Core-shell structured Li[(Ni0.9Co0.05Al0.05)0.6(Ni0.4Co0.2Mn0.4)0.4]O2 cathode material for high-energy lithium ion batteries

Abstract

A layer of Ni0.4Co0.2Mn0.4(OH)2 precursor was uniformly deposited on the surface of Ni0.9Co0.05Al0.05(OH)2 particles through a controlled crystallization method. The resulting particles were then homogeneously mixed with LiOH·H2O and subjected to high-temperature calcination at 800 °C under flowing oxygen to yield layered core-shell cathode material Li[(Ni0.9Co0.05Al0.05)0.6(Ni0.4Co0.2Mn0.4)0.4]O2. The elemental compositions in Ni, Co, and Mn of both the core and outer layer of the particles were analyzed by energy dispersive X-ray spectroscopy (EDX), and the data suggested that the core was rich in Ni and the shell in Mn. The shell thickness was estimated to nearly 1 μm, and the average composition of the prepared material was determined as Li(Ni0.7Co0.11Mn0.16Al0.03)O2. In the voltage range of 2.8–4.3 V, the initial discharge capacity and charge-discharge efficiency at 0.1C were estimated to 192.0 mAh g−1 and 91.3% at 25 °C, respectively. After 200 cycles, the retained capacity was calculated as 170.7 mAh g−1 at 1C charge-discharge rate, which was equivalent to 95.8% retention. High-temperature testing at 55 °C evaluated the initial specific discharge capacity at 0.1C to 207.2 mAh g−1, with capacity retention achieving 88.6% after 200 cycles at 1C, showing excellent electrochemical properties.