Aluminum-phosphate coated lithium-nickel-cobalt-aluminate positive electrode material and preparation method thereof

A technology of nickel-cobalt-lithium-aluminate and positive electrode materials, which is applied in the direction of battery electrodes, electrical components, electrochemical generators, etc., can solve the problems of reduced discharge capacity, poor structural stability, material cycle life and safety hazards, etc. Achieve the effects of improving cycle life and safety performance, solving precipitation problems, and thin and uniform coating layer

Inactive Publication Date: 2019-07-05

JINGMEN GEM NEW MATERIAL +1

5 Cites 3 Cited by

AI-Extracted Technical Summary

Problems solved by technology

[0002] Nickel-cobalt-aluminum ternary lithium-ion battery cathode materials are widely used in IT products and new energy vehicles due to their high energy density and relatively simple preparation process. However, lithium nickel-cobalt aluminate (LNCA) has poor structural stability Good, high-priced nickel is easy to react with the electrolyte, causing the electrolyte to decompose and release gas, causing great harm to the cycle life and safety of the material; to solve the above problems, surface coating is generally used to improve the surface of the positive electrode material. The coated chemically inert material effectively isolates the positive electrode material from the electrolyte, avoids the reaction of high-valent nickel ions and the electrolyte, and maintains the stability of the positive electrode and electrolyte, thereby improvi...

Method used

The present invention is by taking soluble aluminum salt as Al source, with soluble phosphate as precipitating agent, uniformly plated one deck AlPO on positive electrode material surface by control crystallization chemical plating coating layer, this method is simple and easy to operate, accurate The amount of AlPO4 coating is controlled, and the precipitation problem is solved by surfactants during the coating process, so that the coating layer is thin and uniform, and the cycle life and safety performance of the positive electrode material are improved.

Th...

Abstract

The invention discloses an aluminum-phosphate coated lithium-nickel-cobalt-aluminate positive electrode material. The chemical expression of the material is LiaNixCoyAlzPcO2, wherein a is greater thanor equal to 1 and less than or equal to 1.2, x is greater than or equal to 0.3 and less than or equal to 0.98, y is greater than or equal to 0.01 and less than or equal to 0.6, z is greater than or equal to 0.001 and less than or equal to 0.2, b is greater than or equal to 0.00001 and less than or equal to 0.03, and c is greater than or equal to 0.001 and less than or equal to 0.01. The inventionalso discloses a preparation method of the positive electrode material. Soluble aluminum salt is used as an Al source, soluble phosphate is used as a precipitant, and a layer of AlPO4 coating layer is uniformly plated on the surface of a positive electrode material by controlling a crystallization chemical plating method. The method is simple and easy to operate, the coating amount of AlPO4 can be accurately controlled, and the precipitation problem is solved by a surfactant in the coating process, thereby enabling the coating layer to be thin and uniform, prolonging the cycle life of the positive electrode material, and improving the safety performance of the positive electrode material.

Application Domain

Cell electrodesSecondary cells

Technology Topic

Chemical platingCobalt aluminate +11

Image

Examples

Experimental program(3)

Example Embodiment

[0034] Example 1

[0035] A method for preparing aluminum phosphate-coated lithium nickel cobalt aluminate cathode material is specifically implemented according to the following steps:

[0036] Add 1000g of nickel-cobalt-aluminum lithium nickel-cobalt aluminate with a molar ratio of 80:15:5 to 3000g of water, stir fully at a speed of 50r/min, and press AlPO 4 The coating amount is 0.5%, Al:PO 4 3- =1:1.1 At the same time, add the aluminum sulfate and ammonium dihydrogen phosphate solutions with the concentrations of 0.05mol/L and 0.1mol/L respectively in parallel, and ensure that the addition is completed within 0.5h, filtered, dried, and heat treated at 450℃ in an air atmosphere 5h, the AlPO4 coated lithium nickel cobalt aluminate cathode material was obtained.

[0037] With the above materials as the positive electrode and the metal lithium sheet as the negative electrode, a button cell was assembled to conduct a charge and discharge comparison test. The positive electrode material obtained by the method of the present invention has a first discharge specific capacity of 181mAh/g at a rate of 1C, and the capacity remains after 300 charge and discharge cycles. The first discharge specific capacity of the uncoated cathode material is 183mAh/g, and the capacity retention rate after 300 charge-discharge cycles is 96.8%.

Example Embodiment

[0038] Example 2

[0039] A method for preparing aluminum phosphate-coated lithium nickel cobalt aluminate cathode material is specifically implemented according to the following steps:

[0040] Add 1000g of nickel-cobalt-aluminum lithium nickel-cobalt aluminate with a molar ratio of 89:8:3 to 5000g of water, stir fully at a speed of 50r/min, and press AlPO 4 The coating amount is 0.1%, Al:PO 4 3- ==1:1.1 At the same time, add aluminum sulfate and ammonium dihydrogen phosphate solutions with concentrations of 0.05mol/L and 0.1mol/L respectively in parallel, and ensure that the addition is completed within 1.5h, filtered, dried, and placed at 480℃ in an air atmosphere. Heat treatment for 5 hours to obtain AlPO4 coated lithium nickel cobalt aluminate cathode material.

[0041] Using the above-mentioned materials as the positive electrode and the metal lithium sheet as the negative electrode, a button cell was assembled to conduct a charge-discharge comparison test. The positive electrode material obtained by the method of the present invention has a first discharge specific capacity of 188mAh/g at a rate of 1C, and the capacity remains after 300 charge-discharge cycles. The first discharge specific capacity of the uncoated cathode material is 191mAh/g, and the capacity retention rate after 300 charge-discharge cycles is 95.2%.

Example Embodiment

[0042] Example 3

[0043] A method for preparing aluminum phosphate-coated lithium nickel cobalt aluminate cathode material is specifically implemented according to the following steps:

[0044] Add 1000g nickel-cobalt-aluminum lithium nickel-cobalt aluminate with a molar ratio of 85:10:5 to 6000g water, stir fully at a speed of 50r/min, and press AlPO 4 The coating amount is 0.2%, Al:PO 4 3- ==1:1.1 At the same time, add aluminum sulfate and ammonium dihydrogen phosphate solutions with concentrations of 0.05 mol/L and 0.1 mol/L in parallel, and ensure that the addition is completed within 1.5 hours, filter, dry, and place at 455°C in an air atmosphere Heat treatment for 4h to obtain AlPO4 coated lithium nickel cobalt aluminate cathode material.

[0045] Using the above-mentioned materials as the positive electrode and the metal lithium sheet as the negative electrode, a button cell was assembled to conduct a charge-discharge comparison test. The positive electrode material obtained by the method of the present invention has a first discharge specific capacity of 184mAh/g at a rate of 1C, and the capacity remains after 300 charge-discharge cycles. The first discharge specific capacity of the uncoated cathode material is 186mAh/g, and the capacity retention rate after 300 charge-discharge cycles is 96.5%.

[0046] figure 1 A surface scan of a nickel cobalt lithium aluminate cathode material EDS coated with aluminum phosphate is provided for Example 1. As can be seen from the figure, the Al element is uniformly distributed, and there is no local over-concentration or local absence of Al element. .

[0047] The present invention uses soluble aluminum salt as Al source and soluble phosphate as precipitant, and uniformly coats a layer of AlPO on the surface of the positive electrode material by controlled crystallization chemical plating. 4 Coating layer, this method is simple and easy to operate, and accurately controls AlPO 4 In the coating process, the surface active agent is used to solve the precipitation problem, so that the coating layer is thin and uniform, and the cycle life and safety performance of the positive electrode material are improved.

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