Effect of Lithium Bis(oxalato) borate Additive on Electrochemical Performance of Li1.17Ni0.17Mn0.5Co0.17O2 Cathodes for Lithium-Ion Batteries

Abstract

Lithium bis(oxalato) borate (LiBOB) is utilized as an oxidative additive to prevent the unwanted electrolyte decomposition on the surface of Li1.17Ni0.17Mn0.5Co0.17O2 cathodes. Our investigation reveals that the LiBOB additive forms a protective layer on the cathode surface and effectively mitigates severe oxidative decomposition of LiPF6-based electrolytes. Noticeable improvements in the cycling stability and rate capability of Li1.17Ni0.17Mn0.5Co0.17O2 cathodes are achieved in the LiBOB-added electrolyte. After 100 cycles at 60 degrees C, the discharge capacity retention of the Li1.17Ni0.17Mn0.5Co0.17O2 cathode was 28.6% in the reference electrolyte, whereas the LiBOB-containing electrolyte maintained 77.6% of its initial discharge capacity. Moreover, the Li1.17Ni0.17Mn0.5Co0.17O2 cathode with LiBOB additive delivered a superior discharge capacity of 115 mAh g(-1) at a high rate of 2 C compared with the reference electrolyte. The OCV of a full cell charged in the reference electrolyte drastically decreased from 4.22 V to 3.52 V during storage at 60 degrees C, whereas a full cell charged in the LiBOB-added electrolyte exhibited superior retention of the OCV.