Washing method of high-nickel positive electrode material and product and application thereof

Abstract

The invention relates to a washing method of a high-nickel positive electrode material and a product and application thereof, and the washing method comprises the following steps: mixing the high-nickel positive electrode material with a phosphate solution with the concentration of 0.1-1mol/L, reacting and sintering to obtain the washed high-nickel positive electrode material. In the washing process, phosphate reacts with residual alkali on the surface of the high-nickel positive electrode material to generate lithium phosphate precipitate to be attached to the surface of the high-nickel positive electrode material, a lithium phosphate coating layer is formed through subsequent sintering, and part of lithium phosphate can permeate into the surface layer of the material and deep positions of the surface to fill lattice gaps of the material to modify the surface, so that coating is tighter; therefore, the structural stability and the thermal stability of the positive electrode material are improved, and the dual effects of washing to remove residual alkali and improving the stability of the material are achieved; furthermore, the reaction process of washing can be carried out at normal temperature, the washing process is simple to control, the energy consumption is low, the cost is low, and the washing effect is obviously improved.

Description

technical field [0001] The invention belongs to the field of battery material preparation, and relates to a water washing method for a high-nickel positive electrode material and its product and application. Background technique [0002] Due to the high pH of the precursor of the high-nickel positive electrode material and the low primary sintering temperature, the content of free lithium on the surface of the material, that is, the residual alkali (lithium oxide, lithium carbonate, lithium hydroxide), is mainly lithium hydroxide, which is easy to Causing the material to absorb moisture. At present, the general method to reduce the residual alkali on the surface of the precursor of high-nickel cathode material is to mix deionized water and high-nickel cathode material evenly in a certain proportion. Considering that the solubility of residual alkali at low temperature is higher than normal temperature, it is generally at 5 By stirring at a low temperature of ~10°C, the resi...

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Problems solved by technology

At present, the general method to reduce the residual alkali on the surface of the precursor of high-nickel cathode material is to mix deionized water and high-nickel cathode material evenly in a certain proportion. Considering that the solubility of residual alkali at low temperature is higher than normal temperature, it is generally at 5 By stirring at a low temperature of ~10°C, the residual alkali floating on the surface of the high-nickel positive electrode material can be dissolved into the water as much as possible, and then filtered, and the filter element is dried to remove the moisture in the high-nickel positive electrode material to achieve the purpose of reducing the residual alkali ; However, the low-temperature washing control in the washing process is complicated and the cost is high, and the dissolved residual alkali may return to the high-nickel positive electrode material during normal temperature filtration, resulting in a reduction in the washing effect

[0003] CN109546088A discloses a washing method for a high-nickel ternary positive electrode material. The washing method includes weighing a certain amount of lithium battery positive electrode material, adding deionized water with a certain amount of solid-to-liquid ratio, stirring for a period of time, ultrasonication for a period of time, and then After filtering the obtained solution, it was calcined in an oxygen environment at 700°C for 5 hours, and then 5 g of the powder obtained after drying was added to 100 g of deionized water, stirred and then suction filtered; the water washing process was strengthened by ultrasound, but there was still a normal temperature The problem of poor residual alkali removal effect during operation

In the water washing method described in this plan, hydrofluoric acid is added to the washing process of the high-nickel ternary positive electrode material after sintering, which can improve the washing effect and reduce the amount of residual lithium under the premise of the same washing amount; but hydrofluoric acid has a strong Corrosive, difficult to operate, high cost

[0005] CN107256955A discloses a modified lithium-ion battery high-nickel positive electrode material combined with water washing and tin coating and a preparation method thereof; the method includes adding the high-nickel positive electrode material into water, and rapidly stirring and washing at a speed of 500-2000r / min 1 to 20 minutes, filter and dry to obtain a high-nickel cathode material after washing; this solution has the problem of poor residual alkali removal effect during normal temperature operation

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