Battery cell and battery

Abstract

Battery cell (10), characterized in that the battery cell (10) has a first electrode plate (100) and a second electrode plate (200), wherein the first electrode plate (100) and the second electrode plate (200) are stacked and intertwined; wherein one of the two opposite end faces of the battery cell (10) is a correction face (11), wherein a gap is provided between a side edge of the second electrode plate (200) and a side edge of the battery cell (10), and wherein the side edge of the second electrode plate (200) arranged at the innermost side edge of the battery cell (10) is offset relative to a side edge of the second electrode plate (200) arranged at the outermost side of the battery cell (10) towards the correction face (11).

Description

Technical field

[0001] The present application relates to the field of battery technology and in particular to a battery cell and a battery. Technical background

[0002] Rechargeable batteries, also called secondary batteries, are electrochemical energy devices that can be cyclically charged and discharged, such as lithium-ion batteries, and are commonly used in various mobile power supply devices, including consumer electronics, new energy vehicles, energy storage devices, and the like.

[0003] In the prior art, a lithium battery generally consists of a battery cell and a housing, wherein the battery cell is arranged in the housing, the battery cell having a positive electrode plate and a negative electrode plate, wherein a separator is arranged between the positive electrode plate and the negative electrode plate, and the positive electrode plate, the negative electrode plate and the separator, which are provided to be stacked, can be wound, wherein at the beginning end of the battery cell winding the negative electrode plate typically has a structure with a one-sided coated active layer, wherein the one-sided coated negative electrode plate has a certain degree of wrinkling after roller pressing, thereby narrowing the width of the negative electrode plate.

[0004] However, in the current battery cell structure, the active layer of the negative electrode plate, which is coated on one side, becomes narrower, resulting in a poor pre-lithiation effect of the negative electrode plate, which in turn leads to a reduction in the energy density of the battery. Brief summary of the invention

[0005] In view of the problems mentioned above, the embodiments of the present application provide a battery cell and a battery to solve the technical problem in the current battery cell structure that the active layer of the single-sided coated negative electrode plate becomes narrower, resulting in a poor pre-lithiation effect of the negative electrode plate and a reduced energy density of the battery.

[0006] To achieve the above objective, the present application provides, in a first aspect, a battery cell comprising a first electrode plate and a second electrode plate, wherein the first electrode plate and the second electrode plate are arranged to be wound in succession.The end of the first electrode plate has a one-sided coated area, the one-sided coated area being located inside the battery cell; one of the two opposite end faces of the battery cell being a correction face, a gap being provided between the side edge of the second electrode plate and the side edge of the battery cell, and the side edge of the second electrode plate located at the innermost side edge of the battery cell being offset relative to a side edge of the second electrode plate located at the outermost side of the battery cell towards the correction face.

[0007] The coverage value of the interior of the battery cell on the correction side is smaller than the coverage value of the exterior of the battery cell on the correction side, where the coverage value is the distance between the edge of the second electrode plate and the edge of the first electrode plate.

[0008] The advantageous effect of the present application is that during the winding process of the battery cell, the inner and outer coverage values ​​of the battery cell are adjusted by means of correction, so that the relative position of the first electrode plate and the second electrode plate changes from the inside of the battery cell to the outside of the battery cell, thereby increasing the pre-lithiation degree of the correction side and fully exploiting the advantage of the high pre-lithiation degree of the correction side, and at the same time increasing the battery cell capacity on the uncorrected side and thereby improving the energy density of the battery.

[0009] As an optional embodiment, it is provided that on the correction side the distance between the side edge of the second electrode plate located on the innermost side of the battery cell and the side edge of the first electrode plate is smaller than the distance between the side edge of the second electrode plate located on the outermost side of the battery cell and the side edge of the first electrode plate.

[0010] As an optional embodiment, it is provided that the side edge of the second electrode plate, located on the outermost side on both sides of the battery cell, is arranged symmetrically to the side edge of the second electrode plate located on the innermost side of the battery cell.

[0011] As an optional embodiment, it is provided that on the innermost side of the battery cell, the pre-lithiation level on a side of the first electrode plate facing the correction side is higher than the pre-lithiation level on a side of the first electrode plate facing away from the correction side.

[0012] As an optional embodiment, the first electrode plate has a one-sided coated area at its end; the edges on one end of the second electrode plate facing the correction side are connected one after the other from the inside of the battery cell to both sides of the outside of the battery cell to form a first contour line, wherein the distance between a position of the first contour line facing the one-sided coated area and the edge of the first electrode plate is smaller than the distance between a position of the first contour line facing away from the one-sided coated area and the edge of the first electrode plate.

[0013] As an optional embodiment, the first contour line protrudes at the inner position of the battery cell in the direction of the correction side of the battery cell relative to the two sides outside the battery cell.

