Positive pole piece, secondary battery and electric equipment

Abstract

The utility model discloses a positive pole piece, a secondary battery and electric equipment. The positive pole piece comprises a positive current collector, and a lithium supplementing layer and a protective layer which are sequentially arranged on the surface of the positive current collector; the protective layer is provided with through holes penetrating through the protective layer along the direction from being far away from the positive current collector to being close to the positive current collector, and the hole pitch A between the through holes is not greater than 5mm. According to the positive pole piece disclosed by the utility model, the protective layer is arranged on the surface of the lithium supplementing layer, so that a lithium supplementing agent in the lithium supplementing layer is not easy to react with water due to the protection of the protective layer no matter in a preparation process or a storage process of the pole piece, the capacity exertion of the lithium supplementing agent is improved, and the charging capacity of the positive pole piece for a secondary battery (such as a lithium ion battery) is improved. The arrangement of the through holes can reduce the transmission distance of Li < + >, so that the electrolyte can enter the pole piece, the charging capacity of the battery is enhanced, and the charging capacity is high.

Description

Technical Field

[0001] The utility model belongs to the technical field of battery materials, and in particular relates to a positive electrode sheet, a secondary battery and an electrical device. Background Art

[0002] As the negative electrode material, silicon carbon forms a thick SEI layer on the surface of the silicon negative electrode during the formation process, which consumes a lot of Li + , which reduces the battery's initial coulombic efficiency and battery capacity, thereby reducing the battery's energy density. Based on this, a lithium replenisher is needed to compensate for the loss of Li. At present, a lithium replenisher layer is usually coated on the surface of the positive electrode current collector to improve the battery's initial coulombic efficiency. However, the lithium replenisher in the lithium replenisher layer of the positive electrode sheet in the related art is more active and easily absorbs water. During the preparation (such as coating, laser cleaning, rolling, slitting, sheeting, winding, top and side sealing, etc.) and storage process, it is easy to react with water and deteriorate, causing the charging capacity to drop sharply, thereby greatly affecting the lithium replenishment effect, and the battery's initial coulombic efficiency is low. Utility Model Content

[0003] The present invention aims to solve at least one of the technical problems in the prior art. To this end, the present invention provides a positive electrode plate comprising a lithium replenishing layer and a protective layer, which is used in a battery with a high initial coulombic efficiency.

[0004] The utility model also provides a secondary battery.

[0005] The utility model also provides an electrical device.

[0006] In a first aspect of the present invention, a positive electrode sheet is proposed, comprising a positive electrode current collector and a lithium replenishing layer and a protective layer sequentially arranged on the surface of the positive electrode current collector; the protective layer is provided with through holes penetrating the protective layer along a direction from away from the positive electrode current collector to close to the positive electrode current collector, and the hole spacing A between the through holes is not greater than 5 mm.

[0007] The positive electrode sheet according to the embodiment of the present invention has at least the following beneficial effects:

[0008] The surface of the lithium replenishing layer in the positive electrode of the utility model is provided with a protective layer. Whether in the process of preparing the electrode or in the storage process, the lithium replenishing agent in the lithium replenishing layer is not easily reacted with water due to the protection of the protective layer, thereby improving the capacity of the lithium replenishing agent and improving the charging capacity of the positive electrode for secondary batteries (such as lithium-ion batteries). Compared with the setting without through-holes in the protective layer, the setting of through-holes in the utility model can reduce the Li + The transmission distance is good for the electrolyte to enter the electrode, which enhances the battery charging ability and high charging capacity. Therefore, the positive electrode of the present invention has both the stability of the electrode lithium replenishment layer and the Li +The transmission efficiency is high, and the secondary battery used has high coulombic efficiency for the first time.

[0009] In some embodiments of the present invention, the thickness T1 of the lithium replenishing layer is 5-100 μm, such as 10-50 μm. The thickness of the lithium replenishing layer can be adjusted according to different energy density requirements of the battery.

[0010] In some embodiments of the present invention, the thickness T2 of the protective layer is 5-50 μm, such as 5-20 μm.

[0011] In some embodiments of the present invention, T2 <T1。

[0012] The main function of the protective layer is to block water in the air. Compared with T1≤T2, the charging capacity of Li5FeO4 in the lithium replenishment layer will be better.

