Large-scale synthesis of lithium- and manganese-rich materials with uniform thin-film Al2O3 coating for stable cathode cycling

Abstract

The lithium- and manganese-rich layered oxide (LMR) holds great promise as a cathode material for lithium-ion battery (LIB) applications due to its high capacity, high voltage and low cost. Unfortunately, its poor initial Coulombic efficiency (ICE) and unstable electrode/electrolyte interface with continuous growth of the solid electrolyte interphase leads to high impedance and large overpotential. These effects cause severe capacity loss and safety issues. In this work, we have developed a novel approach to fabricate a stable LMR cathode with a uniform thin layer of aluminum oxide (Al2O3) coated on the surface of the LMR particles. This synthesis approach uses the microemulsion method that is environment-friendly, cost-effective and can be easily scaled. Typically, an 8-nm layer of Al2O3 is shown to be effective in stabilizing the electrode/electrolyte interface (enhanced ICE to 82.0% and moderate impedance increase over 200 cycles). Moreover, the phase transformation from layered to spinel is inhibited (96.3% average voltage retention) and thermal stability of the structure is significantly increased (heat release reduced by 72.4%). This study opens up a new avenue to address interface issues in LIB cathodes and prompts the practical applications of high capacity and voltage materials for high energy density batteries.