Cathode sheet, battery cell, battery, and hot press head

Abstract

The utility model discloses a kind of cathode sheet, battery cell, battery and hot press head, wherein cathode sheet includes: current collector, active material layer and positive pole lug. Active material layer is arranged at the two sides of current collector, and active material layer includes first active material part and the second active material part of first active material part at the two sides of the width direction of current collector, in the thickness direction of current collector, the average size of first active material part is a, the average size of second active material part is b, b The positive pole lug includes a connecting portion, which is located in the accommodating groove and connected to the current collector. In the length direction of the current collector, the size of the connecting portion is e, and in the width direction of the current collector, the size of the connecting portion is f, f That is, the connecting portion of the positive pole lug extends in the width direction of the current collector and occupies more area of the second active material part, so that the connection of the positive pole lug reduces a smaller amount of active material, thereby improving the energy density of the battery.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a cathode sheet, a battery cell, a battery, and a hot press head. Background Technology

[0002] Due to factors such as the N / P ratio of the active material (the ratio of the reversible surface capacity of the negative electrode to the positive electrode inside the battery) and lithium-ion enrichment in the electrolyte, lithium batteries are prone to edge lithium plating after high cycle counts. To address this, some technologies remove active material from the edges of the cathode sheet to make the active layer thickness at the edges smaller than at the non-edges, thereby increasing the edge N / P ratio. In the later stages of edge lithium plating, thinning the edge thickness through a thinning design can achieve a slightly larger edge N / P ratio suitable for later stages, thus improving the lithium plating problem. Furthermore, a significant amount of active material needs to be washed away to form a larger empty foil area on the current collector surface, ensuring a large area between the current collector and the positive electrode tab. However, due to factors such as the connection of the positive electrode tab and the need to improve edge lithium plating, the removal of a significant amount of active material results in a lower energy density for the battery. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a cathode sheet that can be used in batteries to improve the energy density of the batteries.

[0004] This invention also provides a battery cell comprising the aforementioned cathode sheet.

[0005] This utility model also provides a battery including the above-mentioned battery cell.

[0006] This invention also provides a hot press head for hot pressing during the above-mentioned battery formation stage.

[0007] The cathode sheet according to a first aspect of the present invention includes: a current collector, an active material layer, and a positive electrode tab.

[0008] The current collector has two coating surfaces facing away from each other in its thickness direction; each of the two coating surfaces is provided with an active material layer, the active material layer including a first active material portion and a second active material portion located on both sides of the first active material portion in the width direction of the current collector, the average size of the first active material portion in the thickness direction of the current collector being a, the average size of the second active material portion being b, b < a, at least one of the active material layers also has a receiving groove, the receiving groove extending to one side of the active material layer in the width direction of the current collector, the coating surface of which is exposed from the receiving groove, the size of the receiving groove in the length direction of the current collector being c, the size of the receiving groove in the width direction of the current collector being d, d < c; the positive electrode tab includes a connecting portion, the connecting portion being located in the receiving groove and connected to the current collector, the size of the connecting portion in the length direction of the current collector being e, the size of the connecting portion in the width direction of the current collector being f, f ≤ d < e ≤ c.

[0009] The cathode sheet according to the embodiments of this utility model has at least the following beneficial effects:

[0010] In this embodiment, the dimension of the receiving groove in the length direction of the current collector is c, and the dimension in the width direction is d, where d < c. The dimension of the positive electrode tab connection in the length direction of the current collector is e, and the dimension in the width direction of the current collector is f, where f ≤ d < e ≤ c. That is, in this embodiment, the positive electrode tab connection extends along the width direction of the current collector and occupies more of the area of ​​the second active material portion. Therefore, compared to the conventional technology where the positive electrode tab extends along the width direction of the current collector and occupies more of the area of ​​the first active material portion, with the same connection area, the positive electrode tab in this embodiment extends along the length direction of the current collector and occupies more of the area of ​​the second active material portion. Since the thickness of the second active material portion is less than the thickness of the first active material portion, less active material is lost. Therefore, when the cathode sheet of this embodiment is used in a battery, the energy density of the battery can be improved.

