Preparation method of lithium-rich manganese-based composite positive electrode material coated with lithium ferric chloride and application of lithium-rich manganese-based composite positive electrode material in solid-state battery

Abstract

The invention provides a preparation method of a lithium-rich manganese-based composite positive electrode material coated with lithium ferric chloride and an application of a solid-state battery, a lithium ferric chloride coating layer is obtained in situ on the surface of the lithium-rich manganese-based positive electrode material through spray drying, and compared with a common coating layer, the lithium ferric chloride coating layer has the advantages that the coating layer is more uniform; the solid electrolyte has the advantages of good compatibility, excellent conductivity and ion conductivity and the like, and is a novel halide positive electrode material researched and developed for adapting to the solid electrolyte, so that the interface incompatibility between the positive electrode and the solid electrolyte is reduced. In addition, the excellent conductivity of lithium ferric chloride can reduce the use of a conductive agent on the positive electrode side, reduce ion and electron diffusion tortuosity and improve the diffusion coefficient. Meanwhile, the synthesis method is simple and effective, the cost is low, and the prepared composite positive electrode material can be used as an integrated all-solid-state positive electrode material and is suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to a method for preparing a lithium-rich manganese-based composite cathode material coated with lithium iron chloride and its application in solid-state batteries, belonging to the field of lithium-ion battery technology. Background Technology

[0002] Driven by the large-scale application of electric vehicles, lithium-ion batteries have experienced rapid development over the past decade, with energy densities exceeding 300 Wh / kg and costs significantly reduced to approximately $100 / kWh. Global electric vehicle battery usage has reached 517.9 GWh, spawning an industry worth tens of billions of dollars. However, lithium-ion batteries based on liquid electrolytes are gradually approaching their energy density limits and pose certain safety risks. To meet the growing demand for high-energy-density, high-safety, and long-life batteries, academia and industry have been actively engaged in the research and development of next-generation battery technologies in recent years, including all-solid-state batteries, lithium-sulfur batteries, and lithium-air batteries. Among these, all-solid-state batteries are widely regarded as a disruptive technology driving the popularization of electric vehicles due to their significant advantages in safety, energy density, power characteristics, temperature adaptability, and electrode material selection. Automakers have high hopes for them, believing that all-solid-state batteries will significantly improve the overall competitiveness of electric vehicles in terms of range, charging speed, cost control, integration efficiency, and environmental adaptability.

[0003] Some traditional cathode materials (such as lithium cobalt oxide and nickel-rich oxide cathodes) have been successfully applied in all-solid-state batteries, but these cathode materials are limited by their intrinsic capacity, mostly below 200 mAh / g. Unlike traditional cathodes that rely solely on the redox reaction of transition metal ions to provide capacity, lithium-rich manganese-based layered oxide cathodes can provide additional capacity (>250 mAh / g) by triggering the redox reaction of anionic oxygen, thus breaking through the capacity bottleneck caused by the traditional transition metal redox mechanism. Therefore, applying lithium-rich manganese-based cathodes to all-solid-state batteries has become an important research direction for improving battery energy density.

[0004] Existing research mainly uses coating technology to modify the surface of lithium-rich manganese-based materials to improve the overall performance of all-solid-state batteries. However, due to poor coating uniformity, complex in-situ synthesis process, and cost, most existing methods cannot achieve the desired effect and are difficult to scale up production. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for preparing lithium-rich manganese-based composite cathode material coated with lithium iron chloride and its application in solid-state batteries.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A lithium-rich manganese-based composite cathode material coated with lithium iron chloride, characterized in that: the material is prepared by the following method, the steps of which are as follows: (1) Lithium chloride, ferrous chloride, ferric chloride and antioxidant were added to an appropriate amount of deionized water in proportion and dispersed by ultrasonication to obtain a uniform solution. (2) Add lithium-rich manganese-based cathode powder to solution І, stir to obtain a uniform mixed solution П, and obtain powder by spray drying of mixed solution П; (3) The obtained powder is placed in a crucible, and then the crucible is placed in a heating device for high-temperature treatment. The temperature is raised to 150℃~400℃ and calcined for 2h~15h. The calcination atmosphere is nitrogen or argon. After calcination, the temperature is lowered and cooled to obtain a lithium-rich manganese-based cathode material coated with lithium iron chloride in the crucible. The molar ratio of lithium chloride, ferrous chloride, and ferric chloride is 13:9:3, and the antioxidant accounts for 1% of the mass of lithium ferric chloride; the lithium ferric chloride coating layer accounts for 2% to 7% of the total mass of the cathode material; the lithium-rich manganese-based cathode powder is xLi2MnO3·(1-x)LiMO2, where M is at least one of Mn, Co, and Ni, and 0≤x≤1.

