Building oxygen-rich vacancy coating for fast Li-ion diffusion kinetics and stable cycling of lithium-rich layered oxide cathode at wide-temperature

Abstract

As a cathode with a high energy density for Li-ion batteries, Li-rich layered oxide (LLO) cathodes suffer from short lifespans and poor rate performance, mainly due to their irreversible lattice oxygen evolution leading to severe structural degradation and oxygen release. Herein, we propose the use of Zn-doped SnO2 coated with LLO cathode to tackle these issues. Compared to the traditional method of coating oxides on the surface of lithium-rich cathodes, Zn doping of SnO2 coating can artificially create abundant oxygen vacancies for LLO cathode, which can provide a buffer boundary for active oxygen generated by lithium-rich cathode during circulation, effectively promoting the reversible reaction of oxygen redox couple and stabilizing lattice oxygen. The experimental results show that the surface of the LLO cathode's Zn-doped SnO2 is rich in oxygen vacancies could significantly boost the kinetics of lithium ion transfer, and effectively inhibit layer-to-spinel phase transition, and lattice oxygen release. By taking advantage of the Zn-doped SnO2 coating, the capacity stability of LLO cathode is raised from 58.1 % to 86.7 % at 1C after 500 cycles and also obtains outstanding rate performance and cycling durability at wide-temperature (−10 to 55 °C).