A potassium/chloride ion co-doped cathode material Li1.18K0.02Ni0.2Mn0.6O1.98Cl0.02 with enhanced electrochemical performance for lithium ion batteries

Abstract

Li-rich layered oxide has drawn attention due to its high capacity, low cost and environmental friendliness. However, its application as cathode material of lithium ion battery is impeded by its poor rate and cycling performance. In this work, a K, Cl co-doped Li-rich layered cathode material Li1.18K0.02Ni0.2Mn0.6O1.98Cl0.02 (LLO-KCl) was successfully synthesized via a rapid nucleation followed by hydrothermal method. The resulting LLO-KCl cathode material was investigated using X-ray diffraction, scanning electron microscopies, X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and charge/discharge tests. For comparison, Li1.2Ni0.2Mn0.6O2 (LLO) samples were prepared under the same condition. LLO-KCl delivered the initial discharge capacity of 265.1 mAh g−1 at a rate of 0.1 C and the capacity retention of 88.4% at 1 C after 100 cycles. Even at the rate of 10 C, the specific capacity was 98.9 mAh g−1. The enhanced electrochemical performance was mainly benefited from expanded Li+ migration path and stabilized crystal lattice via K+ and Cl− simultaneously doped into crystal structure. This finding provides a strategy to explore a cathode material to build high specific battery systems.