Composite positive electrode plate and manufacturing method and application thereof

Abstract

PURPOSE: To provide a composite positive electrode plate and a manufacturing method and an application thereof.SOLUTION: A composite positive electrode plate at least includes a positive electrode active material and a halide solid electrolyte. The chemical formula of the halide solid electrolyte is Li2+aZr1-aFeaCl6-x-yBrxIy, and 0<a≤0.5, x=0 to 6, y=0 to 6, and x+y≤6 are satisfied, and the pressed density of the composite positive electrode plate is 2.8 g / cm3 to 3.4 g / cm3. The composite positive electrode plate and a manufacturing method and an application thereof improve the pressed density of a positive electrode plate, thus enhancing the rate performance and cycle life of a lithium-ion battery.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the field of lithium-ion battery technology, and particularly relates to a composite positive electrode plate, a manufacturing method thereof, and an application thereof.

Background Art

[0002] With the development of secondary batteries represented by lithium-ion batteries, lithium-ion batteries are widely used in fields such as portable electronic products and electric vehicles. However, recently, due to the use of flammable organic solvents as electrolytes in conventional lithium-ion batteries, accidents of new energy vehicles have occurred frequently, bringing serious safety risks, but they cannot be completely solved by conventional improvement methods. In contrast, all-solid-state lithium-ion batteries employing inorganic solid electrolytes exhibit high safety. However, a major problem with all-solid-state lithium-ion batteries is to reduce the interfacial impedance and ensure the stability of the interface by matching between the electrode material and the solid electrolyte. However, generally used solid electrolytes are costly and have low matching between the solid electrolyte and the positive electrode material. The positive electrode material has problems such as a large irreversible capacity loss in the initial cycle, poor rate performance and cycle life, and rapid voltage decay.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The present invention provides a composite positive electrode plate, a manufacturing method thereof, and an application thereof. The composite positive electrode plate, the manufacturing method thereof, and the application provided based on the present application can improve the compression density of the positive electrode plate, so that the rate performance and cycle life of the lithium-ion battery can be improved. In addition, the lithium-ion conduction ability of the composite positive electrode plate can also be improved, and at the same time, side reactions between the composite positive electrode plate and the sulfide electrolyte under high voltage can be effectively suppressed, and the interfacial stability between the positive electrode plate and the solid electrolyte can be improved.

Means for Solving the Problems

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

[0005] The present invention provides a composite positive electrode plate including at least a positive electrode active material and a halide solid electrolyte. 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 where 0 < a ≤ 0.5, x = 0 to 6, y = 0 to 6, and x + y ≤ 6. The compression density of the composite positive electrode plate is 2.8 g / cm 3 ~3.4 g / cm 3

[0006] In one embodiment of the present invention, the median particle diameter D50 of the halide solid electrolyte is 0.1 μm to 10 μm.

[0007] In one embodiment of the present invention, the positive electrode active material includes nLi2MnO3·(1 - n)LiMO2. Here, the element M is selected from at least one of Ni, Co, and Mn, and n = 0 to 1.

[0008] In one embodiment of the present invention, the element M is selected from Mn, and n = 0.2 to 0.5.

[0009] In one embodiment of the present invention, the ionic conductivity of the halide solid electrolyte is 1 mS / cm or more.

[0010] ​The present invention further provides a method for manufacturing a composite positive electrode plate, which at least includes the following steps. A positive electrode active material, a halide solid electrolyte, a conductive agent, and a binder are uniformly mixed based on a mass ratio to obtain a mixed powder. The mixed powder is dry-pressed or sprayed onto a current collector having an acid corrosion-resistant conductive coating to obtain a composite positive electrode plate. Alternatively, the mixed powder is dispersed in a solvent to obtain a slurry, the slurry is applied onto a current collector having an acid corrosion-resistant conductive coating, and then dried and rolled to obtain a composite positive electrode plate.

