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Lithium-ion battery ternary material, preparation and application of a surface-coated lithium pyrophosphate

A surface-coated lithium pyrophosphate and lithium-ion battery technology, which is applied to electrical components, battery electrodes, secondary batteries, etc., can solve the problems of unsatisfactory cycle performance and rate performance of materials, large interface impedance, and invisibility, etc. , to achieve the effects of promoting lithium ion diffusion and interfacial charge transfer, increasing capacity retention, and improving cycle performance

Active Publication Date: 2020-09-08
深圳市费特森新能源有限责任公司
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Problems solved by technology

This invention effectively improves the capacity and cycle performance of lithium-ion batteries, but the ammonia water used in this technical solution will cause certain pollution to the environment; in the process of preparing vanadium phosphate, hydrothermal reaction is used, and the hydrothermal method is invisible and reactive. Due to the disadvantages of long cycle time and high energy consumption, the conductivity of the prepared vanadium phosphate ion is low; and the subsequent coating process uses a mechanical mixing method, which will cause the coating layer to be uneven and affect the coating effect
[0005] Another example is that the Chinese patent document with the publication number CN103618064A discloses a method for preparing an alumina composite nickel-cobalt lithium manganate ternary material, which specifically discloses that aluminum hydroxide is precipitated from an aluminum salt solution or an organic aluminum salt is hydrolyzed into aluminum oxyhydroxide. Then after heat treatment, the positive electrode ternary material coated with alumina is obtained, which improves the electrochemical performance of the material; however, alumina coating generally only plays the role of physical isolation, and cannot effectively reduce the residual alkali content on the surface of the material, and the oxidation Aluminum has disadvantages such as low electrical conductivity and large interface resistance, which hinders the diffusion of lithium ions after coating, which makes the material have to sacrifice part of the effective capacity to compromise cycle performance
[0006] Another example is that the Chinese patent document whose publication number is CN106816600A discloses a lithium manganese iron phosphate material and its preparation method, battery slurry, positive electrode and lithium battery, and specifically discloses a coating method, with a heating rate of 30-80 °C / min, the temperature is raised to 300-500 °C, and the temperature is lowered immediately after rising to the specified temperature to obtain an amorphous coating layer. The properties of the material obtained by this method, such as cycle performance and rate performance, are not ideal.

Method used

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  • Lithium-ion battery ternary material, preparation and application of a surface-coated lithium pyrophosphate

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Effect test

Embodiment 1

[0068] Dissolve 0.9g of lithium dihydrogen phosphate in 7g of deionized water, and ultrasonically stir for 5 minutes in a water bath at 55°C (ultrasonic frequency is 30KHZ, power is 400W) to obtain an aqueous solution of lithium dihydrogen phosphate; 29.1g of LiNi 0.8 co 0.1 mn 0.1 o 2 The ternary material is dispersed in 63g of ethanol to obtain a dispersion; slowly add lithium dihydrogen phosphate solution into the dispersion, and at the same time slowly add lithium hydroxide solution to control the pH value to 11.0, and stir rapidly at a speed of 750r / min to make it fully After reacting for 10 minutes, the resulting solution was suction filtered, washed, dried (160°C) and annealed at 475°C (heating rate: 3°C / min) for 5 hours in an air atmosphere, then cooled to 200°C to obtain a lithium pyrophosphate surface Modified LiNi 0.8 co 0.1 mn 0.1 o 2 Ternary material, wherein the coating amount is 3wt%.

[0069] figure 1 It is the scanning electron microscope picture of th...

Embodiment 2

[0073] Dissolve 1.2g of lithium dihydrogen phosphate in 7.2g of deionized water, and ultrasonically stir for 5 minutes in a water bath at 60°C (ultrasonic frequency is 40kHz, power is 450W) to obtain an aqueous solution of lithium dihydrogen phosphate; 28.8g of LiNi 0.6 co 0.2 mn 0.2 o 2 The ternary material is dispersed in 63.8g of ethanol to obtain a dispersion; slowly add the lithium dihydrogen phosphate solution into the dispersion, and at the same time slowly add ammonia water to control the pH value to 11.5, and stir rapidly at a speed of 800r / min to fully react 10 minutes (reaction time), and then the resulting solution was suction filtered, washed, dried (170°C) and annealed in an air atmosphere at 500°C (heating rate 4°C / min) for 5 hours, then cooled to 200°C to obtain coke LiNi Surface Modified by Lithium Phosphate 0.6 co 0.2 mn 0.2 o 2 Ternary material, wherein the coating amount is 4wt%.

[0074] Figure 4 is the cycle graph of the positive electrode materi...

Embodiment 3

[0076] Dissolve 1.5 g of lithium dihydrogen phosphate in 9 g of deionized water, and stir ultrasonically for 8 minutes in a water bath at 65° C. (ultrasonic frequency is 20 kHz, power is 500 W) to obtain an aqueous solution of lithium dihydrogen phosphate; 28.5 LiNi 0.5 co 0.2 mn 0.3 o 2The ternary material is dispersed in 61g of ethanol to obtain a dispersion; slowly add the lithium dihydrogen phosphate solution into the dispersion, and at the same time slowly add ammonia water to control the pH of the system to 11.5, and stir rapidly at a speed of 850r / min to fully react for 15 Minutes, and then the resulting solution was suction filtered, washed, dried (180°C) and annealed in an air atmosphere at 525°C (heating rate was 5°C / min) for 5 hours, then cooled to 200°C to obtain lithium pyrophosphate surface-modified LiNi 0.5 co 0.2 mn 0.3 o 2 Ternary material, wherein the coating amount is 5wt%.

[0077] Figure 5 is the cycle graph of the positive electrode material befo...

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Abstract

The invention belongs to the field of materials for lithium ion batteries, and in particular discloses a preparation method of a lithium ion battery ternary material having a surface coated with lithium pyrophosphate. The method comprises the steps of adjusting the pH value of a raw material solution containing lithium dihydrogen phosphate and the lithium ion battery ternary material to be 11-12,carrying out a reaction and then performing solid-liquid separation, washing, and drying to obtain a precursor; annealing the obtained precursor under the condition of heat insulation in an oxygen-containing atmosphere at 450-550 DEG C so as to obtain the lithium ion battery ternary material having the surface coated with lithium pyrophosphate. The invention also comprises the ternary material prepared by the using the method, and application of the ternary material. The method provided by the invention controls the pH and the annealing temperature to be within the range, thus surprisingly obtaining the stable lithium pyrophosphate coated material having a good crystal phase; compared with an amorphous state, the material has better electrical properties; for instance, the material obviously improves cycle performance and rate capability.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a method for modifying the surface of lithium pyrophosphate ternary materials for lithium ion batteries. Background technique [0002] As the governments of various countries vigorously promote the development of new energy vehicles, the market for lithium-ion power batteries is becoming wider and wider. The most critical positive electrode materials in the composition of lithium-ion power batteries, NCM and NCA materials have been widely studied. Among them, NCM ternary materials have significant advantages such as high working voltage, high specific energy, good safety, and high energy density, but their cycle performance, rate performance and processing performance in battery systems still need to be greatly improved. . Therefore, it is necessary to modify the ternary materials of lithium-ion batteries. [0003] Surface modification treatment is an...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/505H01M4/525H01M4/62H01M10/0525
CPCH01M4/366H01M4/505H01M4/525H01M4/62H01M4/628H01M10/0525Y02E60/10
Inventor 胡国荣杜柯曹雁冰彭忠东胡凯华亓先跃李小康
Owner 深圳市费特森新能源有限责任公司