Negative electrode sheet and preparation method thereof, winding core and full-ear cylindrical battery

Abstract

The present application provides a negative electrode sheet and its preparation method, a winding core and a full-ear cylindrical battery. The above-mentioned negative electrode sheet preparation method includes the following steps: respectively obtaining a negative current collector, a negative electrode slurry and a modified aerogel adsorption liquid retaining material, and coating the modified aerogel adsorption liquid retaining material on the first blank area at intervals to form at least two first aerogel adsorption liquid retaining spacers in the length direction of the first blank area; coating the negative electrode slurry on the coating area to obtain a negative electrode semi-finished product; performing a roller pressing operation on the negative electrode semi-finished product; and performing a baking operation on the negative electrode semi-finished product after the rolling operation to obtain a negative electrode sheet. The negative electrode sheet reduces the density of the winding core end, improves the battery's infiltration effect and cycle performance, and also plays a good role in retaining liquid, thereby increasing the battery's service life. It can also improve the battery's needle puncture and heavy object impact performance, and improve the safety of battery use.

Description

Technical Field

[0001] The present invention relates to the technical field of battery production, and in particular to a negative electrode sheet and a preparation method thereof, a winding core and a full-tab cylindrical battery. Background Art

[0002] At present, in the production process of full-tab cylindrical batteries, it is usually necessary to flatten the foil (tabs) at both ends of the core, as shown in the figure, and then weld them to the collecting plate to obtain the battery cell, and then package and inject the battery cell.

[0003] However, if Figure 1 and Figure 2 As shown, since the two ends of the core are flattened, compared with traditional ordinary cylindrical batteries, the ends of the battery cell are relatively dense, which makes it difficult for the electrolyte to enter the interior of the core when the battery cell is injected, resulting in a weaker ability to absorb liquid and causing poor battery infiltration effect and cycle performance.

[0004] In addition, since the structure of the cylindrical battery after the flattening operation is dense and compact, when the battery is charging and discharging, the active material of the battery's negative electrode is prone to expansion, causing the electrolyte inside the core to be squeezed out from the middle of the core. However, these squeezed electrolytes are difficult to be reabsorbed by the core, that is, there is a phenomenon of easy loss of electrolyte. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a negative electrode sheet and its preparation method, a winding core and a full-ear cylindrical battery that reduce the density of the core end after the flattening operation, improve the wetting effect and cycle performance of the battery, and at the same time can play a good role in retaining liquid and improve the service life of the battery.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] A method for preparing a negative electrode sheet comprises the following steps:

[0008] Obtaining a negative current collector, a negative electrode slurry, and a modified aerogel adsorption and liquid-retaining material respectively, wherein the negative current collector includes a coating area and a first blank area, and the first blank area is located on one side of the coating area;

[0009] Applying the modified aerogel adsorption and liquid-retaining material to the first blank area at intervals to form at least two first aerogel adsorption and liquid-retaining spacer strips in the length direction of the first blank area;

[0010] coating the negative electrode slurry on the coating area to obtain a negative electrode semi-finished product;

[0011] performing a roller pressing operation on the negative electrode semi-finished product;

[0012] The negative electrode semi-finished product after the rolling operation is baked to obtain the negative electrode sheet.

[0013] In one embodiment, the thickness of the first aerogel adsorption liquid retaining spacer is 0.1 μm to 100 μm.

[0014] In one embodiment, there are multiple first aerogel adsorption and liquid-retaining spacers, and the multiple first aerogel adsorption and liquid-retaining spacers form n successively increasing spacing grooves in the length direction of the first blank area.

[0015] In one embodiment, when the modified aerogel adsorption liquid-retaining material is coated on the first blank area at intervals, the first end of each of the first aerogel adsorption liquid-retaining spacers is controlled to be flush with the first end of the first blank area, and the second end of each of the first aerogel adsorption liquid-retaining spacers is connected to the first end of the negative conductive layer.

[0016] In one embodiment, after the step of coating the modified aerogel adsorption and liquid-retaining material on the first blank area at intervals and before the step of coating the negative electrode slurry on the coating area, the following steps are further included:

[0017] The negative current collector further includes a second blank area, the second blank area being located on the other side of the coating area; and

[0018] The modified aerogel adsorption and liquid-retaining material is applied to the second blank area at intervals to form at least two second aerogel adsorption and liquid-retaining spacer strips in the length direction of the second blank area.

[0019] In one embodiment, there are multiple second aerogel adsorption and liquid-retaining spacers, and the multiple second aerogel adsorption and liquid-retaining spacers form m sequentially increasing spacing grooves in the length direction of the second blank area.

[0020] In one embodiment, after the step of coating the negative electrode slurry on the coating area and after the step of roller-pressing the negative electrode semi-finished product, the following steps are further included:

[0021] The modified aerogel adsorption and liquid-retaining material is coated on the negative electrode conductive layer in a cross-interval manner to form an aerogel adsorption and liquid-retaining network on the negative electrode conductive layer.

[0022] A negative electrode sheet is prepared using the negative electrode sheet preparation method described in any of the above embodiments.

[0023] A winding core comprises a diaphragm, a positive electrode sheet and the negative electrode sheet described in any of the above embodiments, wherein the positive electrode sheet, the diaphragm and the negative electrode sheet are stacked and wound in sequence, and the diaphragm comprises a diaphragm body and an aerogel adsorption and liquid retention layer, and the aerogel adsorption and liquid retention layer is arranged on at least one surface of the diaphragm body.

[0024] A full-tab cylindrical battery comprises the winding core described in any of the above embodiments.

[0025] Compared with the prior art, the present invention has at least the following advantages:

[0026] 1) In the above-mentioned method for preparing a negative electrode sheet, since the negative current collector includes a coating area and a first blank area, and the first blank area is located on one side of the coating area, when the modified aerogel adsorption liquid-retaining material is coated on the first blank area at intervals, at least two first aerogel adsorption liquid-retaining spacers are formed in the length direction of the first blank area, so that two adjacent first aerogel adsorption liquid-retaining spacers can form a spacing groove on one side of the negative conductive layer. When the negative electrode sheet, the diaphragm and the positive electrode sheet are wound into a core, the multiple first aerogel adsorption liquid-retaining spacers can increase the spacing between the negative electrode sheet and the diaphragm. In this way, the density of the end of one side of the core is reduced after the flattening operation, thereby increasing the distance between the core layers, so that the electrolyte can enter the interior of the core more quickly, thereby improving the battery's ability to absorb liquid, and thereby improving the battery's infiltration effect and cycle performance.

