Patent Application
20210104795
The present disclosure relates to the technical field of batteries, and in particular to a secondary battery and a battery unit.
With the development of technology, secondary batteries have an increasingly wide application range, involving production or living. The secondary batteries are also referred to as power batteries and are rechargeable batteries. The secondary batteries are widely used. Low-capacity secondary batteries can be used in small electric vehicles, and high-capacity secondary batteries can be used in large electric vehicles, such as hybrid vehicles or electric vehicles. When the secondary batteries are used in groups, it is necessary to use a bus bar to connect the secondary batteries in series or in parallel. The bus bar is generally welded to positive and negative electrodes of the secondary battery. The battery unit includes a plurality of secondary batteries and a connector for fixing the plurality of secondary batteries.
The secondary battery mainly includes a housing, an electrode assembly, a current collecting member, and a top cover assembly. The electrode assembly is formed by coiling or stacking a positive electrode piece, a negative electrode piece and an isolation film. In the prior art, the electrode assembly included in the secondary battery expands in some cases to release a large expansion force to the outside.
Since the plurality of secondary batteries included in the battery unit are arranged side by side in a direction, and the expansion force released by the electrode assembly is in the arrangement direction of the secondary batteries, the expansion force released by the electrode assemblies included in the plurality of secondary batteries will be combined and then form a large resultant force, so as to not only lead to deterioration of the electrical performance of the secondary battery, but also require the connector to have high structural strength to restrain and offset the expansion force, which can be achieved by means of increasing the volume of the connector and in turn reduces the energy density and space utilization of the secondary battery.
Embodiments of the present disclosure provide a secondary battery and a battery unit. When the secondary battery expands, a first buffer gap can absorb the amount of expansion deformation to prevent the top cover assembly from being disconnected from the housing due to excessive compressive stress on the top cover assembly applied by the expansion deformed electrode assembly, so as to reduce the possibility of failure of the secondary battery due to damage of the overall structure, thereby ensuring the structural integrity and the safety of the secondary battery.
In one aspect, an embodiment of the present disclosure provides a secondary battery, including:
a housing including an accommodating hole with an opening; a top cover assembly connected to the housing in a sealed manner to cover and close the opening; an electrode assembly arranged in the accommodating hole, the electrode assembly including more than two electrode units, the electrode unit being formed by coiling a first electrode piece, a second electrode piece, and a membrane, and having a wide surface and a narrow surface, the more than two electrode units being laminated in an axial direction of the accommodating hole, and the wide surface of the electrode unit being arranged facing the top cover assembly, wherein the top cover assembly is spaced apart from the electrode assembly to form a first buffer gap, the first buffer gap is configured to buffer the amount of expansion deformation of the electrode assembly in the axial direction.
According to one aspect of the embodiment of the present disclosure, in the axial direction, the ratio of the height of the first buffer gap to the height of the electrode assembly is 0.05 to 0.3.
According to one aspect of the embodiment of the present disclosure, the height of the first buffer gap is 0.5 mm to 12 mm.
According to one aspect of the embodiment of the present disclosure, the top cover assembly includes a top cover plate and an insulating plate, the insulating plate being arranged on one side of the top cover plate close to the electrode assembly and being spaced apart from the electrode assembly in the axial direction to form the first buffer gap.
According to one aspect of the embodiment of the present disclosure, the electrode unit is of a coiled structure, and a first gap corresponding to the position of the narrow surface and a second gap corresponding to the position of the wide surface are provided between two adjacent coils of the first electrode piece, the size of the first gap being greater than that of the second gap.
According to one aspect of the embodiment of the present disclosure, the electrode unit is of a coiled structure and has a coiled end face, the housing includes a first side plate and a second side plate connected to each other, the first side plate is arranged corresponding to the narrow surface, the second side plate is arranged corresponding to the coiled end face, and the thickness of the first side plate is less than that of the second side plate.
According to one aspect of the embodiment of the present disclosure, a third gap is provided between the narrow surface and the first side plate, and the size of the third gap is 0.3 mm to 0.9 mm.
According to one aspect of the embodiment of the present disclosure, a fourth gap is provided between the coiled end face and the second side plate, and the size of the fourth gap is 0.3 mm to 0.9 mm.