[0007] Preferably, in step (1), the antioxidant is ascorbic acid or citric acid, which serves to prevent the oxidation of ferrous iron during the synthesis process.

[0008] Preferably, in step (1), the ultrasonic intensity during ultrasonic dispersion is 100~200 KHZ and the ultrasonic time is 0.5h~2h.

[0009] Preferably, in step (2), the stirring temperature is room temperature, the stirring speed is 500~1500 rpm, the stirring time is 0.25h~1h, and the spray drying temperature is 150~250℃.

[0010] Preferably, in step (3), the heating device used is a tubular furnace, and nitrogen or argon is introduced during the calcination process, with a gas flow rate of 50cfm ~ 300cfm.

[0011] Preferably, the particle diameter of the lithium iron chloride-coated composite lithium-rich manganese-based cathode material is 2 to 15 μm, and the thickness of the lithium iron chloride coating layer is 5 to 100 nm.

[0012] The preparation method of lithium-rich manganese-based composite cathode material coated with lithium iron chloride and its application in solid-state batteries as described in any of the above claims, preferably, is applied to all-solid-state lithium batteries.

[0013] Preferably, the solid electrolyte of the all-solid-state lithium battery includes a halide solid electrolyte layer and a sulfide solid electrolyte layer.

[0014] Preferably, the method for preparing the all-solid-state lithium battery includes the following steps: (1) The halide solid electrolyte powder or sulfide solid electrolyte powder is evenly sprinkled into the tableting mold and pressed for 300-500 MPa for 30-60 seconds to compress the powder electrolyte into tablets; the solid electrolyte tablet has a mass of 100 mg and a thickness of 500 μm. (2) The composite lithium-rich manganese cathode material coated with lithium iron chloride is evenly sprinkled on one side of the solid electrolyte sheet and held under pressure of 300-500 MPa for 60-120 seconds; the composite lithium-rich manganese cathode material is 8 mg and the thickness after pressing is preferably 70 μm. (3) Add a negative electrode material to the side of the sulfide solid electrolyte; the negative electrode material is lithium metal, and the thickness after pressing is 30 μm. Beneficial effects

[0015] This invention provides a lithium-iron chloride-coated composite lithium-rich manganese cathode material. A lithium-iron chloride coating layer is uniformly synthesized on the surface of the layered cathode using a spray-drying method without affecting its performance. Compared to common coating layers, the lithium-iron chloride coating layer is inexpensive, has a simple synthesis process, and offers advantages such as good solid-state electrolyte compatibility, excellent conductivity, and superior ion conduction properties. It is also a novel halide cathode material developed specifically for solid-state electrolytes, thereby reducing interfacial incompatibility between the cathode and the solid-state electrolyte. Simultaneously, the excellent conductivity of lithium-iron chloride reduces the need for conductive agents on the cathode side, decreases the diffusion tortuosity of ions and electrons, and improves the diffusion coefficient. Furthermore, the composite cathode material allows for an integrated cathode, further optimizing the all-solid-state battery system and increasing its energy density. The resulting lithium-iron chloride-coated composite lithium-rich manganese cathode material effectively combines cost and performance advantages, meeting the requirements of all-cell cathode materials.

[0016] This invention provides a lithium-rich manganese-based composite cathode material coated with lithium iron chloride. The lithium iron chloride coating layer is obtained in situ on the surface of the lithium-rich manganese-based cathode material by spray drying. The method is simple, effective, and low in cost. The prepared composite cathode material can be used as an integrated all-solid-state cathode material and is suitable for large-scale production. Attached Figure Description

[0017] Figure 1 The energy dispersive spectroscopy (EDS) spectrum of the lithium iron chloride-coated composite lithium-rich manganese cathode material prepared in Example 1 is shown.

[0018] Figure 2 The voltage-capacity diagram of the battery assembled from the lithium iron chloride-coated composite lithium-rich manganese cathode material prepared in Example 1 during the first two cycles (0.1C).

[0019] Figure 3The image shows the cycle data of the battery assembled with the lithium iron chloride-coated composite lithium-rich manganese cathode material prepared in Example 1 (the current density for the first 5 cycles is 0.1C, and the current density for subsequent cycles is 0.2C).

[0020] Figure 4 The voltage-capacity graph of the battery assembled with the lithium-rich manganese cathode material prepared in Comparative Example 1 during the first two cycles (0.1C).

[0021] Figure 5 Cyclic data of the battery assembled with the lithium-rich manganese cathode material prepared in Comparative Example 1 (current density of 0.1C for the first 5 cycles and 0.2C for subsequent cycles).

[0022] Figure 6 Voltage-capacity graph of the battery assembled with the lithium-rich manganese cathode material of Comparative Example 2 during the first two cycles (0.1C).