[0014] As an optional embodiment, the edges on one end of the second electrode plate facing away from the correction side are connected one after the other from the inside of the battery cell to both sides of the outside of the battery cell to form a second contour line, the shape of the first contour line being adapted to the shape of the second contour line.

[0015] As an optional embodiment, it is provided that the distance between the side edge of the second electrode plate on the correction side and the side edge of the first electrode plate gradually increases from the innermost side of the battery cell to the outermost side of the battery cell.

[0016] As an optional embodiment, it is provided that the width of the first electrode plate is W1, wherein the width of the second electrode plate is W2, wherein the width of the first electrode plate is greater than the width of the second electrode plate, wherein the height difference between different positions of the second electrode plate along the winding direction of the battery cell in the first direction is H, where H = (0.13 - 0.86) × (W1 - W2) applies, where the first direction is the height direction of the battery cell.

[0017] As an optional embodiment, it is provided that on the correction side the distance between the side edge of the second electrode plate arranged on the outermost side of the battery cell and the side edge of the battery cell L1 is, wherein the distance between the side edge of the second electrode plate arranged on the innermost side of the battery cell and the side edge of the battery cell L2 is, where L1 = (1.2∼13.5) × L2.

[0018] As an optional embodiment, it is provided that on the correction side the distance between the second electrode plate at the outermost and innermost side of the battery cell and the side edge of the battery cell is in each case greater than the distance between the second electrode plate at the respective position between the outermost and innermost side of the battery cell and the side edge of the battery cell.

[0019] As an optional embodiment, it is provided that the battery cell may further have a tab that is connected to the correction side of the battery cell.

[0020] As an optional embodiment, it is provided that a free area is formed between the side edge of the second electrode plate facing away from the correction side and the side edge of the first electrode plate facing away from the correction side, wherein the amount of electrolyte stored in the free area of ​​the battery cell is greater than the amount of electrolyte stored on the correction side of the battery cell.

[0021] In a second aspect, the present application provides a battery, wherein the battery comprises a housing and a battery cell in the technical solution described above, wherein the battery cell is arranged in the housing.

[0022] The present application provides a battery cell and a battery, the battery cell having a first electrode plate and a second electrode plate, wherein the first electrode plate and the second electrode plate are arranged in a stacked, wound manner, the end of the first electrode plate having a coated area on one side, the coated area being arranged inside the battery cell;The end of the battery cell has a correction side, and the coverage value of the inside of the battery cell on the correction side is smaller than the coverage value of the outside of the battery cell on the correction side, wherein the coverage value is the distance between the edge of the second electrode plate and the edge of the first electrode plate, wherein the battery cell provided by the present application improves the pre-lithiation level of the correction side and fully exploits the advantage of the high pre-lithiation level of the correction side, while at the same time increasing the battery cell capacity on the uncorrected side and thereby improving the energy density of the battery.

[0023] In addition to the technical problems solved by the present application, the technical features that constitute the technical solutions, and the advantageous effects brought about by the technical features of these technical solutions described above, other technical problems that can be solved by the battery cell and battery provided by the present application, other technical features included in the technical solutions, and the advantageous effects brought about by these technical features are described in more detail in the specific implementations. Brief description of the characters

[0024] To clarify the technical solutions of the embodiments of the present application or of the prior art, the drawings necessary for the descriptions in embodiments or of the prior art are briefly described below. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and other drawings can be derived from these drawings by the person skilled in the art without any creative effort. Fig. Figure 1 is a schematic structural representation of the battery cell provided by an embodiment of the present application. Fig. 2 is a sectional view of the battery cell in Fig. 1 along the AA direction. Fig. Figure 3 is a schematic structural representation of the first electrode plate in the battery cell provided by an embodiment of the present application. Fig. Figure 4 is a sectional view of another structure of a battery cell provided by an embodiment of the present application. Reference symbol list

[0025] 10 Battery cell; 11 Correction side; 12 First contour line; 13 Second contour line; 14 Free area; 100 First electrode plate; 101 Single-sided coated area; 110 Current collector; 120 Active layer; 200 Second electrode plate; 300 Separator Detailed description

[0026] To clarify the purpose, technical solutions, and advantages of the present application, the technical solutions of the embodiments of the present application are described below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of this application, and not all of them. All other embodiments that the person skilled in the art in this field could obtain from the embodiments in the present application without any creative activity are within the scope of protection of the present application.

