 100.

[0037] Please also read Figure 2 and Figure 3 At least one sub-cavity 21A1 is provided with a heat absorbing member 30 or a flame retardant member 40. The heat absorbing member 30 is configured to cool or dissipate heat inside the electrode assembly 10, and the flame retardant member 40 is configured to suppress the combustion of the battery cell 100 when the battery cell 100 is in thermal runaway, so as to improve the safety performance of the battery cell 100.

[0038] See also Figure 3 In some embodiments, the heat absorbing member 30 is filled in the sub-cavity 21A1 to improve the cooling or heat dissipation effect. Specifically, when observed along the axial direction Z, there is no gap in the sub-cavity 21A1 where the heat absorbing member 30 is provided.

[0039] See also Figure 4 In some embodiments, the heat absorbing member 30 is coated on the inner wall of the sub-cavity 21A1 to improve the connection stability between the heat absorbing member 30 and the sub-cavity 21A1. Specifically, when viewed along the axial direction Z, a gap is provided in the middle of the sub-cavity 21A1 where the heat absorbing member 30 is provided.

[0040] Please refer again Figure 3 In some embodiments, the flame retardant 40 is filled in the sub-cavity 21A1 to improve the flame retardant effect. Specifically, when viewed along the axial direction Z, there is no gap in the sub-cavity 21A1 where the flame retardant 40 is provided.

[0041] Please refer again Figure 4In some embodiments, the flame retardant 40 is coated on the inner wall of the sub-cavity 21A1 to improve the connection stability between the flame retardant 40 and the sub-cavity 21A1. Specifically, when viewed along the axial direction Z, a gap is provided in the middle of the sub-cavity 21A1 where the flame retardant 40 is provided.

[0042] Please continue reading Figure 1 and Figure 2 In some embodiments, along the axial direction Z of the winding center hole 10A, both ends of the housing 21 are provided with openings 21B communicating with the accommodating cavity 21A. Correspondingly, each opening 21B includes a plurality of sub-openings 21B1, and each sub-opening 21B1 is communicated with a sub-cavity 21A1.

[0043] The battery cell 100 includes a packaging bag 50, a first pole ear 60 and a second pole ear 70. The packaging bag 50 includes a main body 51 and a top seal 52, and the electrode assembly 10 is accommodated in the main body 51. The main body 51 includes a top wall 511 and a bottom wall 512 arranged opposite to each other along the axial direction Z. The top seal 52 is connected to the top wall 511. The first pole ear 60 is connected to the first pole piece 11 and extends from the top seal 52, and the second pole ear 70 is connected to the second pole piece 12 and extends from the top seal 52.

[0044] Along the axial direction Z, the top wall 511 and the bottom wall 512 are respectively disposed on one side of the two openings 21B of the sub-cavity 21A1 to limit the position of the heat absorbing member 30 or the flame retardant member 40 in the corresponding sub-cavity 21A1 .

[0045] Please continue reading Figure 1 and Figure 2 In some embodiments, along the axial direction Z, the edge of the first pole piece 11 close to the top wall 511 is located outside the edge of the second pole piece 12 close to the top wall 511, and the end of the housing 21 with the opening 21B is located between the edge of the first pole piece 11 close to the top wall 511 and the edge of the second pole piece 12 close to the top wall 511. On the first hand, the stability of the housing 21 supporting the first pole piece 11 and the second pole piece 12 can be improved. On the second hand, a first gap 21C can be formed between the end of the housing 21 with the opening 21B and the top wall 511, and the first gap 21C is used to release the flame retardant 40 to dissolve and disperse into the interior of the battery cell 100 when the internal temperature of the battery cell 100 reaches a preset temperature.

[0046] In some embodiments, along the axial direction Z, the edge of the first pole piece 11 close to the bottom wall 512 is located outside the edge of the second pole piece 12 close to the bottom wall 512, and one end of the housing 21 having another opening 21B is located between the edge of the first pole piece 11 close to the bottom wall 512 and the edge of the second pole piece 12 close to the bottom wall 512. On the first hand, the stability of the housing 21 supporting the first pole piece 11 and the second pole piece 12 can be improved. On the second hand, a second gap 21D can be formed between the end of the housing 21 having another opening 21B and the bottom wall 512, and the second gap 21D is used to release the flame retardant 40 to dissolve and disperse into the interior of the battery cell 100 when the internal temperature of the battery cell 100 reaches a preset temperature.

