Composite positive pole piece as well as preparation method and application thereof

Abstract

The invention provides a composite positive pole piece as well as a preparation method and application thereof. The composite positive pole piece at least comprises a positive active material and a negative active material, and a halide solid electrolyte; wherein the chemical formula of the halide solid electrolyte is Li < 2 + a > Zr < 1-a > Fe Cl < 6-x-y > Br < x > I < y >, and a is more than 0 and less than or equal to 0.5; x = 0-6, y = 0-6, and x + y < = 6; and the compaction density of the composite positive pole piece is 2.8 g / cm < 3 >-3.4 g / cm < 3 >. According to the composite positive pole piece as well as the preparation method and the application thereof, the compaction density of the positive pole piece is improved, so that the rate capability and the cycle life of a lithium ion battery are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a composite positive electrode sheet and a preparation method and application thereof. Background Art

[0002] With the development of secondary batteries, mainly lithium-ion batteries, lithium-ion batteries have been widely used in portable electronic products and electric vehicles. However, the recent frequent safety accidents of new energy vehicles are due to the use of flammable organic solvents as electrolytes in traditional lithium-ion batteries, which pose serious safety hazards, and this problem cannot be completely solved by conventional improvement methods. In contrast, all-solid-state lithium-ion batteries using inorganic solid electrolytes have higher safety, and a major challenge facing all-solid-state lithium-ion batteries is the matching between electrode materials and solid electrolytes to reduce interface impedance and ensure interface stability. However, the cost of common solid electrolytes is relatively high, and the matching with positive electrode materials is poor. Positive electrode materials have problems such as large irreversible capacity loss in the first week, poor rate performance and cycle life, and fast voltage decay. Summary of the invention

[0003] The present invention proposes a composite positive electrode sheet and a preparation method and application thereof. The composite positive electrode sheet and a preparation method and application thereof provided in the present application can improve the compaction density of the positive electrode sheet, thereby improving the rate performance and cycle life of the lithium-ion battery. The lithium ion conductivity of the composite positive electrode sheet can be improved, while the side reaction between the composite positive electrode sheet and the sulfide electrolyte under high voltage can be effectively suppressed, and the interface stability between the positive electrode sheet and the solid electrolyte can be improved.

[0004] To solve the above technical problems, the present invention is implemented through the following technical solutions.

[0005] The present invention provides a composite positive electrode plate, comprising at least:

[0006] positive electrode active material; and

[0007] Halide solid electrolyte;

[0008] Wherein: the chemical formula of the halide solid electrolyte is Li 2+a Zr 1-a Fe a Cl 6-x-y Br x I y , and 0<a≤0.5; x=0~6, y=0~6, x+y≤6; the compaction density of the composite positive electrode sheet is 2.8g / cm 3 -3.4g / cm 3 .

[0009] In one embodiment of the present invention, the median particle size D50 of the halide solid electrolyte is 0.1 μm-10 μm.

[0010] In one embodiment of the present invention, the positive electrode active material includes nLi 2 MnO 3 (1-n)LiMO 2 , wherein the element M is selected from at least one of Ni, Co or Mn, and n=0-1.

[0011] In one embodiment of the present invention, the element M is selected from Mn, and n=0.2-0.5.

[0012] In one embodiment of the present invention, the ionic conductivity of the halide solid electrolyte is greater than or equal to 1 mS / cm.

[0013] The present invention also provides a method for preparing a composite positive electrode sheet, which comprises at least the following steps:

[0014] The positive electrode active material, the halide solid electrolyte, the conductive agent and the binder are uniformly mixed according to the mass ratio to obtain a mixed powder; and

[0015] Dry pressing or spraying the mixed powder onto a current collector with a conductive acid corrosion-resistant coating to obtain a composite positive electrode sheet; or

[0016] The mixed powder is dispersed in a solvent to obtain a slurry, the slurry is coated on a current collector with a conductive acid corrosion-resistant coating, and a composite positive electrode sheet is obtained by drying and rolling.

[0017] In one embodiment of the present invention, the conductive corrosion-resistant coating comprises one of a conductive carbon layer, a conductive polymer layer, a gold layer or a silver layer, and the thickness of the conductive corrosion-resistant coating is 0.01 μm-10 μm.

[0018] In one embodiment of the present invention, the mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder is (64-75): (20-30): (1-2): (4-5).