[0013] In some embodiments of the present invention, the lithium replenishing layer is any one of a lithium ferrite lithium replenishing layer, a lithium nickelate lithium replenishing layer, a lithium cobaltate lithium replenishing layer, a lithium manganate lithium replenishing layer, a lithium molybdate lithium replenishing layer, a lithium rhenate lithium replenishing layer, a lithium ruthenium lithium replenishing layer, a lithium oxide lithium replenishing layer, a lithium peroxide lithium replenishing layer, a lithium nitride lithium replenishing layer, a lithium sulfide lithium replenishing layer, a lithium fluoride lithium replenishing layer, a lithium carbonate lithium replenishing layer, and a lithium oxalate lithium replenishing layer. The lithium replenishing material in the lithium ferrite lithium replenishing layer is lithium ferrite such as Li5FeO4. Li5FeO4 has the advantages of high capacity as a positive electrode lithium replenishing agent and is one of the most competitive positive electrode lithium replenishing agents. The lithium replenishing layer contains lithium ferrite, and the lithium replenishing effect of the lithium replenishing layer is good, and the capacity of the battery is high. The lithium replenishing material in the lithium nickelate lithium replenishing layer is lithium nickelate such as Li2NiO2, which is similar to lithium ferrite. It is a composite oxide with a high lithium content and has a good lithium replenishing effect. It can be understood that it also includes Li 0.65 Ni 1.35 O2, etc. In addition, the lithium cobaltate lithium supplement material in the lithium cobaltate lithium supplement material layer is lithium cobaltate such as Li6CoO4, the lithium manganate lithium supplement material in the lithium manganate lithium supplement material layer is lithium manganate such as Li2MnO3, the lithium molybdate lithium supplement material in the lithium molybdate lithium supplement material layer is lithium molybdate such as Li2MoO3, the lithium rhenate lithium supplement material in the lithium rhenate lithium supplement material layer is lithium rhenate such as Li5ReO6, the lithium ruthenium lithium supplement material in the lithium ruthenium lithium supplement material layer is lithium ruthenium such as Li2RuO3, the lithium oxide lithium supplement material in the lithium oxide lithium supplement material layer is lithium oxide such as Li2O, the lithium peroxide lithium supplement material in the lithium peroxide lithium supplement material layer is lithium peroxide such as Li2O2, the lithium nitride lithium supplement material in the lithium nitride lithium supplement material layer is lithium nitride such as Li3N, the lithium sulfide lithium supplement material in the lithium sulfide lithium supplement material layer is lithium sulfide such as Li2S, the lithium fluoride lithium supplement material in the lithium fluoride lithium supplement material layer is lithium fluoride such as LiF, the lithium carbonate lithium supplement material in the lithium carbonate lithium supplement material layer is lithium carbonate such as Li2CO3, and the lithium oxalate lithium supplement material in the lithium oxalate lithium supplement layer is lithium oxalate such as Li2C2O4.

[0014] In some embodiments of the present utility model, the mass fraction of the lithium supplement material in the lithium supplement layer is W1, and W1 is 0.1% - 5%. For example, W1 can be 0.5% - 2%.

[0015] Through the above embodiments, W1 is 0.1% - 5%. Within this range, the demand for improving the positive electrode Coulomb efficiency can be met. Compared with W1 < 0.1%, the lithium supplement effect is more significant when W1 is 0.1% - 5%. Compared with W1 > 5%, when W1 is 0.1% - 5%, while the lithium supplement effect is significant, the discharge specific capacity after the first cycle will increase significantly.

[0016] In some embodiments of the present utility model, the protective layer is any one of a lithium ferrite protective layer, a lithium nickelate protective layer, a lithium cobaltate protective layer, a lithium manganate protective layer, a lithium molybdate protective layer, a lithium rhenate protective layer, a lithium ruthenate protective layer, a lithium oxide protective layer, a lithium peroxide protective layer, a lithium nitride protective layer, a lithium sulfide protective layer, a lithium fluoride protective layer, a lithium carbonate protective layer, a lithium oxalate protective layer. Taking the lithium ferrite protective layer as an example, the lithium ferrite protective layer contains lithium ferrite, and the mass fraction of lithium ferrite in the protective layer is W2, and W2 < W1. By analogy, in some embodiments, the protective layer contains the same lithium supplement material as in the lithium supplement layer. For example, when the lithium supplement layer is a lithium ferrite lithium supplement layer, the protective layer is a lithium ferrite protective layer.

