Patent Application
20200411834
The present application relates to the technical field of energy storage components, and in particular, to a secondary battery and a vehicle.
Under double pressure of energy demand and environmental protection, electric vehicles are growing in applications. As an important power source of electric vehicles, secondary batteries have a crucial effect on the performance and safety of the electric vehicles. Because of higher requirements on the endurance of the vehicles and regulatory policies, higher requirements are imposed on the energy density, cycle life and safety of the secondary batteries. A secondary battery includes an electrode assembly and an electrode terminal, the electrode assembly includes a body and a tab extending from the body, and the body is formed by winding a first electrode plate, a separator, and a second electrode plate; to connect the electrode terminal with the tab so as to transmit out a current produced by the electrode assembly, the secondary battery further includes a connection member, one end of the connection member is connected to the electrode terminal, and the other end of the connection member is connected to the tab.
The present application provides a secondary battery and a vehicle, so as to solve the above problems.
A first aspect of the present application provides a secondary battery, including:
a cap plate;
an electrode terminal, disposed on the cap plate;
an electrode assembly, including a body and a tab extending from the body; and
a connection member, including a first connecting plate connected to the tab, a second connecting plate connected to the electrode terminal, and a support plate connecting the first connecting plate and the second connecting plate, a width direction of the support plate is consistent with a thickness direction of the secondary battery, at least a part of the support plate protruding, relative to the first connecting plate, towards a side close to the body, and the protruding part of the support plate is attached to the body; and
a minimum distance between the support plate and a bottom surface of the electrode assembly in a height direction of the secondary battery is defined as a bare height H of the body on its side, a size of the body in a length direction of the secondary battery is defined as a body length L, and the bare height H and the body length L satisfy the following relationship:
0.1≤H/L≤0.8.
Optionally, in the height direction, an end of the first connecting plate close to the cap plate extends beyond an end of the tab close to the cap plate.
Optionally, the bare height H and the body length L satisfy the following relationship:
0.2≤H/L≤0.6.
Optionally, the bare height H is in a range of 18 mm to 72 mm, and the body length L is in a range of 90 mm to 300 mm.
Optionally, the tab is disposed on a side of the body close to the cap plate, and a ratio of a size A of the tab in the height direction of the secondary battery to a height B of the body is in a range of 0.2 to 0.5.
Optionally, an interval is provided between the tab and the cap plate in the height direction.
Optionally, in the height direction, an end of the tab away from the cap plate extends beyond an end of the first connecting plate away from the cap plate.
Optionally, the tab is disposed on one side of the body in the thickness direction of the secondary battery.
Optionally, two electrode assemblies are disposed side by side in the thickness direction, and the tabs of the two electrode assemblies are respectively located on two sides of the two electrode assemblies facing away from each other.
Optionally, two sides of the support plate in the thickness direction of the secondary battery are connected with the first connecting plates respectively, and the two first connecting plates are fixedly connected to the tabs on the same side respectively.
Optionally, the support plate includes a first part and a second part that are connected to each other, an area of a cross section of the first part is smaller than that of the second part, and the first connecting plate is connected to the first part.
Optionally, the first connecting plate extends in the thickness direction of the secondary battery, and the tab is disposed between the first connecting plate and the body.
A second aspect of the present application provides a vehicle, including the secondary battery according to any of the preceding implementations.
It should be understood that the foregoing general descriptions and the following detailed descriptions are merely examples, and do not constitute any limitation on the present application.
The accompanying drawings herein are incorporated in the specification as a part of the specification, illustrate embodiments that are in accordance with the present application, and are used together with the specification to explain the principle of the present application.
The following describes the present application in detail by using specific embodiments and with reference to the accompanying drawings.
The directional terms such as “above”, “under”, “left”, and “right” described in the embodiments of the present application are described from the angles shown in the accompanying drawings, and should not be construed as limitation to the embodiments of the present application. In addition, in the context, it should be understood that when an element is referred to as being connected “above” or “under” another element, the element can be not only directly connected “above” or “under” the another element, but also indirectly connected “above” or “under” the another element through an intermediate element.