[0027] Rechargeable batteries, also called secondary batteries, are electrochemical energy devices that can be cyclically charged and discharged, such as lithium-ion batteries, and are commonly used in various mobile power supply devices, including consumer electronics, new energy vehicles, energy storage devices, and the like.A lithium battery generally consists of a battery cell and a casing, wherein the battery cell is arranged in the casing, the battery cell having a positive electrode plate and a negative electrode plate, a separator being arranged between the positive electrode plate and the negative electrode plate, and the positive electrode plate, the negative electrode plate and the separator being arranged in a stacked configuration and being wound, wherein at the initial end of the battery cell winding the negative electrode plate typically has a structure with a single-sided coated active layer, wherein the single-sided coated negative electrode plate exhibits some wrinkling after roller pressing, thereby narrowing the projected width of the negative electrode plate.

[0028] In the current battery cell structure, however, due to the narrowing of the active layer of the single-sided coated negative electrode plate during the pre-lithiation process, the negative electrode plate is positioned between two electrode plates, which are anode plates. The narrowing of the active layer on the negative electrode plate also results in a narrower negative electrode plate. Consequently, the distance between the negative electrode plate and the anode plate increases, leading to poor pre-lithiation of the negative electrode plate. Therefore, during battery cell winding, the positive and negative electrode plates are stacked and wound, with the positive electrode plate facing the area on the negative electrode plate with poor pre-lithiation.During the first charging process of the battery cell thus formed, a large amount of lithium ions is consumed in the positive electrode plate during the formation of the solid electrolyte interface membrane (SEI film), which leads to a reduction in the energy density of the battery.

[0029] The SEI film is a passivation layer with solid electrolyte properties, primarily formed on the negative electrode of the battery. During the battery's initial charge and discharge cycles, the negative electrode material and the electrolyte react at the solid-liquid interface to form the SEI film, which is an insulator for electrons and an excellent conductor for lithium ions.

[0030] The present application provides a battery cell and a battery which, by means of a correction, adjusts the inner and outer coverage values ​​of the battery cell so that the relative position of the first electrode plate and the second electrode plate changes from the inside of the battery cell to the outside of the battery cell, thereby increasing the pre-lithiation degree of the negative electrode plate of the correction side and fully exploiting the advantage of the high pre-lithiation degree of the correction side, and at the same time increasing the battery cell capacity on the uncorrected side and thereby improving the energy density of the battery.

[0031] The battery cell and the battery of the embodiments of the present application are described below with reference to the accompanying drawings. It should be noted that the battery cell provided by embodiments of the present application is applied to a battery, and the battery can be a lithium battery that can be charged, discharged, and recycled. The scenarios in which the battery cell and the battery can be used include, but are not limited to, electronic products, energy storage devices, transport vehicles such as new energy vehicles, charging stations, and the like, unless specifically limited in the embodiments of the present application.

[0032] Fig. Figure 1 is a schematic structural representation of a battery cell provided by an embodiment of the present application, Fig. 2 is a sectional view of the battery cell in the AA direction in Fig. 1, and Fig. Figure 3 is a schematic structural representation of a first electrode plate in the battery cell, which is provided by an embodiment of the present application.

[0033] With reference to Fig. 1 to Fig. Figure 3 describes embodiments of the present application providing a battery cell 10, wherein the battery cell 10 comprises a first electrode plate 100 and a second electrode plate 200, the first electrode plate 100 and the second electrode plate 200 being stacked and wound successively, a separator 300 being arranged between the first electrode plate 100 and the second electrode plate 200, thereby forming a winding core structure. The beginning end of the battery cell 10 during winding is the head of the battery cell 10 and the ending end of the battery cell 10 during winding is the rear end of the battery cell 10, and the head of the battery cell 10 is arranged inside the wound battery cell 10 and the rear end of the battery cell 10 is arranged outside the wound battery cell 10.

[0034] In one embodiment of the present application, the end of the first electrode plate 100 has a one-sided coated area 101, and the one-sided coated area 101 is arranged inside the battery cell 10, wherein the first electrode plate 100 has a current collector 110 and an active layer 120 applied to the surface of the current collector 110, wherein the one-sided coated area 101 refers to an area in which only one side of the surface of the current collector 110 of the first electrode plate 100 is coated with the active layer 120, and the side of the one-sided coated area 101 that is not coated with the active layer 120 forms a blank film area.It is understood that the first electrode plate 100 at the head of the battery cell 10, i.e. at the beginning end of the winding, is provided with a one-sided coated area 101, while other areas of the first electrode plate 100 on both sides of the current collector 110 are each coated with an active layer 120.

[0035] In some embodiments, it is provided that one of the two opposite end faces of the battery cell 10 is the correction side 11, wherein a gap is formed between the side edge of the second electrode plate 200 and the side edge of the battery cell 10, and wherein the side edge of the second electrode plate 200 arranged at the innermost side edge of the battery cell 10 is offset relative to a side edge of the second electrode plate 200 arranged at the outermost side of the battery cell 10 towards the correction side 11.

[0036] The coverage value of the interior of the battery cell 10 on the correction side 11 is smaller than the coverage value of the exterior of the battery cell 10 on the correction side 11, where the coverage value is the distance between the edge of the second electrode plate 200 and the edge of the first electrode plate 100.