[0019] The present invention also provides a lithium-ion battery, comprising the composite positive electrode plate described above.

[0020] The present invention also provides an electronic device, comprising the lithium-ion battery described above.

[0021] In summary, the present invention proposes a composite positive electrode sheet and its preparation method and application, which can obtain a low-cost, small-sized, high-ion conductivity and high-voltage resistant halide solid electrolyte, which can improve the compaction density of the positive electrode sheet, thereby improving the rate performance and cycle life of the lithium-ion battery. At the same time, the halide solid electrolyte has good compatibility with the high-voltage positive electrode, which can increase the capacity of the lithium-ion battery and improve the cycle performance. It can improve the lithium ion conductivity of the composite positive electrode sheet, and at the same time effectively inhibit the side reaction of the composite positive electrode sheet and the sulfide electrolyte under high voltage, improve the interface stability between the positive electrode sheet and the solid electrolyte, reduce side reactions, improve the first-cycle coulomb efficiency of the battery, inhibit the dissolution of transition metals, thereby inhibiting the voltage decay during the cycle and improving the cycle life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0023] Figure 1 The present invention is a flow chart for preparing a halide solid electrolyte.

[0024] Figure 2 The present invention is a flow chart for preparing a composite positive electrode sheet. DETAILED DESCRIPTION

[0025] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0026] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make disclosure thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. If not otherwise specified, the "%" and "parts" shown in the following examples refer to "mass %" and "mass parts" respectively.

[0027] The technical solution of the present invention is further described in detail below in conjunction with several embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] The present invention proposes a composite positive electrode plate, which includes a current collector and a positive electrode active layer coated on the current collector. Among them, the current collector is, for example, a current collector with a conductive acid corrosion-resistant coating. The current collector selects any suitable positive electrode current collector, and is also, for example, aluminum foil, stainless steel foil or titanium foil, etc. The conductive acid corrosion-resistant coating includes one of a conductive carbon layer, a conductive polymer layer, a gold layer or a silver layer, etc., and the thickness of the conductive corrosion-resistant coating is 0.01μm-10μm. The positive electrode active layer includes at least a positive electrode active material and a halide solid electrolyte, etc., and the thickness of the positive electrode active layer is, for example, 80μm-140μm. The present application provides a low-cost, small-sized, high-ionic conductivity and high-voltage resistant halide solid electrolyte, which can improve the compaction density of the positive electrode plate, thereby improving the rate performance and cycle life of the battery. At the same time, it can solve the problem of high-voltage lithium-rich manganese-based materials and traditional electrolyte materials (such as Li 3 InCl 6 The interface instability problem between the electrodes (such as electrodes 1 and 2) is solved, which reduces the side reactions, improves the coulombic efficiency of the battery in the first cycle, inhibits the dissolution of transition metals, and thus inhibits the voltage decay during the cycle.

[0029] In one embodiment of the present invention, the chemical formula of the halide solid electrolyte is Li 2+a Zr 1-a Fe a Cl 6-x-y Br x I y , and 0<a≤0.5, x=0~6, y=0~6, x+y≤6, and the ionic conductivity of the halide solid electrolyte is greater than or equal to 1mS / cm, and the median particle size D50 of the halide solid electrolyte is, for example, 0.1μm-10μm, and for example, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm or 8μm. In order to improve the matching of the size of the halide solid electrolyte with the high-voltage lithium-rich manganese-based material, the compaction density of the composite positive electrode sheet can reach 2.8g / cm 3 -3.4g / cm 3 In one embodiment of the present invention, the halide solid electrolyte is, for example, Li 2.3 Zr 0.7 Fe 0.3 Cl 6In the present application, the halide solid electrolyte does not contain rare earth metals, which can significantly reduce the cost, and the halide solid electrolyte uses iron as a doping element, which further reduces the cost while increasing the Fe content in the lattice. 3+ The same-valent substitution can improve the ionic conductivity of the halide solid electrolyte. At the same time, the particle size of the halide solid electrolyte matches the positive electrode active material, which can improve the rate performance and cycle life of the lithium-ion battery. At the same time, it has good compatibility with high-voltage positive electrode active materials, reduces side reactions, improves the first-cycle coulomb efficiency of the battery, inhibits the dissolution of transition metals, thereby inhibiting the voltage decay during the cycle and improving the cycle life of the battery.

