Improving Structure and Electrochemical Performance of Single-Crystal Ni-Rich Cathodes by Aluminium Doping

Ni-rich layered oxide cathode materials LiNi_xCo_yMn_zO₂ (x>0.6) have been widely used in high specific energy Li-ion batteries. Compared with polycrystalline LiNixCoyMnzO₂, single crystal Ni-rich cathode materials have attracted much attention for their unique advantages. However, they also suffer from some drawbacks, such rapid capacity decay and intragranular crack during cycling. In order to enhance the structure and electrochemical performance of single crystal LiNi₀.₈C_o0.1Mn₀.1O₂ (SC811), different amount of aluminium (1 mol%, 2 mol% and 3 mol%) is utilized to substitute the materials. Physical characterizations of SC811 show the successful synthesis and Al doping of the single-crystal materials as well as lower Li/Ni intermixing after Al doping. Electrochemical tests illustrate that the single-crystal materials doped with 2mol% Al (2Al-SC811) shows superior electrochemical performance, and maintains 83.5 % of the initial discharge capacity after 100 cycles at 1 C in comparison with 68.9 % of the pristine SC811. It is hoped this work should shed light on the development of advanced cathode materials for Li-ion batteries.