The electrochemical performance of Li2CuO2-CuO composite-treated LiNi0.6Co0.2Mn0.2O2 cathode for all-solid-state lithium batteries

All-solid-state lithium batteries (ASSLB) are promising candidates for next-generation devices thanks to their safety and high energy density. However, there is an important problem at the interface between the cathode and solid electrolyte which must be addressed for ASSLB. To overcome this problem, the Li2CuO2-CuO composite-treated Li(Ni0.6Co0.2Mn0.2)O-2 (NCM) was used as the cathode with a sulfide-based solid electrolyte for ASSLB. However, the sulfide-based electrolyte has high interfacial resistance because of the side reaction caused by the interfacial instability between sulfide electrolytes and oxide cathodes. Li2CuO2-CuO composite is an effective material for treatment of ASSLB cathodes. In particular, the 1 wt.% Li2CuO2-CuO-treated NCM material showed higher capacity and better cycle retention than the bare NCM cathode material. Electrochemical impedance spectroscopy (EIS) analysis confirmed the reduction in interfacial resistance between the cathode and solid electrolyte. These indicators of the electrochemical performance demonstrate that Li2CuO2-CuO composite treatment is effective for the ASSLB cathode material.