According to one aspect of the embodiment of the present disclosure, the housing includes a bottom plate, the bottom plate is arranged corresponding to the top cover assembly in the axial direction, and the bottom plate is spaced apart from the electrode assembly to form a second buffer gap, the second buffer gap is configured to buffer the amount of expansion deformation of the electrode assembly in the axial direction.
According to one aspect of the embodiment of the present disclosure, the housing includes a bottom plate, the bottom plate is arranged corresponding to the top cover assembly in the axial direction, and the ratio of the width of the wide surface to the thickness of the bottom plate is greater than or equal to 20 and less than or equal to 69.
The secondary battery according to the embodiment of the present disclosure includes the housing with the accommodating hole, and the electrode assembly arranged in the accommodating hole. When the electrode unit of this embodiment expands, the electrode unit mainly expands in the axial direction of the accommodating hole, such that the electrode unit can release the expansion force in the axial direction of the accommodating hole, but release a small expansion force in the thickness direction, which in turn will not generate excessive compressive stress on the side plate of the housing. In this embodiment, the top cover assembly is spaced apart from the electrode assembly in the axial direction of the accommodating hole to form a first buffer gap. The first buffer gap is used to buffer the amount of expansion deformation of the electrode assembly in the axial direction. The amount of expansion deformation of the electrode assembly will preferentially occupy and squeeze the first buffer gap, but will not directly come into contact with the top cover assembly and apply compressive stress to the top cover assembly. As such, when the electrode assembly expands, the electrode assembly will not apply excessive compressive stress to the top cover assembly to not cause the top cover assembly to be disconnected from the housing, thereby preventing the leakage of electrolytic solution and the failure of the secondary battery due to damage of the overall structure, thereby ensuring the structural integrity and the safety of the secondary battery.
In another aspect, according an embodiment of the present disclosure, a battery unit is provided, including more than two secondary batteries as described in the above embodiment, wherein the more than two secondary batteries are arranged side by side in a direction perpendicular to the axial direction, and the narrow surfaces of the electrode units of the two adjacent secondary batteries are arranged correspondingly.
The features, advantages, and technical effects of exemplary embodiments of the present disclosure will be described below with reference to the drawings.
In the drawings, the drawings are not drawn to actual scale.
Implementations of the present disclosure will be further described in detail below in conjunction with the drawings and embodiments. The detailed description and drawings of the following embodiments are used to illustrate the principle of the present disclosure by way of examples, but cannot be used to limit the scope of the present disclosure, that is, the present disclosure is not limited to the described embodiments.
In the description of the present disclosure, it should be noted that, unless otherwise stated, “plurality of” means two or more. Orientations or position relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “inside” and “outside” are only for convenience of describing the present disclosure and simplifying the description, rather than indicates or implies that devices or elements referred to must have a specific orientation or be constructed and operated in the specific orientation, and therefore cannot be construed as limiting the present disclosure. In addition, the terms “first”, “second” and “third”, etc. are for descriptive purposes only and should not be construed as indicating or implying relative importance.
In the description of the present disclosure, it should also be noted that the terms “installed”, “connected”, and “connection” should be understood in a broad sense, unless otherwise explicitly specified and limited, for example, it may be a fixed connection, a detachable connection or an integrated connection; and may be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above terms in the present disclosure could be understood according to specific circumstances.
To better understand the present disclosure, a battery unit 20 and a secondary battery 10 according to the embodiments of the present disclosure will be described in detail below in conjunction with
Referring to
Referring to
The housing 11 of this embodiment may be in a quadrangular prism shape or in other shapes. The housing 11 has an internal space for accommodating the electrode assembly 12 and an electrolytic solution. The housing 11 may be made of a material such as aluminum, aluminum alloy or plastic. The housing 11 includes a bottom plate 111, first side plates 112 connected to the bottom plate 111, and second side plates 113 connected to the bottom plate 111. The bottom plate 111, two first side plates 112, and two second side plates 113 form an accommodating hole 11a and an opening in communication with the accommodating hole 11a. The opening is provided corresponding to the bottom plate 111 in an axial direction Z of the accommodating hole 11a, wherein corresponding provision does not mean that two surfaces are completely opposite each other in a strict sense, but also includes that two surfaces are partially opposite each other and two surfaces are tilted slightly opposite each other. The axial direction Z of the accommodating hole 11a is the extension direction of the accommodating hole 11a. The electrode assembly 12 is arranged in the accommodating hole 11a. The top cover assembly 13 is connected to the housing 11 in a sealed manner to cover and close the opening, sealing the electrode assembly 12 in the housing 11. In one example, the top cover assembly 13 includes a top cover plate 131 and an electrode terminal 132. The top cover plate 131 and the electrode terminal 132 are both located on one side of electrode assembly 12 in the axial direction Z. The top cover assembly 13 is connected to the housing 11 in a sealed manner by the top cover plate 131. The electrode terminal 132 is arranged on the top cover plate 131 and is electrically connected to the electrode assembly 13.