[0027] 2) Because the multiple additional first aerogel adsorption and liquid-retaining spacers are positioned on one side of the negative conductive layer, when the active material of the negative conductive layer expands during the battery's charge and discharge process, squeezing the electrolyte inside the winding core outward, the multiple first aerogel adsorption and liquid-retaining spacers can effectively absorb the squeezed electrolyte, thereby effectively preventing the squeezed electrolyte from flowing outside the winding core and causing loss, thereby providing better liquid retention and thereby increasing the battery's service life. Furthermore, the multiple additional first aerogel adsorption and liquid-retaining spacers can also improve the battery's resistance to needle puncture and heavy object impact, thereby increasing the safety of battery use. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a schematic diagram of the relatively dense structure of the end of the traditional winding core after winding;

[0030] Figure 2 This is a schematic diagram of the relatively dense structure of the ends of a conventional roll core after being flattened;

[0031] Figure 3 This is a flow chart of a method for preparing a negative electrode sheet according to an embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of the structure of a negative electrode sheet in one direction according to an embodiment of the present invention;

[0033] Figure 5 A schematic diagram of the structure of a negative electrode sheet in one direction according to another embodiment of the present invention;

[0034] Figure 6 A schematic diagram of the structure of a negative electrode sheet in one direction according to another embodiment of the present invention;

[0035] Figure 7 A schematic diagram of the structure of a negative electrode sheet in one direction according to another embodiment of the present invention;

[0036] Figure 8 This is a schematic diagram of the structure of a winding core in one direction according to an embodiment of the present invention;

[0037] Figure 9 for Figure 8 A partial enlarged view of point A shown in FIG;

[0038] Figure numerals: 1, winding core; 10, negative electrode sheet; 100, negative current collector; 110, coating area; 120, first blank area; 130, second blank area; 200, negative electrode conductive layer; 300, first aerogel adsorption liquid retention spacer; 400, second aerogel adsorption liquid retention spacer; 500, aerogel adsorption liquid retention net; 600, aerogel adsorption liquid retention connecting bridge; 700, liquid injection port; 800, preset blank gap; 20, diaphragm; 21, aerogel adsorption liquid retention layer; 30, positive electrode sheet. Specific embodiments

[0039] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0040] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0042] The present application provides a method for preparing a negative electrode sheet, comprising the following steps: obtaining a negative current collector, a negative electrode slurry, and a modified aerogel adsorption liquid-retaining material, respectively, wherein the negative current collector comprises a coating area and a first blank area, and the first blank area is located on one side of the coating area; coating the modified aerogel adsorption liquid-retaining material on the first blank area at intervals to form at least two first aerogel adsorption liquid-retaining spacer strips in the length direction of the first blank area; coating the negative electrode slurry on the coating area to obtain a negative electrode semi-finished product; performing a roller pressing operation on the negative electrode semi-finished product; and performing a baking operation on the negative electrode semi-finished product after the roller pressing operation to obtain the negative electrode sheet.

[0043] In the above-mentioned method for preparing a negative electrode sheet, since the negative current collector includes a coating area and a first blank area, and the first blank area is located on one side of the coating area, when the modified aerogel adsorption liquid-retaining material is coated on the first blank area at intervals, at least two first aerogel adsorption liquid-retaining spacers are formed in the length direction of the first blank area, so that two adjacent first aerogel adsorption liquid-retaining spacers can form a spacing groove on one side of the negative conductive layer. When the negative electrode sheet, the diaphragm and the positive electrode sheet are wound into a core, the multiple first aerogel adsorption liquid-retaining spacers can increase the spacing between the negative electrode sheet and the diaphragm. In this way, the density of the end of one side of the core is reduced after the flattening operation, thereby increasing the distance between the core layers, so that the electrolyte can enter the interior of the core more quickly, thereby improving the battery's ability to absorb liquid, and thereby improving the battery's wetting effect and cycle performance. Furthermore, because the multiple additional first aerogel adsorption and liquid-retention spacers are positioned on one side of the negative conductive layer, when the active material in the negative conductive layer expands during charge and discharge, squeezing the electrolyte inside the winding core outward, the multiple first aerogel adsorption and liquid-retention spacers can effectively absorb the squeezed electrolyte, thereby effectively preventing the squeezed electrolyte from flowing outside the winding core and causing loss, thereby effectively maintaining the electrolyte and thereby increasing the battery's service life. Furthermore, the multiple additional first aerogel adsorption and liquid-retention spacers can also improve the battery's resistance to needle puncture and heavy object impact, thereby increasing the safety of battery use.

[0044] See also Figure 3In order to better understand the technical solutions and beneficial effects of the present application, the present application is further described in detail below in conjunction with specific embodiments. The negative electrode sheet preparation method of one embodiment includes some or all of the following steps:

[0045] S101 , respectively obtaining a negative current collector 100 , a negative electrode slurry, and a modified aerogel adsorption and liquid-retaining material, wherein the negative current collector 100 includes a coating area 110 and a first blank area 120 , and the first blank area 120 is located on one side of the coating area 110 .

[0046] It can be understood that since the negative current collector 100 can provide a carrier for the negative electrode slurry and the modified aerogel adsorption liquid retaining material, the negative electrode slurry and the modified aerogel adsorption liquid retaining material are formed. The negative electrode slurry is mainly the negative electrode active material to ensure the conductivity of the negative electrode sheet 10. Further, as Figure 3 As shown, since the negative current collector 100 includes a coating area 110 and a first blank area 120, and the first blank area 120 is located on one side of the coating area 110, the negative current collector 100 is partitioned, so that the user can quickly apply the negative electrode slurry and the modified aerogel adsorption and liquid-retaining material to the corresponding areas respectively.

[0047] S102 , coating the modified aerogel adsorption and liquid-retaining material on the first blank area 120 at intervals to form at least two first aerogel adsorption and liquid-retaining spacer strips 300 along the length direction of the first blank area 120 .

