Preparation method for lithium-rich manganese based anode material hydroxide precursor

Abstract

The invention discloses a preparation method for a lithium-rich manganese based anode material hydroxide precursor. The method includes the steps of: (1) preparing a mixed solution of a nickel salt, a cobalt salt and a manganese salt according to the mole ratio of Mn, Co and Ni in the hydroxide precursor's molecular formula MnxCoyNi1-x-y(OH)2, wherein x is greater than 0.5 and smaller than 1, y is greater than 0 and smaller than 0.5, and x+y is smaller than 1; (2) preparing an additive containing alkaline aqueous solution, and preparing a composite complexing agent solution containing EDTA, chitosan and ammonia water; (3) under inert gas protection, merging the mixed solution of the nickel salt, the cobalt salt and the manganese salt, the alkaline aqueous solution and the composite complexing agent solution and injecting the mixture into a continuous reaction kettle to carry out continuous reaction, controlling the average concentration of EDTA, chitosan and ammonia ions in the reaction solution, and controlling the reaction pH value at 9-13, the reaction temperature at 30-80DEG C and the stirring speed at 100-2000rpm; and (4) filtering, washing and drying the liquid naturally discharged from the reaction kettle. The lithium-rich manganese based anode material hydroxide precursor prepared by the method provided by the invention has the characteristics of uniform components, controllable particle size and compact growth.

Description

technical field [0001] The invention relates to a method for preparing a lithium-rich manganese-based cathode material hydroxide precursor, and belongs to the technical field of lithium battery material preparation. Background technique [0002] The contradiction between the increasing depletion of non-renewable energy such as oil and coal and the increasing energy demand of human beings, as well as the huge damage to the environment caused by the greenhouse gases and pollutants produced by the burning of fossil fuels, have led to global warming, raging diseases and frequent natural disasters , making people aware of the urgency of finding clean alternative energy sources. The next-generation lithium-ion power battery with electric vehicles and grid energy storage as the major application background can not only improve energy efficiency, reduce greenhouse gas and pollutant emissions, but also clean up those periodic wind energy, solar energy, tidal energy, etc. The electri...

AI Technical Summary

Problems solved by technology

However, there are many problems in the precursor technology used to prepare lithium-rich manganese-based solid solution cathode materials: firstly, if it uses alkaline hydroxide as precipitant, the Mn(OH) 2 The solubility product Ksp=1.9×10 -13 , significantly higher than that of Ni(OH) 2 and Co(OH) 2 (respectively 2.0×10 -15 and 1.6×10 -15 ), it is easy to cause the primary particles of the precursor to be small, the distribution uniformity of the transition metal element components is poor, and it is also easy to absorb moisture and be oxidized, and the small particle size of the primary particle is not conducive to surface modification, and it is difficult to obtain stable and consistent modified products.

However, in the prior art, ammonia water etc. are generally used as a single complexing agent, and the growth of precursor crystals with high manganese content is mainly one-dimensional or two-dimensional growth, and the bridging phenomenon between primary particles is obvious, resulting in low material tap density; and if using Carbonate is a precipitating agent. Although it has good spheroidizing properties, it is not easy to control the particle size distribution, and has an important impact on the electrical properties of the final lithium-rich manganese-based material; secondly, the tap density is low, and the amount of residual alkali on the surface may be high, which affects the cycle. Both lifespan and specific energy increase have detrimental effects

These unfavorable factors inhibit the development of its commercialization

[0004] Patent document CN102881886A discloses a method for preparing a lithium-rich solid solution precursor at low temperature using carbonate as a precipitating agent. The particle size of the lithium-rich solid solution positive electrode material obtained in the embodiment of the method is only 1-3 μm, and the small particle size leads to poor processing performance of the material. poor

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