[0011] According to some embodiments of the present invention, the cathode sheet further includes an electrode tab, which is connected to the connecting portion for connection to an external circuit. In the length direction of the current collector, the size of the electrode tab is smaller than the size of the connecting portion.

[0012] According to some embodiments of the present invention, the connecting portion protrudes from both sides of the electrode ear along the length direction of the current collector.

[0013] According to some embodiments of the present invention, the positive electrode tab has a symmetrical structure along the length direction of the current collector.

[0014] According to some embodiments of the present invention, the electrode portion includes a first electrode portion and a second electrode portion distributed and connected to each other along the width direction of the current collector. The first electrode portion is connected to the connecting portion, and the size of the first electrode portion gradually increases in the length direction of the current collector along the direction of the connecting portion toward the electrode portion.

[0015] According to some embodiments of the present invention, the receiving groove is formed within the second active material portion.

[0016] According to some embodiments of the present invention, in the width direction of the current collector, the size of the second active material portion is g, 1≤d / g≤1.3.

[0017] The battery cell according to a second aspect embodiment of the present invention includes the cathode sheet of the first aspect embodiment.

[0018] The battery cell according to the embodiments of this utility model has at least the following beneficial effects:

[0019] Using the cathode sheet in the first aspect embodiment, the dimension of the receiving groove of the cathode sheet in the length direction of the current collector is c, and the dimension in the width direction is d, where d < c. The dimension of the connecting portion of the positive electrode tab in the length direction of the current collector is e, and the dimension in the width direction of the current collector is f, where f ≤ d < e ≤ c. That is, in this embodiment, the connecting portion of the positive electrode tab extends along the width direction of the current collector and occupies more of the area of ​​the second active material portion. Therefore, compared to the conventional technology where the positive electrode tab extends along the width direction of the current collector and occupies more of the area of ​​the first active material portion, under the same connection area, the positive electrode tab in this embodiment extends along the length direction of the current collector and occupies more of the area of ​​the second active material portion. Since the thickness of the second active material portion is less than the thickness of the first active material portion, less active material is lost. Therefore, when the cell of this embodiment is used in a battery, the energy density of the battery can be improved.

[0020] A battery according to a third aspect embodiment of the present invention includes: a casing and a battery cell according to a second aspect embodiment. The casing has a receiving cavity, the battery cell is disposed in the receiving cavity, and the battery cell further includes a negative electrode tab, both the negative electrode tab and the positive electrode tab extending out of the receiving cavity from the casing.

[0021] The battery according to the embodiments of the present invention has at least the following beneficial effects:

[0022] The battery cell of the second aspect embodiment uses the cathode sheet of the first aspect embodiment. The receiving groove of the cathode sheet has a dimension *c* in the length direction and a dimension *d* in the width direction of the current collector, where *d* < *c*. The dimension of the positive electrode tab connection portion in the length direction of the current collector is *e*, and the dimension in the width direction of the current collector is *f*, where *f* ≤ *d* < *e* ≤ *c*. That is, in this embodiment, the connection portion of the positive electrode tab extends along the width direction of the current collector and occupies more of the area of ​​the second active material portion. Therefore, compared to the conventional technology where the positive electrode tab extends along the width direction of the current collector and occupies more of the area of ​​the first active material portion, under the same connection area, the positive electrode tab in this embodiment extends along the length direction of the current collector and occupies more of the area of ​​the second active material portion. Since the thickness of the second active material portion is less than the thickness of the first active material portion, less active material is lost, thereby improving the energy density of the battery in this embodiment.

