Abstract: Lithium nickel cobalt manganese oxide is a critical cathode material for new energy vehicles and consumer electronic products,in which the nickel content directly affects its electrochemical performance.The key conditions including precipitation pH,reagent dosage,aging temperature and time were systematically optimized in this study.Two chemical analytical methods for the determination of nickel(mass fraction:25.00%-55.00%) in lithium nickel cobalt manganese oxide were established,i.e.,the dimethylglyoxime gravimetry and the dimethylglyoxime precipitation separation-EDTA complexation-zinc chloride back titration.The optimal experimental conditions were confirmed as follows:the pH of solution for precipitation was 8.0-9.0;the dosage of both tartaric acid solution and ammonium acetate solution was 10 mL;the dosage of dimethylglyoxime ethanol solution for gravimetry and back titration was 50 mL and 30 mL,respectively;the precipitation aging temperature was 60-70 ℃,the aging time was 60 min,and 6 washing cycles were adopted;the dosage of acetic acid-sodium acetate buffer solution was 10 mL in back titration,and the pH of solution for titration was controlled at 5.0-6.0.The precision tests showed that the relative standard deviations(RSD,n=11) of the two methods for samples were 0.088% and 0.12%,respectively,indicating excellent repeatability. Statistical analysis was carried out on the consistency of nickel determination results for the same NCM622 lithium nickel cobalt manganese oxide sample using two methods,and the t-test showed no significant difference between the two methods.The certified reference material of GSB 04-3990-2022 was used for validation.It was found that the measured values of both methods fell within the standard value and uncertainty ranges,which further confirmed the reliability of proposed method.This method was suitable for the accurate determination of high content nickel in lithium nickel cobalt manganese oxide.