[0017] Taking the lithium ferrite lithium supplement layer and the lithium ferrite protective layer as an example, within this range, the reaction between Li5FeO4 and water can be effectively reduced. If it exceeds the range, the amount of deteriorated Li5FeO4 will increase significantly, thus reducing the lithium supplement effect.

[0018] In some embodiments of the present utility model, W2 is 0.1% - 5%. For example, W2 can be 0.5% - 2%.

[0019] Through the above embodiments, when the positive electrode plate is used in a secondary battery, the lithium supplement effect of the lithium supplement layer is better, and the first Coulomb efficiency of the battery is higher.

[0020] In some embodiments of the present utility model, some or all of the through holes penetrate the lithium supplement layer.

[0021] In some embodiments of the present utility model, the hole pitch A between the through holes is 0.5 - 5 mm.

[0022] Through the above embodiments, compared with A < 0.5 mm, when A is 0.5 - 5 mm, the positive electrode material is not likely to be lost. Compared with A > 5 mm, when A is 0.5 - 5 mm, the charging ability of the battery is significantly improved.

[0023] In some embodiments of the present utility model, some or all of the through holes extend into the lithium supplement layer.

[0024] Through the above embodiments, by providing through holes in the electrode sheet, the entry of the electrolyte into the electrode sheet can be further promoted, thereby enhancing the charging capacity of the materials in the lithium supplement layer of the electrode sheet.

[0025] In some embodiments of the present invention, the hole depth D of the through hole satisfies: T2 ≤ D ≤ T1 + T2.

[0026] Through the above embodiments, compared with D < T2, when T2 ≤ D ≤ T1 + T2, there can be a fast channel in the lithium supplement layer to transport Li + ; compared with D > T1 + T2, when T2 ≤ D ≤ T1 + T2, the chance of the Li5FeO4 in the lithium supplement layer contacting moisture in the air is further reduced, and at the same time, the loss of the positive electrode material is reduced, and the processing difficulty is reduced (for example, during the process of drilling the through hole, it is not easy to drill through the current collector and the tape may break).

[0027] In some embodiments of the present invention, D is 10 - 30 μm.

[0028] In some embodiments of the present invention, the aperture of the through hole is 5 - 100 μm.

[0029] In some embodiments of the present invention, the end face area of the through hole on the surface of the protective layer accounts for 0.01% - 5% of the surface area of the protective layer.

[0030] In some embodiments of the present invention, the thickness of the positive electrode current collector is 3 - 10 μm.

[0031] In the second aspect of the present invention, a secondary battery is proposed, including the above positive electrode sheet.

[0032] In some embodiments of the present invention, the secondary battery includes a lithium ion battery.

[0033] In the third aspect of the present invention, an electrical device is proposed, including the above secondary battery, and the secondary battery is used as the power source of the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The following further describes the present invention with reference to the drawings and embodiments, where:

[0035] Figure 1 It is a schematic structural diagram of Embodiment 1 of the present invention.

[0036] Reference numerals: 1, positive electrode current collector; 2, lithium supplement layer; 3, protective layer; 4, through hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features, and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without inventive effort are also within the scope of protection of the present invention.

[0038] The experimental methods in the following examples, for which specific conditions are not specified, are generally performed in accordance with conventional conditions in the art or conditions recommended by the manufacturers; the raw materials and reagents used, unless otherwise specified, are all commercially available from conventional markets.