Referring to
The secondary battery 10 according to the embodiment of the present disclosure includes the housing 11 with the accommodating hole 11a, and the electrode assembly 12 arranged in the accommodating hole 11a. When the electrode unit 121 of this embodiment expands, the electrode unit 121 mainly expands in the axial direction Z of the accommodating hole 11a, such that the electrode unit 121 can release the expansion force in the axial direction Z of the accommodating hole 11a, but release a small expansion force in its own thickness direction Y of secondary battery 10, which in turn will not generate excessive compressive stress on the first side plate 112 of the housing 11. As such, when the more than two secondary batteries 10 of this embodiment are arranged side by side in their own thickness direction Y to form the battery unit 20, since the direction of the main expansion force generated when each secondary battery 10 expands intersects the thickness direction Y, the main expansion force generated by each secondary battery 10 does not accumulate in the thickness direction Y and not form a large resultant force. When an external fixing member is used to fix the battery unit 20 including the more than two secondary batteries 10 of this embodiment, the requirements for the rigidity and the strength of the fixing member itself are relatively low, which is beneficial to reduce the volume or weight of the fixing member and to improve the energy density and space utilization of the secondary battery 10 and the battery unit 20 as a whole.
Referring to
In one embodiment, referring to
In one embodiment, the top cover assembly 13 further includes an insulating plate 133. The insulating plate 133 is arranged at one side of the top cover plate 131 facing the electrode assembly 12 and is connected and fixed to the top cover plate 131. The top cover plate 131 and the electrode assembly 12 can be insulated and isolated by means of the insulating plate 133. The insulating plate 133 is spaced apart from the electrode assembly 12 in the axial direction Z to form the first buffer gap 14. Optionally, a surface of the insulating plate 133 facing the electrode assembly 12 is a smooth surface, such that when the electrode assembly 12 expands to come into contact with the smooth surface of the insulating plate 133, the insulating plate 133 does not apply local squeeze stress to the electrode unit 121 included in the electrode assembly 12, so as to reduce the possibility of cracks in the first electrode piece 12a and/or the second electrode piece 12b included in the electrode unit 121 due to concentration of stress.
Referring to
When the electrode unit 121 of the embodiment of the present disclosure expands without being restrained by the housing 11, the wide surface 121a and the narrow surface 121b included in the electrode unit 121 have different amounts of expansion deformation, and the wide surface 121a has a larger amount of expansion deformation than the narrow surface 121b. However, when the electrode unit 121 is installed into the housing 11, the bottom plate 111 of the housing 11 of this embodiment is arranged corresponding to the wide surface 121a of the electrode unit 121, and the first side plate 112 is arranged corresponding to the narrow surface 121b, such that the amount of expansion deformation of the electrode unit 121 is limited, and the difference in the expansion degree of the electrode unit 121 in the areas of the wide surface 121a and the narrow surface 121b is reduced, which is in turn beneficial to ensure the uniformity of infiltration of the areas of the electrode unit 121, effectively improve the infiltration effect, and improve the electrical performance of the secondary battery 10.