[0023] According to a fourth aspect embodiment of the present invention, a hot pressing head is used for hot pressing of the battery described in the third aspect embodiment during the formation stage. The hot pressing head includes a first hot pressing part, a second hot pressing part, and a third hot pressing part. The second hot pressing part and the third hot pressing part are respectively connected to two opposite sides of the first hot pressing part in a first direction. The first hot pressing part is used to hot press the area of ​​the battery corresponding to the first active material part. The second hot pressing part and the third hot pressing part are respectively used to hot press the areas of the battery corresponding to two second active material parts. The second hot pressing part has two clearance grooves spaced apart along a second direction. The two clearance grooves correspond to the positive electrode tab and the negative electrode tab, respectively. The second direction is perpendicular to the first direction. In a third direction, the size of the first hot pressing part is h, and the size of the second hot pressing part and the third hot pressing part is i, ih = ab. The third direction is perpendicular to both the first direction and the second direction.

[0024] The hot press head according to the embodiment of this utility model has at least the following beneficial effects:

[0025] The first hot-pressing section is used to hot-press the region of the battery corresponding to the first active material section in the third aspect embodiment. The second hot-pressing section and the third hot-pressing section are respectively used to hot-press the regions of the battery corresponding to the two second active material sections in the third aspect embodiment. The second hot-pressing section has two clearance grooves spaced apart along the second direction, and the two clearance grooves correspond to the positive electrode tab and the negative electrode tab, respectively. In the third direction, the size of the first hot-pressing section is h, and the size of the second hot-pressing section and the third hot-pressing section is i, ih = ab. That is, during the hot-pressing process, the thickness region of the hot-pressing head in this embodiment corresponds and complements the thickness region of the battery, thereby improving the good contact of the cell interface and improving the performance of the battery.

[0026] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0028] Figure 1 This is a schematic diagram of the structure of the first type of cathode sheet according to the first aspect of this utility model;

[0029] Figure 2 for Figure 1 A sectional view;

[0030] Figure 3 for Figure 1 A magnified view of area A in the middle;

[0031] Figure 4 This is a schematic diagram of the structure of the second type of cathode sheet according to the first aspect of this utility model;

[0032] Figure 5 for Figure 4 Enlarged view of region B in the middle;

[0033] Figure 6 This is a schematic diagram of the structure of the third type of cathode sheet according to the first aspect of this utility model;

[0034] Figure 7 This is a schematic diagram of the structure of the fourth type of cathode sheet according to the first aspect of this utility model;

[0035] Figure 8 This is a schematic diagram of the structure of the hot press head according to the fourth aspect embodiment of the present utility model;

[0036] Figure 9 for Figure 8 The sectional view in the image.

[0037] Figure label:

[0038] Current collector 100, coating surface 110;

[0039] Active material layer 200, first active material section 210, second active material section 220, receiving tank 230;

[0040] Positive electrode tab 300, connecting part 310, electrode tab part 320, first electrode tab part 321, second electrode tab part 322;

[0041] First hot pressing section 400;

[0042] Second hot pressing section 500, anti-cavity groove 510;

[0043] Third hot pressing section 600. Detailed Implementation

[0044] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0045] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0046] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0047] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0048] Due to factors such as the N / P ratio of the active material (the ratio of the reversible surface capacity of the negative electrode to the positive electrode inside the battery) and lithium-ion enrichment in the electrolyte, lithium batteries are prone to edge lithium plating after high cycle counts. To address this, some technologies remove active material from the edges of the cathode sheet to make the active layer thickness at the edges smaller than at the non-edges, thereby increasing the edge N / P ratio. In the later stages of edge lithium plating, thinning the edge thickness through a thinning design can achieve a slightly larger edge N / P ratio suitable for later stages, thus improving the lithium plating problem. Furthermore, a significant amount of active material needs to be washed away to form a larger empty foil area on the current collector surface, ensuring a large area between the current collector and the positive electrode tab. However, due to factors such as the connection of the positive electrode tab and the need to improve edge lithium plating, the removal of a significant amount of active material results in a lower energy density for the battery.

