Positive plate, battery and electric equipment

Abstract

The invention provides a positive plate, a battery and electric equipment. Relates to the technical field of batteries. The positive plate comprises a current collector, a conductive coating, a first lithium supplementing layer, an active material layer and a second lithium supplementing layer. The first lithium supplementing layer is arranged on at least one side of the current collector in the thickness direction. The active material layer is arranged on the side, away from the current collector, of the first lithium supplementing layer. The second lithium supplementing layer is arranged on one side, deviating from the first lithium supplementing layer, of the active material layer. Wherein the first lithium supplementing layer and the second lithium supplementing layer are mainly used for providing an additional lithium source. The active material layer is a main region in the cell for electrochemical reaction. According to the positive plate provided by the embodiment of the invention, the conductive effect of the positive plate is improved, the internal resistance of the battery is reduced, and the use performance of electric equipment is improved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and in particular to a positive electrode sheet, a battery, and an electrical device. Background Art

[0002] Lithium-ion batteries are rechargeable batteries that are widely used in various electronic devices and electric vehicles due to their high energy density, long cycle life and light weight.

[0003] In the related art, a solid electrolyte interphase (SEI film) will be formed on the surface of the negative electrode of a lithium-ion battery during the initial charging and formation process, which will consume the active lithium in the lithium-ion battery. In addition, the lithium-ion battery will also consume active lithium during subsequent cycles and storage processes. The loss of active lithium is the main source of capacity decay in lithium-ion batteries. At present, lithium replenishment is often performed on the electrode to replenish the active lithium consumed by the SEI film. Lithium replenishment includes negative electrode lithium replenishment and positive electrode lithium replenishment. Negative electrode lithium replenishment refers to the addition of metallic lithium powder or metallic lithium foil to the negative electrode; positive electrode lithium replenishment refers to the addition of lithium compounds to the positive electrode dressing. However, the positive electrode sheet after the addition of the lithium replenisher has the problems of poor conductivity and poor performance. Summary of the Invention

[0004] The present application provides a positive electrode sheet, a battery, and an electrical device, which avoids the problem of decreased conductivity of the positive electrode sheet after lithium supplementation, reduces the internal resistance of the battery, increases the charge and discharge capacity of the battery, improves the charge and discharge efficiency of the battery, increases the number of battery cycles, and improves the performance of the electrical device.

[0005] In a first aspect, an embodiment of the present application provides a positive electrode sheet, which includes a current collector, a first lithium replenishing layer, an active material layer, and a second lithium replenishing layer.

[0006] The first lithium replenishing layer is disposed on at least one side of the current collector in a thickness direction.

[0007] The active material layer is arranged on a side of the first lithium replenishing layer that is away from the current collector.

[0008] The second lithium replenishing layer is arranged on a side of the active material layer that is away from the first lithium replenishing layer.

[0009] In some embodiments of the present application, the porosity of the active material layer is greater than the porosity of the first lithium replenishing layer, and / or the porosity of the second lithium replenishing layer is greater than the porosity of the first lithium replenishing layer.

[0010] In some embodiments of the present application, the porosities of the first lithium replenishing layer, the active material layer, and the second lithium replenishing layer increase in sequence.

[0011] In some embodiments of the present application, at least one of the following limitations is satisfied: the porosity of the first lithium replenishing layer is P1, and P1 satisfies: 25%≤P1≤29%;

[0012] The porosity of the active material layer is Pm, and Pm satisfies: 30%≤Pm≤40%;

[0013] The porosity of the second lithium replenishing layer is P2, and P2 satisfies: 45%≤P2≤50%.

[0014] In some embodiments of the present application, at least one of the following limitations is met:

[0015] The ratio of Pm to P1 is A1, and A1 satisfies: 1.05≤A1≤1.5;

[0016] The ratio of P2 to Pm is A2, and A2 satisfies: 1.2≤A2≤1.7.

[0017] In some embodiments of the present application, the active material layer includes an active lithium supplement.

[0018] In some embodiments of the present application, the first lithium replenishing layer includes a first lithium replenishing agent; and the particle size of the active lithium replenishing agent is larger than the particle size of the first lithium replenishing agent.

[0019] In some embodiments of the present application, the second lithium replenishing layer includes a second lithium replenishing agent; the particle size of the second lithium replenishing agent is larger than the particle size of the active lithium replenishing agent.

[0020] In some embodiments of the present application, the particle size of the first lithium supplement agent is D1, and D1 satisfies: 10 nm ≤ D1 ≤ 80 nm.

[0021] and / or, the particle size of the active lithium supplement agent is Dm, and Dm satisfies: 100 nm ≤ Dm ≤ 350 nm;

[0022] And / or, the particle size of the second lithium supplement agent is D2, and D2 satisfies: 400 nm ≤ D2 ≤ 600 nm.

[0023] In some embodiments of the present application, the mass of the first lithium supplement is M1, the mass of the active lithium supplement is Mm, the mass of the second lithium supplement is M2, and the active material layer includes an active substance, and the mass of the active substance is Mh.

[0024] The mass ratio of M1 to Mh is B1, and B1 satisfies: 0.5%≤B1≤1%.

[0025] The mass ratio of Mm to Mh is Bm, and Bm satisfies: 1%≤Bm≤10%.

[0026] The mass ratio of M2 to Mh is B2, and B2 satisfies: 0.5%≤B2≤1%.

[0027] In some embodiments of the present application, the first lithium supplement includes one or more of Li2CO3, Li2O and Li2O2.

[0028] And / or, the active lithium supplement includes Li2C2O4 and / or Li5FeO4.

[0029] And / or, the second lithium supplement includes one or more of Li2MO2 and Li2N2O3, wherein M includes at least one of Ni, Fe, Cu, and Co, and N includes at least one of Al, Co, Mn, Ni, Fe, Cu, and Si.

[0030] In some embodiments of the present application, there are multiple active material layers, and the porosity of the multiple active material layers increases sequentially from the first lithium replenishing layer to the second lithium replenishing layer.

[0031] In some embodiments of the present application, the positive electrode sheet further includes a conductive coating, which is disposed between the current collector and the first lithium replenishing layer.

[0032] In some embodiments of the present application, the positive electrode sheet further includes a safety layer, and the safety layer is disposed on a side of the second lithium replenishing layer away from the active material layer.

[0033] In some embodiments of the present application, the positive electrode sheet further includes a liquid retaining layer, which is disposed on a side of the second lithium replenishing layer away from the active material layer.

[0034] In some embodiments of the present application, the positive electrode sheet further includes a safety layer and a liquid retention layer.

[0035] The safety layer is arranged on a side of the second lithium replenishing layer away from the active material layer.

[0036] The liquid retaining layer is arranged on a side of the safety layer away from the second lithium replenishing layer.

[0037] In some embodiments of the present application, at least one of the following limitations is met:

[0038] The porosity of the safety layer is P3, and P3 satisfies: 51%≤P3≤55%;

[0039] The porosity of the liquid retaining layer is P4, and P4 satisfies: 56%≤P4≤60%.

[0040] In some embodiments of the present application, the porosity of the second lithium replenishing layer is P2, and at least one of the following requirements is satisfied:

[0041] The ratio of P3 to P2 is A3, and A3 satisfies: 1.02≤A3≤1.3;

[0042] The ratio of P4 to P3 is A4, and A4 satisfies: 1.02≤A4≤1.3.

[0043] In some embodiments of the present application, the safety layer includes inorganic particles and a binder.

[0044] The inorganic particles include at least one of aluminum oxide, aluminum oxide, silicon dioxide, and calcium oxide;

[0045] The binder includes at least one of polyvinyl pyrrolidone, polymethyl methacrylate, polyvinyl alcohol, and polyacrylic acid.

[0046] In some embodiments of the present application, the liquid retaining layer includes at least one of polyvinylidene fluoride and polyimide.

[0047] In some embodiments of the present application, the active material layer includes active substances, and the mass ratio of the inorganic particles to the active substances is B3, and B3 satisfies: 0.5%≤B3≤1%.

[0048] In some embodiments of the present application, the active material layer includes an active substance, and the mass ratio of the liquid retaining layer to the active substance is B4, and B4 satisfies: 0.5%≤B4≤1%.

[0049] In some embodiments of the present application, the current collector includes a base layer and a conductive layer; the conductive layer is provided on at least one side of the base layer in the thickness direction.

[0050] In some embodiments of the present application, the thickness of the base layer is C1, and C1 satisfies: 0.5 μm≤C1≤3.5 μm.

[0051] And / or, the thickness of the conductive layer is C2, and C2 satisfies: 4 μm≤C2≤7 μm.

[0052] In some embodiments of the present application, the base layer includes at least one of polypropylene and polyethylene terephthalate.

[0053] And / or, the conductive layer includes an aluminum layer.

[0054] In a second aspect, an embodiment of the present application provides a battery comprising a positive electrode sheet.

[0055] In a third aspect, an embodiment of the present application provides an electrical device including a battery.

[0056] The present invention provides a positive electrode sheet, a battery, and an electrical device. The positive electrode sheet includes a current collector, a first lithium replenishing layer, an active material layer, and a second lithium replenishing layer. The first lithium replenishing layer is disposed on at least one side of the current collector in the thickness direction. The active material layer is disposed on the side of the first lithium replenishing layer facing away from the current collector. The second lithium replenishing layer is disposed on the side of the active material layer facing away from the first lithium replenishing layer.

[0057] The main function of the first lithium replenishment layer and the second lithium replenishment layer is to provide additional lithium sources to compensate for the lithium loss that may occur in the battery during the cycle. The active material layer is the main area for electrochemical reactions in the battery. The positive electrode provided in the embodiment of the present application avoids the problem of reduced content of the conductive agent per unit volume in the active material layer of the positive electrode by arranging the first lithium replenishment layer between the active material layer and the current collector, and arranging the second lithium replenishment layer on the side of the active material layer away from the first lithium replenishment layer, thereby improving the conductive effect of the positive electrode, reducing the internal resistance of the battery, increasing the charge and discharge capacity of the battery, increasing the charge and discharge efficiency of the battery, and increasing the number of cycles of the battery, and improving the performance of the electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0059] Figure 1 Schematic diagram of the structure of the positive electrode provided in the embodiment of the present application Figure 1 ;

[0060] Figure 2 Schematic diagram of the structure of the positive electrode provided in the embodiment of the present application Figure 2 .

[0061] Description of reference numerals:

[0062] 100: current collector; 110: base layer; 120: conductive layer;

[0063] 200: conductive coating;

[0064] 300: first lithium replenishment layer;

[0065] 400: active material layer;

[0066] 500: second lithium replenishment layer;

[0067] 600: security layer;

[0068] 700: Liquid retention layer.