[0047] Please continue reading Figure 2 In some embodiments, along the winding direction of the electrode assembly 10, the isolation film 13 includes a first starting section 131 that exceeds the starting end of the first pole piece 11 and the starting end of the second pole piece 12. The first starting section 131 is wound around the support member 20 at least once, and the wound first starting section 131 forms the hole wall of the winding center hole 10A. The first starting section 131 is wound around the support member 20 at least once to improve the tightness of the outer shell 21 and the hole wall of the winding center hole 10A.

[0048] Optionally, the number of turns of the first starting section 131 around the support member 20 is 1, 1.5, 2, 2.5, 3, or any other value greater than 1.

[0049] Please continue to refer to 3. In some embodiments, the housing 21 includes two planar areas 211 and two curved areas 212. When observed along the axial direction Z, the two planar areas 211 are spaced apart along the first direction X, and the two curved areas 212 are spaced apart along the second direction Y and are respectively connected to the two ends of the two planar areas 211. The two planar areas 211 and the two curved areas 212 enclose a receiving cavity 21A, and the first direction X is perpendicular to the second direction Y.

[0050] The reinforcement member 22 connects the two planar areas 211 . The plurality of reinforcement members 22 are arranged along the second direction Y. The subcavity 21A1 is formed between two adjacent reinforcement members 22 or between the curved area 212 and the reinforcement member 22 adjacent to the curved area 212 .

[0051] Optionally, the plurality of reinforcing members 22 are arranged at equal intervals along the second direction Y, so that when the outer shell 21 is subjected to pressure from the electrode assembly 10 , the pressure is evenly distributed to the plurality of reinforcing members 22 , which is beneficial to improving the structural strength of the outer shell 21 .

[0052] In some embodiments, the number of reinforcement members 22 is five, and the five reinforcement members 22 divide the accommodating cavity 21A into six sub-cavities 21A1, wherein four sub-cavities 21A1 are formed between two adjacent reinforcement members 22, and two sub-cavities 21A1 are formed between the arc surface area 212 and the reinforcement member 22 adjacent to the arc surface area 212.

[0053] Optionally, the number of the reinforcement members 22 may also be any one of other positive integers such as 1, 2, 3, 4, 6, etc.

[0054] Please also read Figure 1 and Figure 2 In some embodiments, a first pole piece 11 is provided with a plurality of first sub-pole ears 111 on one side facing the top wall 511, and the first sub-pole ears 111 are assembled into a sub-pole ear bundle and connected to the first pole ear 60. A second pole piece 12 is provided with a plurality of second sub-pole ears 121 on one side facing the top wall 511, and the second sub-pole ears 121 are assembled into a sub-pole ear bundle and connected to the second pole ear 70. When viewed along the axial direction Z, the portion of the first pole piece 11 provided with the first sub-pole ear 111 overlaps with the plane area 211, and the portion of the second pole piece 12 provided with the second sub-pole ear 121 overlaps with the plane area 211, so that the plane area 211 supports the portion of the first pole piece 11 provided with the first sub-pole ear 111 and the portion of the second pole piece 12 provided with the second sub-pole ear 121, and reduces the risk of deformation of the electrode assembly 10 when the first pole ear 60 and the second pole ear 70 are pulled by external force, thereby improving the safety performance of the battery cell 100.

[0055] Please continue reading Figure 3 In some embodiments, the radius of the arc corresponding to the arc surface area 212 is R1, 1mm≤R1≤3mm, so that the arc surface area 212 is adapted to the bending curvature at the corner of the electrode assembly 10, thereby improving the stability of the arc surface area 212 supporting the corner of the electrode assembly 10, reducing the risk of deformation of the electrode assembly 10, and thereby improving the safety performance of the battery cell 100.

[0056] Optionally, R1 is one of 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm and any other value in the range of 1 mm ≤ R1 ≤ 3 mm.