[0049] In view of the above background, the first aspect of this utility model provides a cathode sheet that can be used in a battery to improve the battery's energy density. (See also...) Figures 1 to 3 , Figure 1 This is a schematic diagram of the structure of the first type of cathode sheet according to the first aspect of this utility model. Figure 2 for Figure 1 sectional view, Figure 3 for Figure 1 An enlarged view of region A in this embodiment shows the cathode sheet, which includes: a current collector 100, an active material layer 200, and a positive electrode tab 300.

[0050] The current collector 100 is, for example, made of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy, and has two coating surfaces 110 arranged opposite to each other in its thickness direction. The active material layer 200 includes, but is not limited to, lithium iron phosphate, a composite material of lithium iron phosphate and carbon, or lithium manganese phosphate. Both coating surfaces 110 are provided with the active material layer 200. The active material layer 200 includes a first active material portion 210 and second active material portions 220 located on both sides of the first active material portion 210 in the width direction of the current collector 100. In the thickness direction of the current collector 100, the average size of the first active material portion 210 is a, and the average size of the second active material portion 220 is b, where b < a (e.g., ...). Figure 2 As shown in the figure, for example in some embodiments, 0.88≤b / a<1, that is, the edge of the active material layer 200 is thinned to increase the N / P value of the edge, thereby improving the edge lithium plating situation.

[0051] At least one active material layer 200 also has a receiving groove 230 (such as...) Figure 3As shown, the receiving groove 230 extends to one side of the active material layer 200 in the width direction of the current collector 100, with its coating surface 110 exposed from the receiving groove 230. The dimension of the receiving groove 230 is c in the length direction of the current collector 100 and d in the width direction of the current collector 100, where d < c. The positive electrode tab 300 includes a connecting portion 310 located within the receiving groove 230 and connected to the current collector 100. The dimension of the connecting portion 310 is e in the length direction of the current collector 100 and f in the width direction of the current collector 100, where f ≤ d < e ≤ c. That is, in this embodiment, the positive electrode tab 300 connecting portion 310 extends along the width direction of the current collector 100, occupying a larger area of ​​the second active material portion 220. Therefore, compared to the conventional technology where the positive electrode tab 300 extends along the width direction of the current collector 100 and occupies a larger area of ​​the first active material portion 210, in this embodiment, the positive electrode tab 300 extends along the length direction of the current collector 100 and occupies a larger area of ​​the second active material portion 220, while having the same connection area. Since the thickness of the second active material portion 220 is less than the thickness of the first active material portion 210, less active material is lost. Therefore, when the cathode sheet of this embodiment is used in a battery, the energy density of the battery can be improved.

[0052] Reference Figure 4 and Figure 5 , Figure 4 This is a schematic diagram of the structure of the second type of cathode sheet according to the first aspect of this utility model. Figure 5 for Figure 4 The enlarged schematic diagram of region B shows that, based on the above embodiment, the receiving groove 230 is formed within the second active material portion 220. That is, the receiving groove 230 is completely formed within the second active material portion 220, ensuring that the positive electrode tab 300 connection portion 310 occupies only a thin area, further reducing active material loss and improving the battery's energy density. Conversely, in some embodiments, the dimension of the second active material portion 220 in the width direction of the current collector 100 is g, 1≤d / g≤1.3, meaning the receiving groove 230 extends appropriately into the first active material portion 210 (e.g., ...). Figure 3 As shown), to avoid the connection portion 310 being too narrow, thereby ensuring the connection strength between the positive electrode tab 300 and the current collector 100, so as to improve the structural stability of the cathode sheet in this embodiment. Thus, when the cathode sheet of this embodiment is used in a battery, not only can the energy density be improved, but also the structural stability can be ensured, taking into account both performance and safety.

