Electrode sheet and preparation method therefor, and lithium-iron-phosphate pouch cell

Abstract

An electrode sheet and a preparation method therefor, and a lithium-iron-phosphate pouch cell. The electrode sheet comprises a current collector, and further comprises a first membrane and a second membrane that are sequentially grown on the current collector from inside to outside, wherein the first membrane is arranged between the second membrane and the current collector, and the second membrane is in indirect contact with the current collector.

Description

Electrode sheet, preparation method and lithium iron phosphate soft pack battery Technical Field

[0001] The present disclosure relates to the field of battery technology, and in particular, to an electrode sheet, a method for preparing the electrode sheet, and a lithium iron phosphate soft-pack battery including the electrode sheet. Background Art

[0002] In recent years, new dry electrode manufacturing technology has emerged. The electrode film is prepared by a solvent-free method and then bonded with the current collector to form an electrode. This method is environmentally friendly and does not require solvent evaporation, which greatly reduces costs. In addition, dry electrodes do not use solvents in the production process, and the binder exists in fiber or sheet form, which does not affect the internal contact between the active material particles. The electrode has good conductivity, high capacity, and good rate performance.

[0003] The existing electrode sheet is as follows: a binder, a conductive agent and an active material are uniformly mixed to form a mixed material, the mixed material is subjected to high-intensity shearing to fiberize the binder, and then the mixed material and a foil are hot-pressed to form an electrode sheet.

[0004] However, due to the large interface impedance between the foil and the active material, the bonding effect between the foil and the active material is poor, and the foil is prone to powder loss after multiple cycles of use.

[0005] Application Contents

[0006] In order to solve the above technical problems, the present application provides an electrode sheet, a preparation method and a lithium iron phosphate soft-pack battery.

[0007] In one aspect, the present application provides an electrode sheet, comprising a current collector, and further comprising a first film layer and a second film layer sequentially grown on the current collector from the inside out, wherein the first film layer is disposed between the second film layer and the current collector, and the second film layer is in indirect contact with the current collector;

[0008] The mass ratio of the first film layer to the second film layer is 1:(20-100);

[0009] The first film layer includes a binder and a conductive agent;

[0010] The second film layer includes an active material, a conductive agent and a binder.

[0011] Through the above technical solution, by setting up the first film layer, the active material in the second film layer is in indirect contact with the current collector, thereby increasing the adhesion between the masterbatch and the current collector, overcoming the technical prejudice of the traditional view that the components in the masterbatch must be evenly distributed, and setting up a double-layer structure to increase the adhesion effect between the masterbatch and the current collector while ensuring conductivity; the mass ratio between the film layers is limited to ensure that there can be sufficient active material in the second film layer to ensure the conductive effect.

[0012] As a further technical solution of the present invention, the mass ratio of the binder to the conductive agent in the first film layer is (5-25): (75-95).

[0013] Through the above technical solution, the mass ratio of the conductive agent to the adhesive is proposed, so that the adhesive composition is moderate and the current transmission effect is better. Under the premise of ensuring the conductive effect, the bonding effect is maximized.

[0014] As a further technical solution of the present invention, the mass ratio of the active material, the conductive agent and the binder in the second film layer is (75-95): (2-10): (3-15).

[0015] Through the above technical solution, the proportions of the components in the second film layer are limited, the content of active substances is always constant, and at the same time, a binder is added to enable the active substances to be evenly distributed and tightly bonded.

[0016] As a further technical solution of the present invention, the thickness of the first film layer is 1 μm-10 μm, and the thickness of the second film layer is 30 μm-250 μm.

[0017] As a further technical solution of the present invention, the current collector is aluminum foil or copper foil.

[0018] In a second aspect, the present application provides a method for preparing an electrode sheet, the specific steps of which are as follows:

[0019] S1, preparing a first mixture according to the formula of the first film layer;

[0020] Dissolving the binder with a solvent until the binder is completely dissolved to form a binder solvent, adding a conductive agent to the binder solvent, and mixing them evenly to form a first mixture;

[0021] S2, preparing a second mixture according to the formula of the second film layer;

[0022] Dissolving the binder with a solvent until the binder is completely dissolved to form a binder solvent, adding a conductive agent and an active material to the binder solvent, and mixing them evenly to form a second mixture;

[0023] S3, electrospinning the first mixture onto the surface of the current collector to form a first film layer capable of blocking the current collector and the active substance, and then electrospinning the second mixture onto the surface of the first film layer to form a second film layer;

[0024] S4, rolling the current collector to obtain a dry electrode sheet.