[0048] It is understandable that in actual applications, the negative electrode slurry contains a large amount of graphite and conductive agent. When the battery is charged and discharged multiple times, the active material (graphite) of the negative electrode of the battery is prone to expansion, causing the electrolyte inside the core 1 to be squeezed out from the middle of the core 1. However, these squeezed electrolytes are difficult to be reabsorbed by the core 1, that is, there is a phenomenon of easy loss of electrolyte. Therefore, in the present application, the modified aerogel adsorption liquid-retaining material is coated on the first blank area 120 at intervals, and the first blank area 120 is located on one side of the coating area 110. When the modified aerogel adsorption liquid-retaining material is coated on the first blank area 120 at intervals, at least two first aerogel adsorption liquid-retaining spacers 300 are formed in the length direction of the first blank area 120, so that the two adjacent first aerogel adsorption liquid-retaining spacers 300 can form a spacing groove on one side of the negative conductive layer 200. When the negative electrode sheet 10, the diaphragm 20 and the positive electrode sheet 30 are wound into a core 1, the multiple first aerogel adsorption liquid-retaining spacers 300 can increase the spacing between the negative electrode sheet 10 and the diaphragm 20. In this way, the density of the end of one side of the core 1 after the flattening operation is reduced, thereby increasing the distance between the layers, so that the electrolyte can enter the interior of the core 1 more quickly, thereby improving the battery's ability to absorb liquid, thereby improving the battery's infiltration effect and cycle performance.

[0049] Furthermore, since the additional multiple first aerogel adsorption and liquid-retaining spacers 300 are arranged on one side of the negative conductive layer 200, when the battery is charging and discharging, the active material of the negative conductive layer 200 expands and squeezes the electrolyte inside the winding core 1 outward, the multiple first aerogel adsorption and liquid-retaining spacers 300 can effectively absorb part of the squeezed electrolyte, thereby effectively preventing the squeezed electrolyte from flowing to the outside of the winding core 1 and causing loss, thereby playing a better role in retaining liquid and thus improving the service life of the battery. It is worth mentioning that the improvement of the battery's liquid retention performance will directly improve the battery's multiple cycle performance, that is, the battery capacity retention rate will reach 80% after 5,000 cycles. Furthermore, the additional multiple first aerogel adsorption and liquid-retaining spacers 300 can also improve the battery's needle puncture and heavy object impact performance, thereby improving the safety of battery use.

[0050] S103: coating the negative electrode slurry on the coating area 110 to obtain a negative electrode semi-finished product. It can be understood that by coating the negative electrode slurry on the coating area 110, a negative electrode conductive layer 200 can be obtained on the coating area 110 to ensure the conductivity of the negative electrode sheet 10.

[0051] S104 , rolling the negative electrode semi-finished product to obtain a negative electrode sheet 10 with a high compaction density.

[0052] S105 , baking the negative electrode semi-finished product after the rolling operation to obtain the negative electrode sheet 10 .

[0053] In one embodiment, the thickness of the first aerogel adsorption liquid retaining spacer 300 is 0.1μm to 100μm. It can be understood that if the thickness of the first aerogel adsorption liquid retaining spacer 300 is less than 0.1μm, it will not be able to achieve a good adsorption effect on the squeezed electrolyte. If the thickness of the first aerogel adsorption liquid retaining spacer 300 is greater than 100μm, the thickness is too thick, which affects the winding operation of the core 1 and also increases the difficulty of flattening the core 1. Therefore, in the present application, by controlling the thickness of the first aerogel adsorption liquid retaining spacer 300 to be 0.1μm to 100μm, it is ensured that the thickness of the first aerogel adsorption liquid retaining spacer 300 is more appropriate. In this way, while ensuring that the first aerogel adsorption liquid retaining spacer 300 can better absorb the squeezed electrolyte, it will not increase the difficulty of the winding operation of the core 1 and the difficulty of the flattening operation of the core 1, so as to ensure that the battery is quickly prepared.

[0054] like Figure 3 and Figure 4As shown, in one embodiment, there are multiple first aerogel adsorption liquid retaining spacers 300, and the multiple first aerogel adsorption liquid retaining spacers 300 form n successively increasing spacing grooves in the length direction of the first blank area 120.

[0055] It can be understood that since the multiple first aerogel adsorption liquid-retaining spacers 300 form n successively increasing spacer grooves in the first blank area 120, this can better reduce the density of the end of one side of the core 1 after the flattening operation, so that the electrolyte can flow into the interior of the core 1 from the n spacer grooves at the same time. At the same time, the n successively increasing spacer grooves can also ensure that after the negative electrode sheet 10 is subsequently wound with the positive electrode sheet 30 and the diaphragm 20, each circle of the end of one side of the core 1 is distributed with spacer grooves, so as to better ensure that the electrolyte can better enter the interior of the core 1, so as to better improve the battery's ability to absorb liquid, thereby improving the battery's infiltration effect and cycle performance.

[0056] In one embodiment, when the modified aerogel adsorption liquid-retaining material is coated on the first blank area 120 at intervals, the first end of each first aerogel adsorption liquid-retaining spacer 300 is controlled to be flush with the first end of the first blank area 120 to avoid each first aerogel adsorption liquid-retaining spacer 300 being exposed to the outside of the negative current collector 100, so as to ensure that a winding core 1 with a relatively flat end is obtained for subsequent welding. The second end of each first aerogel adsorption liquid-retaining spacer 300 is connected to the first end of the negative conductive layer 200, so that when the active material of the negative conductive layer 200 expands, the electrolyte can be better diverted into each first aerogel adsorption liquid-retaining spacer 300 to achieve better adsorption of the squeezed electrolyte. In this way, while ensuring that a winding core 1 with a relatively flat end at one end is prepared, it also ensures that each first aerogel adsorption liquid-retaining spacer 300 can well adsorb the squeezed electrolyte to play a better liquid retention role, thereby better improving the service life of the battery.

[0057] like Figure 5 As shown, in one embodiment, after the step of coating the modified aerogel adsorption liquid-retaining material at intervals on the first blank area 120 and before the step of coating the negative electrode slurry on the coating area 110, the following steps are also included: the negative current collector 100 also includes a second blank area 130, and the second blank area 130 is located on the other side of the coating area 110; and, the modified aerogel adsorption liquid-retaining material is coated at intervals on the second blank area 130 to form at least two second aerogel adsorption liquid-retaining spacers 400 in the length direction of the second blank area 130.