[0039] Example 1

[0040] This embodiment discloses a positive electrode plate, the structure of which is as follows: Figure 1 As shown, it includes a positive electrode current collector (aluminum foil with a thickness of 8μm) and a lithium replenishment layer and a protective layer sequentially arranged on the surface of the current collector. The lithium replenishment layer is a lithium ferrite replenishment layer containing lithium ferrite, with a thickness T1 of 40μm, a mass fraction W1 of lithium ferrite in the lithium replenishment layer of 0.8%, a LiCoO2 content of 97.32%, a polyvinylidene fluoride content of 0.5%, a Super P content of 0.5%, and a CNT content of 0.88%. The protective layer has a thickness T2 of 10μm and contains lithium ferrite, with a mass fraction W2 of 0.2%, a LiCoO2 content of 97.92%, a polyvinylidene fluoride content of 0.5%, a Super P content of 0.5%, and a CNT content of 0.88%. The protective layer has through-holes extending from the current collector to the current collector, and the pore spacing A between the through-holes extending into the lithium replenishment layer is 1.0mm. The hole depth D of the through hole is 15 μm, the hole diameter of the through hole is 80 μm, and the end surface area of ​​the through hole on the surface of the protective layer accounts for 0.1% of the surface area of ​​the protective layer.

[0041] The preparation process of the positive electrode sheet specifically includes:

[0042] (I) Preparation of lithium supplementation layer slurry: parameter W1 is 0.8%;

[0043] (II) coating the lithium replenishing layer slurry with a parameter T1 of 40 μm to form a coating 1;

[0044] (III) preparing a protective layer slurry with a parameter W2 of 0.2%;

[0045] (IV) coating the protective layer slurry on coating 1, with parameter T2 being 10 μm;

[0046] (V) Laser drilling the electrode with parameter A of 1.0 mm and parameter D of 15 μm;

[0047] This embodiment also provides a lithium-ion battery, including the positive electrode plate in this embodiment.

[0048] This embodiment further provides an electrical device, including the lithium-ion battery in this embodiment, and the lithium-ion battery serves as a power source for the electrical device.

[0049] Example 2

[0050] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that W1 in the positive electrode plate of this embodiment is set to 5%, and W2 is set to 0.2%.

[0051] This embodiment also provides a lithium-ion battery, including the positive electrode plate in this embodiment.

[0052] This embodiment further provides an electrical device, including the lithium-ion battery in this embodiment, and the lithium-ion battery serves as a power source for the electrical device.

[0053] Example 3

[0054] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that W1 in the positive electrode plate of this embodiment is set to 0.8%, and W2 is set to 0.6%.

[0055] This embodiment also provides a lithium-ion battery, including the positive electrode plate in this embodiment.

[0056] This embodiment further provides an electrical device, including the lithium-ion battery in this embodiment, and the lithium-ion battery serves as a power source for the electrical device.

[0057] Example 4

[0058] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that W1 in the positive electrode plate of this embodiment is set to 0.2%, and W2 is set to 0%.

[0059] This embodiment also provides a lithium-ion battery, including the positive electrode plate in this embodiment.

[0060] This embodiment further provides an electrical device, including the lithium-ion battery in this embodiment, and the lithium-ion battery serves as a power source for the electrical device.

[0061] Example 5

[0062] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that: in this embodiment, T1 of the positive electrode plate is set to 30 μm, T2 is set to 20 μm, and the through-hole depth D is set to 25 μm.

[0063] This embodiment also provides a lithium-ion battery, including the positive electrode plate in this embodiment.

[0064] This embodiment further provides an electrical device, including the lithium-ion battery in this embodiment, and the lithium-ion battery serves as a power source for the electrical device.

[0065] Example 6

[0066] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that the hole spacing A in the positive electrode plate in this embodiment is set to 2.0 mm.

[0067] This embodiment also provides a lithium-ion battery, including the positive electrode plate in this embodiment.

[0068] This embodiment further provides an electrical device, including the lithium-ion battery in this embodiment, and the lithium-ion battery serves as a power source for the electrical device.

[0069] Example 7

[0070] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that the hole spacing A in the positive electrode plate in this embodiment is set to 1.5 mm.

[0071] This embodiment also provides a lithium-ion battery, including the positive electrode plate in this embodiment.

[0072] This embodiment further provides an electrical device, including the lithium-ion battery in this embodiment, and the lithium-ion battery serves as a power source for the electrical device.

[0073] Example 8

[0074] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that the hole spacing A in the positive electrode plate in this embodiment is set to 0.5 mm.

[0075] This embodiment also provides a lithium-ion battery, including the positive electrode plate in this embodiment.

[0076] This embodiment further provides an electrical device, including the lithium-ion battery in this embodiment, and the lithium-ion battery serves as a power source for the electrical device.

[0077] Example 9

[0078] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that the through-hole depth D in the positive electrode plate in this embodiment is 10 μm.