[0011] In one embodiment of the present invention, the acid corrosion-resistant conductive coating includes any one of a conductive carbon layer, a conductive polymer layer, a gold layer, and a silver layer, and the thickness of the acid corrosion-resistant conductive coating is 0.01 μm to 10 μm.

[0012] 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 to 75):(20 to 30):(1 to 2):(4 to 5).

[0013] The present invention further provides a lithium-ion battery including the above composite positive electrode plate.

[0014] The present invention further provides an electronic device including the above lithium-ion battery.

Advantages of the Invention

[0015] As described above, the present invention provides a composite positive electrode plate, a method for manufacturing the same, and an application thereof, which can obtain a halide solid electrolyte with low cost, small size, high ionic conductivity, and high breakdown voltage, and improve the rate performance and cycle life of a lithium-ion battery by improving the compression density of the positive electrode plate. At the same time, the halide solid electrolyte has excellent compatibility with a high-voltage positive electrode, so that the capacity of the lithium-ion battery can be improved and the cycling performance can be enhanced. In addition, the lithium-ion conduction ability of the composite positive electrode plate can be improved. At the same time, the side reaction between the composite positive electrode plate and the sulfide electrolyte under high voltage can be effectively suppressed, the interfacial stability between the positive electrode plate and the solid electrolyte can be improved, the side reaction can be reduced, the initial Coulombic efficiency of the battery can be improved, and the elution of transition metals can also be suppressed. Therefore, the voltage decay during the cycling process can be suppressed, and the cycle life of the battery can be improved.

Brief Description of the Drawings

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings necessary for the description of the embodiments will be briefly described below. Obviously, the drawings described below only show some embodiments of the present invention. Those skilled in the art can obtain other drawings based on these drawings without creative efforts.

[0017]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0018] The following specific examples are for explaining the embodiments of the present invention. However, those skilled in the art can easily understand other advantages and effects of the present invention based on the content disclosed in this specification. In addition, the present invention may be implemented or applied according to other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0019] It should be understood that the present invention may be implemented in different forms and is not limited to the embodiments described herein. Rather, the description of these embodiments is intended to fully and completely disclose the present invention and convey the scope of the present invention to those skilled in the art. Unless otherwise specified, "%" and "parts" shown in the following embodiments and examples refer to "mass%" and "parts by mass", respectively.

[0020] With reference to some embodiments and the accompanying drawings, the technical solution of the present invention will be described in more detail. Obviously, the described embodiments merely form a part of the embodiments of the present invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts shall all be included within the protection scope of the present invention.

[0021] The present invention provides a composite positive electrode plate including a current collector and a positive electrode active material layer coated on the current collector. The current collector is, for example, a current collector having an acid corrosion-resistant conductive coating. The current collector is any suitable positive electrode current collector such as an aluminum foil, a stainless steel foil, or a titanium foil. The acid corrosion-resistant conductive coating includes one of a conductive carbon layer, a conductive polymer layer, a gold layer, and a silver layer, and the thickness of the acid corrosion-resistant conductive coating is 0.01 μm to 10 μm. The positive electrode active material layer includes at least a positive electrode active material and a halide solid electrolyte, and the thickness of the positive electrode active material layer is, for example, 80 μm to 140 μm. The present application provides a low-cost, small-sized, high ion conductivity, and high withstand voltage halide solid electrolyte that can improve the compression density of the positive electrode plate and improve the rate performance and cycle life of the battery. At the same time, it can solve the problem of interface instability between the high-voltage lithium-rich manganese-based material and the conventional electrolyte material (for example, Li3InCl6), reduce side reactions, improve the initial Coulomb efficiency of the battery, and suppress the dissolution of transition metals, so that the voltage decay during the cycling process can be suppressed.