[0069] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0070] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0071] In the related art, there are many types of positive electrode lithium replenishers, including conventional lithium salts (such as Li2CO3), lithium oxides (such as Li2O), and lithium salts containing other metals (such as Li5FeO4).

[0072] The positive electrode lithium replenisher decomposes during the battery's initial charge, releasing lithium ions and replenishing the battery. Currently, when preparing positive electrode sheets, the positive electrode active material, positive electrode lithium replenisher, and conductive agent are mixed and then coated on the current collector. However, the conductivity of the positive electrode lithium replenisher is lower than that of the positive electrode active material, which reduces the conductive agent content per unit volume of the positive electrode sheet, thereby reducing the conductivity of the positive electrode sheet.

[0073] In view of this, embodiments of the present application provide a positive electrode sheet, a battery, and an electrical device. The positive electrode sheet includes a current collector, a first lithium replenishing layer, an active material layer, and a second lithium replenishing layer. The first lithium replenishing layer is disposed on the side of the conductive coating layer facing away from the current collector. The active material layer is disposed on the side of the first lithium replenishing layer facing away from the conductive coating layer. The second lithium replenishing layer is disposed on the side of the active material layer facing away from the first lithium replenishing layer.

[0074] The main function of the first lithium replenishment layer and the second lithium replenishment layer is to provide additional lithium sources to compensate for the lithium loss that may occur in the battery during the cycle. The active material layer is the main area for electrochemical reactions in the battery. The positive electrode provided in the embodiment of the present application avoids the problem of reduced content of the conductive agent per unit volume in the active material layer of the positive electrode by arranging the first lithium replenishment layer between the active material layer and the current collector, and arranging the second lithium replenishment layer on the side of the active material layer away from the first lithium replenishment layer, thereby improving the conductive effect of the positive electrode, reducing the internal resistance of the battery, increasing the charge and discharge capacity of the battery, increasing the charge and discharge efficiency of the battery, and increasing the number of cycles of the battery, and improving the performance of the electrical equipment.

[0075] The following specific embodiments describe in detail the technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0076] First, refer to Figure 1As shown, an embodiment of the present application provides a positive electrode sheet, which includes a current collector 100, a first lithium replenishing layer 300, an active material layer 400 and a second lithium replenishing layer 500.

[0077] The first lithium replenishing layer 300 is disposed on at least one side of the current collector 100 in the thickness direction.

[0078] The active material layer 400 is disposed on a side of the first lithium replenishing layer 300 that is away from the current collector 100 .

[0079] The second lithium replenishing layer 500 is disposed on a side of the active material layer 400 that is away from the first lithium replenishing layer 300 .

[0080] Exemplarily, the current collector 100 is the base material of the positive electrode sheet. The current collector 100 includes aluminum foil. The main function of the current collector 100 is to collect and conduct current, ensuring that the battery has good conductivity during the charge and discharge process.

[0081] Exemplarily, the main function of the first lithium replenishing layer 300 is to provide an additional lithium source to compensate for the lithium loss that may occur during the battery cycle.

[0082] The active material layer is the primary area of ​​electrochemical reactions within a battery. In lithium-ion batteries, the active materials in the positive and negative electrodes are responsible for the insertion and removal of lithium ions, respectively. The active material layer directly impacts the battery's capacity. The theoretical specific capacity (the amount of charge that can be stored per unit mass) of the active material layer is a key factor in determining battery capacity.

[0083] The second lithium replenishment layer 500 further increases the lithium replenishment capability, ensuring that sufficient lithium sources are available throughout the entire life cycle of the battery.

[0084] For example, the amount of lithium replenisher added to the positive electrode sheet is fixed. In the related art, the first lithium replenisher layer 300 and the second lithium replenisher layer 500 are not provided in the positive electrode sheet. The lithium replenisher and the active material layer used to replenish lithium for the positive electrode sheet are mixed to form an active material layer. This will cause poor coating of the active material layer during the preparation process, and this will reduce the content of the conductive agent per unit volume of the active material layer, affecting the conductivity of the positive electrode sheet.

[0085] Therefore, in the embodiments of this application, reference is made to Figure 1 As shown, the first lithium replenishment layer 300 is disposed between the active material layer 400 and the current collector 100, and the second lithium replenishment layer 500 is disposed on the side of the active material layer 400 facing away from the first lithium replenishment layer 300. This avoids reducing the conductive agent content per unit volume in the active material layer 400, improves the coating uniformity of the positive electrode sheet, and enhances the conductive effect of the positive electrode sheet. In addition, the second lithium replenishment layer 500 is in direct contact with the electrolyte, which helps to improve the lithium replenishment efficiency.

[0086] Illustratively, the first lithium replenishing layer 300 includes a first lithium replenishing agent, and the first lithium replenishing layer 300 may further include a conductive agent and a binder.

[0087] The active material layer 400 includes an active material, a conductive agent, and a binder.

[0088] The second lithium replenishing layer 500 includes a second lithium replenishing agent, and the second lithium replenishing layer 500 may further include a conductive agent and a binder.

[0089] As a feasible implementation, the first lithium replenishing layer 300 , the active material layer 400 , and the second lithium replenishing layer 500 all have pores.

[0090] Furthermore, considering that the first lithium-replenishing layer 300 and the second lithium-replenishing layer 500 of the positive electrode generate gas during the battery reaction, the first lithium-replenishing layer 300, the active material layer 400, and the second lithium-replenishing layer 500 are all configured to have pores. This multi-layered porous structure of the positive electrode provides channels for gas flow, facilitating the smooth discharge of gas generated by the positive electrode during battery use, preventing gas accumulation within the battery and preventing battery expansion and deformation. It also prevents black spots on the negative electrode interface caused by gas accumulation at the negative electrode, thereby improving the battery's electrochemical performance and cycle stability, and enhancing the performance of electrical devices.

[0091] As a feasible implementation, the porosity of the active material layer 400 is greater than the porosity of the first lithium replenishing layer 300 .

[0092] As a feasible implementation, the porosity of the second lithium replenishing layer 500 is greater than the porosity of the first lithium replenishing layer 300 .

[0093] For example, the first lithium replenishment layer 300, the active material layer 400, and the second lithium replenishment layer 500 have different functions in the positive electrode sheet. The first lithium replenishment layer 300 ensures the structural stability of the positive electrode sheet while providing a lithium source. The active material layer 400 primarily performs electrochemical reactions and ion transport. The second lithium replenishment layer 500 provides a lithium source. Setting the porosity of the active material layer 400 greater than that of the first lithium replenishment layer 300 and / or the porosity of the second lithium replenishment layer 500 greater than that of the first lithium replenishment layer 300 can further promote gas discharge from the first lithium replenishment layer 300.

[0094] As a feasible implementation, the porosity of the first lithium replenishing layer 300 , the active material layer 400 , and the second lithium replenishing layer 500 increases in sequence.

[0095] For example, the primary function of the first lithium-replenishing layer 300 is to provide a lithium source and ensure the structural stability of the positive electrode sheet. The first lithium-replenishing layer 300 has the lowest porosity. Despite its low porosity, the first lithium-replenishing layer 300 still provides a preliminary gas exhaust channel.

[0096] The active material layer 400 has a medium porosity. The active material layer 400 is used for electrochemical reaction and lithium ion transport. The medium porosity of the active material layer 400 facilitates gas flow.

[0097] The second lithium replenishment layer 500 has the highest porosity. It provides the largest gas flow path, ensuring that any gas generated anywhere in the positive electrode can be rapidly discharged. This layer's design helps maximize gas discharge efficiency and reduce internal pressure in the positive electrode.

[0098] During the electrochemical reaction of the battery, the gas generated by the first lithium replenishing layer 300 is discharged through the pores of the first lithium replenishing layer 300, the pores of the active material layer 400, and the pores of the second lithium replenishing layer 500 in sequence; the gas generated by the second lithium replenishing layer 500 is discharged through the pores of the second lithium replenishing layer 500.

[0099] By increasing the pores of the first lithium-replenishing layer 300, the active material layer 400, and the second lithium-replenishing layer 500 in sequence, the pores not only provide a channel for gas flow but also facilitate the discharge of gas from any location near the positive electrode sheet. Furthermore, the further the positive electrode sheet faces away from the current collector 100, the greater the amount of gas. By increasing the pores of the first lithium-replenishing layer 300, the active material layer 400, and the second lithium-replenishing layer 500 in sequence, the efficiency of gas discharge from the positive electrode sheet during the electrochemical reaction is improved.

[0100] As a feasible implementation, the porosity of the first lithium replenishing layer 300 is P1, and P1 satisfies: 25%≤P1≤29%.

[0101] For example, when the porosity of the first lithium replenishing layer 300 is in the range of 25%-29%, the first lithium replenishing layer 300 has mechanical strength and structural stability, which helps to reduce the degradation of the material during the charge and discharge process.

[0102] In some embodiments of the present application, the porosity of the active material layer 400 is Pm, and Pm satisfies: 30%≤Pm≤40%.

[0103] For example, when the porosity of the active material layer 400 is in the range of 30%-40%, it helps to improve the efficiency of the electrochemical reaction, provide higher current density and rate performance, and also helps to effectively discharge gas, reduce internal pressure accumulation, and improve safety.

[0104] In some embodiments of the present application, the porosity of the second lithium replenishing layer 500 is P2, and P2 satisfies: 45%≤P2≤50%.

[0105] For example, when the porosity of the second lithium-replenishing layer 500 is between 45% and 50%, the higher porosity provides a good gas discharge channel, ensuring that gases generated during the electrochemical reaction of the battery can be quickly discharged. High porosity helps improve lithium-ion conductivity and supports long-term cycling stability.

[0106] As a feasible implementation, the ratio of Pm to P1 is A1, and A1 satisfies: 1.05≤A1≤1.5.

[0107] In some embodiments of the present application, the ratio of P2 to Pm is A2, and A2 satisfies: 1.2≤A2≤1.7.

[0108] For example, when A1 is between 1.05 and 1.5, the porosity (Pm) of the active material layer 400 is moderately increased relative to the first lithium replenishment layer 300 (P1). The higher porosity of the active material layer 400 results in a larger surface area and more reactive sites within the active material layer 400, which helps improve ion and electron transport efficiency, supporting higher current densities and faster charge and discharge rates.

[0109] When A2 is between 1.2 and 1.7, the porosity (P2) of the second lithium replenishment layer 500 is significantly increased relative to the active material layer 400 (Pm). This design ensures that gases generated during the electrochemical reaction of the battery can be quickly discharged, reducing internal pressure and safety risks.