[0079] This embodiment also provides a lithium-ion battery, including the positive electrode plate in this embodiment.

[0080] This embodiment further provides an electrical device, including the lithium-ion battery in this embodiment, and the lithium-ion battery serves as a power source for the electrical device.

[0081] Example 10

[0082] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that the through-hole depth D in the positive electrode plate in this embodiment is 30 μm.

[0083] This embodiment also provides a lithium-ion battery, including the positive electrode plate in this embodiment.

[0084] This embodiment further provides an electrical device, including the lithium-ion battery in this embodiment, and the lithium-ion battery serves as a power source for the electrical device.

[0085] Example 11

[0086] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that the through-hole depth D in the positive electrode plate in this embodiment is 45 μm.

[0087] This embodiment also provides a lithium-ion battery, including the positive electrode plate in this embodiment.

[0088] This embodiment further provides an electrical device, including the lithium-ion battery in this embodiment, and the lithium-ion battery serves as a power source for the electrical device.

[0089] Example 12

[0090] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that the hole spacing A in the positive electrode plate in this embodiment is set to 3.0 mm.

[0091] Example 13

[0092] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that W1 in the positive electrode plate of this embodiment is 0.2% and W2 is 0.8%.

[0093] Example 14

[0094] This embodiment discloses a positive electrode plate, which differs from the embodiment 1 only in that T1 in the positive electrode plate of this embodiment is 10 μm and T2 is 40 μm.

[0095] Test example

[0096] This test example tested the performance of the positive electrode sheets obtained in the examples and comparative examples, specifically including:

[0097] The negative electrode material (graphite negative electrode), electrolyte (lithium ion battery electrolyte), separator (PP) and other components were controlled to be the same. The positive electrode sheets were prepared according to Examples 1-14, and the soft pack batteries were assembled and the first performance test was carried out. The test results are shown in Table 1:

[0098] Table 1

[0099]

[0100]

[0101] It can be seen from the data in Table 1 that the first coulombic efficiency of Example 2 is 0.3% lower than that of Example 1. The main reason is that the lithium replenishing agent content of the lithium replenishing layer of Example 2 is relatively high (5%), and the capacity of the lithium replenishing agent is not fully utilized. The coulombic efficiency of Example 3 is 0.1% lower than that of Example 1. The main reason is that the lithium replenishing agent content of the protective layer is relatively high (0.6%). The high content of the lithium replenishing agent will lead to increased contact between the lithium replenishing agent and the air, thereby increasing side reactions, and the de-Li capacity will be reduced. The first efficiency of Example 4 is 92.3%. The main reason is that the amount of lithium replenishing agent used is low (0.2%), and the lithium replenishing effect is not as obvious as that of Example 1. The first efficiency of Example 5 is reduced by 1.4% compared with Example 1. The main reason is that the thickness of the protective layer is too thick, resulting in a lower capacity of the lithium replenishing layer compared to Example 1. At the same time, the deeper the drilling depth, the more lithium replenishing agent is exposed to the air, resulting in increased failure of the lithium replenishing agent, and thus the first efficiency is reduced compared to Example 1. In Example 12 and Examples 6-7, 1, the perforation spacing decreases successively (3 / 2 / 1.5 / 1mm), showing a pattern of increasing first efficiency. This is mainly due to the significant improvement in the charging capacity of the material after the perforation spacing decreases. At the same time, since the lithium replenisher content in the protective layer is relatively low, the perforation does not cause more lithium replenisher to react with water in the air. Therefore, as the perforation spacing decreases, the first efficiency continues to increase. When the spacing is further reduced to 0.5mm (Example 8), the first efficiency is slightly lower than that of Example 1 (-0.1%). The main reason is that the perforation spacing is too small, and the side reaction between the positive electrode lithium replenisher in the protective layer material and water in the air increases compared to Example 1. Compared with Example 1, the first effect of Example 9 is reduced by 0.5%, mainly because the drilling depth is shallower than that of Example 1, and the capacity of the positive electrode lithium replenisher is not fully utilized; compared with Example 1, the first effects of Examples 10-11 are reduced by 1% and 2.2% respectively. The main reason is that as the drilling depth deepens, the capacity of the lithium replenisher increases accordingly, but the side reaction with water in the air also increases, so that the lithium replenishment effect is worse than that of Example 1. Compared with Example 1, the first effect of Example 13 is reduced by 6%, mainly because the content of the protective layer (0.8%) is much higher than the content of the lithium replenisher layer (0.2%), resulting in the protective layer on the upper layer of the electrode unable to play a protective role. A large amount of lithium replenisher will still react with the air and become inactivated, so the lithium replenishment effect is not good. Compared with Example 1, the first effect of Example 14 is reduced by 4%, mainly because the lithium replenisher layer is thin (10μm) and the protective layer is thick (40μm), and the content of lithium replenisher in the protective layer is low, so it cannot play a good role in improving the first effect.