[0030] In one embodiment of the present invention, the positive electrode active material includes, for example, nLi 2 MnO 3 (1-n)LiMO 2 The positive electrode active material is a high voltage lithium manganese-based composite oxide or other lithium-rich manganese-based material, wherein the element M is selected from at least one of Ni, Co or Mn, and n=0-1. In one embodiment of the present invention, the element M is selected from Mn, and n=0.2-0.5. 2 MnO 3 and LiMO 2 The two components are compounded in different proportions, and the structure of the positive electrode active material is similar to α-NaFeO 2 Layered structure with higher discharge specific capacity to increase the capacity of lithium-ion batteries.

[0031] In one embodiment of the present invention, the positive electrode active layer further includes a conductive agent and a binder, etc., wherein the conductive agent is, for example, one or a combination of at least two of conductive carbon black (Super P, SP), carbon nanotubes (Carbon Nano-tube, CNT), vapor grown carbon fiber (VaporGrown Carbon Fiber, VGCF) or graphene, etc. In this embodiment, the conductive agent is, for example, a combination of conductive carbon black and vapor grown carbon fiber, and the mass ratio of the conductive carbon black to the vapor grown carbon fiber is, for example, 1:1. The binder can be dispersed in a low-polarity solvent, for example, including one or at least two of hydrogenated nitrile rubber (HNBR), styrene-butadiene-styrene block copolymers (SBS), styrene acrylate (SAC), acrylate (Acrylate), styrene-butadiene rubber (SBR), nitrile rubber (NBR), silica gel, polyvinylidene fluoride (PVDF) or carboxymethyl cellulose lithium (CMC-Li), and for example, hydrogenated nitrile rubber, fluororubber, styrene-butadiene-styrene block copolymer or styrene-butadiene rubber. In one embodiment of the present invention, the mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder is, for example, (64-75): (20-30): (1-2): (4-5).

[0032] See also Figure 1 As shown, the present invention also proposes a method for preparing a halide solid electrolyte, which includes but is not limited to steps S11 and S12.

[0033] Step S11: According to the chemical formula of the halide solid electrolyte, corresponding amounts of compounds containing Li, Zr and Fe are mixed to obtain a mixed powder.

[0034] Step S12: Grind and sinter the mixed powder to obtain a halide solid electrolyte.

[0035] See also Figure 1 As shown, in step S11, according to the chemical formula of the halide solid electrolyte Li 2+a Zr 1- a Fe a Cl (6-x-y) Br x Iy , mixing corresponding molar amounts of compounds containing Li, Zr and Fe ions to obtain a mixed powder. In one embodiment of the present invention, the chemical formula of the halide solid electrolyte is, for example, Li 2.3 Zr 0.7 Fe 0.3 Cl 6 The raw materials selected are, for example, lithium chloride (LiCl), zirconium chloride (ZrCl 4 ) and ferric chloride (FeCl 3 ) etc. In this embodiment, the multiple raw materials are mixed, for example, by ball milling, so that the raw materials are mixed and contacted more evenly, and the rotation speed of the ball milling is, for example, 200rpm-500rpm, and for example, 300rpm, the ball milling mixing time is, for example, 1h-2h, and for example, 1h, the diameter of the ball milling zirconium beads is, for example, 8mm-15mm, and for example, 10mm, and the ball-to-material ratio is, for example, (20-30):1, and for example, 30:1.

[0036] See also Figure 1 As shown, in one embodiment of the present invention, in step S12, after obtaining the mixed powder, the mixed powder is processed by ball milling, solid phase sintering or heating eutectic method, for example, and the mixed powder is prepared by grinding and sintering method. Among them, the grinding speed is, for example, 500rpm-800rpm, for example, 600rpm, and the grinding time is, for example, 8h-15h, for example, 10h. After the mixed powder is ground, the median particle size D50 of the mixed powder is, for example, 0.1μm-10μm, for example, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm or 8μm. The ground mixture is sintered to obtain a halide solid electrolyte. The sintering heating rate is, for example, 4°C / min-5°C / min, the sintering temperature is, for example, 250°C-350°C, the sintering time is 3-5 hours, the sintering atmosphere is, for example, an inert gas, and the sintering time is the time after the temperature is raised to the sintering temperature. The sintering process can enhance the crystallinity of the halide solid electrolyte. After the sintering is completed, the halide solid electrolyte is cooled by furnace cooling. In the halide solid electrolyte, the present invention uses Fe as the doping element, and Fe in the lattice is 3+ The same-valent substitution can improve the ionic conductivity of the electrolyte. In one embodiment of the present invention, the ionic conductivity of the halide solid electrolyte is, for example, ≥1 mS / cm.