[0110] As a feasible embodiment, the active material layer 400 includes an active lithium replenisher. By providing the active lithium replenisher in the active material layer 400, the lithium replenishment capability of the electrode can be further enhanced and the lithium replenishment efficiency can be improved.

[0111] As a feasible implementation, the first lithium replenishing layer 300 includes a first lithium replenishing agent; the particle size of the active lithium replenishing agent is larger than the particle size of the first lithium replenishing agent.

[0112] For example, smaller particle sizes generally mean a larger surface area between particles, which can lead to smaller pores when the particles are packed together. Because the particles can be packed more tightly, materials with smaller particle sizes typically have lower porosity. This structure helps increase the material's density and mechanical strength.

[0113] Larger particle sizes mean less surface area between particles, which can lead to larger pores when the particles are packed together. Due to the larger gaps between particles, materials with larger particle sizes typically have higher porosity. This structure contributes to improved gas permeability and ion conductivity.

[0114] The first lithium replenishing layer 300 uses a first lithium replenishing agent with a smaller particle size to form a lower porosity, providing a more stable structure for the positive electrode sheet and providing a lithium source supply.

[0115] The active material layer 400 uses an active lithium supplement with a larger particle size to form a medium porosity, which supports better ion transport and electrochemical activity. In addition, the active material layer 400 provides an additional lithium source to compensate for the lithium loss that may occur during battery cycling.

[0116] As a feasible implementation, the second lithium replenishing layer 500 includes a second lithium replenishing agent; the particle size of the second lithium replenishing agent is larger than the particle size of the active lithium replenishing agent.

[0117] For example, since the particles are larger, the pores formed when stacked are also larger, so the second lithium replenishing layer 500 generally has a higher porosity. Such high porosity is conducive to the discharge of gas and the rapid transmission of lithium ions.

[0118] The high porosity of the second lithium-replenishing layer 500 provides a good channel, ensuring that gases generated during the battery's electrochemical reaction can be quickly discharged, reducing internal pressure accumulation. The high porosity of the second lithium-replenishing layer 500 not only facilitates gas discharge but also improves lithium-ion conductivity, supporting high-rate charge and discharge performance.

[0119] In the positive electrode sheet, the porosity of the first lithium replenishing layer 300, the active material layer 400 and the second lithium replenishing layer 500 is set to increase layer by layer. Gas can be discharged from the first lithium replenishing layer 300 to the active material layer 400, and from the active material layer 400 to the second lithium replenishing layer 500, and then to the outside of the battery, thereby improving the gas discharge efficiency of the positive electrode sheet and avoiding the problem of black spots on the negative electrode sheet caused by gas accumulation inside the battery.

[0120] As a feasible implementation, the particle size of the first lithium supplement agent is D1, and D1 satisfies: 10 nm ≤ D1 ≤ 80 nm.

[0121] In some embodiments of the present application, the particle size of the active lithium supplement is Dm, and Dm satisfies: 100 nm ≤ Dm ≤ 350 nm.

[0122] In some embodiments of the present application, the particle size of the second lithium supplement is D2, and D2 satisfies: 400nm≤D2≤600nm.

[0123] For example, the smaller particle size of the first lithium replenisher allows the particles to pack more densely, forming a dense layer structure. This compactness helps improve the mechanical strength and stability of the first lithium replenisher layer 300, thereby providing a solid foundation for the entire positive electrode sheet. Compared to the first and second lithium replenishers, the moderate particle size of the active lithium replenisher ensures that the active material layer 400 can effectively provide lithium replenishment, maintaining the battery's capacity and lifespan. Furthermore, the moderate particle size of the active lithium replenisher means that the active material layer 400 can maintain an appropriate porosity. This porosity balance supports lithium ion conduction while providing sufficient channels for gas discharge, preventing gas accumulation within the battery. The larger particle size of the second lithium replenisher increases the spaces between the particles, forming a highly porous second lithium replenisher layer 500. This structure facilitates the rapid discharge of gas, reduces internal battery pressure, and mitigates the risk of explosion or expansion.

[0124] Illustratively, D1 refers to the average particle size of the first lithium supplement. Dm refers to the average particle size of the active lithium supplement. D2 refers to the average particle size of the second lithium supplement. The average particle size of the first lithium supplement is in the range of 10-80 nm. The average particle size of the active lithium supplement is in the range of 100-350 nm. The average particle size of the third lithium supplement is in the range of 400-600 nm.

[0125] In some embodiments of the present application, the average particle size of the first lithium supplement agent, the active lithium supplement agent, and the second lithium supplement agent can be measured by the following method: by performing a scanning electron microscope (SEM) analysis on the lithium supplement agent, measuring the diameters of at least 20 (for example, 20, 30, 40, or 50) lithium supplement agents within the field of view using a measuring tool, performing statistics based on the measurement results, and taking the average value of the measured diameters of the at least 20 lithium supplement agents as the main test result.

[0126] As a feasible implementation, the mass of the first lithium supplement is M1, the mass of the active lithium supplement is Mm, the mass of the second lithium supplement is M2, and the active material layer includes an active substance, the mass of the active substance is Mh.

[0127] The mass ratio of M1 to Mh is B1, and B1 satisfies: 0.5%≤B1≤1%.

[0128] The mass ratio of Mm to Mh is Bm, and Bm satisfies: 1%≤Bm≤10%.

[0129] The mass ratio of M2 to Mh is B2, and B2 satisfies: 0.5%≤B2≤1%.

[0130] For example, the first lithium replenishing layer 300 is closest to the current collector 100, and the mass ratio of the first lithium replenishing agent in the first lithium replenishing layer 300 to the active material in the active material layer 400 is 0.5%-1%. That is to say, the amount of the first lithium replenishing agent is very small relative to the active material, so the first lithium replenishing agent produces relatively less gas, thereby avoiding the problem of excessive gas production inside the positive electrode sheet and poor discharge.

[0131] During the electrochemical reaction in the battery, the active lithium replenisher in the active material layer 400 dissolves into the electrolyte. This replenishes the electrolyte lithium salt lost during the subsequent recharge process, while also creating a degassing path within the active material layer 400. The mass ratio of active lithium replenisher to active material should be between 1% and 10%. Adding less than 1% results in insignificant recharge. Adding more than 10% results in a high recharge volume but low utilization, and mixing with the active material can easily lead to process issues such as excessive slurry viscosity and agglomeration.

[0132] The mass ratio of the second lithium replenisher to the active material in the second lithium replenisher layer 500 is 0.5%-1%. The amount of lithium replenisher added to the positive electrode sheet is fixed. The provision of the second lithium replenisher layer 500 prevents the introduction of excessive lithium replenisher into the active material layer 400, which could lead to poor coating during the preparation of the active material layer 400. It also avoids reducing the conductive agent content per unit volume in the active material layer 400, thereby improving the conductivity of the positive electrode sheet. Furthermore, the second lithium replenisher layer 500 is in direct contact with the electrolyte, which improves lithium replenishment efficiency and shortens the diffusion distance of gases generated during the lithium replenishment process, accelerating gas discharge.

[0133] When preparing the positive electrode sheet, the masses of the first lithium supplement agent, the active lithium supplement agent, and the second lithium supplement agent are all weighed using an electronic balance.

[0134] As a feasible implementation manner, the first lithium supplement includes one or more of Li2CO3, Li2O and Li2O2.

[0135] For example, Li2CO3 provides a stable lithium source that is easily decomposed in the battery and releases lithium ions.

[0136] Li2CO3 has good thermal stability and can remain stable under high temperature conditions.

[0137] Li2O provides a high concentration of lithium ions, which helps to increase the capacity of the battery. Li2O exhibits good chemical stability in the battery environment.

[0138] It is understood that the first lithium supplement may be one of Li2CO3 and Li2O. The first lithium supplement may also include Li2CO3 and Li2O. When the first lithium supplement includes Li2CO3 and Li2O, the mass ratio of Li2CO3 and Li2O may be equal.

[0139] As a feasible implementation, the active lithium supplement includes Li2C2O4 and / or Li5FeO4.

[0140] For example, Li2C2O4 can effectively release lithium ions in the electrochemical reaction, supporting the charge and discharge cycle of the battery.

[0141] Li5FeO4 has a high lithium content, which enables it to provide an additional lithium source during battery cycling, compensating for lithium loss due to side reactions or irreversible processes. Furthermore, Li5FeO4 exhibits good chemical and thermal stability during electrochemical cycling, which helps improve battery safety and cycle life.

[0142] It is understood that the active lithium supplement may be one of Li2C2O4 and Li5FeO4. The active lithium supplement may also include Li2C2O4 and Li5FeO4. When the active lithium supplement includes Li2C2O4 and Li5FeO4, the mass ratio of Li2C2O4 and Li5FeO4 may be equal.

[0143] As a feasible embodiment, the second lithium supplement includes one or more of Li2MO2 and Li2N2O3, wherein M includes at least one of Ni, Fe, Cu, and Co, and N includes at least one of Al, Co, Mn, Ni, Fe, Cu, and Si.

[0144] For example, Li2MO2 can adjust the electrochemical performance and stability of the material by selecting different transition metals (such as Ni, Fe, Cu, and Co). Certain metals (such as Ni and Co) can improve the conductivity of the material and support high-rate performance.

[0145] Illustratively, Li2MO2 may be Li2NiO2.

[0146] Li2N2O3 can be doped with different metal elements (such as Al and Mn) to enhance the structural stability and cycle life of the material. Certain elements (such as Al and Si) can improve the thermal stability of the material and reduce the risk of thermal runaway.

[0147] Illustratively, Li2N2O3 may be Li2Ni2O3.

[0148] As a feasible implementation, there are multiple active material layers 400 , and the porosity of the multiple active material layers increases sequentially from the first lithium replenishing layer 300 to the second lithium replenishing layer 500 .

[0149] For example, multiple active material layers 400 are stacked sequentially from the first lithium-replenishing layer 300 to the second lithium-replenishing layer 500, with increasing porosity. Increasing the number of active material layers 400 increases the total amount of active material within a limited battery volume, thereby improving the battery's energy density and capacity. By arranging the multiple active material layers 400 to have increasing porosity, this facilitates the discharge of gases generated by the lithium-replenishing agent.

[0150] As an achievable embodiment, the positive electrode sheet further includes a conductive coating 200 . The conductive coating 200 is disposed on both sides of the current collector 100 in the thickness direction. The conductive coating 200 is disposed between the current collector 100 and the first lithium replenishing layer 300 .