[0058] It can be understood that since the modified aerogel adsorption liquid-retaining material is coated at intervals on the second blank area 130 to form at least two second aerogel adsorption liquid-retaining spacers 400 in the length direction of the second blank area 130, the two adjacent second aerogel adsorption liquid-retaining spacers 400 can form a spacing groove on the other side of the negative conductive layer 200. In this way, on the one hand, the density of the end of the other side of the core 1 after the flattening operation is reduced, and at the same time, the flow rate of the electrolyte inside the core 1 is improved, thereby better improving the battery's ability to absorb liquid, and further better improving the battery's infiltration effect and cycle performance; on the other hand, it can also improve the liquid retention effect on the other side of the core 1, thereby better avoiding the loss of electrolyte at both ends of the core 1, thereby better improving the service life of the battery.

[0059] like Figure 5 and Figure 7 As shown, in one embodiment, there are multiple second aerogel adsorption liquid retaining spacers 400, and the multiple second aerogel adsorption liquid retaining spacers 400 form m sequentially increasing spacing grooves in the length direction of the second blank area 130.

[0060] It can be understood that by adding multiple second aerogel adsorption and liquid-retaining spacers 400, multiple second aerogel adsorption and liquid-retaining spacers 400 form m successively increasing spacing grooves in the second blank area 130. In this way, the density of the other end of the core 1 after the flattening operation can be better reduced, so that the electrolyte can flow into the interior of the core 1 from the m spacing grooves at the same time. At the same time, the m successively increasing spacing grooves can also ensure that after the negative electrode sheet 10 is subsequently wound with the positive electrode sheet 30 and the diaphragm 20, each circle of the end on the other side of the core 1 is distributed with spacing grooves, so as to better ensure that the electrolyte can better enter the interior of the core 1, so as to better improve the battery's ability to absorb liquid, thereby improving the battery's infiltration effect and cycle performance.

[0061] like Figure 6 and Figure 7 As shown, in one embodiment, after the step of coating the negative electrode slurry on the coating area 110 and after the step of rolling the negative electrode semi-finished product, the following step is also included: cross-coating the modified aerogel adsorption and liquid-retaining material on the negative electrode conductive layer 200 to form an aerogel adsorption and liquid-retaining network 500 on the negative electrode conductive layer 200.

[0062] It can be understood that by adding an aerogel adsorption liquid retaining net 500 to the negative conductive layer 200, the aerogel adsorption liquid retaining net 500 can be attached to the surface of the negative conductive layer 200 like a net. In this way, the aerogel adsorption liquid retaining net 500 can better absorb the squeezed electrolyte, and at the same time, it can also play a certain role in inhibiting the expansion of the negative conductive layer 200, so as to effectively avoid the phenomenon of more electrolyte being squeezed out, and at the same time, it can better improve the impact performance inside the battery, thereby improving the safety performance of the battery.

[0063] It should be noted that although the additional multiple first aerogel adsorption and liquid-retaining spacers 300, multiple second aerogel adsorption and liquid-retaining spacers 400 and the adsorption and liquid-retaining net can more comprehensively adsorb the squeezed electrolyte, since the spacing grooves between each two adjacent first aerogel adsorption and liquid-retaining spacers 300 and each adjacent second aerogel adsorption and liquid-retaining spacers 400 are relatively large, when the active material of the battery negative electrode is prone to severe expansion, the spacing grooves at both ends of the winding core 1 will still have the phenomenon of electrolyte being squeezed out. Therefore, if Figure 7 As shown, in the present application, after the step of cross-coating the modified aerogel adsorption liquid-retaining material on the negative electrode conductive layer 200, and after the step of rolling the negative electrode semi-finished product, the following steps are also included: the negative current collector 100 also includes a plurality of third blank areas, each of the third blank areas is respectively located in n spacing grooves and m spacing grooves; and the modified aerogel adsorption liquid-retaining material is respectively coated on the plurality of third blank areas to form a plurality of aerogel adsorption liquid-retaining connecting bridges 600 on the plurality of third blank areas, so that the plurality of first aerogel adsorption liquid-retaining spacers 300 and the plurality of second aerogel adsorption liquid-retaining spacers 400 together form an adsorption liquid-retaining sealing wall, so that the squeezed electrolyte is more comprehensively adsorbed, so as to better improve the liquid retention performance of the battery, thereby improving the service life of the battery.

[0064] like Figure 7As shown, in one embodiment, the liquid injection port 700 is disposed in the first blank area 120 and is staggered with the first aerogel adsorption and liquid retention spacer 300 and the aerogel adsorption and liquid retention connecting bridge 600 . It can be understood that by staggering the liquid injection port 700 and the first aerogel adsorption liquid retaining spacer 300 and the aerogel adsorption liquid retaining connecting bridge 600, the electrolyte will not directly contact the multiple first aerogel adsorption liquid retaining spacers 300 and the aerogel adsorption liquid retaining connecting bridge 600 during the injection process, effectively preventing the electrolyte from entering the multiple first aerogel adsorption liquid retaining spacers 300, the multiple aerogel adsorption liquid retaining connecting bridges 600 and the multiple second aerogel adsorption liquid retaining spacers 400, so as to ensure that the amount of electrolyte injected into the battery in a single time does not increase. At the same time, it is also ensured that after the injection is completed, the multiple first aerogel adsorption liquid retaining spacers 300, the multiple second aerogel adsorption liquid retaining spacers 400 and the multiple aerogel adsorption liquid retaining connecting bridges 600 can fully and quickly absorb the squeezed electrolyte during the subsequent charging process, effectively avoiding the phenomenon of partial loss of electrolyte.

[0065] It can be understood that if multiple first aerogel adsorption liquid-retaining spacers 300, multiple second aerogel adsorption liquid-retaining spacers 400 and multiple aerogel adsorption liquid-retaining connecting bridges 600 are all connected to the negative conductive layer 200, when the battery is injected with liquid, part of the electrolyte will flow into the multiple first aerogel adsorption liquid-retaining spacers 300, multiple second aerogel adsorption liquid-retaining spacers 400 and multiple aerogel adsorption liquid-retaining connecting bridges 600 on both sides. In this way, not only will the amount of electrolyte used increase, but it will also reduce the subsequent adsorption amount of the squeezed-out electrolyte by the multiple first aerogel adsorption liquid-retaining spacers 300, multiple second aerogel adsorption liquid-retaining spacers 400 and multiple aerogel adsorption liquid-retaining connecting bridges 600, that is, it is impossible to achieve good absorption of the squeezed-out electrolyte during the charging process, resulting in the phenomenon that some electrolyte is still lost.

