Improved electrochemical performances of Ni-rich LiNi0.83Co0.12Mn0.05O2 by Mg-doping

Ni-rich layered oxide LiNi0.83Co0.12Mn0.05O2 (NCM) has advantages of high energy density, low price, and so on. However, the application of NCM is impeded by low cycle stability. To address this issue, (Ni0.83Co0.12Mn0.05)1-xMgx(OH)2 is coated on (Ni0.83Co0.12Mn0.05)(OH)2 precursor particles with coprecipitation method, which ensures full and uniform coverage of precursor particle by the coating layer. Mg2+ ions evenly distribute in the cathode particles due to the diffusion during sintering. The pristine and doped cathodes are cycled in a voltage range of 2.8–4.5 V at 1C. NCM exhibits an initial discharge capacity of 201.8 mAh g−1 and capacity retention of 74.0% after 200 cycles, and NCM particles have been fractured by the cycle process. Mg doping could significantly improve the cycle stability, where 0.96 at% Mg-doped sample achieves the best electrochemical performance. The Mg-doped sample delivers an initial discharge capacity of 199.7 mAh g−1 and capacity retention of 87.2%. The structural integrity of the Mg-doped particles is retained after cycles, which agrees well with the enhanced cycle stability.