Enhanced high-voltage cycling stability of LiNi0.5Co0.2Mn0.3O2 based on stable Li+-conductive ceramic Li6.5La3Zr1.5Ta0.5O12 nano cladding layer

Abstract

Enhancing the cycling stability of conventional LiNixCoyMn1-x-yO2 cathode materials under high cut-off voltage (>4.3 V) is an efficient route for the fabrication of ternary layered lithium-ion batteries (LIBs) with superior capacity. A garnet ceramic Li6.5La3Zr1.5Ta0.5O12 (LLZTO) is used as a functional nano-cladding layer on LiNi0.5Co0.2Mn0.3O2 (NCM) particle surface to endow NCM with improved reversible capacities and cycling stabilities. The NCM modified with 2 wt % LLZTO delivered the highest discharge capacity (146.6 mA h g−1, 88.5% capacity retention) at 1 C between 2.7 and 4.5 V after 100 cycles, and its rate capability was also significantly enhanced to 112.9 mA h g−1 at 5 C compared with 96.2 mA h g−1 for the unmodified NCM. These improved properties can be ascribed to the LLZTO cladded layer, the chemical stability of which strengthens the stability of the interface between NCM bulk and electrolyte, and the high Li+ conductivity of which accelerates the transport of Li+ through the three-dimensional channels. Due to the above inherent merits, the ceramic LLZTO is a promising material for stabilizing interfaces between the cathode and electrolyte and for optimizing the high-voltage cycling stability of other cathode materials for LIBs.