[0037] See also Figure 2 As shown, the present invention also provides a method for preparing a composite positive electrode sheet, and the preparation method includes but is not limited to steps S100 to S200.

[0038] Step S100, the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder are uniformly mixed according to the mass ratio to obtain a mixed powder.

[0039] Step S200: Prepare the mixed powder on a current collector with a conductive acid corrosion-resistant coating by a dry method or a wet method to obtain a composite positive electrode sheet.

[0040] See also Figure 2 As shown, in one embodiment of the present invention, in step S100, the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder are uniformly mixed in a mass ratio to obtain a mixed powder. Among them, the mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder is, for example, (64-75): (20-30): (1-2): (4-5). In this embodiment, the mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder is, for example, 70:25:1:4. Among them, the conductive agent is a combination of conductive carbon black and vapor-grown carbon fiber, and the mass ratio of the conductive carbon black and the vapor-grown carbon fiber is 1:1.

[0041] See also Figure 2 As shown, in one embodiment of the present invention, in step S200, during dry production, the uniformly mixed powder is dry pressed or sprayed and rolled on a current collector with a conductive acid-resistant coating to obtain a composite positive electrode sheet. The current collector selects any suitable positive current collector, such as aluminum foil, stainless steel foil or titanium foil, and the conductive acid-resistant coating includes one of a conductive carbon layer, a conductive polymer layer, a gold layer or a silver layer, and the thickness of the conductive corrosion-resistant coating is 0.01 μm-10 μm. During wet production, the uniformly mixed powder is dispersed in a solvent to obtain a slurry, and the slurry is coated on a current collector with a conductive acid-resistant coating, and a composite positive electrode sheet is obtained by drying and rolling. The solvent is, for example, a good solvent for a binder, such as a low-polarity solvent alkane, benzene, ether or ester. The slurry is coated on the current collector with the conductive acid corrosion resistant coating by the conventional wet method, and the drying temperature is, for example, 80°C-200°C, and the time is, for example, 0.5h-12h. The rolling temperature is, for example, 50°C-70°C, and the pressure is, for example, 70MPa-95MPa. The compaction density of the composite positive electrode sheet after rolling is, for example, 2.8g / cm 3 -3.4g / cm 3 The cathode active layer in the present application has high compactness, which can enhance the ion transport between the cathode active material, the halide solid electrolyte itself and each other, and has higher capacity and better electrochemical performance.

[0042] The present invention also provides a lithium-ion battery, comprising a positive electrode sheet, a solid electrolyte and a negative electrode sheet, wherein the solid electrolyte is arranged between the positive electrode sheet and the negative electrode sheet. The solid electrolyte is selected from one or more of halides, sulfides, oxides or polymers. In this embodiment, the solid electrolyte is selected from Li 6 PS 5 Cl, etc. The positive electrode sheet is the composite positive electrode sheet obtained above. The negative electrode sheet is, for example, selected from metal indium, metal lithium, alloy, carbon negative electrode, tin-based negative electrode or nano oxide, etc. In this embodiment, the negative electrode sheet is, for example, selected from metal indium sheet. Add the positive electrode sheet to one side of the solid electrolyte, for example, press the sheet at a pressure of 300MPa, and press the positive electrode sheet and the electrolyte layer together. Then put the negative electrode sheet on the other side of the solid electrolyte, and after sealing under vacuum or inert atmosphere, an all-solid-state lithium-ion battery can be obtained.

[0043] Hereinafter, the present invention will be explained in more detail by citing examples, which should not be construed as limiting. Appropriate modifications may be made within the scope consistent with the gist of the present invention, all of which fall within the technical scope of the present invention.