In an actual application, the tab is prone to be broken due to the vibration and shock subjected by the secondary battery, and in the related technology, the tab and the connection member usually have a larger size in a height direction of the secondary battery to solve a battery safety problem resulting from breakage of the tab. With the increasing sizes of the tab and the connection member in the height direction of the secondary battery, the tab and the connection member may block discharge of gas from internal of the electrode assembly, and especially when the connection member is attached to the body, the gas discharge from the electrode assembly is particularly difficult at a blocked area of the body. If a speed of gas production within the electrode assembly is greater than a speed of gas discharge, bubbles will remain in the electrolyte, which affects transmission of lithium-ions in the electrolyte, and may cause black spots on the electrode plate, thereby decreasing the energy density and cycle life of the secondary battery and possibly resulting in potential safety hazards.
A secondary battery shown in
As shown in
Specifically, in the height direction Z of the secondary battery, a minimum distance between the support plate 43 and a bottom surface of the electrode assembly 30 is defined as a bare height H of the body 31 on its side (namely the side on which the tab 32 extends from the body 31), a size of the body 31 in the length direction Y of the secondary battery is defined as a body length L, and the bare height H and the body length L satisfy the following relationship: 0.1≤H/L≤0.8, for example, H/L is 0.1, 0.15, 0.2, 0.5, 0.55, 0.6, 0.7, 0.79, 0.8, or the like.
It can be understood that the electrode assembly 30 includes a first electrode plate, a second electrode plate, and a separator disposed between the first electrode plate and the second electrode plate, and an active substance on the first electrode plate and the second electrode plate is mainly disposed in the body 31; to increase an energy density of the secondary battery, it needs to increase the body length L as much as possible, while this may cause a longer gas discharge path inside the electrode assembly 30, and is not good for effective release of gas; especially for some active substance producing a relatively large amount of gas, once the gas inside the electrode assembly 30 cannot be effectively released, a lot of gas accumulates between the first electrode plate, the second electrode plate and the separator, and cuts off a transmission channel of ions in the active substance, which may cause the black spots to be produced on the electrode assembly 30 after formation, and greatly affect the energy density and cycle life of the secondary battery.
In the present application, the side of the body 31 is partially bare, and the gas produced inside the electrode assembly 30 flows to the side of the body 31 through a gap between the first electrode plate, the second electrode plate and the separator, and is discharged from the bare part; considering that the length of the body 31 of the electrode assembly 30 affects the length of the gas discharge path inside the electrode assembly 30 and a bare area of the side of the body 31 affects a gas discharge speed, in the present application, the size of the tab 32 in the height direction Z of the secondary battery is smaller than the size of the body 31 in the height direction Z, and a ratio of the bare height H of the electrode assembly 30 to the body length L of the body 31 of the electrode assembly 30 is set to a range of 0.1 to 0.8; in this way, the gas path of the electrode assembly 30 matches the gas discharge speed, and further the gas production speed inside the electrode assembly 30 is smaller than the gas discharge speed, thereby ensuring normal transmission of ions in the electrolyte, preventing the black spots from being produced on the first electrode plate or the second electrode plate, increasing the energy density and cycle life of the secondary battery, and improving safety of the secondary battery.
Further, the bare height H and the body length L satisfy the following relationship: 0.2≤H/L≤0.6, and for example, H/L is 0.2, 0.3, 0.4, 0.5, 0.55, 0.58, 0.6, or the like, so that the gas path of the electrode assembly 30 better matches the gas discharge speed, thereby further increasing the energy density and cycle life of the secondary battery and improving safety of the secondary battery.
When H/L is less than 0.1, the bare height H of the body 31 is relatively small, the gas discharge efficiency of the electrode assembly is relatively low, and meanwhile, the body length L is relatively large, causing that the gas discharge path is increased; consequently, the black spots are produced on the electrode assembly 30 after formation, greatly affecting the energy density and cycle life of the secondary battery.
When H/L is greater than 0.8, the bare height H of the body 31 is relatively large; although the gas discharge speed inside the electrode assembly 30 being greater than the gas production speed may be ensured, the size of the support plate 43 is reduced in the height direction Z, and meanwhile, a contact area between the tab 32 and the first connecting plate 41 may be reduced, causing overheating of the contact area between the tab 32 and the first connecting plate 41, thereby increasing a temperature of the electrode assembly 30 and affecting the cycle life of the secondary battery.
In some embodiments, the bare height H is set to be in a range of 18 mm to 72 mm, such as 18 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 65 mm, 70 mm, and 72 mm, which not only ensures the gas discharge efficiency of the electrode assembly 30, but also can ensure the contact area between the tab 32 and the first connecting plate 41 so as to prevent overheating of the contact area between the tab 32 and the first connecting plate 41; moreover, such setting can also ensure the connection strength between the first connecting plate 41 and the tab 32, thereby increasing reliability of the secondary battery.