[0066] Therefore, if Figure 7As shown, in one embodiment, preset blank gaps 800 are provided between the plurality of first aerogel adsorption liquid retaining spacers 300 and the negative electrode conductive layer 200, between the plurality of second aerogel adsorption liquid retaining spacers 400 and the negative electrode conductive layer 200, and between the plurality of aerogel adsorption liquid retaining connecting bridges 600 and the negative electrode conductive layer 200, so as to avoid the plurality of first aerogel adsorption liquid retaining spacers 300, the plurality of second aerogel adsorption liquid retaining spacers 400 and the plurality of aerogel adsorption liquid retaining connecting bridges 600 from being connected to the negative electrode conductive layer 200, and at the same time, the liquid injection port 700 is provided in the first blank area 120, and is staggered with the first aerogel adsorption liquid retaining spacers 300 and the aerogel adsorption liquid retaining connecting bridge 600; when the winding core 1 is injected with liquid, the electrolyte will flow directly into the interior of the winding core 1 from the liquid injection port 700. In the negative electrode conductive layer 200, the additional preset blank gap 800 can block the electrolyte from entering the multiple first aerogel adsorption liquid-retaining spacers 300, the multiple second aerogel adsorption liquid-retaining spacers 400, and the multiple aerogel adsorption liquid-retaining connecting bridges 600. In this way, while ensuring that the amount of electrolyte injected into the battery at a single time does not increase, it also ensures that after the injection is completed, no electrolyte is adsorbed inside the multiple first aerogel adsorption liquid-retaining spacers 300, the multiple second aerogel adsorption liquid-retaining spacers 400, and the multiple aerogel adsorption liquid-retaining connecting bridges 600, so as to ensure that the multiple first aerogel adsorption liquid-retaining spacers 300, the multiple second aerogel adsorption liquid-retaining spacers 400, and the multiple aerogel adsorption liquid-retaining connecting bridges 600 can fully and quickly adsorb the squeezed-out electrolyte during the subsequent charging process, effectively avoiding the phenomenon of partial loss of electrolyte. In addition, the addition of multiple first aerogel adsorption liquid-retaining spacers 300, multiple second aerogel adsorption liquid-retaining spacers 400 and multiple aerogel adsorption liquid-retaining connecting bridges 600 can reduce the density of the end of one side of the core 1 after the flattening operation, thereby increasing the distance between each layer, so that the electrolyte can enter the interior of the core 1 more quickly, thereby improving the battery's ability to absorb liquid, and thereby improving the battery's wetting effect and cycle performance.

[0067] It should be noted that although the added preset blank gap 800 can block the electrolyte from entering the multiple first aerogel adsorption liquid-retaining spacers 300, the multiple second aerogel adsorption liquid-retaining spacers 400 and the multiple aerogel adsorption liquid-retaining connecting bridges 600 during liquid injection, it will also affect the adsorption of the squeezed electrolyte by the multiple first aerogel adsorption liquid-retaining spacers 300, the multiple second aerogel adsorption liquid-retaining spacers 400 and the multiple aerogel adsorption liquid-retaining connecting bridges 600, especially when the amount of electrolyte squeezed out is small, the multiple first aerogel adsorption liquid-retaining spacers 300, the multiple second aerogel adsorption liquid-retaining spacers 400 and the multiple aerogel adsorption liquid-retaining connecting bridges 600 cannot achieve good adsorption of a small amount of electrolyte. Therefore, in the present application, by presetting the blank gap 800 to be no larger than the expansion amount of the negative conductive layer 200, when the negative conductive layer 200 expands during the charging process of the battery, it can respectively contact the multiple first aerogel adsorption liquid-retaining spacers 300, the multiple second aerogel adsorption liquid-retaining spacers 400 and the multiple aerogel adsorption liquid-retaining connecting bridges 600. In this way, the adsorption of the squeezed electrolyte by the multiple first aerogel adsorption liquid-retaining spacers 300, the multiple second aerogel adsorption liquid-retaining spacers 400 and the multiple aerogel adsorption liquid-retaining connecting bridges 600 is well ensured, which is particularly suitable for applications where a small amount of electrolyte is squeezed out.

[0068] like Figure 7 As shown, in one embodiment, each aerogel adsorption liquid retaining connection bridge 600 is a wavy aerogel adsorption liquid retaining connection bridge 600, so that multiple wavy aerogel adsorption liquid retaining connection bridges 600 can form multiple bent buffer chambers on one side of the negative conductive layer 200. In this way, on the one hand, the density of the end of one side of the core 1 after the flattening operation can be better reduced, thereby increasing the distance between the layers. On the other hand, the adsorption area of ​​each aerogel adsorption liquid retaining connection bridge 600 is increased, and the adsorption amount of the aerogel adsorption liquid retaining connection bridge 600 to the squeezed electrolyte is increased to achieve better liquid retention performance.

[0069] It can be understood that if the wavy aerogel adsorption liquid retaining connecting bridge 600 has more undulations, the flatness of the core 1 after being flattened will be increased. Therefore, in one embodiment, the number of undulations of the wavy aerogel adsorption liquid retaining connecting bridge 600 is 1 to 5. In this way, while ensuring that the core 1 has a high flatness after being flattened, it also reduces the density of the end of one side of the core 1 after the flattening operation, thereby increasing the adsorption area of ​​each aerogel adsorption liquid retaining connecting bridge 600 and increasing the adsorption amount of the squeezed electrolyte by the aerogel adsorption liquid retaining connecting bridge 600, so as to achieve better liquid retention performance. Specifically, the number of undulations can be 1, 2, 3, 4 and 5, and those skilled in the art can choose and use them according to actual needs. No specific limitation is made here.