[0044] Example 1

[0045] In an environment with a dew point of -30°C, the positive electrode active material 0.5Li 2 MnO 3 0.5LiMnO 2 、Halide solid electrolyte Li 2.3 Zr 0.7 Fe 0.3 Cl 6 , conductive agent Super P and VGCF, and binder hydrogenated nitrile rubber are dispersed in xylene in a mass ratio of 70:25:0.5:0.5:4. The viscosity of the slurry is adjusted by adjusting the amount of xylene added. The solid content of the slurry is about 50%. The slurry is coated on an aluminum foil with a conductive carbon layer by a doctor blade method. The thickness of the aluminum foil is 13μm and the thickness of the conductive carbon layer is 1μm. The coated current collector is blown dried at 110°C for 2h, and then rolled and compacted at 60°C at a pressure of 80MPa. The compaction density of the obtained composite positive electrode sheet is 3.1g / cm 3 In the composite positive electrode sheet, the thickness of the positive electrode active layer is 100 μm.

[0046] The thin indium sheet is used as the negative electrode, and the solid electrolyte layer is Li 6 PS 5Cl, add a composite positive electrode sheet to one side of the solid electrolyte layer, press it at a pressure of 300MPa to press the positive electrode sheet and the electrolyte layer together. Then put a thin indium sheet as the negative electrode sheet on the other side of the electrolyte, seal it under vacuum, and you can get an all-solid-state lithium-ion battery.

[0047] Example 2

[0048] The composite positive electrode sheet was rolled and compacted at 60°C and 95 MPa, and the compaction density was 3.4 g / cm 3 , other operations remain the same as those in Example 1.

[0049] Example 3

[0050] The composite positive electrode sheet was compacted by roller pressing at 60°C and 70 MPa, and the compaction density was 2.8 g / cm 3 , other operations remain the same as those in Example 1.

[0051] Comparative Example 1

[0052] The halide solid electrolyte in the composite positive electrode is replaced by a sulfide electrolyte Li 6 PS 5 C1, other operations are consistent with those in Example 1.

[0053] Comparative Example 2

[0054] The composite positive electrode sheet was rolled and compacted at 60°C and 30 MPa, and the compaction density was 2.0 g / cm 3 , other operations remain the same as those in Example 1.

[0055] Comparative Example 3

[0056] The composite positive electrode sheet was compacted by roller pressing at 60°C and 120 MPa, and the compaction density was 4.0 g / cm 3 , other operations remain the same as those in Example 1.

[0057] In Examples 1-3 and Comparative Examples 1-3 of the present invention, different composite positive electrode sheets are used to prepare lithium-ion batteries. The all-solid lithium-ion batteries prepared above are subjected to long-cycle charge and discharge at 25°C, and their first-cycle discharge specific capacity and cycle number are measured. The operating voltage range of the battery test is 1.5V-4.2V, the test rate is 0.3C, and the discharge capacity of each cycle is recorded. When the battery capacity reaches 80% of the first cycle capacity (80% State of Health, 80% SOH), the test is terminated to obtain the number of cycles at room temperature.

[0058] Table 1. Performance test results of lithium ion batteries in Examples 1-3 and Comparative Examples 1-3

[0059]

[0060] Please refer to Table 1. By comparing Example 1 and Comparative Example 1, the first-week discharge specific capacity and room-temperature cycle performance of the all-solid-state lithium-ion battery can be improved by adding a halide solid electrolyte to the composite positive electrode plate. That is, by adding a halide solid electrolyte, the capacity of the lithium-ion battery can be increased and the cycle performance can be improved, indicating that the halide solid electrolyte has good compatibility with the high-voltage lithium-rich manganese-based material, and can effectively inhibit the side reaction of the composite positive electrode plate and the sulfide electrolyte under high voltage, improve the interface stability between the positive electrode and the solid electrolyte, reduce side reactions, improve the first-week coulomb efficiency of the battery, inhibit the dissolution of transition metals, thereby inhibiting the voltage decay during the cycle and improving the cycle life of the battery.

[0061] Please refer to Table 1. Comparing Examples 1-3 and Comparative Examples 2-3, as the compaction density of the composite positive electrode sheet increases, the first-week discharge specific capacity and room temperature cycle performance of the all-solid-state lithium-ion battery first increase and then decrease. Because when the compaction density is low, the porosity of the composite positive electrode sheet increases, a small amount or part of the active material loses contact, resulting in a decrease in the performance of the lithium-ion battery. However, when the compaction density is high, a small amount of halide solid electrolyte is crushed, resulting in a decrease in the internal ionic conductivity of the composite positive electrode sheet, and the performance of the lithium-ion battery decreases. As the compaction density further increases, the electrode sheet will wrinkle and cause a short circuit. Therefore, while increasing the compaction density of the composite positive electrode sheet, the present application controls the range of the compaction density, thereby improving the rate performance and cycle life of the battery.

