Interphase engineering toward superior structural stability of Co-free Li-rich layered oxides

Undesirable interfacial reactions and the resulting capacity degradation hinder the widespread application of lithium-rich layered oxide (LLO) as a cathode in high-energy lithium-ion batteries. Herein, a method to suppress the interfacial reactions of LLO is devised by treating the carbonate precursor with weak-base salts to induce elemental segregation and promote particle growth, by which a rock-salt structure is in-situ constructed on the particle surface. This rock-salt structure is in excellent lattice alignment with the internal structure, which is conducive to enhancing surface structural stability and suppressing interfacial reactions. As a result, the two treated samples deliver a capacity retention ratio larger than 93.9 % after 200 cycles, with much superior voltage and capacity stability than the untreated sample. This in-situ construction method is beneficial for developing advanced LLO cathodes.