[0070] It can be understood that if the bending angle of the bending buffer chamber of the wavy aerogel adsorption liquid retaining connecting bridge 600 is small, the electrolyte entering the bending buffer chamber is prone to retention, thereby affecting the recovery of the squeezed electrolyte. Therefore, in the present application, by setting the bending angle of the wavy aerogel adsorption liquid retaining connecting bridge 600 to 120°~160°, the electrolyte entering the bending buffer chamber is effectively avoided from being easily retained, thereby improving the recovery rate of the squeezed electrolyte. Specifically, the bending angle can be 120°, 125°, 130°, 135°, 140°, 145°, 148°, 150°, 158°, 160°, and those skilled in the art can choose to use it according to actual conditions, and no specific limitation is made here.

[0071] In one embodiment, the modified aerogel adsorption and liquid retention material includes the following components by mass: 20 to 30 parts of lightweight aerogel particles, 2 to 5 parts of binder, and 55 to 60 parts of water; wherein the lightweight aerogel particles include at least one of SiO2 aerogel, Al203 aerogel, resorcinol-formaldehyde aerogel and melamine-formaldehyde aerogel.

[0072] It can be understood that due to the addition of 20 to 30 parts of lightweight aerogel particles with a highly permeable three-dimensional nano-network structure, high porosity, good fire resistance and stability, the first aerogel adsorption liquid retaining spacer 300, the second aerogel adsorption liquid retaining spacer 400 and the aerogel adsorption liquid retaining connecting bridge 600 can achieve the adsorption of the squeezed electrolyte, thereby improving the liquid retention performance of the battery during use, thereby extending the service life, and at the same time improving the battery's needle puncture and heavy object impact performance; the addition of 2 to 5 parts of binder can improve the connectivity between the lightweight aerogel particles and the negative electrode current collector, effectively avoiding the condensation of lightweight aerogel particles. The colloidal particles are prone to shedding, which reduces the adsorption of the extruded electrolyte by the first aerogel adsorbing liquid-retaining spacer 300, the second aerogel adsorbing liquid-retaining spacer 400, and the aerogel adsorbing liquid-retaining connecting bridge 600. The addition of 55 to 60 parts of water helps disperse the lightweight aerogel particles, ensuring that the lightweight aerogel particles are mixed with 2 to 5 parts of the binder to obtain a more uniform modified aerogel adsorbing liquid-retaining material, thereby ensuring that the first aerogel adsorbing liquid-retaining spacer 300, the second aerogel adsorbing liquid-retaining spacer 400, and the aerogel adsorbing liquid-retaining connecting bridge 600 have good connectivity and adsorption performance. Specifically, the lightweight aerogel particles can be 20 parts, 22 parts, 25 parts, 28 parts, or 30 parts, the binder can be 2 parts, 3 parts, 4 parts, or 5 parts, and the water can be 55 parts, 56 parts, 57 parts, 58 parts, and 60 parts. No specific limitations are given here, and those skilled in the art can select and use them according to actual needs.

[0073] Furthermore, since the lightweight aerogel particles include at least one of SiO2 aerogel, Al2O3 aerogel, resorcinol-formaldehyde aerogel, and melamine-formaldehyde aerogel, it can be understood that since SiO2 aerogel, Al2O3 aerogel, resorcinol-formaldehyde aerogel, and melamine-formaldehyde aerogel all have a highly permeable three-dimensional nano-network structure, high porosity, and good fire resistance and stability, the prepared first aerogel adsorption liquid-retaining spacer 300, the second aerogel adsorption liquid-retaining spacer 400, and the aerogel adsorption liquid-retaining connecting bridge 600 also have a highly permeable three-dimensional nano-network structure, high porosity, and good fire resistance and stability, thereby improving the liquid retention performance and infiltration effect of the battery.

[0074] In a preferred embodiment, the lightweight aerogel particles include SiO2 aerogel, Al2O3 aerogel and melamine-formaldehyde aerogel. It can be understood that since SiO2 inorganic aerogel and Al203 inorganic aerogel are inorganic aerogels, and melamine-formaldehyde aerogel is an organic aerogel, by using SiO2 inorganic aerogel, Al203 inorganic aerogel and melamine-formaldehyde aerogel in combination, the three can play a better synergistic role to ensure high adsorption performance while also ensuring good flexibility, so that the first aerogel adsorption liquid-retaining spacer 300, the second aerogel adsorption liquid-retaining spacer 400 and the aerogel adsorption liquid-retaining connecting bridge 600 are not prone to breakage during the flattening operation, thereby ensuring a relatively complete structure and high flatness of the winding core 1, and at the same time ensuring that the prepared first aerogel adsorption liquid-retaining spacer 300, the second aerogel adsorption liquid-retaining spacer 400 and the aerogel adsorption liquid-retaining connecting bridge 600 also have a highly permeable three-dimensional nano-network structure, high porosity, and good fire resistance and stability, thereby improving the liquid retention performance and infiltration effect of the battery.

[0075] In one embodiment, the binder is sodium carboxymethyl cellulose. Of course, the binder can also be other materials that can achieve the same function. Those skilled in the art can choose to use it according to actual conditions, and no specific limitation is made here.

[0076] The present application also provides a negative electrode sheet 10, which is prepared by the negative electrode sheet 10 preparation method described in any of the above embodiments. It is understood that the negative electrode sheet 10 obtained by the preparation method of the present application is Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 and Figure 7The different structures of the negative electrode sheet 10 shown enable the addition of the first aerogel adsorption and liquid-retention spacers 300 to reduce the density of the end of the winding core 1 after the flattening operation, thereby increasing the distance between the layers. This allows the electrolyte to enter the interior of the winding core 1 more quickly, thereby improving the battery's ability to absorb liquid, thereby improving the battery's wetting effect and cycle performance. The first aerogel adsorption and liquid-retention spacers 300 can also absorb some of the squeezed electrolyte, effectively preventing the squeezed electrolyte from flowing to the outside of the winding core 1 and causing loss, thereby providing better liquid retention and increasing the battery's service life. Furthermore, the addition of multiple first aerogel adsorption and liquid-retention spacers 300 can also improve the battery's resistance to needle puncture and heavy object impact, thereby improving the safety of battery use.