[0022] 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 where 0 < a ≤ 0.5, x = 0 to 6, y = 0 to 6, and x + y ≤ 6. The ionic conductivity of the halide solid electrolyte is 1 mS / cm or more, and the median particle size D50 of the halide solid electrolyte is, for example, 0.1 μm to 10 μm, or, for example, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, etc. Therefore, the matching between the size of the halide solid electrolyte and the high-voltage lithium-rich manganese-based material can be improved, and the compression density of the composite positive electrode plate can reach 2.8 g / cm 3 ~3.4 g / cm 3 In one embodiment of the present invention, the halide solid electrolyte is, for example, Li 2.3 Zr 0.7 Fe 0.3C l6 is. In the present application, since the halide solid electrolyte does not contain rare earth metals, the cost can be significantly reduced, and the halide solid electrolyte employs iron as a doping element. Therefore, while further reducing the cost, the ionic conductivity of the halide solid electrolyte can be improved by the equivalent substitution of Fe 3+ in the lattice. At the same time, since the particle size of the halide solid electrolyte matches that of the positive electrode active material, the rate performance and cycle life of the lithium-ion battery can be improved. In addition, it has excellent compatibility with the high-voltage positive electrode active material, reduces side reactions, improves the initial Coulomb efficiency of the battery, suppresses the dissolution of transition metals, and thus suppresses the voltage decay during the cycling process and improves the cycle life of the battery.

[0023] In one embodiment of the present invention, the positive electrode active material includes, for example, a lithium-rich manganese-based material such as a high-voltage lithium-manganese composite oxide of nLi2MnO3·(1-n)LiMO2. Here, the element M is selected from at least one of Ni, Co, and Mn, and n = 0 to 1. In one embodiment of the present invention, the element M is selected from Mn, and n = 0.2 to 0.5. In this embodiment, the positive electrode active material is composed of two components, Li2MnO3 and LiMO2, combined in different ratios. Since the structure of the positive electrode active material is similar to the α-NaFeO2 layered structure, it has a higher discharge specific capacity and improves the capacity of the lithium-ion battery.

[0024] In one embodiment of the present invention, the positive electrode active layer further includes a conductive agent, a binder, and the like. The conductive agent is, for example, one or at least a combination of two of conductive carbon black (Super P, SP), carbon nanotube (CNT), vapor grown carbon fiber (VGCF), and graphene. 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 conductive carbon black to vapor grown carbon fiber is, for example, 1:1. The binder can be dispersed in a low-polarity solvent and includes, for example, one or at least a combination of two of hydrogenated nitrile rubber (HNBR), styrenic block copolymers (SBS), styrene acrylate copolymer (SAC), acrylate, polymerized styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), silica gel, polyvinylidene fluoride (PVDF), and lithium carboxymethyl cellulose (CMC-Li). For example, the binder may be hydrogenated nitrile rubber, fluororubber, styrenic block copolymer, or polymerized 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 to 75):(20 to 30):(1 to 2):(4 to 5).

[0025] Referring to FIG. 1, the present invention further provides a method for manufacturing a halide solid electrolyte, including steps S11 to S12 (however, the present invention is not limited thereto).

[0026] In step S11, based on the chemical formula of the halide solid electrolyte, compounds containing corresponding amounts of Li, Zr, and Fe are mixed to obtain a mixed powder material.

[0027] In step S12, the mixed powder material is pulverized and sintered to obtain a halide solid electrolyte.

[0028] Referring to FIG. 1, in step S11, based on the chemical formula Li 2+a Zr 1-a Fe a Cl (6-x-y) Br x I y of the halide solid electrolyte, compounds containing corresponding moles of Li, Zr, and Fe ions are mixed to form a mixture, and a mixed powder material is obtained. 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 Cl6, and the selected raw materials are, for example, lithium chloride (LiCl), zirconium chloride (ZrCl4), iron chloride (FeCl3), etc. In this embodiment, for example, the raw materials are mixed by a ball mill to make the mixing and contact of the raw materials more uniform. The rotation speed of the ball mill is, for example, 200 rpm to 500 rpm, or, for example, 300 rpm. The mixing time of the ball mill is, for example, 1 h to 2 h, or, for example, 1 h. The diameter of the zirconia mill beads is, for example, 8 mm to 15 mm, or, for example, 10 mm. The ball-to-material ratio is, for example, (20 to 30):1, or, for example, 30:1.

