The effects of multiple metals (K, Cu, Al) substitution on LiNi0.66Co0.20Mn0.14O2 for lithium-ion batteries

Abstract

The high-nickel ternary cathode material LiNixCoyMn1-x-yO2 has high theoretical capacity and can be filled the power density requirement of a foot-powered car. It is placed on high expectations. However, Li/Ni mixing occurred during charging and discharging, resulting in poor cycle performance of the material. The related literatures have found that the K, Cu, and Al doping can improve the cycle performance of high-nickel materials. In this paper, we designed the orthogonal experiment and synthesized [Li(1-y)Ky](Ni0.66Co0.20Mn0.14)(1-x-z)[CuxAlz]O2 (x,y,z) = 0.00, 0.01, 0.02, 0.03, 0.04) cathode materials by the co-precipitation method. The initial charge–discharge specific capacity of [Li0.99K0.01](Ni0.66Co0.20Mn0.14)0.94[Cu0.03Al0.03]O2 can reach 214.7 mAh/g and 210.8 mAh/g, coulomb efficiency is 98.18%. After 30 cycles at 1C, capacity retention is 87%. According to the orthogonal test, results are as follows: about initial discharge specific capacity of the material, K presents the greatest effect, followed by Al, with minimal effect on Cu. However, Al has the greatest influence on the capacity retention rate of the material at high rate, followed by K element and Cu element. This will provide guidance for the future study of the modification of doping metal elements in high-nickel ternary lithium ion cathode materials.