[0023] Figure 7 Cyclic data of the battery assembled with the lithium-rich manganese cathode material of Comparative Example 2 (current density of 0.1C for the first 5 cycles and 0.2C for subsequent cycles). Detailed Implementation

[0024] To better clarify and understand the objectives, process solutions, and advantages of this invention, the technical solutions and implementation methods of this invention will be further described clearly, completely, and in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the embodiments described in this invention are implemented under the premise of the technical solutions of this invention, providing detailed implementation methods and specific operating procedures, but are only some embodiments of this invention, not all embodiments. The specific implementation methods described are limited to illustrating and explaining this invention and do not limit this invention. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] Unless otherwise specified, the experimental methods and conditions used in the embodiments of this invention are conventional methods and conditions. The materials, reagents, and instruments used in the embodiments, unless otherwise specified, can be obtained commercially or prepared by conventional methods. The reaction conditions described in the invention can all achieve the reactions and obtain the desired products. Due to space limitations, some embodiments are listed below to further illustrate the advantages of the technical solution of this invention. Example

[0026] A molar ratio of lithium chloride, ferrous chloride, and ferric chloride (13:9:3) along with 1% ascorbic acid (the total mass of the first three samples) was dissolved in deionized water and dispersed by ultrasonication to obtain a homogeneous solution. Then, lithium-rich manganese-based (Li-based) solutions (20 times the total mass of the lithium chloride, ferrous chloride, and ferric chloride samples) were added. 1.2 Ni 0.2 Mn 0.6 O2) Positive electrode powder was added to solution І and stirred to obtain a homogeneous mixed solution П. The mixed solution П was spray-dried at 200℃ to obtain powder. The obtained powder was placed in a crucible, and then the crucible was placed in a heating device for high-temperature treatment. The temperature was raised to 200℃ and calcined for 5 hours in an argon atmosphere. After calcination, the temperature was lowered and cooled to obtain Li in the crucible. 1.3 Fe 1.2 Cl4@Li 1.2 Ni 0.2 Mn 0.6 O2 composite cathode material.

[0027] In a glove box, 100 mg of Li6PS5Cl solid electrolyte powder was evenly sprinkled into a tableting mold and pressed into tablets at 400 MPa for 50 seconds; then 10 mg of Li 1.3 Fe 1.2 Cl4@Li 1.2 Ni 0.2 Mn 0.6 O2 composite cathode material is evenly sprinkled on one side of the solid electrolyte sheet and held at 400 MPa for 100 s; a lithium metal sheet with a thickness of 30 μm is added to the side of the sulfide solid electrolyte and held at 400 MPa for 50 s to obtain an all-solid-state battery.

[0028] The electrochemical performance of the all-solid-state battery was tested on the Blue Electric system. The test voltage range was 2.5-4.8 V, the test temperature was 30℃, and the test current density was 0.1C-0.2C (1C=250 mA / g).

[0029] Lithium-rich manganese-based (Li 1.2 Ni 0.2 Mn 0.6 O2) positive electrode powder was added to the solution and stirred until homogeneous. The mixture was then spray-dried at 200°C to obtain powder. The resulting powder was placed in a crucible, which was then placed in a heating device for high-temperature treatment. The temperature was raised to 200°C and calcined for 5 hours in an argon atmosphere. After calcination, the mixture was cooled, and Li (Comparative Example 1) was obtained in the crucible. 1.2 Ni 0.2 Mn 0.6 O2 cathode material.

[0030] In a glove box, 100 mg of Li6PS5Cl solid electrolyte powder was evenly sprinkled into a tableting mold and pressed into tablets at 400 MPa for 50 seconds; then 10 mg of the Li obtained in Comparative Example 1 was added. 1.2 Ni 0.2 Mn 0.6 O2 cathode material is evenly sprinkled on one side of the solid electrolyte sheet and held at 400 MPa for 100 s; a lithium metal sheet with a thickness of 30 μm is added to the side of the sulfide solid electrolyte and held at 400 MPa for 50 s to obtain an all-solid-state battery.

[0031] The electrochemical performance of the all-solid-state battery was tested on the Blue Electric system. The test voltage range was 2.5-4.8 V, the test temperature was 30℃, and the test current density was 0.1C-0.2C (1C=250 mA / g).

[0032] Directly take untreated lithium-rich manganese-based (Li) 1.2 Ni 0.2 Mn 0.6 O2) positive electrode powder was used as the Li in Comparative Example 2 1.2 Ni 0.2 Mn 0.6 O2 cathode material.