[0025] Through the above technical solution, the first film layer can be directly grown on the surface of the aluminum foil, increasing the bonding effect between the film layer and the aluminum foil. At the same time, the second film layer can continue to grow based on the first film layer, and the prepared electrode sheet has a more outstanding tensile effect.

[0026] As a further technical solution of the present invention, the parameters of the electrospinning in S3 are an extrusion speed of 1 mL / min to 1000 mL / min, a high voltage of 15 kV to 22 kV, and a negative pressure of -1 kV to -3 kV.

[0027] As a further technical solution of the present invention, the rolling temperature in S4 is 100°C-300°C.

[0028] In a third aspect, the present application provides a lithium iron phosphate soft-pack battery, including an electrode sheet.

[0029] In summary, the present invention includes at least one of the following beneficial technical effects:

[0030] 1. The electrode sheet is designed to have a double-layer structure, with the side in contact with the current collector set as the first film layer. At the same time, a second film layer is set on the basis of the first film layer, and all active materials are set in the second film layer. The second film layer is separated from the current collector by the first film layer, so that the active material is in indirect contact with the current collector, thereby increasing the adhesion between the masterbatch and the current collector and alleviating the problem of powder loss.

[0031] 2. By using electrospinning, the first film layer can be grown directly on the surface of the aluminum foil, increasing the bonding effect between the film layer and the aluminum foil. At the same time, the second film layer can continue to grow based on the first film layer, and the prepared electrode sheet has a more outstanding tensile effect. DETAILED DESCRIPTION

[0032] The following examples further illustrate the present application in detail.

[0033] The present application designs an electrode sheet, including a current collector, and also includes a first film layer and a second film layer grown on the current collector from the inside to the outside, the first film layer is arranged between the second film layer and the current collector, and the second film layer is in indirect contact with the current collector to block the current collector from the active substance.

[0034] The mass ratio of the first film layer to the second film layer is 1:(20-100).

[0035] The first film layer includes a binder and a conductive agent, and the second film layer includes an active material, a conductive agent and a binder.

[0036] The mass ratio of the binder to the conductive agent in the first film layer is (5-25): (75-95), and the mass ratio of the active material, the conductive agent and the binder in the second film layer is (75-95): (2-10): (3-15).

[0037] Prior to this application, a binder was added to the masterbatch to connect it to the current collector. However, the existing electrode sheets were all single-layer structures, and the simple consideration was to increase the adhesion between the masterbatch and the current collector by adding a binder. The problem of large interface impedance between the active material and the current collector was not considered, resulting in powder shedding after a period of use.

[0038] In response to the above-mentioned technical problems, the inventors of this application designed the electrode sheet into a double-layer structure, setting the side in contact with the current collector as the first film layer, and not adding active substances in the first film layer. At the same time, a second film layer is set on the basis of the first film layer, and all active substances are set in the second film layer. The second film layer is separated from the current collector by the first film layer, so that the active substances are in indirect contact with the current collector, thereby increasing the adhesion between the masterbatch and the current collector.

[0039] At the same time, a conductive agent and an adhesive are arranged in the first film layer to increase the adhesion between the masterbatch and the current collector while ensuring the conductivity of the electrode sheet. This application overcomes the technical prejudice that the components in the traditional masterbatch must be evenly distributed. While ensuring conductivity, a double-layer structure is set up to increase the adhesion effect between the masterbatch and the current collector.

[0040] The electrode sheet provided in this application is preferably prepared by the following method. The prepared electrode sheet has higher adhesion. The specific steps of the preparation method of the electrode sheet provided in this application are as follows:

[0041] S1, preparing a first mixture according to the formula of the first film layer;

[0042] Dissolving the binder with a solvent until the binder is completely dissolved to form a binder solvent, adding a conductive agent to the binder solvent, and mixing them evenly to form a first mixture;

[0043] S2, preparing a second mixture according to the formula of the second film layer;

[0044] Dissolving the binder with a solvent until the binder is completely dissolved to form a binder solvent, adding a conductive agent and an active material to the binder solvent, and mixing them evenly to form a second mixture;

[0045] S3, electrospinning the first mixture onto the surface of the current collector to form a first film layer capable of blocking the current collector and the active substance, and then electrospinning the second mixture onto the surface of the first film layer to form a second film layer;

[0046] S4, rolling the membrane to obtain a dry electrode sheet.