[0053] In some embodiments, the active material layers 200 of the two coating surfaces 110 in the thickness direction of the current collector 100 each have receiving grooves 230, referred to as the first receiving groove and the second receiving groove, respectively. The first receiving groove and the second receiving groove are aligned or staggered. It should be noted that when the first receiving groove and the second receiving groove are aligned, the positive electrode tabs 300 connected in the first receiving groove and the second receiving groove are welded together. In other words, the positive electrode tab 300 includes a forked first connecting portion and a second connecting portion, which are located in the first receiving groove and the second receiving groove, respectively, thereby increasing the connection area between the positive electrode tab 300 and the current collector 100. Further, in some embodiments, each active material layer 200 has a plurality of spaced receiving grooves 230 distributed in the length direction of the current collector, and the corresponding cathode sheet is provided with a plurality of positive electrode tabs 300. Therefore, the cathode sheet of this embodiment can be processed into a multi-positive electrode tab battery cell.

[0054] Reference Figure 6 , Figure 6 This is a schematic diagram of the structure of a third type of cathode sheet according to the first aspect of this utility model. In some embodiments, the cathode sheet further includes an electrode tab 320, which is connected to the connecting portion 310 for connection with an external circuit. In the length direction of the current collector, the size of the electrode tab 320 is smaller than the size of the connecting portion 310. Specifically, it is known that if the width of the current collector is too large, that is, if the positive electrode tab 300 is too large in the length direction of the electrode sheet, it will not only increase the risk of contact between the positive and negative electrodes 300, but also, when used in a soft-pack battery, the excessively wide positive electrode tab 300 will encroach on the sealing space of the aluminum-plastic film, resulting in insufficient fusion between the adhesive of the positive electrode tab 300 and the aluminum-plastic film during heat sealing, increasing the risk of leakage. In this embodiment, the size of the electrode tab 320 in the length direction of the current collector is smaller than that of the connecting portion 310. Therefore, while ensuring that the positive electrode tab 300 and the current collector 100 have sufficient connection area, the sealing space occupied by the positive electrode tab 300 is reduced, thereby reducing the risk of battery leakage.

[0055] Reference Figure 6 In some embodiments, the connecting portion 310 protrudes from both sides of the tab portion 320 along the length direction of the current collector 100, thereby preventing excessive current concentration on one side of the positive tab 300 along the length direction of the current collector 100, thus reducing excessive local temperature rise of the positive tab 300 and improving battery life and safety. Furthermore, based on the above embodiments, the positive tab 300 has a symmetrical structure along the length direction of the current collector 100, for example, the positive tab 300 is an inverted "T" shape, which makes the current distribution on the positive tab 300 more uniform, thereby further reducing excessive local temperature rise of the positive tab 300 and improving battery life and safety.

[0056] Reference Figure 7 , Figure 7 This is a schematic diagram of the structure of a fourth type of cathode sheet according to the first aspect of this utility model. In some embodiments, the tab 320 includes a first tab 321 and a second tab 322 distributed and interconnected along the width direction of the current collector 100. The first tab 321 is connected to the connecting portion 310. Along the direction from the connecting portion 310 toward the tab 320, the size of the first tab 321 gradually increases in the length direction of the current collector, thereby making the connection between the tab 320 and the connecting portion 310 a smooth transition. This not only reduces the risk of breakage caused by stress concentration at the connection, thus extending the battery's service life, but also avoids a rapid increase in current at emergency concentration points, reducing local overheating and further improving the overall stability and safety of the battery. In addition, it can reduce the abrupt change in the area of ​​the positive tab 300 in the direction of current flow, thereby reducing resistance, optimizing current distribution, reducing energy loss, and further improving the battery's energy utilization efficiency and range.

[0057] The battery cell according to a second aspect embodiment of the present invention includes the cathode sheet of the first aspect embodiment. The battery cell is, for example, a wound battery cell or a stacked battery cell. Exemplarily, the battery cell further includes an anode sheet and a separator, wherein the cathode sheet and anode sheet are stacked and wound to form a wound battery cell, and the separator is disposed between the cathode sheet and the anode sheet to separate them.