[0077] like Figure 8 and Figure 9 As shown, the present application also provides a winding core 1, comprising a diaphragm 20, a positive electrode sheet 30 and the negative electrode sheet 10 described in any of the above embodiments, wherein the positive electrode sheet 30, the diaphragm 20 and the negative electrode sheet 10 are stacked and wound in sequence, and the diaphragm 20 comprises a diaphragm body and an aerogel adsorption and liquid-retaining layer 21, and the aerogel adsorption and liquid-retaining layer 21 is arranged on at least one surface of the diaphragm 20 body.

[0078] It can be understood that by arranging the aerogel adsorption and liquid retention layer 21 on at least one side of the diaphragm 20 body, it is ensured that the diaphragm 20 can also absorb the electrolyte squeezed when the negative electrode conductive layer 200 expands, thereby playing a better role in retaining liquid, while also better improving the impact performance and safety performance inside the battery.

[0079] The present application also provides a full-pole ear cylindrical battery, including the core 1 described in any of the above embodiments. It can be understood that since the end of the full-pole ear cylindrical battery adopts a flattening operation, on the one hand, when the foil at the end of the core 1 is bent inward, the multiple first aerogel adsorption liquid-retaining spacers 300 and the multiple aerogel adsorption liquid-retaining connecting bridges 600 can increase the distance between the layers at one end of the core 1, which not only reduces the density of the end of one side of the core 1 after the flattening operation, improves the battery's liquid absorption capacity, but also improves the battery's infiltration effect and cycle performance; on the other hand, it also ensures that the inward-bent end of the core 1 can achieve the limiting fixation of the multiple first aerogel adsorption liquid-retaining spacers 300 and the multiple aerogel adsorption liquid-retaining connecting bridges 600, thereby improving the multiple first aerogel adsorption liquid-retaining spacers. The strips 300 and the multiple aerogel adsorption liquid retaining connecting bridges 600 are connected to the negative electrode current collector, thereby ensuring the adsorption of the squeezed electrolyte by the multiple first aerogel adsorption liquid retaining spacers 300 and the multiple aerogel adsorption liquid retaining connecting bridges 600; on the other hand, due to the good flexibility of the multiple first aerogel adsorption liquid retaining spacers 300 and the multiple aerogel adsorption liquid retaining connecting bridges 600, it can effectively avoid the multiple first aerogel adsorption liquid retaining spacers 300 and the multiple aerogel adsorption liquid retaining connecting bridges 600 from being easily broken during the flattening operation, which leads to a decrease in their adsorption performance of the squeezed electrolyte, and better ensures the flatness of the end of the winding core 1.

[0080] Similarly, the other side of the core 1 can also be provided with a plurality of second aerogel adsorption and liquid retention spacers 400 and a plurality of aerogel adsorption and liquid retention connecting bridges 600, so that the other side of the core 1 also has the structure of one side of the core 1. In this way, the density of the end of the other side of the core 1 after the flattening operation is further reduced, thereby improving the battery's liquid absorption capacity, and also improving the battery's wetting effect and cycle performance, and better improving the needle puncture and heavy object impact performance at both ends of the full-pole ear cylindrical battery, thereby better improving the safety performance of the full-pole ear cylindrical battery.

[0081] Compared with the prior art, the present invention has at least the following advantages:

[0082] 1) In the above-mentioned method for preparing the negative electrode sheet 10, since the negative current collector 100 includes a coated area 110 and a first blank area 120, and the first blank area 120 is located on one side of the coated area 110, when the modified aerogel adsorption liquid-retaining material is applied to the first blank area 120 at intervals, at least two first aerogel adsorption liquid-retaining spacers 300 are formed in the length direction of the first blank area 120, so that two adjacent first aerogel adsorption liquid-retaining spacers 300 can form a spacing groove on one side of the negative conductive layer 200. When the negative electrode sheet 10, the separator 20 and the positive electrode sheet 30 are wound into a core 1, the multiple first aerogel adsorption liquid-retaining spacers 300 can increase the spacing between the negative electrode sheet 10 and the separator 20. In this way, the density of the end of one side of the core 1 after the flattening operation is reduced, thereby increasing the distance between the layers, so that the electrolyte can enter the interior of the core 1 more quickly, thereby improving the battery's liquid absorption ability, and thereby improving the battery's infiltration effect and cycle performance.

[0083] 2) Because the multiple additional first aerogel adsorption and liquid-retaining spacers 300 are positioned on one side of the negative conductive layer 200, when the active material of the negative conductive layer 200 expands during the charge and discharge process, squeezing the electrolyte inside the winding core 1 outward, the multiple first aerogel adsorption and liquid-retaining spacers 300 can effectively absorb the squeezed electrolyte, thereby effectively preventing the squeezed electrolyte from flowing outside the winding core 1 and causing loss, thereby effectively maintaining the electrolyte and thereby increasing the battery's service life. Furthermore, the multiple additional first aerogel adsorption and liquid-retaining spacers 300 can also improve the battery's resistance to needle puncture and heavy object impact, thereby improving the safety of battery use.

[0084] The following examples illustrate some specific embodiments, where percentages are expressed by weight. It should be noted that the following examples do not exhaust all possible situations, and that the materials used in the following examples, unless otherwise specified, can be obtained from commercial sources.

[0085] Table 1 Recipe

[0086]

[0087] The formulations of Examples 1 to 3 in Table 1 were prepared according to the following steps: lightweight aerogel particles (SiO2 aerogel, Al203 aerogel, melamine-formaldehyde aerogel), sodium carboxymethyl cellulose and water were mixed to obtain modified aerogel adsorption and liquid-retaining materials, and negative current collectors and negative electrode slurries were obtained. The negative current collectors were then divided into zones (coating area, first blank area, second blank area and third blank area), and the modified aerogel adsorption and liquid-retaining materials were then coated on the first blank area and the second blank area, respectively, to obtain a plurality of first aerogel adsorption and liquid-retaining spacers (thickness 10 μm) and a plurality of second aerogel adsorption and liquid-retaining spacers (thickness 10 μm), and then the negative electrode slurry was coated on the coating area to obtain a negative electrode conductive layer. , and the modified aerogel adsorption liquid-retaining material is cross-coated on the negative electrode conductive layer to form an adsorption liquid-retaining network. Then, the modified aerogel adsorption liquid-retaining material is coated on the third blank area to form a plurality of aerogel adsorption liquid-retaining connecting bridges (with a thickness of 10 μm, a number of undulations of 2, and a bending angle of 150°) in the n spacing grooves and the m spacing grooves respectively to obtain a negative electrode semi-finished product. Subsequently, the negative electrode semi-finished product is subjected to a rolling operation and a baking operation to obtain a negative electrode sheet, wherein the negative electrode slurry is mainly graphite, and a preset blank gap is set between the plurality of first aerogel adsorption liquid-retaining spacers, the plurality of second aerogel adsorption liquid-retaining spacers and the plurality of aerogel adsorption liquid-retaining connecting bridges and the negative electrode conductive layer, and the preset blank gap is equal to the expansion amount of the negative electrode conductive layer.