[0029] Referring to FIG. 1, in one embodiment of the present invention, in step S12, after obtaining the mixed powder material, the mixed powder material is processed by methods such as ball milling, solid-phase sintering, or heat eutectic melting. For example, the mixed powder material is manufactured by grinding and sintering. The rotation speed of grinding is, for example, 500 rpm to 800 rpm, or, for example, 600 rpm. The grinding time is, for example, 8 h to 15 h, or, for example, 10 h. After grinding the mixed powder material, the median particle size D50 of the mixed powder is, for example, 0.1 μm to 10 μm, or, for example, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, or 8 μm. The ground mixture is sintered to obtain a halide solid electrolyte. The heating rate of sintering is, for example, 4 °C / min to 5 °C / min. The sintering temperature is, for example, 250 °C to 350 °C. The sintering time is 3 hours to 5 hours. The sintering atmosphere is, for example, an inert gas. The sintering time is the time after heating to the sintering temperature. The sintering process can improve the crystallinity of the halide solid electrolyte. After sintering is completed, the halide solid electrolyte is cooled by furnace cooling. In the present invention, in the halide solid electrolyte, Fe element is used as a doping element, and the ionic conductivity of the electrolyte can be improved by the equivalent substitution of Fe 3+ in the lattice. In one embodiment of the present invention, the ionic conductivity of the halide solid electrolyte is, for example, ≧1 mS / cm.

[0030] Referring to FIG. 2, the present invention further provides a method for manufacturing a composite positive electrode plate including steps S100 to S200 (however, the present invention is not limited thereto).

[0031] In step S100, a positive electrode active material, a halide solid electrolyte, a conductive agent, and a binder are uniformly mixed based on a mass ratio to obtain a mixed powder.

[0032] In step S200, the mixed powder is supplied onto a current collector having an acid-resistant and corrosion-resistant conductive coating by a dry process or a wet process to obtain a composite positive electrode plate.

[0033] Referring to FIG. 2, in one embodiment of the present invention, in step S100, a cathode active material, a halide solid electrolyte, a conductive agent, and a binder are uniformly mixed based on a mass ratio to obtain a mixed powder. The mass ratio of the cathode active material, the halide solid electrolyte, the conductive agent, and the binder is, for example, (64 to 75):(20 to 30):(1 to 2):(4 to 5). In this embodiment, the mass ratio of the cathode active material, the halide solid electrolyte, the conductive agent, and the binder is, for example, 70:25:1:4. The conductive agent is a combination of conductive carbon black and vapor-grown carbon fibers, and the mass ratio of the conductive carbon black to the vapor-grown carbon fibers is 1:1.

[0034] Referring to FIG. 2, in one embodiment of the present invention, in step S200, in the dry process, the uniformly mixed powder is dry-pressed or sprayed and rolled onto a current collector having an acid-resistant and corrosion-resistant conductive coating to obtain a composite cathode plate. The current collector may be any suitable positive current collector, such as aluminum foil, stainless steel foil, titanium foil, etc. The acid-resistant and corrosion-resistant conductive coating includes one of a conductive carbon layer, a conductive polymer layer, a gold layer, and a silver layer, and the thickness of the acid-resistant and corrosion-resistant conductive coating is 0.01 μm to 10 μm. In the wet process, the uniformly mixed powder is dispersed in a solvent to obtain a slurry. The slurry is applied onto a current collector having an acid-resistant and corrosion-resistant conductive coating, and dried and rolled to obtain a composite cathode plate. The solvent is, for example, a good solvent for the binder for obtaining the slurry, and is, for example, a low-polarity solvent such as alkane, benzene, ether, ester, etc. The slurry is applied onto a current collector having an acid-resistant and corrosion-resistant conductive coating by a conventional wet process, the drying temperature is, for example, 80°C to 200°C, and the time is, for example, 0.5 h to 12 h. The rolling temperature is, for example, 50°C to 70°C, the pressure is, for example, 70 MPa to 95 MPa, and the compression density of the composite cathode plate after rolling is, for example, 2.8 g / cm 3 ~3.4 g / cm 3That is. The high compactness of the positive electrode active layer in the present application can enhance the ion transport inside the positive electrode active material and the halide solid electrolyte and between the two, exhibit a higher capacity, and have excellent electrochemical performance.