[0047] Unless otherwise specified, the important components involved in this application were purchased from commercially available products, including:

[0048] The solvent was N-methylpyrrolidone (NMP).

[0049] The binder is polyvinylidene chloride.

[0050] The conductive agent is conductive carbon black.

[0051] The active material is lithium iron phosphate.

[0052] It should be noted that the above-mentioned materials are used to prepare electrode sheets in this application, but this should not be understood as a limitation to this application. In some other embodiments, other materials can also be used to prepare electrode sheets according to the preparation method of this application.

[0053] Preparation Examples 1 to 5 were used to prepare different first mixtures.

[0054] Preparation Example 1

[0055] The binder is dissolved using a solvent until the binder is completely dissolved to form a binder solvent, a conductive agent is added to the binder solvent, and the mixture is evenly mixed to form a first mixture, wherein the mass ratio of the binder to the conductive agent is 5:95.

[0056] Preparation Example 2

[0057] The binder is dissolved using a solvent until the binder is completely dissolved to form a binder solvent, a conductive agent is added to the binder solvent, and the mixture is evenly mixed to form a first mixture, wherein the mass ratio of the binder to the conductive agent is 10:90.

[0058] Preparation Example 3

[0059] The binder is dissolved using a solvent until the binder is completely dissolved to form a binder solvent, a conductive agent is added to the binder solvent, and the mixture is evenly mixed to form a first mixture, wherein the mass ratio of the binder to the conductive agent is 15:85.

[0060] Preparation Example 4

[0061] The binder is dissolved using a solvent until the binder is completely dissolved to form a binder solvent, a conductive agent is added to the binder solvent, and the mixture is evenly mixed to form a first mixture, wherein the mass ratio of the binder to the conductive agent is 20:80.

[0062] Preparation Example 5

[0063] The binder is dissolved using a solvent until the binder is completely dissolved to form a binder solvent, a conductive agent is added to the binder solvent, and the mixture is evenly mixed to form a first mixture, wherein the mass ratio of the binder to the conductive agent is 25:75.

[0064] Preparations 6 to 10 were used to prepare different second mixtures.

[0065] Preparation Example 6

[0066] A solvent is used to dissolve the binder until the binder is completely dissolved to form a binder solvent, and a conductive agent and an active material are added to the binder solvent. After mixing evenly, a second mixture is formed, wherein the mass ratio of the active material, the conductive agent and the binder is 75:10:15.

[0067] Preparation Example 7

[0068] A solvent is used to dissolve the binder until the binder is completely dissolved to form a binder solvent, and a conductive agent and an active material are added to the binder solvent. After mixing evenly, a second mixture is formed, wherein the mass ratio of the active material, the conductive agent and the binder is 80:8:12.

[0069] Preparation Example 8

[0070] A solvent is used to dissolve the binder until the binder is completely dissolved to form a binder solvent, and a conductive agent and an active material are added to the binder solvent. After mixing evenly, a second mixture is formed, wherein the mass ratio of the active material, the conductive agent and the binder is 85:5:10.

[0071] Preparation Example 9

[0072] The binder is dissolved using a solvent until the binder is completely dissolved to form a binder solvent, a conductive agent and an active material are added to the binder solvent, and the mixture is evenly mixed to form a second mixture, wherein the mass ratio of the active material, the conductive agent and the binder is 90:3:7.

[0073] Preparation Example 10

[0074] A solvent is used to dissolve the binder until the binder is completely dissolved to form a binder solvent, and a conductive agent and an active material are added to the binder solvent. After mixing evenly, a second mixture is formed, wherein the mass ratio of the active material, the conductive agent and the binder is 95:2:3.

[0075] It should be noted that the embodiments of this application use aluminum foil as the current collector to prepare the positive electrode sheet, but this should not be understood as a limitation of this application. In some other specific embodiments, copper foil can also be used as the current collector to prepare the negative electrode sheet.

[0076] Example 1

[0077] The electrode sheet of this embodiment adopts:

[0078] 10 g of the first mixture in Preparation Example 1;

[0079] 200 g of the second mixture of Preparation Example 10.