As described above, if body length L is too large, the gas discharge path is lengthened and the gas inside the secondary battery cannot be discharge timely; if the body length L is too small, the energy density of the secondary battery is decreased; therefore, in the present application, the body length L is in a range of 90 mm to 300 mm, such as 90 mm, 95 mm, 120 mm, 150 mm, 180 mm, 200 mm, 220 mm, 250 mm, 280 mm, 290 mm, 295 mm, or 300 mm, so as to ensure that the gas discharge path of the electrode assembly 30 is not too long, and also ensure the energy density of the secondary battery.
It can be understood that if a size A of the tab 32 in the height direction Z is excessively small, severe overheating may occur at the tab 32 during use of the secondary battery, especially at the contact part between the tab 32 and the first connecting plate 41; if the size A is excessively large, the bare area on the side of the body 31 will reduce, causing gas discharge problems. In one embodiment, a ratio of the size A of the tab 32 in the height direction Z of the secondary battery to a height B of the body 31 (the height B is the size of the body 31 in the height direction Z) is in a range of 0.2 to 0.5, and for example, A/B is 0.2, 0.28, 0.3, 0.4, 0.5, or the like, which not only can ensure a current flow area at the contact part between the tab 32 and the first connecting plate 41 to avoid safety hazards caused by overheating, but also can ensure smooth gas discharge of the electrode assembly 30.
In some embodiments, the tab 32 is disposed on one side of the body 31 close to the cap plate 10; as such, a size of the first connecting plate 41 in the height direction Z may be reduced, thereby facilitating connection between the tab 32 and the first connecting plate 41, and a size of the connection member 40 in the height direction Z also may be reduced, thereby reducing the cost.
In the foregoing structure, the reduce of the size of the connection member 40 in the height direction Z reduces the contact area between the tab 32 and the first connecting plate 41, which may cause partial overheating of the contact part between the tab 32 and the first connecting plate 41; to solve this problem, an end of the first connecting plate 41 close to the cap plate 10 extends beyond an end of the tab 32 close to the cap plate 10 in the height direction Z, that is, the first connecting plate 41 includes a connection part connected to the tab 32, and a cooling part, wherein the connection part is connected to the cooling part, and the cooling part is disposed on a side of the first connecting plate 41 close to the cap plate 10, so as to increase an area of the first connecting plate 41, facilitate the cooling and thus alleviate partial overheating at the connection part between the first connecting plate 41 and the tab 32.
To minimize the size of the secondary battery in the thickness direction X and increase the energy density of the secondary battery, both the connection member 40 and the tab 32 do not extend beyond the body 31 in the thickness direction X; therefore, the first connecting plate 41 is connected to one side of the protruding part of the support plate 43 in the thickness direction X, as shown in
As shown in
The above electrode assembly 30 includes two tabs 32, namely, a first tab and a second tab, and correspondingly, there are two electrode terminals 20 and two connection members 40; the two electrode terminals 20 includes a first electrode terminal and a second electrode terminal, the first tab is connected to the first electrode terminal via one connection member 40, the second tab is connected to the second electrode terminal via the other connection member 40, and the first tab and the second tab may be located on two sides of the body 31 in the length direction Y, respectively; the specific connection manner may be the same for the two tabs 32, and below, the description is made by taking the manner, in which one of the tabs 32 is connected to one electrode terminal 20 via one connection member 40, as an example.
Specifically, the electrode assembly 30 may be formed by winding, that is, the body 31 is formed by winding the first electrode plate, the second electrode plate, and the separator. In various winding layers, first conductive parts extending from the first electrode plate are stacked to form the first tab, and second conductive parts extending from the second electrode plate are stacked to form the second tab. Specifically, the first conductive parts and the second conductive parts may be cut to form the first tab and the second tab respectively, so that the size of the tab 32 (including the first tab and the second tab) in the height direction Z of the secondary battery is smaller than the size of the body 31, thereby facilitating gas discharge of the electrode assembly 30.
After the tab 32 is connected to the first connecting plate 41, the tab 32 is bent relative to the length direction Y to reduce the size of the secondary battery in the length direction Y; because the tab 32 is formed by cutting and stacking the conductive parts (including the first conductive parts and the second conductive parts), the conductive parts may be misaligned at an end of the tab 32 (including two ends in the height direction Z and an end in an extension direction of the tab 32), and the larger the thickness (the size of the tab 32 in a stacking direction of the conductive parts) of the tab 32, the more severe the misalignment, resulting in that the conductive parts on the innermost side may be highly redundant, while the conductive parts on the outermost side may not be connected to the first connecting plate 41.