[0062] The present invention also provides an electronic device, the electronic device includes at least one of the above-mentioned lithium-ion batteries, and the lithium-ion battery is used to provide electrical energy. Among them, the electronic device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy and an electric tool, etc. In one embodiment of the present invention, the vehicle is, for example, a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. Spacecraft include airplanes, rockets, space shuttles and spacecrafts, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers, etc. The electronic device includes the above-mentioned lithium-ion battery, so the advantages of the above-mentioned lithium-ion battery are included, which will not be elaborated here.

[0063] In summary, the present invention proposes a composite positive electrode sheet and its preparation method and application, which can obtain a low-cost, small-sized, high-ion conductivity and high-voltage resistant halide solid electrolyte, which can improve the compaction density of the positive electrode sheet, thereby improving the rate performance and cycle life of the lithium-ion battery. At the same time, the halide solid electrolyte has good compatibility with the high-voltage positive electrode, which can increase the capacity of the lithium-ion battery and improve the cycle performance. It can improve the lithium ion conductivity of the composite positive electrode sheet, and at the same time effectively inhibit the side reaction of the composite positive electrode sheet and the sulfide electrolyte under high voltage, improve the interface stability between the positive electrode sheet and the solid electrolyte, reduce side reactions, improve the first-cycle coulomb efficiency of the battery, inhibit the dissolution of transition metals, thereby inhibiting the voltage decay during the cycle and improving the cycle life of the battery.

[0064] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept, such as a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

[0065] Except for the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described here in detail.

Claims

1. A composite positive electrode sheet, It is characterized in that At least: Positive electrode active material; as well as Halide solid electrolyte; Wherein: the chemical formula of the halide solid electrolyte is Li 2+a Zr 1-a Fe a Cl 6-x-y Br x I y , and 0<a≤0.5; x=0~6, y=0~6, x+y≤6; the compaction density of the composite positive electrode sheet is 2.8g / cm 3 -3.4g / cm 3 .

2. The composite positive electrode sheet according to claim 1, It is characterized in that The median particle size D50 of the halide solid electrolyte is 0.1 μm-10 μm.

3. The composite positive electrode sheet according to claim 1, It is characterized in that The positive electrode active material includes nLi 2 MnO 3 (1-n)LiMO 2 , wherein the element M is selected from at least one of Ni, Co or Mn, and n=0-1.

4. The composite positive electrode sheet according to claim 3, It is characterized in that The element M is selected from Mn, and n=0.2-0.

5.

5. The composite positive electrode sheet according to claim 1, It is characterized in that The ion conductivity of the halide solid electrolyte is greater than or equal to 1 mS / cm.

6. A method for preparing a composite positive electrode sheet, It is characterized in that At least the following steps are included: The positive electrode active material, the halide solid electrolyte, the conductive agent and the binder are uniformly mixed according to the mass ratio to obtain a mixed powder; as well as Dry pressing or spraying the mixed powder onto a current collector with a conductive acid corrosion-resistant coating to obtain a composite positive electrode sheet; or The mixed powder is dispersed in a solvent to obtain a slurry, the slurry is coated on a current collector with a conductive acid corrosion-resistant coating, and a composite positive electrode sheet is obtained by drying and rolling.

7. The method for preparing the composite positive electrode sheet according to claim 6, It is characterized in that The conductive corrosion-resistant coating comprises one of a conductive carbon layer, a conductive polymer layer, a gold layer or a silver layer, and the thickness of the conductive corrosion-resistant coating is 0.01 μm-10 μm.

8. The method for preparing the composite positive electrode sheet according to claim 6, It is characterized in that The mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent and the binder is (64-75):(20-30):(1-2):(4-5).

9. A lithium ion battery, It is characterized in that A composite positive electrode sheet comprising any one of claims 1 to 5.

10. An electronic device, It is characterized in that Includes the lithium ion battery as claimed in claim 9.

Images