[0033] In a glove box, 100 mg of Li6PS5Cl solid electrolyte powder was evenly sprinkled into a tableting mold and pressed into tablets at 400 MPa for 50 seconds; then 10 mg of Li6PS5Cl solid electrolyte powder from Comparative Example 2 was added. 1.2 Ni 0.2 Mn 0.6 O2 cathode material is evenly sprinkled on one side of the solid electrolyte sheet and held at 400 MPa for 100 s; a lithium metal sheet with a thickness of 30 μm is added to the side of the sulfide solid electrolyte and held at 400 MPa for 50 s to obtain an all-solid-state battery.

[0034] The electrochemical performance of the all-solid-state battery was tested on the Blue Electric system. The test voltage range was 2.5-4.8 V, the test temperature was 30℃, and the test current density was 0.1C-0.2C (1C=250 mA / g).

Claims

1. A composite lithium-rich manganese-based cathode material coated with lithium iron chloride, characterized in that: The material is prepared by the following method, the steps of which are as follows: (1) Lithium chloride, ferrous chloride, ferric chloride and antioxidant were added to an appropriate amount of deionized water in proportion and dispersed by ultrasonication to obtain a uniform solution. (2) Add lithium-rich manganese-based cathode powder to solution І, stir to obtain a uniform mixed solution П, and obtain powder by spray drying of mixed solution П; (3) The obtained powder is placed in a crucible, and then the crucible is placed in a heating device for high-temperature treatment. The temperature is raised to 150℃~400℃ and calcined for 2h~15h. The calcination atmosphere is nitrogen or argon. After calcination, the temperature is lowered and cooled to obtain a lithium-rich manganese-based cathode material coated with lithium iron chloride in the crucible. The molar ratio of lithium chloride, ferrous chloride, and ferric chloride is 13:9:3, and the antioxidant accounts for 1% of the mass of lithium ferric chloride; the lithium ferric chloride coating layer accounts for 2% to 7% of the total mass of the cathode material; the lithium-rich manganese-based cathode powder is xLi2MnO3·(1-x)LiMO2, where M is at least one of Mn, Co, and Ni, and 0≤x≤1.

2. The lithium iron chloride-coated composite lithium-rich manganese-based cathode material as described in claim 1, characterized in that: In step (1), the antioxidant is ascorbic acid or citric acid, which is used to prevent the oxidation of ferrous iron during the synthesis process.

3. The lithium iron chloride-coated composite lithium-rich manganese-based cathode material as described in claim 1, characterized in that: In step (1), the ultrasonic intensity is 100~200 KHZ and the ultrasonic time is 0.5h~2h during ultrasonic dispersion.

4. The lithium iron chloride-coated composite lithium-rich manganese-based cathode material as described in claim 1, characterized in that: In step (2), the stirring temperature is room temperature, the stirring speed is 500~1500 rpm, the stirring time is 0.25h~1h, and the spray drying temperature is 150~250℃.

5. The lithium iron chloride-coated composite lithium-rich manganese-based cathode material as described in claim 1, characterized in that: In step (3), the heating device used is a tubular furnace, and nitrogen or argon is introduced during the calcination process, with a gas flow rate of 50cfm ~ 300cfm.

6. The lithium iron chloride-coated composite lithium-rich manganese-based cathode material as described in claim 1, characterized in that: The lithium iron chloride-coated composite lithium-rich manganese-based cathode material has a particle diameter of 2-15 μm and a lithium iron chloride coating thickness of 5-100 nm.

7. The preparation method of a lithium iron chloride-coated composite lithium-rich manganese-based cathode material and its application in solid-state batteries as described in any one of claims 1-6, characterized in that, It is used in all-solid-state lithium batteries.

8. The solid-state battery application of a lithium iron chloride-coated composite lithium-rich manganese-based cathode material as described in claim 7, characterized in that, The solid electrolyte of the all-solid-state lithium battery includes a halide solid electrolyte layer and a sulfide solid electrolyte layer.

9. The solid-state battery application of a lithium iron chloride-coated composite lithium-rich manganese-based cathode material as described in claim 7, characterized in that, The method for preparing the all-solid-state lithium battery includes the following steps: (1) The halide solid electrolyte powder or sulfide solid electrolyte powder is evenly sprinkled into the tableting mold and pressed for 30s to 60s under a pressure of 300 to 500 MPa to compress the powder electrolyte into tablets; the solid electrolyte tablet has a mass of 100 mg and a thickness of 500 μm. (2) The composite lithium-rich manganese cathode material coated with lithium iron chloride is evenly sprinkled on one side of the solid electrolyte sheet and held under pressure of 300-500 MPa for 60-120 seconds; the composite lithium-rich manganese cathode material is 10 mg and the thickness after pressing is preferably 70 μm. (3) Add a negative electrode material to the side of the sulfide solid electrolyte; the negative electrode material is lithium metal, and the thickness after pressing is 30 μm.

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