[0080] The electrode sheet of this embodiment is prepared by the following method:

[0081] 1. Rolling the first mixture to form a first film layer, and rolling the second mixture to form a second film layer;

[0082] 2. The first film layer and the aluminum foil are hot-pressed and laminated at 200° C., and then the second film layer and the aluminum foil are hot-pressed and laminated to form an electrode sheet.

[0083] Example 2

[0084] The electrode sheet of this embodiment adopts:

[0085] 5g of the first mixture in Preparation Example 2;

[0086] 200 g of the second mixture of Preparation Example 9.

[0087] The electrode sheet of this embodiment is prepared by the following method:

[0088] 1. Rolling the first mixture to form a first film layer, and rolling the second mixture to form a second film layer;

[0089] 2. The first film layer and the aluminum foil are hot-pressed and laminated at 200° C., and then the second film layer and the aluminum foil are hot-pressed and laminated to form an electrode sheet.

[0090] Example 3

[0091] The electrode sheet of this embodiment adopts:

[0092] 3.4 g of the first mixture in Preparation Example 3;

[0093] 200 g of the second mixture of Preparation Example 8.

[0094] The electrode sheet of this embodiment is prepared by the following method:

[0095] 1. Rolling the first mixture to form a first film layer, and rolling the second mixture to form a second film layer;

[0096] 2. The first film layer and the aluminum foil are hot-pressed and laminated at 200° C., and then the second film layer and the aluminum foil are hot-pressed and laminated to form an electrode sheet.

[0097] Example 4

[0098] The electrode sheet of this embodiment adopts:

[0099] 2.5 g of the first mixture in Preparation Example 4;

[0100] 200 g of the second mixture of Preparation Example 7.

[0101] The electrode sheet of this embodiment is prepared by the following method:

[0102] 1. Rolling the first mixture to form a first film layer, and rolling the second mixture to form a second film layer;

[0103] 2. The first film layer and the aluminum foil are hot-pressed and laminated at 200° C., and then the second film layer and the aluminum foil are hot-pressed and laminated to form an electrode sheet.

[0104] Example 5

[0105] The electrode sheet of this embodiment adopts:

[0106] 2g of the first mixture in Preparation Example 5;

[0107] 200 g of the second mixture of Preparation Example 6.

[0108] The electrode sheet of this embodiment is prepared by the following method:

[0109] 1. Rolling the first mixture to form a first film layer, and rolling the second mixture to form a second film layer;

[0110] 2. The first film layer and the aluminum foil are hot-pressed and laminated at 200° C., and then the second film layer and the aluminum foil are hot-pressed and laminated to form an electrode sheet.

[0111] Comparative Example 1

[0112] The electrode sheet of this comparative example adopts:

[0113] 10 g of the first mixture in Preparation Example 1;

[0114] 200 g of the second mixture of Preparation Example 10.

[0115] The electrode sheet of this comparative example was prepared by the following method:

[0116] 1. Evenly mixing the first mixture and the second mixture to form a third mixture, and rolling the third mixture to form an electrode film;

[0117] 2. Hot pressing the electrode film and aluminum foil at 200°C to form an electrode sheet.

[0118] Comparative Example 2

[0119] The electrode sheet of this comparative example adopts:

[0120] 5g of the first mixture in Preparation Example 2;

[0121] 200 g of the second mixture of Preparation Example 9.

[0122] The electrode sheet of this comparative example was prepared by the following method:

[0123] 1. Evenly mixing the first mixture and the second mixture to form a third mixture, and rolling the third mixture to form an electrode film;

[0124] 2. Hot pressing the electrode film and aluminum foil at 200°C to form an electrode sheet.

[0125] Comparative Example 3

[0126] The electrode sheet of this comparative example adopts:

[0127] 3.4 g of the first mixture in Preparation Example 3;

[0128] 200 g of the second mixture of Preparation Example 8.

[0129] The electrode sheet of this comparative example was prepared by the following method:

[0130] 1. Evenly mixing the first mixture and the second mixture to form a third mixture, and rolling the third mixture to form an electrode film;

[0131] 2. Hot pressing the electrode film and aluminum foil at 200°C to form an electrode sheet.

