Profiting the Co-Modifications of Li<sub>2</sub>SnO<sub>3</sub> Coating and Sn<sup>4+</sup> Doping in Co-Free Ni-Rich Cathode Particles for Lithium-Ion Batteries
Miaomiao Gong, Yukun Fu, Wenli Yao, Xianfa Rao, Qian Zhang, Shengwen Zhong, Qiangchao Sun, Hongwei Cheng
Abstract
Layered oxides with high nickel content are advanced cathode materials for high-energy-density lithium-ion batteries but still suffer from severe voltage decay and cycling instability. Herein, a nano-Li 2 SnO 3 coating and Sn 4+ -doping co-stabilized Co-free LiNi 0.8 Mn 0.2 O 2 (NM-82) cathodes were synthesized through the adsorption of tin dioxide sol, followed by high-temperature calcination. Profiting from co-benefits, the electrochemical reversibility and rate capability of the NM-82 electrode have been significantly improved. Herein, the NM-82 electrode modified with 2 wt % Li 2 SnO 3 (NM@Sn-2) achieves the largest specific capacity with remarkable capacity retention. The enhanced cycle stability is also revealed in the graphite/NM@Sn-2 soft pack battery, which features a reversible capacity of 173.20 mA h g –1 and a high capacity retention of 90.54%, outperforming those of the NM-82 cathode (154.09 mA h g –1 and 81.23%) at 0.2 C after 300 cycles. The improved performance of the NM@Sn-2 cathode originates from its stronger structure, lower Li/Ni cation mixing degree, and faster Li + kinetics, also verified by theoretical calculations. Therefore, the one-step construction of nano-Li 2 SnO 3 coating coupling with Sn 4+ doping strategy shows a promising strategy to mitigate the capacity deterioration of the Co-free Ni-rich layered oxides.