The material of the housing 11 of this embodiment is preferably a metal material. The housing 11 includes two first side plates 112 oppositely arranged in the thickness direction Y of the secondary battery 10 and two second side plates 113 oppositely arranged in the width direction X of the secondary battery 10. The first side plate 112 and the second side plate 113 are alternately arranged so as to be configured in a cylindrical structure with a rectangular cross section. The bottom plate 111 has a rectangular plate-shaped structure and is connected to the first side plates 112 and the second side plates 113 in a sealed manner. The first side plate 112 is arranged corresponding to the narrow surface 121b of the electrode unit 121. The top cover assembly 13 is arranged corresponding to the bottom plate 111 in the axial direction Z of the accommodating hole 11a. The top cover assembly 13 is connected to the first side plates 112 and the second side plates 113 in a sealed manner. In a particular situation, the narrow surface 121b of the electrode unit 121 also expands, but has small amount of expansion deformation. Therefore, the compressive stress applied to the first side plate 112 is small, such that the resultant force of the expansion force accumulated by the secondary batteries 10 in their own thickness direction Y is small. Moreover, the greater the amount of expansion deformation of the electrode unit 121 is, the smaller the size of the first gap 12d and the size L2 of the second gap 12e will be. During the use of the electrode unit 121, the electrolytic solution inside will be consumed, so it is necessary to constantly replenish the electrolytic solution from the outside. When the electrode unit 121 expands, the first side plate 112 can restrain the narrow surface 121b, such that the first gap 12d will become smaller, such that the electrolytic solution in the housing 12 is difficult to be replenished to the inside of the electrode unit 121 through the first gap 12d, affecting the electrical performance of the electrode unit 121. In addition, when the electrode unit 121 expands, the outermost layer of the first electrode piece 12a or the second electrode piece 12b will receive large tensile stress, which is liable to cause fracture of the first electrode piece 12a or the second electrode piece 12b. The first side plate 112 of this embodiment can restrain the narrow surface 121b and prevent an excessive amount of expansion deformation of the narrow surface 121b, thereby effectively reducing the possibility of fracture of the first electrode piece 12a or the second electrode piece 12b.
In one embodiment, referring to
Referring to
In one embodiment, a fourth gap 12g is provided between the coiled end face 121c and the second side plate 113. The size L4 of the fourth gap 12g is 0.3 mm to 0.9 mm. The fourth gap 12g can be used to buffer the impact force of the second side plate 113 caused by the high-temperature gas released from the inside of the electrode unit 121, so as to reduce the possibility of damage or melting of the second side plate 113, thereby improving the safety in use of the secondary battery 10. When the size L4 of the fourth gap 12g is less than 0.3 mm, the buffering effect of the high-temperature gas released from the inside of the electrode unit 121 is reduced, and the buffering function cannot be effectively exerted. When the size L4 of the fourth gap 12g is greater than 0.9 mm, the gap between the electrode unit 121 and the second side plate 113 is too large, resulting in the increased overall size of the secondary battery 10, which in turn causing an adverse effect on the energy density of the secondary battery 10.
Referring to
In this embodiment, the ratio of the width C of the wide surface 121a (see
The battery unit 20 of the above embodiment of the present disclosure includes more than two secondary batteries 10. The more than two secondary batteries 10 are arranged side by side in their thickness direction Y. In this embodiment, the thickness direction Y is perpendicular to the axial direction Z. The narrow surfaces of the electrode units of two adjacent secondary batteries are arranged correspondingly. The electrode units 121 included in each secondary battery 10 are laminated in the axial direction Z of the accommodating hole 11a of the housing 11. When the electrode unit 121 of this embodiment expands, it expands and deforms mainly in the axial direction Z of the accommodating hole 11a, and the amount of expansion deformation in the thickness direction Y is small. As such, the resultant force of expansion accumulated by the secondary batteries 10 in their own thickness direction Y is small. In the thickness direction Y, the battery unit 20 does not need to use a structural member with high strength to restrain and offset the expansion force, or can restrain and offset the expansion force by using a structural member with low strength, thereby effectively reducing the overall mass of the battery unit 20, such that the battery unit 20 itself has a more compact structure, and the energy density of the battery unit 20 is effectively improved. Moreover, the battery unit 20 itself has a small or no amount of expansion deformation in its own thickness direction Y of the secondary battery 10, which can effectively improve the safety during use.
Although the present disclosure has been described with reference to preferred embodiments, various modifications can be made to it and equivalents can be substituted for components therein without departing from the scope of the present disclosure, especially as long as there is no structural conflict, various technical features mentioned in various embodiments can be combined in any way. The present disclosure is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201822274288.8 | Dec 2018 | CN | national |
This application is a continuation of International Application No. PCT/CN2019/129622, filed on Dec. 28, 2019, which claims priority to Chinese Patent Application No. 201822274288.8, filed on Dec. 29, 2018. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2019/129622 | Dec 2019 | US |
| Child | 17125331 | US |