[0102] This utility model minimizes side reactions between Li5FeO4 and water in the air by controlling the content of the lithium-replenishing agent in the lithium-replenishing layer and protective layer, the coating thickness, and the drilling depth. This simultaneously improves the charging capacity of Li5FeO4, thereby maximizing the lithium-replenishing effect of Li5FeO4. Specifically, a double-layer coating technique is used to control the Li5FeO4 content in the protective layer, thereby reducing side reactions between Li5FeO4 and water in the air. Furthermore, laser drilling is used to increase the charging capacity of the Li5FeO4 in the lithium-replenishing layer material. By leveraging the synergistic effect of these two technologies, the capacity of Li5FeO4 in the composite electrode is enhanced, maximizing the lithium-replenishing effect of the positive electrode lithium-replenishing agent.

[0103] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various modifications can be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. In addition, the embodiments of the present invention and the features of the embodiments can be combined with each other unless there is a conflict.

Claims

1. A positive electrode plate, characterized in that: It includes a positive electrode current collector and a lithium replenishing layer and a protective layer sequentially arranged on the surface of the positive electrode current collector; along the direction from away from the positive electrode current collector to close to the positive electrode current collector, the protective layer is provided with through holes penetrating the protective layer, and the hole spacing A between the through holes is not greater than 5mm.

2. The positive electrode sheet according to claim 1, characterized in that: The thickness T1 of the lithium replenishing layer is 5-100 μm; and / or the thickness T2 of the protective layer is 5-50 μm.

3. The positive electrode sheet according to claim 1, characterized in that: The lithium-supplementing layer is any one of a lithium ferrite lithium-supplementing layer, a lithium nickelate lithium-supplementing layer, a lithium cobaltate lithium-supplementing layer, a lithium manganate lithium-supplementing layer, a lithium molybdate lithium-supplementing layer, a lithium rhenate lithium-supplementing layer, a lithium ruthenate lithium-supplementing layer, a lithium oxide lithium-supplementing layer, a lithium peroxide lithium-supplementing layer, a lithium nitride lithium-supplementing layer, a lithium sulfide lithium-supplementing layer, a lithium fluoride lithium-supplementing layer, a lithium carbonate lithium-supplementing layer, and a lithium oxalate lithium-supplementing layer.

4. The positive electrode sheet according to claim 3, characterized in that: The protective layer is any one of a lithium ferrite protective layer, a lithium nickelate protective layer, a lithium cobaltate protective layer, a lithium manganate protective layer, a lithium molybdate protective layer, a lithium rhenate protective layer, a lithium ruthenium oxide protective layer, a lithium oxide protective layer, a lithium peroxide protective layer, a lithium nitride protective layer, a lithium sulfide protective layer, a lithium fluoride protective layer, a lithium carbonate protective layer, and a lithium oxalate protective layer.

5. The positive electrode sheet according to claim 1, characterized in that: Part or all of the through holes penetrate the lithium replenishing layer.

6. The positive electrode sheet according to claim 1, characterized in that: The hole spacing A between the through holes is 0.5-5 mm.

7. The positive electrode sheet according to claim 1, characterized in that: The hole depth D of the through hole satisfies: T2≤D≤T1+T2.

8. The positive electrode sheet according to claim 1, characterized in that: The through hole has a diameter of 5-100 μm.

9. A secondary battery, characterized in that: The positive electrode sheet comprises the positive electrode sheet according to any one of claims 1 to 8.

10. An electrical device, characterized in that: The secondary battery according to claim 9 is included, and the secondary battery is used as a power source for the electric device.

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