[0037] Since the first electrode plate 100 has a one-sided coated area 101 within the battery cell 10, it is understandable that the position of the edge of the second electrode plate 200 and the edge of the first electrode plate 100 can be adjusted during the winding process of the battery cell 10 by a correction process, thereby creating a correction side 11 at one end of the battery cell 10, wherein on the correction side 11 within the battery cell 10 the edge of the second electrode plate 200 is closer to the edge of the first electrode plate 100, thus the area of ​​the first electrode plate 100 with a high pre-lithiation degree is fully utilized, and the area of ​​the first electrode plate 100 opposite the second electrode plate 200 has a higher pre-lithiation degree.

[0038] It should be noted that in the battery cell 10 provided by embodiments of the present application, the first electrode plate 100 can be a negative electrode plate and the second electrode plate 200 a positive electrode plate. That is, the first electrode plate 100 can be pre-lithiated during the manufacturing process, and the purpose of pre-lithiation is to introduce lithium ions into the first electrode plate 100 in advance so that when the battery cell 10 is charged and discharged for the first time to form the SEI film, the lithium ions pre-charged by pre-lithiation in the first electrode plate 100 can be consumed, and excessive consumption of lithium ions in the second electrode plate 200 can be avoided. The more lithium ions contained in the second electrode plate 200, the higher the capacity of the battery.

[0039] During the prelithiation process of the first electrode plate 100, the first electrode plate 100 can be corrected because the width of the single-sided coated area 101 of the first electrode plate 100 becomes smaller after roller pressing, so that when the single-sided coated area 101 of the first electrode plate 100 is prelithiated, one side edge is closer to the electrode plate of the prelithiation device than the other side edge, so that the prelithiation degree on one side of the single-sided coated area 101 facing the electrode plate is higher than on the other side.

[0040] During the winding process of the battery cell 10, the coverage values ​​inside and outside the battery cell 10 are adjusted by means of a correction, so that the relative positions of the first electrode plate 100 and the second electrode plate 200 change from the inside of the battery cell 10 to the outside of the battery cell 10, with the side of the single-sided coated area 101 with a high pre-lithiation level being opposite the correction side 11 in order to improve the utilization of the area with a high pre-lithiation level on the correction side 11, to fully exploit the advantage of the high pre-lithiation level on the correction side 11 and at the same time to improve the capacity of the battery cell 10 on the uncorrected side 11.In this way, during the formation of the SEI film during the first charging and discharging, the lithium ions in the area with a high pre-lithiation level on the first electrode plate 100 can be completely consumed, thereby reducing the consumption of lithium ions on the second electrode plate 200 and thus improving the energy density of the battery.

[0041] First, the specific position rule of the second electrode plate 200 relative to the first electrode plate 100 from the inside of the battery cell 10 to the outside of the battery cell 10 is described in detail below.

[0042] With reference to Fig. 1 to Fig. In one embodiment of the present application, as an optional implementation, the side edge of the first electrode plate 100 is provided flush with the end face of the battery cell 10; on the correction side 11, the distance between the side edge of the second electrode plate 200 arranged on the innermost side of the battery cell 10 and the side edge of the first electrode plate 100 is smaller than the distance between the side edge of the second electrode plate 200 arranged on the outermost side of the battery cell 10 and the side edge of the first electrode plate 100.

[0043] The side edge of the first electrode plate 100 is flush with the end face of the battery cell 10, with the side edge of the first electrode plate 100 forming a boundary line S on the correction side 11, namely the outermost left boundary line S in Fig. 2, where the boundary line S is simultaneously the edge line of the battery cell 10.

[0044] Since the battery cell 10 has a winding core structure, in the cross-sectional view of the battery cell 10 the side edges of the second electrode plate 200, which are arranged on the outermost side on both sides of the battery cell 10, can be arranged symmetrically to the side edge of the second electrode plate 200 arranged on the innermost side of the battery cell 10.

[0045] It is understood that the pre-lithiation degree of one end of the single-sided coated area 101 on the first electrode plate 100 inside the battery cell 10 facing the correction side 11 is higher than the pre-lithiation degree of an end facing away from the correction side 11. Within an inner position of the battery cell 10, the second electrode plates 200 can be positioned in an area opposite the single-sided coated area 101. This means the second electrode plate 200 is located closer to the correction side 11, opposite the single-sided coated area 101, and the overlap area between the second electrode plate 200 on the correction side 11 and the single-sided coated area 101 can be larger.