[0035] The present invention further provides a lithium-ion battery including a positive electrode plate, a solid electrolyte, and a negative electrode plate, wherein the solid electrolyte is disposed between the positive electrode plate and the negative electrode plate. The solid electrolyte is selected from one or more of halides, sulfides, oxides, and polymers. In this embodiment, the solid electrolyte is selected from, for example, Li6PS5Cl. The positive electrode plate is the composite positive electrode plate obtained as described above. The negative electrode plate is selected from, for example, metal indium, metal lithium, alloys, carbon negative electrodes, tin-based negative electrodes, or nano-oxides. In this embodiment, the negative electrode plate is selected from, for example, a metal indium plate. The positive electrode plate is added to one side of the solid electrolyte and pressed, for example, at a pressure of 300 MPa to press the positive electrode plate and the electrolyte layer together. Subsequently, the negative electrode plate is disposed on the other side of the solid electrolyte and sealed under a vacuum or an inert atmosphere to obtain an all-solid-state lithium-ion battery.

[0036] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Appropriate modifications can be made within the scope consistent with the gist of the present invention, and all such modifications are intended to be included within the technical scope of the present invention. Example 1

[0037] In an environment with a dew point of -30°C, the positive electrode active material 0.5Li2MnO3·0.5LiMnO2, the halide solid electrolyte Li 2.3 Zr 0.7 Fe 0.3Cl6, conductive agent Super P and VGCF, and a binder of hydrogenated nitrile rubber were dispersed in xylene based on a mass ratio of 70:25:0.5:0.5:4. By adjusting the amount of xylene added, the viscosity of the slurry was adjusted, and the solid content of the slurry was about 50%. The slurry was applied onto an aluminum foil having a conductive carbon layer by scrape coating. The thickness of the aluminum foil was 13 μm, and the thickness of the conductive carbon layer was 1 μm. After the coated current collector was air-dried at 110 °C for 2 hours, it was rolled and compressed at 60 °C under a pressure of 80 MPa. The compression density of the obtained composite positive electrode plate was 3.1 g / cm 3 It was. The thickness of the positive electrode active layer in the composite positive electrode plate was 100 μm.

[0038] A thin indium plate was used as the negative electrode, and the solid electrolyte layer was Li6PS5Cl. The composite positive electrode plate was added to one side of the solid electrolyte layer and pressed under a pressure of 300 MPa to press the positive electrode plate and the electrolyte layer together. Subsequently, a thin indium plate was placed as the negative electrode plate on the other side of the electrolyte and sealed under vacuum to obtain an all-solid-state lithium-ion battery. Example 2

[0039] The composite positive electrode plate was rolled and compressed at 60 °C under a pressure of 95 MPa, and the compression density of the obtained composite positive electrode plate was 3.4 g / cm 3 It was. All other operations were the same as in Example 1. Example 3

[0040] The composite positive electrode plate was rolled and compressed at 60 °C under a pressure of 70 MPa, and the compression density of the obtained composite positive electrode plate was 2.8 g / cm 3 It was. All other operations were the same as in Example 1. Comparative Example 1

[0041] The halide solid electrolyte in the composite positive electrode plate was replaced with a sulfide electrolyte Li6PS5Cl. All other operations were the same as in Example 1. Comparative Example 2

[0042] The composite positive electrode plate was rolled and compressed at a pressure of 60 °C and 30 MPa, and the compression density of the obtained composite positive electrode plate was 2.0 g / cm 3 . All other operations were the same as in Example 1. Comparative Example 3

[0043] The composite positive electrode plate was rolled and compressed at a pressure of 60 °C and 120 MPa, and the compression density of the obtained composite positive electrode plate was 4.0 g / cm 3 . All other operations were the same as in Example 1.

