Elevating cycle stability of Ni-rich NCM811 cathode via single-crystallization integrating dual-modification strategy for lithium-ion batteries

Abstract

Nickel-rich layered oxide LiNi0.8Co0.1Mn0.1O2 (NCM811), as an attractive next-generation cathode material for lithium-ion batteries, still encounters grievously poor cycling stability triggered by irreversible phase transition in the layered structure and side reactions at the particle surface. Herein, a straightforward sol-gel method was proposed to fabricate highly stable Na+-doped and carbon-coated NCM811 single crystal, where the sodium glutamate acts as the common source of carbon-coating and Na+-doping. The Na ions prefer to occupy Li-sites that can lower the Li+ diffusion energy barrier and raise the threshold energy of Ni2+/Li+ irreversible migration to facilitate boosting Li+ migration rate and structural reversibility, as confirmed by theoretical calculation in conjunction with experimentation. And the carbon coating constructs a protective layer to effectively suppress parasitic reactions at the particle surface for enhancing cycling stability upon cycles. Consequently, the modified NCM-1 cathode displays the initial discharge capacity of 213.8 mAh·g−1 at 0.1 C and distinguished cycling stability at 5 C after 500 cycles with only approximately 0.034% capacity fading per cycle, which will be a strong competitive cathode material for developing high-power and long-lifespan lithium-ion batteries.