[0058] Specifically, in this embodiment, the dimension of the receiving groove 230 of the cathode sheet in the length direction of the current collector 100 is c, and the dimension in the width direction is d, where d < c. The dimension of the connecting portion 310 of the positive electrode tab 300 in the length direction of the current collector 100 is e, and the dimension in the width direction of the current collector 100 is f, where f ≤ d < e ≤ c. That is, in this embodiment, the connecting portion 310 of the positive electrode tab 300 extends along the width direction of the current collector 100 and occupies more of the area of ​​the second active material portion 220. Therefore, compared to the conventional technology where the positive electrode tab 300 extends along the width direction of the current collector 100 and occupies more of the area of ​​the first active material portion 210, under the same connection area, the positive electrode tab 300 in this embodiment extends along the length direction of the current collector 100 and occupies more of the area of ​​the second active material portion 220. Since the thickness of the second active material portion 220 is less than the thickness of the first active material portion 210, less active material is lost. Therefore, when the cell of this embodiment is used in a battery, the energy density of the battery can be improved.

[0059] It should be noted that this embodiment adopts all the technical features of the cathode sheet of the first aspect embodiment, and therefore this embodiment has all the beneficial effects brought by the first aspect embodiment, which will not be repeated here.

[0060] According to a third aspect embodiment of the present invention, the battery is, for example, a pouch battery or a hard-shell battery. The battery includes a casing and a cell according to a second aspect embodiment. The casing has a receiving cavity, and the cell is located within the receiving cavity. The cell also includes a negative electrode tab, and both the positive electrode tab 300 and the negative electrode tab extend out of the receiving cavity from the casing. Specifically, the cell uses a cathode sheet according to a first aspect embodiment. The receiving groove 230 of the cathode sheet has a dimension c in the length direction of the current collector 100 and a dimension d in the width direction, where d < c. The connecting portion 310 of the positive electrode tab 300 has a dimension e in the length direction of the current collector 100 and a dimension f in the width direction of the current collector 100, where f ≤ d < e ≤ c. That is, in this embodiment, the connecting portion 310 of the positive electrode tab 300 extends along the width direction of the current collector 100 and occupies more of the area of ​​the second active material portion 220. Therefore, compared to the traditional technology where the positive electrode tab 300 extends along the width direction of the current collector 100 and requires more space in the first active material portion 210, in the same connection area, the positive electrode tab 300 in this embodiment extends along the length direction of the current collector 100 and occupies more space in the second active material portion 220. Since the thickness of the second active material portion 220 is less than the thickness of the first active material portion 210, less active material can be lost, thereby improving the energy density of the battery.

[0061] Reference Figure 8 and Figure 9 , Figure 8 This is a schematic diagram of the structure of the hot press head according to the fourth aspect embodiment of the present invention. Figure 9 for Figure 8The cross-sectional view shows a hot pressing head according to a fourth aspect embodiment of the present invention, used for hot pressing of a battery in the formation stage of a third aspect embodiment. The hot pressing head includes a first hot pressing part 400, a second hot pressing part 500, and a third hot pressing part 600. The second hot pressing part 500 and the third hot pressing part 600 are respectively connected to opposite sides of the first hot pressing part 400 in a first direction. The first hot pressing part 400 is used to hot press the region of the battery corresponding to the first active material part 210. The second hot pressing part 500 and the third hot pressing part 600 are respectively used to hot press the regions of the battery corresponding to the two second active material parts 220. The second hot pressing part 500 has two clearance grooves 510 spaced apart along a second direction, which correspond to the positive electrode tab 300 and the negative electrode tab, respectively. The second direction is perpendicular to the first direction. In the third direction (the third direction is perpendicular to both the first and second directions), the dimension of the first hot pressing part 400 is h, and the dimensions of the second hot pressing part 500 and the third hot pressing part 600 are both i, where ih = ab. In the hot-pressing process of pouch cell formation, the hot-pressing head of this embodiment compensates for the insufficient thickness of the non-tab areas at both ends of the battery due to the thinning of the active material. This ensures that the contact pressure distribution between each area of ​​the cell and the clamp is uniform during hot pressing, avoiding poor interface connection or insufficient electrolyte wetting caused by uneven local pressure. This ensures that the electrode active material and the electrolyte fully react to form a stable SEI film (Solid Electrolyte Interface), while reducing contact resistance and improving the overall performance and safety of the cell.