[0046] After the first electrode plate 100 has been rolled, the width of the single-sided coated area 101 of the first electrode plate 100 is smaller than the area where the active layer 120 is coated on both sides. During the prelithiation of the first electrode plate 100, a correction process can be used to bring one side of the single-sided coated area 101 closer to the electrode plate in the prelithiation process, thereby enabling the single-sided coated area 101 on that side to achieve a higher degree of prelithiation. The degree of prelithiation refers to the mass fraction of lithium in the film layer that forms on the surface of the first electrode plate 100 after prelithiation.

[0047] It should be noted that pre-lithiation serves to pre-fill a portion of the lithium ions into the first electrode plate 100 to form a SEI film, reduce the consumption of lithium ions in the second electrode plate 200 of the battery, and improve the battery's energy density. In an embodiment of the present application, the degree of pre-lithiation of the single-sided coated area 101 of the first electrode plate 100 is increased on the correction side 11, thus reducing the consumption of lithium ions in the second electrode plate 200 and improving the initial coulomb efficiency of the battery when the battery is first charged and the SEI film is formed, where the initial coulomb efficiency refers to the ratio of the battery's initial charge and discharge capacity to its nominal charge capacity.

[0048] In one possible implementation, the edges on one end of the second electrode plate 200 facing the correction side 11 are connected one after the other from the inside of the battery cell 10 to both sides of the outside of the battery cell 10 to form a first contour line 12, wherein the distance between a position of the first contour line 12 facing the single-sided coated area 101 and the edge of the first electrode plate 100 is smaller than the distance between a position of the first contour line 12 facing away from the single-sided coated area 101 and the edge of the first electrode plate 100.

[0049] It is understood that the first contour line 12 is a contour line formed by connecting the endpoints of the second electrode plate 200 successively on the correction side 11 at different layers inside and outside the battery cell 10 on the cut surface of the battery cell 10, wherein the first contour line 12 represents the variation patterns of the relative positions of the second electrode plate 200 with respect to the first electrode plate 100 during the winding process of the battery cell 10.

[0050] Since the pre-lithiation degree of the single-sided coated area 101 on the correction side 11 is high, the first contour line 12 can be located closer to the edge of the first electrode plate 100 at a position near the single-sided coated area 101, that is, at a position of the first contour line 12 facing the single-sided coated area 101, the coverage value of the battery cell 10 is lower, and the area with a high pre-lithiation degree on the single-sided coated area 101 is fully utilized.

[0051] In some embodiments, the width of the first electrode plate is 100 W1, the width of the second electrode plate is 200 W2, the width of the first electrode plate 100 being greater than the width of the second electrode plate 200, the height difference between different positions of the second electrode plate 200 along the winding direction of the battery cell 10 in the first direction is H, where H = (0.13~0.86) × (W1-W2), the first direction being the height direction of the battery cell 10.

[0052] The first direction is defined as the X-direction, the second direction being the Y-direction, and the X-direction being perpendicular to the Y-direction, where the X-direction is the height direction of the battery cell 10 and the Y-direction is the width direction of the battery cell 10, and the Y-direction is also the thickness direction of the first electrode plate 100 and the second electrode plate 200 in the sectional view of the battery cell 10.

[0053] It is understood that the first contour line 12 is formed by connecting the cut surfaces of the second electrode plate 200 at the end of the correction side 11 along the Y direction, and wherein the first contour line 12 has waves in the X direction, since the second electrode plate 200 is arranged in different winding positions at different positions relative to the first electrode plate 100.

[0054] For example, the ratio of the height difference H in the first direction at various positions of the second electrode plate 200 along the winding direction of the battery cell 10 to the difference W1-W2 between the width W1 of the first electrode plate 100 and the width W2 of the second electrode plate 200 can be in the range of 0.13 to 0.86, including but not limited to 0.13, 0.14, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.85, 0.86 or the like, and the embodiments of the present application do not impose any specific limitations in this respect.

[0055] In some embodiments, the coverage value of the outside of the battery cell 10 on the correction side 11 is L1 and the coverage value of the inside of the battery cell 10 on the correction side 11 is L2, where L1 = (1.2∼13.5) × L2.

[0056] It is understood that for the first contour line 12, the first contour line 12 can protrude at the inner position of the battery cell 10 in relation to the two sides outside the battery cell 10 in the direction of the correction side 11 of the battery cell 10, i.e., the coverage value L2 inside the battery cell 10 is smaller than the coverage value L1 outside the battery cell 10.

[0057] For example, the ratio of the coverage value L1 of the outside of the battery cell 10 on the correction side 11 to the coverage value L2 of the inside of the battery cell 10 on the correction side 11 can be 1.2 to 13.5, including but not limited to 1.2, 1.21, 1.3, 2, 3, 5, 8, 10, 13, 13.4, 13.5 or the like, and the embodiments of the present application do not impose any specific limitations in this respect.

[0058] The following section provides an example of the different shapes of the first contour lines.