[0151] The first lithium replenishing layer 300 is arranged on the side of the conductive coating 200 away from the current collector 100, the active material layer 400 is arranged on the side of the first lithium replenishing layer 300 away from the conductive coating 200, and the second lithium replenishing layer 500 is arranged on the side of the active material layer 400 away from the first lithium replenishing layer 300.

[0152] For example, referring to Figure 1 As shown, conductive coatings 200 are provided on both sides of the current collector 100. By providing the conductive coatings 200 on both sides of the current collector 100, the conductivity of the conductive coatings 200 is utilized to further improve the conductivity of the positive electrode sheet and enhance the overall electrochemical performance of the battery.

[0153] During the battery preparation process, the positive electrode sheet, the separator, and the negative electrode sheet are stacked in sequence. By setting the first lithium replenishing layer 300, the active material layer 400, and the second lithium replenishing layer 500 on both sides of the positive electrode sheet, the two sides of the positive electrode sheet are respectively set corresponding to the negative electrode sheet to enable an electrochemical reaction to occur between the positive electrode sheet and the negative electrode sheet.

[0154] A conductive agent, a binder, and a solvent are mixed into a conductive slurry and coated on the surface of the current collector 100 to form a conductive coating 200. The conductive coating 200 can reduce the interfacial resistance between the current collector 100 and the first lithium-replenishing layer 300. This helps improve the overall conductivity of the battery, thereby enhancing the battery's power performance and energy efficiency.

[0155] As a feasible implementation method, refer to Figure 2 As shown, the positive electrode sheet further includes a safety layer 600 , which is disposed on a side of the second lithium replenishing layer 500 facing away from the active material layer 400 .

[0156] For example, the first lithium replenisher, the active lithium replenisher, and the second lithium replenisher react to generate delithiation products. By setting the safety layer 600, the delithiation products can be protected from puncturing the battery and causing micro-short circuit problems inside the battery, thereby improving the problem of excessive self-discharge of the battery caused by the delithiation products in the battery.

[0157] As a feasible implementation, the positive electrode sheet further includes a liquid retaining layer 700 , which is disposed on a side of the second lithium replenishing layer 500 facing away from the active material layer 400 .

[0158] For example, the primary function of the liquid-retention layer 700 is to absorb and retain electrolyte. This helps maintain good contact between the positive electrode and the electrolyte during battery cycling, thereby improving ion transfer efficiency. By providing the liquid-retention layer 700, it can absorb a certain amount of electrolyte, thus enabling the positive electrode to retain electrolyte and improving the battery's cycling performance.

[0159] As a feasible implementation, the positive electrode sheet further includes a safety layer 600 and a liquid retention layer 700 .

[0160] The safety layer 600 is disposed on a side of the second lithium replenishing layer 500 facing away from the active material layer 400 .

[0161] The liquid retaining layer 700 is disposed on a side of the safety layer 600 away from the second lithium replenishing layer 500 .

[0162] For example, the main function of the safety layer 600 is to prevent the delithiation products from penetrating the battery separator and causing internal short circuits. By providing a physical barrier, the safety layer 600 can effectively reduce the risk of internal short circuits in the battery.

[0163] The electrolyte retention layer 700 absorbs and retains the electrolyte, ensuring good contact between the positive electrode and the electrolyte. This helps maintain efficient ion transport, reduces battery internal resistance, and improves charge and discharge efficiency.

[0164] The combination of the safety layer 600 and the liquid retention layer 700 can effectively reduce the self-discharge phenomenon caused by internal short circuit of the battery, while improving the cycle performance of the battery.

[0165] In some embodiments of the present application, the porosity of the safety layer 600 is P3, and P3 satisfies: 51%≤P3≤55%.

[0166] For example, when the porosity of the safety layer 600 is in the range of 51%-55%, it is helpful to discharge the gas generated by the first lithium replenishing layer 300 , the active material layer 400 and the second lithium replenishing layer 500 .

[0167] In some embodiments of the present application, the porosity of the liquid retaining layer 700 is P4, and P4 satisfies: 56%≤P4≤60%.

[0168] For example, a porosity of 56%-60% in the liquid-retention layer 700 facilitates the discharge of gases generated by the first lithium-replenishing layer 300, the active material layer 400, and the second lithium-replenishing layer 500. Furthermore, the larger porosity of the liquid-retention layer 700 facilitates the storage of a portion of the electrolyte, ensuring good contact between the positive electrode and the electrolyte.

[0169] In this way, the porosity of the first lithium replenishing layer 300, the active material layer 400, the second lithium replenishing layer 500, the safety layer 600, and the liquid retention layer 700 gradually increases, providing a channel for the discharge of the gas generated by the first lithium replenishing agent, the active lithium replenishing agent, and the second lithium replenishing agent during the reaction, enabling the gas generated during the lithium replenishing process to be discharged smoothly, effectively improving the problem of interface black spots.

[0170] As a feasible implementation, the porosity of the second lithium replenishing layer 500 is P2, the ratio of P3 to P2 is A3, and A3 satisfies: 1.02≤A3≤1.3.

[0171] For example, when A3 is between 1.02 and 1.3, the porosity (P3) of the safety layer 600 is moderately increased relative to that of the second lithium replenishment layer 500 (P2). The higher porosity of the safety layer 600 ensures that gases generated during the electrochemical reaction of the battery can be rapidly discharged, reducing internal pressure and safety risks.

[0172] As a feasible implementation, the ratio of P4 to P3 is A4, and A4 satisfies: 1.02≤A4≤1.3.

[0173] For example, when A4 is between 1.02 and 1.3, the porosity of the liquid retention layer (P4) increases modestly relative to the safety layer 600 (P3). This higher porosity ensures that gases generated during the battery's electrochemical reactions can be rapidly discharged, reducing internal pressure and safety risks. It also facilitates the storage of a portion of the electrolyte in the liquid retention layer 700, ensuring good contact between the positive electrode and the electrolyte.

[0174] As a feasible implementation, the security layer 600 includes inorganic particles and a binder.

[0175] The inorganic particles include at least one of aluminum oxide, aluminum oxide, silicon dioxide, and calcium oxide.

[0176] The binder includes at least one of polyvinyl pyrrolidone, polymethyl methacrylate, polyvinyl alcohol, and polyacrylic acid.

[0177] For example, aluminum oxide, aluminum oxide, silicon dioxide, and calcium oxide all have stability and mechanical strength, and can improve the structural stability of the positive electrode sheet while avoiding chemical reactions with the second lithium replenishing layer 500 that would affect the lithium replenishing effect of the battery.

[0178] For example, polyvinyl pyrrolidone, polymethyl methacrylate, polyvinyl alcohol, and polyacrylic acid all have adhesive properties and can bind the inorganic particles together.

[0179] Illustratively, the mass ratio of the inorganic particles to the active material is B3, and B3 satisfies: 0.5%≤B3≤1%.

[0180] As an achievable embodiment, the active material layer 400 includes an active substance, and the liquid retaining layer 700 includes at least one of polyvinylidene fluoride and polyimide.

[0181] PVDF is chemically stable and resistant to corrosion from electrolytes. It also has mechanical strength and flexibility, allowing it to maintain structural integrity during the battery's charge and discharge processes.

[0182] The porous structure of polyvinylidene fluoride can effectively absorb and retain electrolyte, ensure good contact between the electrode and the electrolyte, and improve ion transmission efficiency.

[0183] Polyimide is thermally stable and can maintain stable performance in high temperature environments, which is very important for battery safety.

[0184] Polyimide has excellent mechanical properties and can provide the necessary support and protection during battery cycling.

[0185] As a feasible embodiment, the active material layer 400 includes an active substance. The mass ratio of the liquid retaining layer 700 to the active substance is B4, and B4 satisfies: 0.5%≤B4≤1%.

[0186] In some embodiments, when the liquid retaining layer 700 includes polyvinylidene fluoride, the mass ratio of polyvinylidene fluoride to the active material is B4, and B4 satisfies: 0.5%≤B4≤1%.

[0187] In some other embodiments, when the liquid retaining layer 700 includes polyimide, the mass ratio of the polyimide to the active material is B4, where B4 satisfies: 0.5%≤B4≤1%.

[0188] In some other embodiments, when the liquid retaining layer 700 includes polyvinylidene fluoride and polyimide, the mass ratio of the sum of the mass of the polyvinylidene fluoride and the polyimide to the mass ratio of the active material is B4, and B4 satisfies: 0.5%≤B4≤1%.

[0189] For example, when preparing the safety layer 600, inorganic particles, a binder, and a solvent are mixed and stirred to form a safety layer slurry, wherein the solvent can be at least one of N-methylpyrrolidone, N-dimethylformamide, and dimethylacetamide.

[0190] When preparing the liquid retaining layer 700, polyvinylidene fluoride and a solvent are mixed to form a liquid retaining layer slurry. The solvent can be at least one of N-methylpyrrolidone, N-dimethylformamide, and dimethylacetamide.

[0191] The safety layer slurry is coated on the side of the second lithium replenishing layer 500 away from the active material layer, and the liquid retention layer slurry is coated on the side of the safety layer slurry away from the second lithium replenishing layer 500. After drying, the safety layer 600 and the liquid retention layer 700 are formed.

[0192] For example, the thickness of the first lithium replenishing layer 300 is in the range of 2-4 μm. The thickness of the second lithium replenishing layer 500 is in the range of 2-4 μm. The thickness of the safety layer 600 is in the range of 0.5-2 μm. The thickness of the liquid retaining layer 700 is in the range of 0.5-2 μm.

[0193] As a feasible implementation, the current collector 100 includes a base layer 110 and a conductive layer 120 ; the conductive layer 120 is provided on at least one side of the base layer 110 in the thickness direction.

[0194] The base layer 110 primarily provides mechanical support to ensure that the current collector 100 maintains structural integrity during battery assembly and operation.

[0195] In some embodiments, the conductive layer 120 is located on one side in the thickness direction of the base layer 110. Meanwhile, the first lithium replenishing layer 300, the active material layer 400, and the second lithium replenishing layer 500 are all located on this side.

[0196] In other embodiments, the conductive layer 120 is located on opposite sides of the base layer 110 to provide a double-sided conductive path. This design can maximize the current conduction efficiency.

[0197] As a feasible implementation manner, as a feasible implementation manner, the thickness of the base layer 110 is C1, and C1 satisfies: 0.5 μm≤C1≤3.5 μm.

[0198] In some embodiments, the thickness of the conductive layer 120 is C2, and C2 satisfies: 4 μm≤C2≤7 μm.

[0199] For example, a moderate thickness of the base layer 110 provides good mechanical support, ensuring the stability of the battery structure, while a thicker conductive layer 120 provides lower resistance, improves current transmission efficiency, and supports high power output.