[0057] Please continue reading Figure 3In some embodiments, along the second direction Y, the spacing between two adjacent reinforcing members 22 is W1, 10mm≤W1≤20mm. When W1 is too small (less than 10mm), the space of the sub-cavity 21A1 is too small to accommodate the heat absorbing member 30 or the flame retardant member 40; when W1 is too large (greater than 20mm), the span of the plane area 211 is too long to form a weak area, which will reduce the support stability of the housing 21 to the electrode assembly 10. By limiting 10mm≤W1≤20mm, the space of the sub-cavity 21A1 can accommodate the heat absorbing member 30 or the flame retardant member 40, and the support stability of the housing 21 to the electrode assembly 10 can be improved.

[0058] Optionally, W1 is 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm and any other value in the range of 10mm≤W1≤20mm.

[0059] Please continue reading Figure 3 In some embodiments, the thickness of the plane area 211 is T1, 0.3mm≤T1≤2mm. When T1 is too small (less than 0.3mm), the structural strength of the plane area 211 is likely to be weak, resulting in reduced support stability of the plane area 211 to the electrode assembly 10; when T1 is too large (greater than 2mm), it is easy for the housing 21 to occupy a large space in the first direction X, resulting in space waste, resulting in reduced energy density of the battery cell 100. By limiting 0.3mm≤T1≤2mm, the support stability of the plane area 211 to the electrode assembly 10 is improved, and the energy density of the battery cell 100 is improved.

[0060] Optionally, T1 is 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm and any other value in the range of 0.3mm≤T1≤2mm.

[0061] Please continue reading Figure 3 In some embodiments, the thickness of the curved area 212 is T2, 0.3mm≤T2≤2mm. When T2 is too small (less than 0.3mm), the structural strength of the curved area 212 is likely to be weak, resulting in reduced support stability of the curved area 212 on the electrode assembly 10; when T2 is too large (greater than 2mm), it is easy for the outer shell 21 to occupy a large space in the second direction Y, resulting in space waste, resulting in reduced energy density of the battery cell 100. By limiting 0.3mm≤T2≤2mm, the support stability of the curved area 212 on the electrode assembly 10 is improved, and the energy density of the battery cell 100 is improved.

[0062] Optionally, T2 is 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm and any other value in the range of 0.3mm≤T2≤2mm.

[0063] In some embodiments, T1 = T2 so that the circumference of the housing 21 is subjected to uniform force.

[0064] In some embodiments, T1>T2, so as to improve the structural strength of the planar area 211 specifically, so as to be suitable for the scenario where the planar area 211 is more susceptible to external impact than the curved area 212.

[0065] In some embodiments, T1<T2, so as to improve the structural strength of the curved area 212 specifically, so as to be suitable for the scenario where the curved area 212 is more susceptible to external impact than the flat area 211 .

[0066] Please continue reading Figure 3 In some embodiments, the sub-cavity 21A1 provided with the heat absorbing member 30 and the sub-cavity 21A1 provided with the flame retardant member 40 are arranged at intervals to improve the balance between the heat absorbing capacity and the flame retardant capacity.

[0067] Please continue reading Figure 3 In some embodiments, the heat absorbing member 30 has a phase transition temperature, and the heat absorbing member 30 is configured to generate a phase transition and absorb heat when the temperature rises to the phase transition temperature, so as to reduce the temperature inside the battery cell 100, so that the electrode assembly 10 is within a suitable temperature range, which is beneficial to improving the safety of the battery cell 100. In addition, the heat absorbing member 30 is located in the sub-cavity 21A1, and does not occupy additional space in the battery cell 100, which is beneficial to improving the energy density of the battery cell 100.

[0068] When the temperature inside the battery cell 100 drops below the phase change temperature of the heat absorbing member 30, the heat absorbing member 30 stops absorbing heat and undergoes a reverse phase change, that is, a phase change releases heat. In this way, the heat absorbing member 30 can repeatedly undergo a phase change and a reverse phase change during the cycle of the battery cell 100.

[0069] It is understandable that the housing 21 can act as a heat conductor to conduct heat between the heat absorbing member 30 and the electrode assembly 10 .