[0132] Comparative Example 4

[0133] The electrode sheet of this comparative example adopts:

[0134] 2.5 g of the first mixture in Preparation Example 4;

[0135] 200 g of the second mixture of Preparation Example 7.

[0136] The electrode sheet of this comparative example was prepared by the following method:

[0137] 1. Evenly mixing the first mixture and the second mixture to form a third mixture, and rolling the third mixture to form an electrode film;

[0138] 2. Hot pressing the electrode film and aluminum foil at 200°C to form an electrode sheet.

[0139] Comparative Example 5

[0140] The electrode sheet of this comparative example adopts:

[0141] 2g of the first mixture in Preparation Example 5;

[0142] 200 g of the second mixture of Preparation Example 6.

[0143] The electrode sheet of this comparative example was prepared by the following method:

[0144] 1. Evenly mixing the first mixture and the second mixture to form a third mixture, and rolling the third mixture to form an electrode film;

[0145] 2. Hot pressing the electrode film and aluminum foil at 200°C to form an electrode sheet.

[0146] Performance Testing

[0147] Peel strength test

[0148] According to GB / T 2792-1998, the electrode sheets prepared in Examples 1-5 and Comparative Examples 1-5 were subjected to a peel strength test.

[0149] Resistance test: Four-probe method to test the electrode resistance;

[0150] Experimental method: Cut the electrode into a square size of 4cm×8cm, then place the electrode under the two probes. The two probes are connected to the resistance meter through two poles. Turn the handle of the test device to squeeze the electrode with a stable pressure. The pressure is controlled by the pressure gauge. After reaching a certain pressure, read the resistance data of the resistance meter. This data is the relative value of the electrode resistance.

[0151] The performance of the electrode sheets prepared in Examples 1 to 5 and Comparative Examples 1 to 5 was tested according to the above method, as shown in Table 1 below.

[0152] Table 1

[0153] From the data in Table 1, the test results of Examples 1 to 5, and Comparative Examples 1 to 5, it can be seen that, under the same hot pressing method, the double-layer composite structure film layer has better conductive bonding than the single-layer structure film layer, and the masterbatch and the aluminum foil are more firmly bonded and not easy to fall off. Specifically:

[0154] First, the first film layer does not contain active substances, so that the active substances do not directly contact the aluminum foil, eliminating the influence of the large interface impedance between the foil and the active substances, so the adhesion between the first film layer and the aluminum foil is stronger;

[0155] Secondly, the second film layer and the first film layer have the same adhesive composition, and the same substances are more likely to combine at the molecular level, so the overall bonding effect between the second film layer and the first film layer is good;

[0156] Finally, the conductive agent of the second film layer has the same composition as that of the first film layer. Therefore, the first film layer can form a current transmission channel between the second film layer and the aluminum foil, ensuring that the conductivity of the electrode sheet is not affected.

[0157] In the present application, the ratio of the conductive agent, the binder in the first film layer and the conductive agent, the binder and the active material in the second film layer has a synergistic effect. Based on this, the present application is based on Example 2 and designs Examples 6 to 14. In Examples 6 to 14, except for the changes in the preparation examples selected for the first mixture and the second mixture, the preparation methods remain unchanged. See Table 2 for details.

[0158] Table 2

[0159] Electrode sheets were prepared and tested for Examples 6 to 14. The test results are shown in Table 3.

[0160] Table 3

[0161] From the data in Table 3 combined with Examples 2 and 6 to 14, it can be seen that when the mass ratio of the binder to the conductive agent in the first film layer is (10-20): (80-90) and the mass ratio of the active material, the conductive agent and the binder in the second film layer is (85-90): (3-5): (7-10), the binder is well balanced in the two film layers, the bond between the masterbatch and the aluminum foil is stronger, and the tensile properties of the electrode sheet are more prominent.

[0162] This application also provides another preparation method, which uses electrospinning to prepare electrode sheets. Based on this, this application sets Examples 15-17 corresponding to Examples 8-10. Except for the preparation method, everything else remains unchanged, as follows:

[0163] Example 15

[0164] Different from Example 8, the preparation method of the electrode sheet in this embodiment is:

[0165] 1. Under a high voltage of 15 kV and a negative voltage of -2 kV, the first mixture was electrospun onto the surface of an aluminum foil at a rate of 50 mL / min to form a first film layer, and then the second mixture was electrospun onto the surface of the first film layer to form a second film layer;

[0166] 2. Roll-press the aluminum foil at 200°C to obtain an electrode sheet.