[0200] As a feasible implementation, the base layer 110 includes at least one of polypropylene and polyethylene terephthalate.

[0201] In some embodiments of the present application, the conductive layer 120 includes an aluminum layer.

[0202] Polypropylene is a lightweight material that helps reduce the overall weight of the battery. Polypropylene provides sufficient mechanical strength to support the structural integrity of the current collector 100.

[0203] Polyethylene terephthalate has high heat resistance and can remain stable at higher temperatures. Polyethylene terephthalate provides excellent mechanical strength and toughness, enhancing the durability of the current collector 100.

[0204] Aluminum has excellent electrical conductivity, which can effectively reduce the internal resistance of the battery and improve current transmission efficiency.

[0205] In a second aspect, an embodiment of the present application provides a battery comprising a positive electrode sheet, a negative electrode sheet, and a separator. The negative electrode sheet and the positive electrode sheet are stacked, and the separator is located between the positive electrode sheet and the negative electrode sheet.

[0206] For example, let's take a lithium-ion battery as an example. The positive electrode is the electrode in the battery responsible for the intercalation and deintercalation of lithium ions. The negative electrode is the electrode in the battery responsible for the intercalation of lithium ions. The negative electrode comprises graphite or other carbon-based materials. The separator is a key component located between the positive and negative electrodes. Its main function is to prevent direct contact between the electrodes, thereby avoiding short circuits. The separator includes polyethylene (PE) and polypropylene (PP). The separator has ion conductivity to ensure that lithium ions can pass smoothly during the charging and discharging process.

[0207] It is understandable that since the battery of the embodiment of the present application adopts the technical solution of the above-mentioned positive electrode sheet embodiment, it at least has the beneficial effects brought by the technical solution of the above-mentioned embodiment, which will not be described one by one here.

[0208] Thirdly, embodiments of the present application provide an electrical device. The electrical device includes a battery. The electrical device provided in embodiments of the present application can be implemented in a variety of ways. For example, it can be a vehicle, a ferry, an energy storage cabinet, a computer, an aircraft, and the like. This application does not limit the specific type of electrical device.

[0209] It can be understood that since the electrical equipment in the embodiment of the present application adopts the technical solution of the above-mentioned battery embodiment, it at least has the beneficial effects brought by the technical solution of the above-mentioned embodiment, which will not be described one by one here.

[0210] The particle size test method is as follows:

[0211] The images of the first lithium supplement agent, the active lithium supplement agent and the second lithium supplement agent were taken using a scanning electron microscope, and the average particle sizes of the first lithium supplement agent, the active lithium supplement agent and the second lithium supplement agent were calculated.

[0212] The lithium supplement is analyzed by scanning electron microscopy (SEM). The diameters of at least 20 (e.g., 20, 30, 40, or 50) lithium supplements within a field of view are measured using a measuring tool. Statistics are collected based on the measurement results, and the average of the measured diameters of the at least 20 lithium supplements is used as the test result.

[0213] Specified masses of the first, active, and second lithium replenishers are weighed and mixed with a conductive agent and a binder to form the first, active material, and second lithium replenisher layers 300, 400, and 500, respectively. During this process, the first, active, and second lithium replenishers undergo no chemical changes, but their particle sizes are unchanged. In other words, the particle sizes of the first, active, and second lithium replenishers tested on the raw material side and measured on the finished product side differ very little, falling within the error range.

[0214] The present invention is further described below through specific examples.

[0215] Example 1

[0216] The first lithium replenishment layer 300 includes Li2CO3 and Li2O. The Li2CO3 and Li2O are ball-milled to a particle size of 40 nm. A slurry is prepared by mixing the materials in a mass ratio of Li2CO3:Li2O:conductive agent:binder:solvent (NMP) = 50:50:5:5:60, defining this slurry as lithium replenishment slurry 1, which is used to form the first lithium replenishment layer 300.

[0217] Active material layer: lithium iron phosphate: conductive agent: binder: solvent NMP are added and stirred in a mass ratio of 100:2:2:60, which is defined as active slurry and used to form the active material layer.

[0218] The second lithium-replenishing layer 500 includes Li2NiO2 and Li2Ni2O3. The Li2NiO2 and Li2Ni2O3 are ball-milled to a particle size of 500 nm. A slurry, designated as lithium-replenishing slurry 2, is prepared by mixing the materials in a mass ratio of 50:50:5:5:60 (Li2NiO2:Li2Ni2O3:conductive agent:binder:NMP solvent). The mixture is then stirred. The mixture is then used to form the second lithium-replenishing layer 500.

[0219] The conductive coating 200 includes a conductive agent, a binder, and a solvent. The conductive agent, the binder, and the solvent are mixed into a conductive slurry, and then coated on the surface of the current collector 100 to form the conductive coating 200 .

[0220] The conductive agent is acetylene black and the adhesive is polyvinylidene fluoride.

[0221] The above four slurries are sequentially coated on both sides of the current collector 100 coated with the conductive coating 200. The single-side coating density of the first lithium replenishing layer 300, the active material layer 400, and the second lithium replenishing layer 500 is 2 g / m 2 , 200g / m 2 , 2g / m 2 Then roll it to 2.5g / cm 3 Compacted density. Keep the positive electrode sheet to test the liquid absorption time and porosity. The other positive electrode sheets and double-sided density are 220g / m 2 The graphite negative electrode sheets are assembled into soft-pack batteries.

[0222] The finished battery is obtained through baking, liquid injection, impregnation, formation, aging, exhaust and capacity separation.

[0223] Example 2

[0224] The first lithium replenishment layer 300 includes Li2CO3 and Li2O. The Li2CO3 and Li2O are ball-milled to a particle size of 40 nm. A slurry is prepared by mixing the materials in a mass ratio of Li2CO3:Li2O:conductive agent:binder:solvent (NMP) = 50:50:5:5:60, defining this slurry as lithium replenishment slurry 1, which is used to form the first lithium replenishment layer 300.

[0225] The active material layer 400 includes Li5FeO4. The Li5FeO4 is ball-milled to a particle size of 150 nm. A slurry is prepared by mixing lithium iron phosphate, Li5FeO4, conductive agent, binder, and solvent NMP in a mass ratio of 100:1:2:2:60. This slurry is defined as an active slurry and is used to form the active material layer 400.

[0226] The second lithium-replenishing layer 500 includes Li2NiO2 and Li2Ni2O3. The Li2NiO2 and Li2Ni2O3 are ball-milled to a particle size of 500 nm. A slurry, designated as lithium-replenishing slurry 2, is prepared by mixing the materials in a mass ratio of 50:50:5:5:60 (Li2NiO2:Li2Ni2O3:conductive agent:binder:NMP solvent). The mixture is then stirred. The mixture is then used to form the second lithium-replenishing layer 500.

[0227] The conductive coating 200 includes a conductive agent, a binder, and a solvent. The conductive agent, the binder, and the solvent are mixed into a conductive slurry, which is then coated on the surface of the current collector 100 to form the conductive coating 200 .

[0228] The above four slurries are sequentially coated on both sides of the current collector 100 coated with the conductive coating 200. The single-side coating density of the first lithium replenishing layer 300, the active material layer 400, and the second lithium replenishing layer 500 is 2 g / m 2 , 200g / m 2 , 2g / m 2 Then roll it to 2.5g / cm 3Compacted density. Keep the positive electrode sheet to test the liquid absorption time and porosity. The other positive electrode sheets and double-sided density are 220g / m 2 The graphite negative electrode sheets are assembled into soft-pack batteries.

[0229] The finished battery is obtained through baking, liquid injection, impregnation, formation, aging, exhaust and capacity separation.

[0230] Example 3

[0231] Compared with Example 2, the first lithium supplement in Example 3 is replaced by Li2CO3 from Li2O. In addition, the mass ratio of Li2CO3: conductive agent: binder: solvent NMP is 100:5:5:60. The other conditions are the same as those in Example 2.

[0232] Example 4

[0233] Compared with Example 2, in Example 4, the first lithium supplement agent is replaced by Li2CO3 and Li2O with Li2O, and the mass ratio of Li2O: conductive agent: binder: solvent NMP is 100:5:5:60; the other conditions are the same as in Example 2.

[0234] Example 5

[0235] Compared with Example 2, in Example 5, the active lithium supplement agent is replaced by Li2C2O4 from Li5FeO4, the mass ratio of lithium iron phosphate: Li2C2O4: conductive agent: binder: solvent NMP is 100:1:2:2:60, and the other conditions are the same as in Example 2.

[0236] Example 6

[0237] Compared with Example 2, in Example 6, the active lithium supplement agent is replaced by Li5FeO4 with Li5FeO4 and Li2C2O4, and the mass ratio of lithium iron phosphate: Li5FeO4: Li2C2O4: conductive agent: binder: solvent NMP is 100:0.5:0.5:2:2:60; the other conditions are the same as in Example 2.

[0238] Example 7

[0239] Compared with Example 2, the second lithium supplement in Example 7 is replaced by Li2NiO2 from Li2Ni2O3 and Li2NiO2, and the mass ratio of Li2NiO2: conductive agent: binder: solvent NMP is 100:5:5:60; the other conditions are the same as those in Example 2.

[0240] Example 8

[0241] Compared with Example 2, the second lithium supplement in Example 8 is replaced by Li2NiO2 and Li2Ni2O3 with Li2Ni2O3, and the mass ratio of Li2Ni2O3: conductive agent: binder: solvent NMP is 100:5:5:60; the other conditions are the same as Example 2.

[0242] Example 9

[0243] Compared with Example 2, in Example 9, the amount of active lithium supplement Li5FeO4 is increased from 1 to 2, and the mass ratio of lithium iron phosphate: Li5FeO4: conductive agent: binder: solvent NMP is 100:2:2:2:2:60; the other conditions are the same as in Example 2.

[0244] Example 10

[0245] Compared with Example 2, in Example 10, the amount of active lithium supplement Li5FeO4 is increased from 1 to 5, and the mass ratio of lithium iron phosphate: Li5FeO4: conductive agent: binder: solvent NMP is 100:5:2:2:60; the other conditions are the same as Example 2.

[0246] Example 11

[0247] Compared with Example 2, in Example 11, the amount of active lithium supplement agent Li5FeO4 is increased from 1 to 10, and the mass ratio of lithium iron phosphate: Li5FeO4: conductive agent: binder: solvent NMP is 100:10:2:2:60; the other conditions are the same as Example 2.