[0070] Optionally, the material of the heat absorbing member 30 includes paraffin wax, which has a wide phase change temperature range. The phase change temperature of the heat absorbing member 30 can be adjusted by adjusting the content and type of paraffin wax in the heat absorbing member 30. Paraffin wax has a high latent heat of phase change and can store more heat. Paraffin wax has good chemical stability and can repeatedly undergo endothermic phase change and exothermic phase change, with low leakage risk and high safety. In addition, paraffin wax has viscosity, which facilitates contact with the inner wall of the sub-cavity 21A1.

[0071] Please continue reading Figure 3 In some embodiments, the flame retardant 40 includes a shell and a flame retardant, the shell is provided with a receiving cavity, and the flame retardant is disposed in the receiving cavity. The melting point of the shell is 100°C to 130°C. When the temperature inside the battery cell 100 reaches the melting point of the shell, the shell melts, and the flame retardant is released, dissolved and dispersed into the battery cell 100 to inhibit the battery cell 100 from burning when the battery cell 100 thermally runs away. The shell seals the flame retardant when the inside of the battery cell 100 does not reach the melting point of the shell, reducing the risk of the flame retardant affecting the normal use of the battery cell 100.

[0072] Optionally, the melting point of the shell is 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C and any other value in the range of 100°C to 130°C.

[0073] In some embodiments, the material of the shell includes polymethyl methacrylate, and the weight percentage of the shell in the flame retardant 40 is 3% to 10%, so that the shell can wrap the flame retardant and improve the flame retardant effect.

[0074] Optionally, the shell is in the form of a hollow particle, and the specific shape of the particle may be a sphere or a polyhedron.

[0075] Optionally, the material of the flame retardant includes at least one of alkyl phosphate ester, fluoroalkyl phosphate ester, aromatic phosphate ester, fluorine-containing flame retardant, and carbonate to enhance the flame retardant effect.

[0076] Specifically, the alkyl phosphate includes at least one of trimethyl phosphate (TMP) and triethyl phosphate (TEP). Fluoroalkyl phosphate includes at least one of tri-(2,2,2-trifluoroethyl) phosphate (TFP), di-(2,2,2-trifluoroethyl)-methyl phosphate (BMP), (2,2,2-trifluoroethyl)-diethyl phosphate (TDP). Aromatic phosphate includes at least one of diphenylcresyl phosphate (CDP) and diphenyl isooctyl phosphate (DPOF). Fluorinated flame retardants include allyl tris (2,2,2-trifluoroethyl). Carbonates include allyl (trifluoroethyl) carbonate (ATFEC).

[0077] In some embodiments, the material of the support member 20 includes at least one of aluminum, nickel, copper, and ceramic to improve the structural strength of the support member 20 and facilitate the shell 21 to act as a heat conductor to conduct heat between the heat absorption member 30 and the electrode assembly 10.

[0078] See also Figure 5 One embodiment of the present application further provides an electronic device 200, which includes the battery cell 100 in any of the above embodiments. Optionally, the electronic device 200 may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc.

[0079] In the above-mentioned battery cell 100 and electronic device 200, the multiple reinforcement members 22 are arranged at intervals to improve the structural strength of the shell 21. The shell 21 is attached to the hole wall of the winding center hole 10A to support the electrode assembly 10, reduce the risk of deformation of the electrode assembly 10, and thus improve the safety performance of the battery cell 100. A heat absorber 30 or a flame retardant 40 is provided in at least one sub-cavity 21A1. The heat absorber 30 is configured to cool or dissipate heat inside the electrode assembly 10, and the flame retardant 40 is configured to suppress the combustion of the battery cell 100 when the battery cell 100 is in thermal runaway, so as to improve the safety performance of the battery cell 100.

[0080] The specific implementation of the battery cells in the embodiments and comparative examples are described below.

[0081] 1. Expansion rate test The battery cell was charged to 4.3V at 0.5C constant current at 25°C, and then charged to 0.05C cut-off at 4.3V constant voltage, and then left to stand for 10 minutes; the battery cell was discharged to 3.0V at 1.0C constant current, and then left to stand for 15 minutes. The battery cell was cycled 1000 times according to the above battery cell cycle process. The initial battery cell thickness and the battery cell thickness after 1000 cycles were tested by PPG thickness tester, and the thickness expansion rate was calculated.