[0059] With reference to Fig. 1 to Fig. 3 In one possible implementation, the coverage value of battery cell 10 on correction side 11 gradually increases from the inside of battery cell 10 to the outside of battery cell 10. From the inside of battery cell 10 to the outside of battery cell 10, the end edge of the second electrode plate 200 on correction side 11 gradually moves away from the edge of the first electrode plate 100.

[0060] It is understood that the first contour line 12 forms a structure resembling a “V” shape or a cone shape, allowing the second electrode plate 200 to be oriented as far as possible towards the area of ​​high pre-lithiation of the single-sided coated area 101 of the first electrode plate 100 and to fully utilize the area of ​​high pre-lithiation to improve the energy density of the battery.

[0061] Fig. Figure 4 is a sectional view of another structure of a battery cell provided by an embodiment of the present application.

[0062] With reference to Fig. 4 in combination with Fig. 1 and Fig. In another possible implementation on correction page 11, the distance between the second electrode plate 200 at the outermost and innermost sides of the battery cell 10 and the side edge of the battery cell 10 is each greater than the distance between the second electrode plate 200 at the respective position between the outermost and innermost sides of the battery cell 10 and the side edge of the battery cells 10.

[0063] The position of the first contour line 12 relative to the single-sided coated area 101 can be concave in a direction away from the correction side 11. The distance between the concave position in the middle of the first contour line 12 and the end of the first electrode plate 100 is even smaller than the distance between the position at the two ends of the first contour line 12 and the end of the first electrode plate 100.

[0064] It is understood that during the winding correction process of the battery cell 10, a certain hysteresis may occur when correcting the position of the second electrode plate 200 relative to the first electrode plate 100, whereby the first contour line 12 may form a structure approximately in the shape of a "W". Such an arrangement ensures that waves are present within a certain region of the first contour line 12 relative to the interior of the battery cell 10, while simultaneously positioning the first contour line as close as possible to the end of the first electrode plate 100 on the correction side 11. This improves the utilization rate of the area with a high pre-lithiation level and increases the energy density of the battery.

[0065] It should be noted that the first contour line 12 may also have other wavy shapes relative to the first direction, for example a wave shape, a sawtooth shape or the like, as long as the second electrode plate 200 can be corrected and adjusted in such a way that it is opposite the area with a high pre-lithiation level in the first electrode plate 100.

[0066] In some embodiments, the edges on one end of the second electrode plate 200 facing away from the correction side 11 are connected one after the other from the inside of the battery cell 10 to both sides of the outside of the battery cell 10 to form a second contour line 13, the shape of the first contour line 12 being adapted to the shape of the second contour line 13.

[0067] The battery cell 10 may further have a tab (not shown here) which is connected to the correction side 11 of the battery cell 10. The tab has a positive tab and a negative tab, and the positive tab and the negative tab are each connected to one of the first electrode plate 100 and the second electrode plate 200, respectively.

[0068] It is understood that the width of the second electrode plate 200 is kept approximately constant in the winding direction of the battery cell 10. Therefore, if one end of the second electrode plate 200 moves relative to the first electrode plate 100 in the direction of the correction side 11, the distance between the end of the second electrode plate 200 facing away from the correction side 11 and the end of the first electrode plate 100 facing away from the correction side 11 increases. Therefore, the second contour line 13, which is formed at the edge of an end of the second electrode plate 200 facing away from the correction side 11, can resemble the shape of the first contour line 12.

[0069] It should be noted that a free area 14 may be formed between the second contour line 13 and the edge at the end of the first electrode plate 100 facing away from the correction side 11, and that the amount of electrolyte stored in the free area 14 of the battery cell 10 is greater than the amount of electrolyte stored in the battery cell 10 on the correction side 11. Since the pre-lithiation degree of the single-sided coated area of ​​the first electrode plate 100 is lower at the end facing away from the correction side 11 than at the end of its correction side 11, the free area 14 stores more electrolyte. During the battery's charge and discharge cycle, more electrolyte can be used to realize the recombination process of the SEI film and thus improve the battery's cycle performance.

[0070] The present application also relates to a battery, wherein the battery comprises a housing and the battery cell 10 in the above technical solution, and the battery cell 10 is arranged in the housing. Electrolyte is injected into the interior of the housing. The battery provided by the present application exhibits all the technical methods and effects of the battery cell 10 in the above technical solution, which will not be discussed in detail here.

[0071] The effects of the battery cell and battery provided by embodiments of the present application are described below by a comparison of the test data.

[0072] Using the Si-C system as an example, the second electrode plate is the negative electrode plate with a width of 78 mm and a compaction density of 1.71 g / cm³. 3, wherein the first electrode plate is a positive electrode plate and its width is 76 mm.

