Tailoring structure of Ni-rich layered cathode enable robust calendar life and ultrahigh rate capability for lithium-ion batteries

Abstract

Tailoring the structure of Ni-rich ternary layered cathode is considered as an effective way to solve its poor cycling and rate capability. Herein, a special structure of Ni0.6Co0.2Mn0.2(OH)2 precursor, in which strips composed of lamellar primary particles are vertically inserted, is rationally designed through feasible industrialized co-precipitation process. Particularly, precursor possesses a loose interior and dense exterior structure by observation of cross section. After sintering, LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode shows monodispersed microspheres whose external surface is tightly wrapped rod-like primary particles. Moreover, NCM622 microspheres inherits the properties of Ni0.6Co0.2Mn0.2(OH)2 precursor, displaying hollow structure and aligned primary particles along the radial direction. NCM622 cathode shows optimal electrochemical properties in the voltage window of 2.8–4.4 V. It displays a revisable capacity of 142.4 mAh g−1 (79.3% for capacity retention ratio) after 300 cycles under current density of 1 C. A reversible capacity of 110.3 mAh g−1 can be obtained after 500 cycles even at current density of 3 C, and corresponding capacity decay rate is only 0.068% for each cycle. The tailored cathode has great potential applications in batteries of high-power and long calendar life as well as provides an idea for structural design of high nickel cathode.