Synthesis and electrochemical performance of La2CuO4 as a promising coating material for high voltage Li-rich layered oxide cathodes

Abstract

The structural transformations, oxygen releasing and side reactions with electrolytes on the surface are considered as the main causes of the performance degradation of Li-rich layered oxides (LROs) cathodes in Li-ion batteries. Thus, stabilizing the surfaces of LROs is the key to realize their practical application in high energy density Li-ion batteries. Surface coating is regarded as one of the most effective strategies for high voltage cathodes. The ideal coating materials should prevent cathodes from electrolyte corrosion and possess both electronic and Li-ionic conductivities simultaneously. However, commonly reported coating materials are unable to balance these functions well. Herein, a new type of coating material, La2CuO4 was introduced to mitigate the surface issues of LROs for the first time, due to its superb electronic conductivity (26–35 mS⋅cm−1) and lithium-ionic diffusion coefficient (10−12–10−13 cm2⋅s−1). After coating with the La2CuO4, the capacity retention of Li1.2Ni0.54Co0.13Mn0.13O2 cathode was increased to 85.9% (compared to 79.3% of uncoated cathode) after 150 cycles in the voltage range of 2.0–4.8 V. In addition, only negligible degradations on the deliverable capacity and rate capability were observed.