In one embodiment, the tab 32 is disposed on one side of the body 31 in the thickness direction X of the secondary battery; specifically, the body 31 includes an initial winding layer, the initial winding layer is a winding start part of the electrode plate of the body 31 at the innermost layer, and the tab 32 extends out on the one side in the thickness direction X from the initial winding layer; that is, among the various winding layers, merely the winding layers on a side of the initial winding layer are extended with the conductive parts, as shown in
The secondary battery may be provided with one electrode assembly 30 or a plurality of electrode assemblies, for example, two or more electrode assemblies. As shown in
When two electrode assemblies 30 are provided, only one first connecting plate 41 may be provided; in this case, two tabs 32 on the same side of the two electrode assemblies 30 are connected to two sides of the first connecting plate 41 respectively, and then the first connecting plate 41 is bent; as a result, a space that matches the thickness of the two tabs 32 needs to be provided in the secondary battery in the length direction Y, affecting the energy density of the secondary battery. In one embodiment, two sides of the support plate 43 in the thickness direction X of the body 31 are connected to the first connecting plates 41 respectively, and when the support plate 43 includes the first part 431, two first connecting plates 41 are connected to two sides of the first part 431, as shown in
In some embodiments, after the tabs 32 are bent, the first connecting plate 41 extends in the thickness direction X, and the tabs 32 are disposed between the first connecting plate 41 and the body 31; in other words, the tabs 32 are each bent away from the second side of the body 31 on which the tabs 32 are each located, and the first connecting plate 41 is located on a surface of the tabs 32 facing away from the body 31, as shown in
During assembly, the support plate 43 may be attached to the body 31, and in this case, the first connecting plate 41 is approximately vertical to the support plate 43, as shown in
Since the tab 32 is formed by stacking and cutting the conductive parts (including the first conductive parts and the second conductive parts), the various conductive parts obtained by cutting may be misaligned at the end of the tab 32 close to the cap plate 10; and during installation of the electrode assembly 30 and the cap plate 10, the cap plate 10 may press the end of the tab 32 close to the cap plate 10 and bend this end, resulting in that the tab 32 cannot be effectively welded to the first connecting plate 41 and thus severe overheating of the welding part may occur. To avoid the above problem, an interval is provided between the tab 32 and the cap plate 10 in the height direction Z, to avoid bending of the tab 32 caused by pressing from the cap plate 10.
Likewise, the conductive parts obtained by cutting may be also misaligned at the end of the tab 32 away from the cap plate 10, and if the first connecting plate 41 is aligned with this end, the welding part between the first connecting plate 41 and the tab 32 may not penetrate through all the conductive parts, causing false welding of the tab 32 and thereby affecting the electric performance of the secondary battery. To solve this problem, the end of the tab 32 away from the cap plate 10 extends beyond the end of the first connecting plate 41 away from the cap plate 10 in the height direction Z, and in this way, at the end of the tab 32 away from the cap plate 10, the welding part between the tab 32 and the first connecting plate 41 can penetrate through as many layers of conductive parts as possible so as to improve the electric performance of the secondary battery. In some embodiments, at the end of the tab 32 away from the cap plate 10, the first connecting plate 41 does not extend beyond the conductive part closest to the cap plate 10 at the end, thereby further improving the electric performance of the secondary battery.
Because the misalignment may also occur to the tab 32 in the extension direction of the tab 32, the end of the tab 32 extends beyond the first connecting plate 41 in the thickness direction X, to ensure that all conductive parts at this end can be connected to the first connecting plate 41.
It should be noted that the above tab 32 may be connected to the first connecting plate 41 by welding.
Further, the present application further provides a vehicle, including the secondary battery according to any of the foregoing embodiments.
The foregoing embodiments are merely exemplary embodiments of the present application, and are not intended to limit the present application, and for the person skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, or improvement made without departing from the spirit and principle of the present application shall fall within the protection scope of the present application.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201810173296.5 | Mar 2018 | CN | national |
This application is a National Stage of International Application No. PCT/CN2018/081596 filed on Apr. 2, 2018, which claims the priority of the Chinese patent application No. 201810173296.5, entitled “SECONDARY BATTERY AND VEHICLE” and filed on Mar. 1, 2018, both of which are incorporated herein by reference in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2018/081596 | 4/2/2018 | WO | 00 |