[0073] After the positive electrode plates have undergone conventional processes such as coating and roller pressing, the positive electrode plates of equal weight are selected and divided into two groups for winding. Following coating and roller pressing, the negative electrode plate is transferred to the pre-lithiation process. After pre-lithiation is complete, the degree of pre-lithiation on the corrected side of the negative electrode plate is higher than on the uncorrected side. Within 3 mm of the edge of the negative electrode plate, the degree of pre-lithiation on the corrected side is approximately 95%, and on the uncorrected side, it is approximately 32%.

[0074] The conventional battery cell structure is used as a control group. The electrode plates of the positive and negative electrodes are arranged during the winding process according to the conventional arrangement; that is, the positive electrode plate is designed so that it is centered relative to the negative electrode plate, and the positive electrode plate is positioned approximately flush from the inside of the battery cell to the end outside the battery cell. The coverage value of the battery cell inside and outside is uniform and is 1.0 mm in each case. After completion of the winding, the next production step is the assembly of the battery.

[0075] The battery cell provided by the present application is used as the test group. During the winding process, the positive electrode plate inside the battery cell deviates towards the correction side, with an X-ray measurement showing that the contour of the positive electrode plate at the end from the inside of the battery cell to both sides of the outside of the battery cell is conical, wherein the coverage value of the outside of the battery cell is 0.9 mm, the coverage value of the inside of the battery cell is 0.2 mm, and the height difference between the inside and outside of the positive electrode plate is 1.0 mm.

[0076] The batteries formed by the control group and the experimental group were formed and divided in the same environment, with the same equipment, and under the same conditions. After division, the average battery capacity for the control group is 2132 mAh, while the average battery capacity of the experimental group is 2145 mAh, representing a 0.6% increase in capacity for the experimental group. Therefore, the battery capacity of the battery provided by embodiments of the present application can be increased.

[0077] For the batteries of the test group and the control group after 800 cycles at 25 °C and 1C / 1C, the battery capacity retention rate of the control group is 83% and the rate of thickness expansion is 14.5%; the battery capacity retention rate of the test group is 86.4% and the rate of thickness expansion is 12.1%. Therefore, the battery provided by embodiments of the present application can improve the battery capacity retention rate during the cycling process and reduce the rate of thickness expansion of the battery.

[0078] The present application provides a battery cell and a battery, wherein the battery cell comprises a first electrode plate and a second electrode plate, wherein the first electrode plate and the second electrode plate are arranged wound one behind the other, wherein the end of the first electrode plate has a one-sided coated area, the one-sided coated area being arranged inside the battery cell; the end of the battery cell has a correction side and the coverage value of the inside of the battery cell on the correction side is less than the coverage value of the outside of the battery cell on the correction side, wherein the coverage value is the distance between the edge of the second electrode plate and the edge of the first electrode plate.The battery cell provided by the present application improves the pre-lithiation level on the correction side, fully exploits the advantage of the high pre-lithiation level on the correction side, and simultaneously increases the battery cell capacity on the uncorrected side, thereby improving the energy density of the battery.

[0079] In describing the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "mounted", "connected", and "linked" are to be understood in their broadest sense, encompassing, for example, a fixed connection or an indirect connection via an intermediate medium, and the internal connection of two elements or an interaction between two elements. The person skilled in the art in this field will be able to understand the specific meanings of the foregoing terms in the present application according to specific situations.

[0080] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "top", "bottom", "front", "back", "vertical", "horizontal", "roof", "floor", "inside", "outside" and the like are the orientations or positional relationships shown based on the drawings and serve only for the convenience and simplification of the description of the present application, rather than indicating or implying that the device or element in question must have a particular orientation or orientation or be designed and operated in a particular orientation, and should therefore not be construed as limiting the present application.

[0081] The terms “first”, “second”, “third”, “fourth”, or the like (if any) in the description and claims of this application and the drawings above are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It is understood that the data thus used are interchangeable under suitable circumstances, so that the embodiments of the present application described herein may, for example, be carried out in different sequences than those shown or described herein.

[0082] Furthermore, the terms "include" and "include," and all variations thereof, are to be understood as encompassing non-exclusive inclusions. For example, a process, procedure, system, product, or device comprising a sequence of steps or elements is not necessarily limited to the steps or units expressly listed, but may include other steps or elements not expressly listed or inherent in the process, procedure, product, or device.

[0083] Finally, it should be noted that the above embodiments are used only to illustrate, rather than limit, the technical solutions of the present application; although the present application has been described in detail with reference to the above embodiments, the average person skilled in the art should understand that he or she may still modify the technical solutions recorded in the above embodiments or make equivalent substitutions to some or all of the technical features; however, such modifications or substitutions shall not result in the essence of the corresponding technical solutions differing from the scope of the technical solutions of the embodiments of the present application.