[0248] Example 12

[0249] Compared with Example 2, in Example 12, the active lithium supplement agent is replaced by Li2C2O4 from Li5FeO4, and the mass ratio of lithium iron phosphate: Li2C2O4: conductive agent: binder: solvent NMP is 100:2:2:2:2:60; the other conditions are the same as in Example 2.

[0250] Example 13

[0251] Compared with Example 2, in Example 13, the active lithium supplement agent is replaced by Li2C2O4 from Li5FeO4, and the ratio of lithium iron phosphate: Li2C2O4: conductive agent: binder: solvent NMP is 100:5:2:2:60; the other conditions are the same as those in Example 2.

[0252] Example 14

[0253] Compared with Example 2, in Example 14, the active lithium supplement agent is replaced by Li2C2O4 from Li5FeO4, and the mass ratio of lithium iron phosphate: Li2C2O4: conductive agent: binder: solvent NMP is 100:10:2:2:60; the other conditions are the same as in Example 2.

[0254] Example 15

[0255] Compared with Example 2, the surface density of the lithium replenishing slurry coating of the first lithium replenishing layer 300 in Example 15 is increased from 2 g / m 2 Increased to 10g / m 2 ; The remaining conditions are the same as in Example 2.

[0256] Example 16

[0257] Compared with Example 2, in Example 16, the surface density of the lithium replenishing slurry coating of the second lithium replenishing layer 500 is increased from 2 g / m 2 Increased to 10g / m 2 ; The remaining conditions are the same as in Example 2.

[0258] Example 17

[0259] Compared with Example 2, in Example 17, the surface density of the lithium replenishing slurry coating of the first lithium replenishing layer 300 is increased from 2 g / m 2 Increased to 10g / m 2 The surface density of the lithium replenishing slurry coating of the second lithium replenishing layer 500 is from 2g / m 2 Increased to 10g / m 2 ; The remaining conditions are the same as in Example 2.

[0260] Example 18

[0261] The first lithium replenishment layer 300 includes Li2CO3 and Li2O. The Li2CO3 and Li2O are ball-milled to a particle size of 40 nm. A slurry is prepared by mixing the materials in a mass ratio of Li2CO3:Li2O:conductive agent:binder:solvent (NMP) = 50:50:5:5:60, defining this slurry as lithium replenishment slurry 1, which is used to form the first lithium replenishment layer 300.

[0262] The active material layer 400 includes Li5FeO4. The Li5FeO4 is ball-milled to a particle size of 150 nm. A slurry is prepared by mixing lithium iron phosphate, Li5FeO4, conductive agent, binder, and solvent NMP in a mass ratio of 100:1:2:2:60. This slurry is defined as an active slurry and is used to form the active material layer 400.

[0263] The second lithium-replenishing layer 500 includes Li2NiO2 and Li2Ni2O3. The Li2NiO2 and Li2Ni2O3 are ball-milled to a particle size of 500 nm. A slurry, designated as lithium-replenishing slurry 2, is prepared by mixing the materials in a mass ratio of 50:50:5:5:60 (Li2NiO2:Li2Ni2O3:conductive agent:binder:NMP solvent). The mixture is then stirred. The mixture is then used to form the second lithium-replenishing layer 500.

[0264] Safety layer 600 includes aluminum oxide. The aluminum oxide is ball-milled to a particle size of 650 nm. A slurry consisting of aluminum oxide, polyvinyl pyrrolidone, and solvent N-methylpyrrolidone (NMP) is added at a mass ratio of 100:10:70 to form safety layer slurry 3, which is used to form safety layer 600.

[0265] The conductive coating 200 includes a conductive agent, a binder, and a solvent. The conductive agent, the binder, and the solvent are mixed into a conductive slurry, which is then coated on the surface of the current collector 100 to form the conductive coating 200 .

[0266] The above five slurries are sequentially coated on both sides of the current collector 100 coated with the conductive coating 200. The first lithium replenishing layer 300, the active material layer 400, the second lithium replenishing layer 500, and the safety layer 600 are coated on each side with a surface density of 2 g / m 2 , 200g / m 2 , 2g / m 2 , 2g / m 2 Then roll it to 2.5g / cm 3 Compacted density. Keep the positive electrode sheet to test the liquid absorption time and porosity. The other positive electrode sheets and double-sided density are 220g / m 2 The graphite negative electrode sheets are assembled into soft-pack batteries.

[0267] The finished battery is obtained through baking, liquid injection, impregnation, formation, aging, exhaust and capacity separation.

[0268] Example 19

[0269] The first lithium replenishment layer 300 includes Li2CO3 and Li2O. The Li2CO3 and Li2O are ball-milled to a particle size of 40 nm. A slurry is prepared by mixing the materials in a mass ratio of Li2CO3:Li2O:conductive agent:binder:solvent (NMP) = 50:50:5:5:60, defining this slurry as lithium replenishment slurry 1, which is used to form the first lithium replenishment layer 300.

[0270] The active material layer 400 includes Li5FeO4. The Li5FeO4 is ball-milled to a particle size of 150 nm. A slurry is prepared by mixing lithium iron phosphate, Li5FeO4, conductive agent, binder, and solvent NMP in a mass ratio of 100:1:2:2:60. This slurry is defined as an active slurry and is used to form the active material layer 400.

[0271] The second lithium-replenishing layer 500 includes Li2NiO2 and Li2Ni2O3. The Li2NiO2 and Li2Ni2O3 are ball-milled to a particle size of 500 nm. A slurry, designated as lithium-replenishing slurry 2, is prepared by mixing the materials in a mass ratio of 50:50:5:5:60 (Li2NiO2:Li2Ni2O3:conductive agent:binder:NMP solvent). The mixture is then stirred. The mixture is then used to form the second lithium-replenishing layer 500.

[0272] Liquid-retaining layer 700 includes polyvinylidene fluoride (PVDF). PVDF is ball-milled to a particle size of 750 nm. A slurry of PVDF and solvent N-methylpyrrolidone (NMP) is added at a mass ratio of 5:100, defining the slurry as liquid-retaining layer slurry 4, to form liquid-retaining layer 700.

[0273] The conductive coating 200 includes a conductive agent, a binder, and a solvent. The conductive agent, the binder, and the solvent are mixed into a conductive slurry, which is then coated on the surface of the current collector 100 to form the conductive coating 200 .

[0274] The above five slurries are sequentially coated on both sides of the current collector 100 coated with the conductive coating 200. The first lithium replenishing layer 300, the active material layer 400, the second lithium replenishing layer 500, and the liquid retaining layer 700 are coated on each side with a density of 2 g / m 2 , 200g / m 2 , 2g / m 2 , 2g / m 2 Then roll it to 2.5g / cm 3 Compacted density. Keep the positive electrode sheet to test the liquid absorption time and porosity. The other positive electrode sheets and double-sided density are 220g / m 2 The graphite negative electrode sheets are assembled into soft-pack batteries.

[0275] The finished battery is obtained through baking, liquid injection, impregnation, formation, aging, exhaust and capacity separation.

[0276] Example 20

[0277] The first lithium replenishment layer 300 includes Li2CO3 and Li2O. The Li2CO3 and Li2O are ball-milled to a particle size of 40 nm. A slurry is prepared by mixing the materials in a mass ratio of Li2CO3:Li2O:conductive agent:binder:solvent (NMP) = 50:50:5:5:60, defining this slurry as lithium replenishment slurry 1, which is used to form the first lithium replenishment layer 300.

[0278] The active material layer 400 includes Li5FeO4. The Li5FeO4 is ball-milled to a particle size of 150 nm. A slurry is prepared by mixing lithium iron phosphate, Li5FeO4, conductive agent, binder, and solvent NMP in a mass ratio of 100:1:2:2:60. This slurry is defined as an active slurry and is used to form the active material layer 400.

[0279] The second lithium-replenishing layer 500 includes Li2NiO2 and Li2Ni2O3. The Li2NiO2 and Li2Ni2O3 are ball-milled to a particle size of 500 nm. A slurry, designated as lithium-replenishing slurry 2, is prepared by mixing the materials in a mass ratio of 50:50:5:5:60 (Li2NiO2:Li2Ni2O3:conductive agent:binder:NMP solvent). The mixture is then stirred. The mixture is then used to form the second lithium-replenishing layer 500.

[0280] Safety layer 600 includes aluminum oxide. The aluminum oxide is ball-milled to a particle size of 650 nm. A slurry consisting of aluminum oxide, polyvinyl pyrrolidone, and solvent N-methylpyrrolidone (NMP) is added at a mass ratio of 100:10:70 to form safety layer slurry 3, which is used to form safety layer 600.

[0281] Liquid-retaining layer 700 includes polyvinylidene fluoride (PVDF). PVDF is ball-milled to a particle size of 750 nm. A slurry of PVDF and solvent N-methylpyrrolidone (NMP) is added at a mass ratio of 5:100, defining the slurry as liquid-retaining layer slurry 4, to form liquid-retaining layer 700.

[0282] The conductive coating 200 includes a conductive agent, a binder, and a solvent. The conductive agent, the binder, and the solvent are mixed into a conductive slurry, which is then coated on the surface of the current collector 100 to form the conductive coating 200 .

[0283] The six slurries are sequentially coated on both sides of the current collector 100 coated with the conductive coating 200. The first lithium replenishing layer 300, the active material layer 400, the second lithium replenishing layer 500, the safety layer 600, and the liquid retaining layer 700 are coated on each side with a surface density of 2 g / m 2 , 200g / m 2 , 2g / m 2 , 2g / m 2 , 2g / m 2 Then roll it to 2.5g / cm 3 Compacted density. Keep the positive electrode sheet to test the liquid absorption time and porosity. The other positive electrode sheets and double-sided density are 220g / m 2 The graphite negative electrode sheets are assembled into soft-pack batteries.

[0284] The finished battery is obtained through baking, liquid injection, impregnation, formation, aging, exhaust and capacity separation.

[0285] Example 21

[0286] The first lithium replenishment layer 300 includes Li2CO3 and Li2O. The Li2CO3 and Li2O are ball-milled to a particle size of 40 nm. A slurry is prepared by mixing the materials in a mass ratio of Li2CO3:Li2O:conductive agent:binder:solvent (NMP) = 50:50:5:5:60, defining this slurry as lithium replenishment slurry 1, which is used to form the first lithium replenishment layer 300.

[0287] The active material layer 400 includes Li5FeO4. The Li5FeO4 is ball-milled to a particle size of 150 nm. A slurry is prepared by mixing lithium iron phosphate, Li5FeO4, conductive agent, binder, and solvent NMP in a mass ratio of 100:1:2:2:60. This slurry is defined as an active slurry and is used to form the active material layer 400.