[0044] In the present invention, lithium-ion batteries were manufactured using the different composite positive electrode plates of Examples 1 to 3 and Comparative Examples 1 to 3. In an environment of 25 °C, long-cycle charge and discharge were performed on the obtained all-solid-state lithium-ion batteries, and their initial discharge specific capacity and number of cycles were measured. The operating voltage range of the battery test was 1.5 V to 4.2 V, and the test rate was 0.3C. The discharge capacity of each cycle was recorded. The test was terminated when the battery capacity reached 80% of the initial cycle capacity (80% state of health, SOH), and the number of cycles at room temperature was obtained. Performance test results of the lithium-ion batteries of Examples 1 to 3 and Comparative Examples 1 to 3

[0045]

Table 1

[0046] As shown in Table 1, when comparing Example 1 with Comparative Example 1, by adding a halide solid electrolyte to the composite positive electrode plate, the initial discharge specific capacity and room temperature cycle performance of the all-solid-state lithium-ion battery were improved. That is, by adding a halide solid electrolyte, the capacity and cycle performance of the lithium-ion battery can be improved. This is because the halide solid electrolyte has excellent compatibility with the high-voltage lithium-rich manganese-based material, effectively suppresses the side reaction between the composite positive electrode plate and the sulfide electrolyte under high voltage, strengthens the interfacial stability between the positive electrode and the solid electrolyte, reduces the side reaction, improves the initial Coulomb efficiency of the battery, and can suppress the elution of transition metals, indicating that it can suppress the voltage decay during the cycle process and increase the cycle life of the battery.

[0047] As shown in Table 1, when comparing Examples 1 to 3 and Comparative Examples 2 to 3, as the compression density of the composite positive electrode plate increased, the initial discharge specific capacity and room temperature cycle performance of the all-solid-state lithium-ion battery first increased and then decreased. When the compression density is low, the porosity of the composite positive electrode plate increases, so that a small amount or some of the active substances do not come into contact, and the performance of the lithium-ion battery deteriorates. However, when the compression density is high, a small amount of the halide solid electrolyte is destroyed, so that the ionic conductivity inside the composite positive electrode plate decreases, and the performance of the lithium-ion battery deteriorates. If the compression density is further increased, creases will occur in the electrode plate and short circuits will occur. Therefore, the present application improves the battery rate performance and cycle life by controlling the range of the compression density while improving the compression density of the composite positive electrode plate.

[0048] The present invention further provides an electronic device including at least one of the above-described lithium-ion batteries and using the lithium-ion battery to provide electrical energy. The electronic device may be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, a power tool, etc. In one embodiment of the present invention, the vehicle is, for example, a new energy vehicle, and may be a pure electric vehicle, a hybrid vehicle, a range-extended vehicle, etc. The spacecraft includes an airplane, a rocket, a space shuttle, a spacecraft, etc. The electric toy includes stationary or mobile electric toys such as a game console, an electric toy car, an electric toy ship, an electric toy airplane. The power tool includes an electric metal cutting tool, an electric grinding tool, an electric assembly tool, and an electric railway tool, and includes, for example, an electric drill, an electric grinder, an electric wrench, an electric driver, an electric hammer, an impact drill, a concrete vibrator, an electric cutter, etc. Since the electronic device includes the above-described lithium-ion battery, it includes the advantages of the lithium-ion battery, but the detailed description is omitted here.