Claims

[1] Battery cell (10), characterized by , that the battery cell (10) has a first electrode plate (100) and a second electrode plate (200), wherein the first electrode plate (100) and the second electrode plate (200) are stacked and intertwined; wherein one of the two opposite end faces of the battery cell (10) is a correction face (11), wherein a gap is provided between a side edge of the second electrode plate (200) and a side edge of the battery cell (10), and wherein the side edge of the second electrode plate (200) arranged at the innermost side edge of the battery cell (10) is offset relative to a side edge of the second electrode plate (200) arranged at the outermost side of the battery cell (10) towards the correction face (11). [2] Battery cell (10) according to claim 1, characterized by, that on the correction side (11) the distance between the side edge of the second electrode plate (200) located on the innermost side of the battery cell (10) and the side edge of the first electrode plate (100) is smaller than the distance between the side edge of the second electrode plate (200) located on the outermost side of the battery cell (10) and the side edge of the first electrode plate (100). [3] Battery cell (10) according to claim 2, characterized by , that the side edge of the second electrode plate (200) arranged on the outermost side on both sides of the battery cell (10) is arranged symmetrically to the side edge of the second electrode plate (200) arranged on the innermost side of the battery cell (10). [4] Battery cell (10) according to one of claims 1 to 3, characterized by, that on the innermost side of the battery cell (10) the pre-lithiation degree on a side of the first electrode plate (100) facing the correction side (11) is higher than the pre-lithiation degree on a side of the first electrode plate (100) facing away from the correction side (11). [5] Battery cell (10) according to any one of claims 1 to 4, characterized by, that the end of the first electrode plate (100) has a one-sided coated area (101); wherein the edges on one end of the second electrode plate (200) facing the correction side (11) are connected one after the other from the inside of the battery cell (10) to both sides of the outside of the battery cell (10) to form a first contour line (12), wherein the distance between a position of the first contour line (12) facing the one-sided coated area (101) and the edge of the first electrode plate (100) is less than the distance between a position of the first contour line (12) facing away from the one-sided coated area (101) and the edge of the first electrode plate (100). [6] Battery cell (10) according to claim 5, characterized by, that the first contour line (12) protrudes at the inner position of the battery cell (10) in the direction of the correction side (11) of the battery cell (10) relative to the two sides outside the battery cell (10). [7] Battery cell (10) according to claim 5 or 6, characterized by , that the edges on one end of the second electrode plate (200) facing away from the correction side (11) are connected one after the other from the inside of the battery cell (10) to both sides of the outside of the battery cell (10) to form a second contour line (13), the shape of the first contour line (12) being adapted to the shape of the second contour line (13). [8] Battery cell (10) according to any one of claims 1 to 7, characterized by, that the distance between the side edge of the second electrode plate (200) on the correction side (11) and the side edge of the first electrode plate (100) gradually increases from the innermost side of the battery cell (10) to the outermost side of the battery cell (10). [9] Battery cell (10) according to any one of claims 1 to 8, characterized by , that the width of the first electrode plate (100) is W1, wherein the width of the second electrode plate (200) is W2, wherein the width of the first electrode plate (100) is greater than the width of the second electrode plate (200), wherein the height difference between different positions of the second electrode plate (200) along the winding direction of the battery cell (10) in the first direction is H, where H = (0.13~0.86) × (W1-W2), where the first direction is the height direction of the battery cell (10). [10] Battery cell (10) according to any one of claims 1 to 9, characterized by, that on the correction side (11) the distance between the side edge of the second electrode plate (200) arranged on the outermost side of the battery cell (10) and the side edge of the battery cell (10) is L1, wherein the distance between the side edge of the second electrode plate (200) arranged on the innermost side of the battery cell (10) and the side edge of the battery cell (10) is L2, where L1 = (1.2∼13.5) × L2. [11] Battery cell (10) according to any one of claims 1 to 7, characterized by , that on the correction side (11) the distance between the second electrode plate (200) at the outermost and innermost side of the battery cell (10) and the side edge of the battery cell (10) is each greater than the distance between the second electrode plate (200) at the respective position between the outermost and innermost side of the battery cell (10) and the side edge of the battery cell (10). [12] Battery cell (10) according to any one of claims 1 to 11, characterized by , that the battery cell (10) further has a tab, wherein the tab is connected to the correction side (11) of the battery cell (10). [13] Battery cell (10) according to any one of claims 1 to 12, characterized by , that a free area (14) is formed between the side edge of the second electrode plate (200) facing away from the correction side (11) and the side edge of the first electrode plate (100) facing away from the correction side (11), wherein the amount of electrolyte stored in the free area (14) of the battery cell (10) is greater than the amount of electrolyte stored on the correction side (11) of the battery cell (10). [14] Battery, characterized by , that the battery has a housing and a battery cell (10) according to one of claims 1 to 13, wherein the battery cell (10) is arranged in the housing.

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