[0288] The second lithium-replenishing layer 500 includes Li2NiO2 and Li2Ni2O3. The Li2NiO2 and Li2Ni2O3 are ball-milled to a particle size of 500 nm. A slurry, designated as lithium-replenishing slurry 2, is prepared by mixing the materials in a mass ratio of 50:50:5:5:60 (Li2NiO2:Li2Ni2O3:conductive agent:binder:NMP solvent). The mixture is then stirred. The mixture is then used to form the second lithium-replenishing layer 500.

[0289] Safety layer 600 includes aluminum oxide. The aluminum oxide is ball-milled to a particle size of 650 nm. A slurry consisting of aluminum oxide, polyvinyl pyrrolidone, and solvent N-methylpyrrolidone (NMP) is added at a mass ratio of 100:10:70 to form safety layer slurry 3, which is used to form safety layer 600.

[0290] Liquid-retaining layer 700 includes polyvinylidene fluoride (PVDF). PVDF is ball-milled to a particle size of 750 nm. A slurry of PVDF and solvent N-methylpyrrolidone (NMP) is added at a mass ratio of 5:100, defining the slurry as liquid-retaining layer slurry 4, to form liquid-retaining layer 700.

[0291] The conductive coating 200 includes a conductive agent, a binder, and a solvent. The conductive agent, the binder, and the solvent are mixed into a conductive slurry, which is then coated on the surface of the current collector 100 to form the conductive coating 200 .

[0292] The six slurries are sequentially coated on both sides of the current collector 100 coated with the conductive coating 200. The first lithium replenishing layer 300, the active material layer 400, the second lithium replenishing layer 500, the safety layer 600, and the liquid retaining layer 700 are coated on each side with a surface density of 2 g / m 2 , 200g / m 2 , 2g / m 2 , 10g / m 2 , 10g / m 2 Then roll it to 2.5g / cm 3 Compacted density. Keep the positive electrode sheet to test the liquid absorption time and porosity. The other positive electrode sheets and double-sided density are 220g / m 2 The graphite negative electrode sheets are assembled into soft-pack batteries.

[0293] The finished battery is obtained through baking, liquid injection, impregnation, formation, aging, exhaust and capacity separation.

[0294] Comparative Example 1

[0295] Compared with Example 1, Comparative Example 1 does not include the first lithium replenishing layer 300 and the second lithium replenishing layer 500; the other conditions are the same as those of Example 1.

[0296] Comparative Example 2

[0297] Compared with Example 2, Comparative Example 2 includes the first lithium replenishing layer 300 , but does not include the active lithium replenishing agent and the second lithium replenishing layer 500 ; the other conditions are the same as those of Example 2.

[0298] Comparative Example 3

[0299] Compared with Example 1, Comparative Example 3 includes an active lithium replenishing agent, but does not include the first lithium replenishing layer 300 and the second lithium replenishing layer 500; the other conditions are the same as those of Example 1.

[0300] Comparative Example 4

[0301] Compared with Example 2, Comparative Example 4 includes the second lithium replenishing layer 500 but does not include the active lithium replenishing agent and the first lithium replenishing layer 300; the other conditions are the same as those of Example 2.

[0302] Comparative Example 5

[0303] Compared with Example 2, Comparative Example 5 includes the first lithium replenishing layer 300 and the active lithium replenishing agent, but does not include the second lithium replenishing layer 500; the other conditions are the same as those of Example 2.

[0304] Comparative Example 6

[0305] Compared with Example 2, Comparative Example 6 includes an active lithium replenishing agent and a second lithium replenishing layer 500 , but does not include the first lithium replenishing layer 300 ; the remaining conditions are the same as those of Example 2.

[0306] Test Case

[0307] (1) Porosity test

[0308] Porosity is the distance between particles of a material, and porosity is the percentage of the pore volume in a bulk material to the total volume of the material in its natural state. Porosity reflects the density of a material, and a high porosity indicates a low density of the material. The porosity P of different layers in this application can be tested by the following method: first, the positive electrode sheet is punched into a disc with a diameter of 20 mm, and the surface of the disc is flat, without gaps or powder loss, and the number of small discs is greater than 50. The cross section can be scanned by an SEM scanning electron microscope to obtain the thickness of the current collector 100 layer, the conductive coating 200, the first lithium replenishing layer 300, the active material layer 400, and the second lithium replenishing layer 500 respectively. Then, according to the thickness of each layer, the three-layer first lithium replenishing layer 300, the active material layer 400, and the second lithium replenishing layer 500 are divided into different porosity membranes, and then cleaned and dried with dimethyl carbonate (DMC), and then tested by gas replacement method to obtain the porosity of different membranes. The test results are shown in Tables 1 to 5.

[0309] (2) DCIR internal resistance test

[0310] The DCIR internal resistance test involves discharging the battery at a constant current rate of 1C to 2.0V after the initial charge and discharge efficiency performance test. The battery is then left at room temperature for 60 minutes at 25°C, then charged at a rate of 0.1C to 25% SOC, and then the DCIR internal resistance test is performed again. After charging the battery at a rate of 0.1C to 25% SOC, the battery is left for 12 hours before the DCIR internal resistance test. The test method is as follows: first, the battery is left for 10 minutes, then discharged at a constant current rate of 1.5C for 10 seconds, then stopped, and left for 10 minutes. The voltage V1 before the 1.5C discharge current is recorded, and the voltage V2 after the 10-second 1.5C discharge current is recorded. The discharge DCIR internal resistance is calculated as follows: Discharge DCIR = (V1-V2) / I, where V1 is the voltage before the 10-second 1.5C discharge current, V2 is the voltage after the 10-second 1.5C discharge current, and I is the 1.5C current. The test results are shown in Table 6.

[0311] (3) Battery initial charge and discharge efficiency performance test

[0312] Each experimental soft-pack battery (the examples are Examples 1 to 21 in sequence, and the comparative examples are Comparative Examples 1 to 6 in sequence) was baked, injected, infiltrated, formed, aged, exhausted, and capacity divided to obtain a finished battery, wherein the formation process temperature was 25°C, the current was 0.02C constant current charging for 5 hours, the capacity division process temperature was changed to 25°C, the current was 0.1C constant current and constant voltage charging to 3.8V, the current was cut off at 0.05C, and then the current was changed to 0.05C constant current and constant voltage charging to 4.52V, and the current was cut off at 0.005C. The first discharge capacity was measured under normal temperature 25°C and constant current discharge was performed at 1C current to 2.0V, the total charge capacity and the first discharge capacity of the battery for the first charge were recorded, and the first charge and discharge efficiency (%) = charge capacity / discharge capacity × 100% was calculated. The test results are shown in Table 7.

[0313] (4) Battery self-discharge test

[0314] The safety layer 600 is arranged on the side of the second lithium replenishment layer 500 away from the active material layer 400. The safety layer 600 can protect the battery from internal micro-short circuits caused by puncture of the delithiation product, and can pass the normal temperature self-discharge test of the battery. The normal temperature self-discharge test is to discharge the battery to 2.0V at a constant current rate of 1C after the first charge and discharge efficiency performance test of the battery, and then leave it at room temperature for 60 minutes. Then, charge it to 25% SOC at a current rate of 0.1C and then conduct the normal temperature self-discharge test. First, the battery voltage 1 is tested after being left for 12 hours, and then the battery voltage 2 is tested after being left for 48 hours. The self-discharge test at room temperature of 25°C is the voltage drop of the battery. The voltage drop of the normal temperature self-discharge test = battery voltage 2 - battery voltage 1. The test results are shown in Table 8.

[0315] (5) Battery fluid retention test

[0316] The liquid retention layer 700 is positioned on the side of the safety layer 600 facing away from the second lithium replenishment layer 500. This polymer layer, made of a high-molecular-weight material, can absorb electrolyte and maintain a certain level of electrolyte retention. This structure provides electrolyte to the core, achieving a long-lasting cycle. The finished cells from each experimental battery were tested for electrolyte retention. The electrolyte retention value is calculated as follows: the weight of the finished single cell minus the weight of the cell before electrolyte injection. The results are shown in Table 9.

[0317] (6) Battery cycle test at 25°C

[0318] The battery was charged at a constant current rate of 1C to a cutoff voltage of 3.8V at a constant temperature of 25°C. The battery was then switched to a 3.8V constant voltage charge with a cutoff current of 0.05C and allowed to rest for 30 minutes. The battery was then discharged at a constant current rate of 1C to 2.0V. This cycle was repeated 500 times. The discharge capacity at the 500th cycle was recorded, and the post-cycle capacity retention (%) was calculated as: discharge capacity at 500 cycles / initial discharge capacity × 100%. The battery was cycled again until the capacity decayed to 80% of the initial capacity. The total number of cycles was recorded. The test results are shown in Table 10.

[0319] Table 1 Porosity and porosity ratio of different embodiments

[0320]

[0321] Table 2 Porosity of different examples

[0322] Porosity P1 Porosity Pm Porosity P2 Porosity P3 Porosity P4 Example 18 26.8％ 32.8％ 46.3％ 52.6％ / Example 19 26.8％ 32.8％ 46.3％ / 58.2％ Example 20 26.8％ 32.8％ 46.3％ 52.6％ 58.2％ Example 21 26.8％ 32.8％ 46.3％ 53.2％ 58.9％

[0323] Table 3 Porosity ratio of different examples

[0324]

[0325]

[0326] Table 4 Porosity and porosity ratio of different comparative examples

[0327]

[0328] Table 5 Porosity and porosity ratio of different comparative examples

[0329]

[0330] Table 6 DCIR of different embodiments and comparative examples

[0331]

[0332]

[0333] Table 7 First charge and discharge capacity and first charge and discharge efficiency of different embodiments and comparative examples

[0334]

[0335]

[0336] Table 8 Self-discharge of different embodiments and comparative examples

[0337]

[0338]

[0339] Table 9 Liquid retention capacity of different embodiments and comparative examples

[0340]

[0341]

[0342] Table 10 Initial charge and discharge capacity, discharge capacity after 500 cycles, capacity retention rate, and number of cycles to 80% of initial capacity for different embodiments and comparative examples

[0343]

[0344]

[0345] By configuring the positive electrode sheet with a first lithium replenishment layer 300, an active material layer 400, and a second lithium replenishment layer 500, a reduction in the conductive agent content per unit volume in the active material layer of the positive electrode sheet is avoided, thereby improving the conductivity of the positive electrode sheet. The conductivity of the positive electrode sheet directly affects the conductivity of the battery, which can be determined by its internal resistance. As shown in Table 6, the internal resistance of the battery in Example 1 is 11.1 mΩ, while the internal resistance of the battery in Comparative Example 1 is 14.7 mΩ; the internal resistance of the battery in Example 1 is lower than that in Comparative Example 1. The internal resistance of the battery in Example 2 is 10.2 mΩ, while the internal resistance of the battery in Comparative Example 1 is 14.7 mΩ; the internal resistance of the battery in Comparative Example 3 is 12.2 mΩ. The internal resistance of the battery in Example 2 is lower than that in Comparative Examples 1 and 3.