[0167] Example 16

[0168] Different from Example 9, the preparation method of the electrode sheet in this embodiment is:

[0169] 1. Under a high voltage of 15 kV and a negative voltage of -2 kV, the first mixture was electrospun onto the surface of an aluminum foil at a rate of 50 mL / min to form a first film layer, and then the second mixture was electrospun onto the surface of the first film layer to form a second film layer;

[0170] 2. Roll-press the aluminum foil at 100°C to obtain an electrode sheet.

[0171] Example 17

[0172] Different from Example 10, the preparation method of the electrode sheet in this embodiment is:

[0173] 1. Under a high voltage of 15 kV and a negative voltage of -2 kV, the first mixture was electrospun onto the surface of an aluminum foil at a rate of 50 mL / min to form a first film layer, and then the second mixture was electrospun onto the surface of the first film layer to form a second film layer;

[0174] 2. Roll-press the aluminum foil at 300°C to obtain an electrode sheet.

[0175] Electrode sheets were prepared and tested for Examples 15-17. The test results are shown in Table 4.

[0176] Table 4

[0177] Through the data in Table 3 and Table 4, and the test results of Examples 8-10 and 15-17, it can be seen that the electrode sheet prepared by the electrospinning method has a more outstanding tensile effect than the traditional hot pressing method. Specifically, the first film layer can be directly grown on the surface of the aluminum foil, thereby increasing the bonding effect between the film layer and the aluminum foil. At the same time, the second film layer can continue to grow based on the first film layer, thereby forming the prototype of the electrode sheet and improving the bonding effect between the aluminum foil, the first film layer and the second film layer.

[0178] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. An electrode sheet, including a current collector, wherein: It also includes a first film layer and a second film layer sequentially stacked on the current collector, wherein the first film layer is disposed between the second film layer and the current collector; The mass ratio of the first film layer to the second film layer is 1:(20-100); The first film layer includes a binder and a conductive agent; The second film layer includes an active material, a conductive agent and a binder.

2. The electrode sheet according to claim 1, wherein The mass ratio of the binder to the conductive agent in the first film layer is (5-25): (75-95).

3. The electrode sheet according to claim 1 or 2, wherein: The mass ratio of the active material, the conductive agent and the binder in the second film layer is (75-95): (2-10): (3-15).

4. The electrode sheet according to any one of claims 1 to 3, wherein: The thickness ratio of the first film layer to the second film layer is (1:100)-(5:100).

5. The electrode sheet according to any one of claims 1 to 4, wherein: The thickness of the first film layer is 1 μm-10 μm.

6. The electrode sheet according to any one of claims 1 to 5, wherein: The thickness of the second film layer is 30 μm-250 μm.

7. The electrode sheet according to any one of claims 1 to 6, wherein: The current collector includes aluminum foil or copper foil.

8. The electrode sheet according to any one of claims 1 to 7, wherein: The peel strength of the first film layer is greater than or equal to 160 N / m.

9. A method for preparing the electrode sheet according to any one of claims 1 to 8, wherein: Dissolving the binder with a solvent until the binder is completely dissolved to form a binder solvent, adding a conductive agent to the binder solvent, and mixing them evenly to form a first mixture; Dissolving the binder with a solvent until the binder is completely dissolved to form a binder solvent, adding a conductive agent and an active material to the binder solvent, and mixing them evenly to form a second mixture; Electrospinning the first mixture onto the surface of the current collector to form a first film layer, and then electrospinning the second mixture onto the surface of the first film layer to form a second film layer; The current collector having the first film layer and the second film layer stacked in sequence on its surface is rolled to obtain an electrode sheet.

10. The method for forming an electrode sheet according to claim 9, wherein: The electrospinning parameters are: an extrusion speed of 1 mL / min to 1000 mL / min; and / or a high voltage of 15 kV to 22 kV; and / or a negative pressure of -1 kV to -3 kV.

11. The method for producing an electrode sheet according to claim 9 or 10, wherein: The temperature of the roller pressing is 100°C-300°C.

12. Lithium iron phosphate soft pack battery, wherein: The electrode sheet comprises the electrode sheet according to any one of claims 1 to 8, or the electrode sheet prepared by the method according to any one of claims 9 to 11.

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