[0088] Comparative Example 1

[0089] Compared with Example 1, Comparative Example 1 did not use modified aerogel adsorption liquid-retaining material for coating operation, that is, Comparative Example 1 was not coated with multiple first aerogel adsorption liquid-retaining spacers, multiple second aerogel adsorption liquid-retaining spacers and multiple aerogel adsorption liquid-retaining connecting bridges, and the formula and preparation method of the remaining negative electrode slurry remained unchanged.

[0090] The negative electrode sheet and the positive electrode sheet (lithium iron phosphate) obtained in Examples 1 to 3 above, and the separator (dry-process base film with an aerogel adsorption and liquid retention layer coated on one side) were wound, flattened, packaged, and liquid-filled to obtain a full-tab cylindrical battery (model 34145). The liquid filling and immersion time, cycle performance, and safety performance of the battery were then tested to obtain the data in Table 2 below:

[0091] The injection time is calculated as the time from the beginning of injection to the complete penetration of the positive and negative electrode active materials by the electrolyte;

[0092] The cycle performance is the capacity retention rate of the battery measured by charging at 0.5C and discharging at 1C at room temperature for 5000 times;

[0093] Safety performance is tested using a battery combustion tester.

[0094] Table 2

[0095]

[0096] From the comparison between Examples 1 to 3 and Comparative Example 1, it can be seen that since the negative electrode sheets of Examples 1 to 3 are additionally provided with multiple first aerogel adsorption liquid-retaining spacers, multiple second aerogel adsorption liquid-retaining spacers, and multiple aerogel adsorption liquid-retaining connecting bridges, the density of the ends of the winding core can be effectively reduced, thereby shortening the battery's liquid injection and infiltration time, and improving the battery's liquid retention performance, safety performance, and cycle performance. In particular, the comprehensive indicators of Example 3 are the best.

[0097] The above-described embodiments merely represent several embodiments of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a negative electrode sheet, characterized in that: The steps include: Obtaining a negative current collector, a negative electrode slurry, and a modified aerogel adsorption and liquid-retaining material respectively, wherein the negative current collector includes a coating area and a first blank area, and the first blank area is located on one side of the coating area; The modified aerogel adsorption and liquid-retaining material comprises lightweight aerogel particles, a binder and water; The modified aerogel adsorption and liquid-retaining material is applied to the first blank area at intervals to form a plurality of first aerogel adsorption and liquid-retaining spacer strips along the length direction of the first blank area; the plurality of first aerogel adsorption and liquid-retaining spacer strips form n sequentially increasing spacing grooves along the length direction of the first blank area; Applying the modified aerogel adsorption and liquid-retaining material to the second blank area at intervals to form a plurality of second aerogel adsorption and liquid-retaining spacer strips in the length direction of the second blank area, wherein the plurality of second aerogel adsorption and liquid-retaining spacer strips form m sequentially increasing spacing grooves in the length direction of the second blank area; Wherein, the negative current collector further includes a second blank area, and the second blank area is located on the other side of the coating area; applying the negative electrode slurry on the coating area to form a negative electrode conductive layer on the coating area to obtain a negative electrode semi-finished product; The modified aerogel adsorption and liquid-retaining material is respectively coated on a plurality of third blank areas to form a plurality of aerogel adsorption and liquid-retaining connection bridges on the plurality of third blank areas, wherein the negative current collector further includes a plurality of the third blank areas, and each of the third blank areas is respectively located in the n spacing grooves and the m spacing grooves; Preset blank gaps are provided between the plurality of first aerogel adsorption and liquid-retaining spacers and the negative electrode conductive layer, between the plurality of second aerogel adsorption and liquid-retaining spacers and the negative electrode conductive layer; and between the plurality of aerogel adsorption and liquid-retaining connecting bridges and the negative electrode conductive layer; performing a roller pressing operation on the negative electrode semi-finished product; The negative electrode semi-finished product after the rolling operation is baked to obtain the negative electrode sheet.

2. The method for preparing a negative electrode sheet according to claim 1, wherein: The thickness of the first aerogel adsorption and liquid-retaining spacer is 0.1 μm to 100 μm.

3. The method for preparing a negative electrode sheet according to claim 1, wherein: After the step of coating the negative electrode slurry on the coating area and before the step of coating the modified aerogel adsorption and liquid-retaining material on the plurality of third blank areas, the following steps are further included: The modified aerogel adsorption and liquid-retaining material is coated on the negative electrode conductive layer in a cross-interval manner to form an aerogel adsorption and liquid-retaining network on the negative electrode conductive layer.

4. The method for preparing a negative electrode sheet according to claim 1, wherein: The modified aerogel adsorption and liquid-retaining material comprises the following mass components: 20~30 parts of lightweight aerogel particles; 2 to 5 parts of adhesive; 55-60 parts water; The lightweight aerogel particles include at least one of SiO2 aerogel, Al2O3 aerogel, resorcinol-formaldehyde aerogel and melamine-formaldehyde aerogel.

5. A negative electrode sheet, characterized in that: The negative electrode sheet preparation method according to any one of claims 1 to 4 is adopted.

6. A winding core, characterized in that: It comprises a diaphragm, a positive electrode sheet and the negative electrode sheet according to claim 5, wherein the positive electrode sheet, the diaphragm and the negative electrode sheet are stacked and wound in sequence, the diaphragm comprises a diaphragm body and an aerogel adsorption and liquid retention layer, and the aerogel adsorption and liquid retention layer is arranged on at least one surface of the diaphragm body.

7. A full-tab cylindrical battery, characterized in that: Comprising the winding core according to claim 6.

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