[0346] Referring to Table 7, the first charge capacity of Example 2 is 2553 mAh, the first discharge capacity is 2291 mAh, and the first discharge efficiency is 89.74%. The first charge capacity of Comparative Example 1 is 2512 mAh, the first discharge capacity is 2202 mAh, and the first discharge efficiency is 87.66%. The first discharge efficiency of Example 2 is higher than that of Comparative Example 1.

[0347] Referring to Table 8, Examples 18, 20, and 21 are all provided with a safety layer 600. The self-discharge voltage drops of the batteries in Examples 18, 20, and 21 are 0.79 mV, 0.72 mV, and 0.65 mV, respectively. The self-discharge voltage drop of the battery in Example 2 is 0.92 mV. The self-discharge voltage drops of the batteries in Examples 18, 20, and 21 are lower than the self-discharge voltage drop of the battery in Example 2. The self-discharge voltage drops of the batteries in Examples 18, 20, and 21 are lower than the self-discharge voltage drops of the batteries in Comparative Examples 1-6.

[0348] Referring to Table 9, Examples 19-21 are all provided with a liquid retention layer 700. The electrolyte retention amounts of the batteries in Examples 19-21 are 10.44 g, 10.76 g, and 11.03 g, respectively. The electrolyte retention amount of the battery in Example 2 is 9.05 g. The electrolyte retention amounts of the batteries in Examples 19-21 are higher than those in Example 2. Furthermore, the electrolyte retention amounts of the batteries in Examples 19-21 are higher than those in Comparative Examples 1-6.

[0349] Referring to Table 10, the capacity retention rate of the battery of Example 2 after 500 cycles is 97.51%. At the same time, the capacity retention rates of the batteries of Examples 2-17 after 500 cycles are all greater than 97%. The capacity retention rate of Comparative Example 1 after 500 cycles is 94.28%, and the cycle performance of the embodiment is better than that of Comparative Example 1. At the same time, the capacity retention rate of Example 2 after 2000 cycles is greater than 80%, while the capacity retention rate of Comparative Example 1 after 1200 cycles is 80%, indicating that Example 2 is far superior to Comparative Example 1. The main functions of the first lithium replenishment layer and the second lithium replenishment layer are to provide additional lithium sources to compensate for the lithium loss that may occur in the battery during the cycle. The active material layer is the main area where electrochemical reactions occur in the battery. Moreover, the active material layer also provides additional lithium sources to compensate for the lithium loss that may occur in the battery during the cycle.

[0350] By providing pores in the first lithium replenishment layer 300, the active material layer 400, and the second lithium replenishment layer 500, the multi-layered porous structure of the positive electrode provides channels for gas flow, facilitating the smooth discharge of gas generated by the positive electrode during battery use, preventing gas accumulation inside the battery, and preventing battery expansion and deformation, thereby improving the battery's electrochemical performance and cycle stability.

[0351] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of the present application and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0352] It should be understood that the present application is not limited to the exact structure described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A positive electrode sheet, characterized in that: include: current collector(100); a first lithium replenishing layer (300), the first lithium replenishing layer (300) being arranged on at least one side in the thickness direction of the current collector (100); an active material layer (400), the active material layer (400) being disposed on a side of the first lithium replenishing layer (300) facing away from the current collector (100); A second lithium replenishing layer (500) is provided on a side of the active material layer (400) that is away from the first lithium replenishing layer (300).

2. The positive electrode sheet according to claim 1, characterized in that The porosity of the active material layer (400) is greater than the porosity of the first lithium replenishing layer (300), and / or the porosity of the second lithium replenishing layer (500) is greater than the porosity of the first lithium replenishing layer (300).

3. The positive electrode sheet according to claim 2, characterized in that: The porosities of the first lithium replenishing layer (300), the active material layer (400), and the second lithium replenishing layer (500) increase in sequence.

4. The positive electrode sheet according to claim 3, characterized in that: At least one of the following limitations is satisfied: the porosity of the first lithium replenishing layer (300) is P1, and P1 satisfies: 25%≤P1≤29%; The porosity of the active material layer (400) is Pm, and Pm satisfies: 30%≤Pm≤40%; The porosity of the second lithium replenishing layer (500) is P2, and P2 satisfies: 45%≤P2≤50%.

5. The positive electrode sheet according to claim 4, characterized in that: At least one of the following conditions is met: the ratio of Pm to P1 is A1, and A1 satisfies: 1.05≤A1≤1.5; The ratio of P2 to Pm is A2, and A2 satisfies: 1.2≤A2≤1.

7.

6. The positive electrode sheet according to claim 1, characterized in that The active material layer (400) includes an active lithium replenisher.

7. The positive electrode sheet according to claim 6, characterized in that: The first lithium replenishing layer (300) comprises a first lithium replenishing agent; the particle size of the active lithium replenishing agent is larger than the particle size of the first lithium replenishing agent.

8. The positive electrode sheet according to claim 7, characterized in that: The second lithium replenishing layer (500) includes a second lithium replenishing agent; the particle size of the second lithium replenishing agent is larger than the particle size of the active lithium replenishing agent.

9. The positive electrode sheet according to claim 8, characterized in that: The particle size of the first lithium supplement agent is D1, and D1 satisfies: 10nm≤D1≤80nm; And / or, the particle size of the active lithium supplement agent is Dm, and Dm satisfies: 100 nm ≤ Dm ≤ 350 nm; And / or, the particle size of the second lithium supplement agent is D2, and D2 satisfies: 400nm≤D2≤600nm.

10. The positive electrode sheet according to claim 9, characterized in that: The mass of the first lithium supplement is M1, the mass of the active lithium supplement is Mm, the mass of the second lithium supplement is M2, the active material layer (400) includes an active substance, and the mass of the active substance is Mh; The mass ratio of M1 to Mh is B1, and B1 satisfies: 0.5%≤B1≤1%; The mass ratio of Mm to Mh is Bm, and Bm satisfies: 1%≤Bm≤10%; The mass ratio of the M2 to the Mh is B2, and the B2 satisfies: 0.5%≤B2≤1%.

11. The positive electrode sheet according to claim 9, characterized in that: The first lithium supplement comprises one or more of Li2CO3, Li2O and Li2O2; And / or, the active lithium supplement includes Li2C2O4 and / or Li5FeO4; And / or, the second lithium supplement includes one or more of Li2MO2 and Li2N2O3, wherein M includes at least one of Ni, Fe, Cu, and Co, and N includes at least one of Al, Co, Mn, Ni, Fe, Cu, and Si.

12. The positive electrode sheet according to any one of claims 1 to 11, characterized in that: There are multiple active material layers (400), and the porosity of the multiple active material layers (400) increases sequentially from the first lithium replenishing layer (300) to the second lithium replenishing layer (500).

13. The positive electrode sheet according to any one of claims 1 to 11, characterized in that: It also includes a conductive coating (200), which is arranged between the current collector (100) and the first lithium replenishing layer (300).

14. The positive electrode sheet according to any one of claims 1 to 11, characterized in that: The invention also includes a safety layer (600), wherein the safety layer (600) is arranged on a side of the second lithium replenishing layer (500) facing away from the active material layer (400).

15. The positive electrode sheet according to any one of claims 1 to 11, characterized in that: The invention also includes a liquid retaining layer (700), wherein the liquid retaining layer (700) is arranged on a side of the second lithium replenishing layer (500) away from the active material layer (400).

16. The positive electrode sheet according to any one of claims 1 to 11, characterized in that: It also includes a safety layer (600) and a liquid-retaining layer (700); The safety layer (600) is arranged on a side of the second lithium replenishing layer (500) facing away from the active material layer (400); The liquid retaining layer (700) is arranged on a side of the safety layer (600) away from the second lithium replenishing layer (500).

17. The positive electrode sheet according to claim 16, characterized in that: At least one of the following conditions must be met: The porosity of the safety layer (600) is P3, and P3 satisfies: 51%≤P3≤55%; The porosity of the liquid retaining layer (700) is P4, and P4 satisfies: 56%≤P4≤60%.

18. The positive electrode sheet according to claim 17, characterized in that: The porosity of the second lithium replenishing layer (500) is P2, and at least one of the following conditions is satisfied: The ratio of P3 to P2 is A3, and A3 satisfies: 1.02≤A3≤1.3; The ratio of P4 to P3 is A4, and A4 satisfies: 1.02≤A4≤1.

3.

19. The positive electrode sheet according to claim 14, characterized in that: The safety layer (600) includes inorganic particles and a binder; The inorganic particles include at least one of aluminum oxide, aluminum oxide, silicon dioxide, and calcium oxide; The binder includes at least one of polyvinyl pyrrolidone, polymethyl methacrylate, polyvinyl alcohol, and polyacrylic acid.

20. The positive electrode sheet according to claim 15, characterized in that: The liquid retaining layer (700) includes at least one of polyvinylidene fluoride and polyimide.

21. The positive electrode sheet according to claim 19, characterized in that: The active material layer (400) includes active substances, and the mass ratio of the inorganic particles to the active substances is B3, and B3 satisfies: 0.5%≤B3≤1%.

22. The positive electrode sheet according to claim 15, characterized in that: The active material layer (400) includes an active substance, and the mass ratio of the liquid retaining layer (700) to the active substance is B4, and the B4 satisfies: 0.5%≤B4≤1%.

23. The positive electrode sheet according to any one of claims 1 to 11, characterized in that: The current collector (100) comprises a base layer (110) and a conductive layer (120); the conductive layer (120) is provided on at least one side of the base layer (110) in a thickness direction.

24. The positive electrode sheet according to claim 23, characterized in that: The thickness of the base layer (110) is C1, and C1 satisfies: 0.5 μm≤C1≤3.5 μm; And / or, the thickness of the conductive layer (120) is C2, and C2 satisfies: 4 μm≤C2≤7 μm.

25. The positive electrode sheet according to claim 23, characterized in that: The base layer (110) includes at least one of polypropylene and polyethylene terephthalate; And / or, the conductive layer (120) includes an aluminum layer.

26. A battery, characterized in that: A positive electrode sheet comprising any one of claims 1 to 25.

27. An electrical device, characterized in that: Including the battery of claim 26.

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