[0082] 2. Discharge temperature rise test Place the battery cell at a test temperature of 25°C for 5 minutes, then charge it at a constant current of 0.5C to a voltage of 4.3V, and then charge it at a constant voltage of 0.05C; after standing for 2 hours to allow the temperature of the lithium-ion battery to drop to 25°C, discharge it at a constant current of 5C to a voltage of 3V. During the charging and discharging process, place a temperature sensor on the center surface of the lithium-ion battery, wrap the lithium-ion battery with thermal insulation cotton, and record the charging and discharging temperature rise during the charging and discharging process. For example, during the discharge process, record the temperature at the time of discharge completion, and subtract 25°C from this temperature to obtain the 25°C discharge temperature rise (°C) of the battery cell.

[0083] 3. Hot box test First, the battery cell to be tested is pretreated. The pretreatment conditions are as follows: after standing at a test temperature of 25±2℃ for 60 minutes, discharge to 3.0V with a constant current of 0.7C and stand for 10 minutes; then charge to 4.3V with a constant current of 0.5C, and then charge to 0.05C with a constant voltage of 4.3V. After the pretreatment is completed, the battery cell is placed vertically in a hot box for hot box testing, in which the temperature in the hot box is raised to 150℃ at 5℃ / min and maintained for 60 minutes. During the test, if the battery cell does not burn or explode, it means that the hot box test has passed, otherwise, the hot box test has failed. Test 100 battery cells, and the number of battery cells that pass the test is X, then the test pass rate is X / 100.

[0084] Embodiment 1: A battery cell with an initial thickness of 12 mm, a length of 200 mm, and a width of 150 mm is assembled as follows: (1) Preparation of negative electrode sheet: Mix the negative electrode active materials artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) in a weight ratio of 96:1.5:2.5, add deionized water as a solvent, prepare a slurry with a weight percentage of 50wt%, and stir evenly. The slurry is evenly coated on one surface of a copper foil with a thickness of 8μm, and then dried at 110°C to obtain a negative electrode sheet coated with a negative electrode active material layer on one side. When preparing a double-sided coated negative electrode sheet, repeat the above steps on the other surface of the negative electrode sheet to obtain a negative electrode sheet coated with a negative electrode active material layer on both sides. Then the coated sheet is cold pressed to a thickness of 105μm, and a negative electrode tab is die-cut on the copper foil at the edge of the negative electrode sheet, and then the negative electrode tabs are assembled into a tab bundle and connected to the first tab.

[0085] (2) Preparation of positive electrode sheet: The positive electrode active material lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75wt%, and stirred evenly. The slurry is evenly coated on one surface of an aluminum foil with a thickness of 10μm, and then dried at 90°C to obtain a positive electrode sheet coated with positive electrode active material on one side. When preparing a double-sided coated positive electrode sheet, repeat the above coating steps on the other surface of the aluminum foil. Then the coated electrode sheet is cold pressed to a thickness of 95μm, and the positive electrode tabs are die-cut on the aluminum foil at the edge of the positive electrode sheet, and then the positive electrode tabs are assembled into a tab bundle and connected to the second tab.

[0086] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of EC:EMC:DEC = 30:50:20 to form a basic organic solvent. Then, lithium salt lithium hexafluorophosphate (LiPF6) was added to the basic organic solvent to dissolve and mix well to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0087] (4) Preparation of isolation membrane: A 7 μm thick polyethylene porous polymer film was used as the isolation membrane.

[0088] (5) Preparation of electrode assembly: The negative electrode sheet, the separator and the positive electrode sheet are wound around the support member. The outer shell and the reinforcement of the support member are made of Figure 3 The structure has a width along the first direction of 135 mm, a length along the second direction of 173 mm, R1=2 mm, and W1=15 mm.

[0089] (6) Electrode assembly: The electrode assembly is packaged in a shell.

[0090] (7) Liquid injection packaging: The assembled electrode assembly is injected with electrolyte, and the battery cell is obtained through processes such as vacuum packaging, static standing, hot pressing, and shaping.

[0091] Examples 2 and 3: Except for the parameters mentioned in Table 1, all other parameters are the same as those in Example 1.

[0092] Comparative Example 1: No heat absorbing component and flame retardant component are provided in the supporting member. It should be noted that other parameters of Comparative Example 2 are the same as those of Example 1.