[0062] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, in the description of the present invention, the reference to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A cathode plate, characterized in that, include: The current collector has two coated surfaces that are arranged opposite to each other in its own thickness direction; An active material layer is provided on both coating surfaces. The active material layer includes a first active material portion and second active material portions located on both sides of the first active material portion in the width direction of the current collector. In the thickness direction of the current collector, the average size of the first active material portion is 'a', the average size of the second active material portion is 'b', and b < a. At least one of the active material layers further has a receiving groove extending to one side of the active material layer in the width direction of the current collector, and the coating surface is exposed from the receiving groove. The size of the receiving groove is c in the length direction of the current collector and d in the width direction of the current collector, where d < c. The positive electrode tab includes a connecting portion located within the receiving groove and connected to the current collector. The dimension of the connecting portion is e in the length direction of the current collector and f in the width direction of the current collector, where f ≤ d < e ≤ c.

2. The cathode sheet according to claim 1, characterized in that, The positive electrode tab also includes an electrode portion connected to the connecting portion for connection to an external circuit. In the length direction of the current collector, the size of the electrode portion is smaller than the size of the connecting portion.

3. The cathode sheet according to claim 2, characterized in that, The connecting portion protrudes from both sides of the electrode ear along the length direction of the current collector.

4. The cathode sheet according to claim 3, characterized in that, The positive electrode tab has a symmetrical structure along the length of the current collector.

5. The cathode plate according to any one of claims 2 to 4, characterized in that, The electrode portion includes a first electrode portion and a second electrode portion distributed and connected to each other along the width direction of the current collector. The first electrode portion is connected to the connecting portion, and the size of the first electrode portion gradually increases in the length direction of the current collector along the direction of the connecting portion toward the electrode portion.

6. The cathode sheet according to claim 1, characterized in that, The receiving groove is formed within the second active material portion.

7. The cathode sheet according to claim 1, characterized in that, In the width direction of the current collector, the size of the second active material portion is g, 1≤d / g≤1.

3.

8. A battery cell, characterized in that, Includes the cathode sheet according to any one of claims 1 to 7.

9. A battery, characterized in that, include: The outer shell has a receiving cavity; The battery cell of claim 8 is disposed within the receiving cavity, and the battery cell further includes a negative electrode tab, both of which extend out of the receiving cavity from the outer casing.

10. A hot press head, characterized in that, For hot pressing of the battery as described in claim 9 during the formation stage, the hot pressing head includes a first hot pressing section, a second hot pressing section, and a third hot pressing section. The second hot pressing section and the third hot pressing section are respectively connected to two opposite sides of the first hot pressing section in a first direction. The first hot pressing section is used to hot press the region of the battery corresponding to the first active material portion. The second hot pressing section and the third hot pressing section are respectively used to hot press the regions of the battery corresponding to two second active material portions. The second hot-pressing section has two clearance slots spaced apart along a second direction, the two clearance slots corresponding to the positive electrode tab and the negative electrode tab respectively, and the second direction is perpendicular to the first direction; In the third direction, the size of the first hot-pressing part is h, and the size of the second hot-pressing part and the third hot-pressing part are both i, ih = ab, and the third direction is perpendicular to the first direction and the second direction.

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