Effective reinforcement on the structural stability and electrochemical performances of ultra-high nickel cobalt free cathode material by co-doping

Ultra-high nickel ternary cathode material with high energy density is a very important material to meet the long driving range of new energy vehicles. However, cobalt has high toxicity, high price and supply chain risks, so the material is being developed in the direction of low cobalt or no cobalt. For ultra-high nickel cobalt free cathode material with high theoretical capacity (LiNi0.9Mn0.1O2, NM90), the lattice collapse and particle fragmentation caused by microcracks during long cycle will lead to inferior rate performance and cycle life. At present, the effect of different cobalt content on structure and electrochemical properties of cobalt-free cathode material is rarely reported. Therefore, based on cobalt-free precursors, the effects of proper Co doping on structure and electrochemical properties of NM90 material are studied in depth. It showed that proper Co doping can effectively reduce cationic mixing and improve Li+ diffusion rate of NM90 material. The NM90–1.5%Co material exhibits discharge specific capacity of 167.1 mA h g−1 after 100 cycles at 1C and 121.2 mA h g−1 after 200 cycles at 5C, respectively. Furthermore, NM90–1.5%Co material shows an initial discharge specific capacity of 144.1 mA h g−1 at 10C. Therefore, Co doping provides a feasible way to improve the structural stability and electrochemical performances of ultra-high nickel cobalt free cathode material.