[0049] As described above, the present invention provides a composite positive electrode plate, a manufacturing method thereof, and an application that can improve the rate performance and cycle life of a lithium-ion battery by obtaining a low-cost, small-sized, high ion conductivity, and high withstand voltage halide solid electrolyte and improving the compression density of the positive electrode plate. At the same time, since the halide solid electrolyte has excellent compatibility with the high-voltage positive electrode, the capacity of the lithium-ion battery can be improved and the cycling performance can be improved. In addition, the lithium-ion conduction ability of the composite positive electrode plate can be improved. At the same time, the side reaction between the composite positive electrode plate and the sulfide electrolyte under high voltage can be effectively suppressed, the interfacial stability between the positive electrode plate and the solid electrolyte can be improved, the side reaction can be reduced, the initial Coulomb efficiency of the battery can be improved, and the elution of transition metals can be suppressed. Therefore, the voltage decay during the cycling process can be suppressed and the cycle life of the battery can be improved.

Industrial Applicability

[0050] The composite positive electrode plate and its manufacturing method provided by the present invention can be applied to lithium-ion batteries.

[0051] The above description only shows the exemplary embodiments and examples of the present application and explains the included technical principles. As can be understood by those skilled in the art, the scope of the present invention included in the present application is not limited to the technical solutions formed by specific combinations of the above technical features, and without departing from the concept of the present invention, other technical solutions formed by any combination of the above technical features or their equivalent features, for example, the technical solutions formed by replacing the above features with technical features having the same functions (but not limited to this) disclosed in the present application should also be included.

[0052] Except for the technical features described in this specification, the remaining technical features are known technical features to those skilled in the art. In order to emphasize the innovative features of the present invention, the remaining features will not be repeatedly described here.

Description of Reference Signs

[0053] Steps S11, S12, S100, S200

Claims

1. A positive electrode active material, a halide solid electrolyte, and at least includes 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 where 0 < a ≤ 0.5, x = 0 to 6, y = 0 to 6, and x + y ≤ 6, and the compression density of the composite positive electrode plate is 2.8 g / cm ３ to 3.4 g / cm ３ A composite positive electrode plate.

2. The median particle size D50 of the halide solid electrolyte is 0.1 μm to 10 μm. The composite positive electrode plate according to Claim 1.

3. The positive electrode active material includes nLi ２ MnO ３ ·(1 - n)LiMO ２ where the element M is selected from at least one of Ni, Co, and Mn, and n = 0 to 1. The composite positive electrode plate according to Claim 1.

4. The element M is selected from Mn, and n = 0.2 to 0.

5. The composite positive electrode plate according to Claim 3.

5. The ionic conductivity of the halide solid electrolyte is 1 mS / cm or more. The composite positive electrode plate according to Claim 1.

6. Uniformly mixing a positive electrode active material, a halide solid electrolyte, a conductive agent, and a binder based on a mass ratio to obtain a mixed powder, Dry pressing or spraying the mixed powder onto a current collector having an acid corrosion-resistant conductive coating to obtain a composite positive electrode plate, Dispersing the mixed powder in a solvent to obtain a slurry, coating the slurry onto the current collector having the acid corrosion-resistant conductive coating, and performing drying and rolling to obtain the composite positive electrode plate, A method for manufacturing a composite positive electrode plate including at least.

7. The method for manufacturing a composite positive electrode plate according to claim 6, wherein the acid-resistant and corrosion-resistant conductive coating includes one of a conductive carbon layer, a conductive polymer layer, a gold layer, and a silver layer, and the thickness of the acid-resistant and corrosion-resistant conductive coating is 0.01 μm to 10 μm.

8. The method for manufacturing a composite positive electrode plate according to claim 6, wherein the mass ratio of the positive electrode active material, the halide solid electrolyte, the conductive agent, and the binder is (64 to 75):(20 to 30):(1 to 2):(4 to 5).

9. A lithium-ion battery including the composite positive electrode plate according to any one of claims 1 to 5.

10. An electronic device including the lithium-ion battery according to claim 9.

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