Chemical assay method for cobalt in lithium ion battery anode material LiCoxMnyNi1-x-yO2

Abstract

The invention provides a chemical detection method for cobalt. The method is characterized in that: a sample containing manganese-nickel-cobalt is heated and dissolved under the action of strong acid, the interfering ion manganese is oxidized into manganese dioxide which undergoes filtering separation, the cobalt-nickel is precipitated by a precipitator and then filtered, and the obtained precipitate is separated from other trace elements; a mixture of Co(OH)2 and Ni(OH)2 is dissolved by acid; under ammonia condition, the cobalt is reacted with excessive and quantitative iodine standard solution to generate [CO(NH3)5I](NO3)2(S), and the excessive iodine undergoes back titration by sodium arsenite standard solution ; and the content of the cobalt is worked out according to the stoichiometric relationship.

Description

technical field [0001] The invention relates to a chemical determination method of metal element cobalt. Especially the chemical determination method of cobalt under the coexistence of manganese and nickel in the cathode material of lithium ion battery. Background technique [0002] Due to the widespread application of lithium-ion batteries in various portable electronic products, the research on their cathode materials has become a hot spot. There are three main types of cathode materials for lithium-ion batteries: LiNiO 2 、LiCoO 2 , LiMn 2 o 4 . LiCoO 2 Reliable performance, long cycle life, but not high reversible capacity; LiNiO 2 The reversible capacity of LiNiO is high, but in the process of charging and discharging, LiNiO 2 The crystal structure of LiMn is easily destroyed, resulting in the attenuation of cycle capacity; LiMn 2 o 4 The cycle performance is poor, and the lithium intercalation capacity decays rapidly at high temperature. Doping transition met...

AI Technical Summary

Problems solved by technology

The ratio of Ni, Co, Mn to LiCo x mn y Ni 1-x-y o 2 Co can effectively stabilize the layered structure of the composite, reduce the cation mixing between the Li layer and the transition metal layer, thereby making it easier to deintercalate lithium ions, and improve the conductivity of the material and improve its full capacity. Discharge cycle performance; but as the proportion of Co increases, the volume of the unit cell becomes smaller, resulting in a decrease in the reversible lithium intercalation capacity of the material

[0003] In the constant chemical analysis when manganese and nickel coexist, the determination method of cobalt is mainly cobalt potassium nitrite-EDTA volumetric method, in which cobalt is separated from most interfering elements by cobalt potassium nitrite precipitation, and then dissolved with dilute hot hydrochloric acid Precipitate, use ammonia water and glacial acetic acid to adjust the acidity to make the pH 4-5, use xylenol orange and methylene blue mixed indicator, and titrate with EDTA solution. The main defect of this method is that the precipitation of cobalt potassium nitrite and the aging time exceed 5 hours , the operation requirements are high, so that the entire measurement cycle can be as long as more than 8 hours

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