[0093] Comparative Example 2: No support member is provided in the winding center hole of the electrode assembly. It should be noted that other parameters of Comparative Example 1 are the same as those of Example 1.

[0094] Note: “ / ” in Table 1 means that the parameter is not included.

[0095] From Comparative Examples 1-2 and Examples 1-3, it can be seen that the support member includes a shell and a plurality of reinforcement members, the shell is provided with a receiving cavity, at least part of the outer side of the shell is in contact with the hole wall of the winding center hole, and the plurality of reinforcement members are connected to the inner side of the shell, which can reduce the expansion rate of the battery core. The heat absorption member is provided in the sub-cavity, which can reduce the temperature rise of the battery core. The flame retardant member is provided in the sub-cavity, which can improve the pass rate of the hot box test.

[0096] The above description is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the disclosure scope of the present application.

Claims

1. A battery cell, characterized in that: The battery cell comprises: An electrode assembly, comprising a first pole piece, a second pole piece and a separator, wherein the separator is arranged between the first pole piece and the second pole piece, the electrode assembly has a winding center hole, and the first pole piece, the separator and the second pole piece are wound around the winding center hole; A support member is arranged in the winding center hole, and the support member includes an outer shell and a plurality of reinforcement members. The outer shell is provided with a accommodating cavity, and at least part of the outer side surface of the outer shell is in contact with the hole wall of the winding center hole. The plurality of reinforcement members are connected to the inner side surface of the outer shell. The plurality of reinforcement members are arranged at intervals and divide the accommodating cavity into a plurality of sub-cavities, and at least one of the sub-cavities is provided with a heat absorbing member or a flame retardant member.

2. The battery cell according to claim 1, characterized in that: Along the winding direction of the electrode assembly, the isolation film includes a first starting section exceeding the starting end of the first pole piece and the starting end of the second pole piece, and the first starting section is wound around the support member for at least one circle.

3. The battery cell according to claim 1 or 2, characterized in that: The housing includes two plane areas and two curved surface areas, the two plane areas are spaced apart along a first direction, the two curved surface areas are spaced apart along a second direction and are respectively connected to two ends of the two plane areas, the two plane areas and the two curved surface areas enclose the accommodation cavity, and the first direction is perpendicular to the second direction; The reinforcement member connects the two planar areas, the plurality of reinforcement members are arranged along the second direction, and the subcavity is formed between two adjacent reinforcement members or between the arc surface area and the reinforcement member adjacent to the arc surface area.

4. The battery cell according to claim 3, characterized in that: The radius of the circular arc corresponding to the arc surface area is R1, 1mm≤R1≤3mm.

5. The battery cell according to claim 3, characterized in that: Along the second direction, the distance between two adjacent reinforcement members is W1, 10 mm ≤ W1 ≤ 20 mm.

6. The battery cell according to claim 3, characterized in that: The thickness of the planar area is T1, 0.3 mm ≤ T1 ≤ 2 mm; and / or the thickness of the curved area is T2, 0.3 mm ≤ T2 ≤ 2 mm.

7. The battery cell according to any one of claims 1 to 6, characterized in that: The sub-cavity provided with the heat absorbing element and the sub-cavity provided with the flame retardant element are arranged at intervals.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The material of the heat absorbing element includes paraffin.

9. The battery cell according to any one of claims 1 to 8, characterized in that: The flame retardant comprises a shell and a flame retardant. The shell is provided with a receiving cavity. The flame retardant is arranged in the receiving cavity. The melting point of the shell is 100° C. to 130° C.

10. The battery cell according to claim 9, characterized in that: The material of the shell includes polymethyl methacrylate, and the weight percentage of the shell in the flame retardant component is 3% to 10%.

11. The battery cell according to claim 9 or 10, characterized in that: The material of the flame retardant includes at least one of alkyl phosphate ester, fluoroalkyl phosphate ester, aromatic phosphate ester, fluorine-containing flame retardant and carbonate ester.

12. The battery cell according to any one of claims 1 to 11, characterized in that: The material of the support member includes at least one of aluminum, nickel, copper and ceramic.

13. An electronic device, characterized in that: The electronic device comprises the battery cell as claimed in any one of claims 1 to 12.

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