Effect of Lithium Bis(oxalato)borate Additive on Electrochemical Performance of Li_1.17Ni_0.17Mn_0.5Co_0.17O₂Cathodes for Lithium-Ion Batteries

Lithium bis(oxalato)borate (LiBOB) is utilized as an oxidative additive to prevent the unwanted electrolyte decomposition on the surface of Li 1.17 Ni 0.17 Mn 0.5 Co 0.17 O 2 cathodes. Our investigation reveals that the LiBOB additive forms a protective layer on the cathode surface and effectively mitigates severe oxidative decomposition of LiPF 6 –based electrolytes. Noticeable improvements in the cycling stability and rate capability of Li 1.17 Ni 0.17 Mn 0.5 Co 0.17 O 2 cathodes are achieved in the LiBOB-added electrolyte. After 100 cycles at 60°C, the discharge capacity retention of the Li 1.17 Ni 0.17 Mn 0.5 Co 0.17 O 2 cathode was 28.6% in the reference electrolyte, whereas the LiBOB-containing electrolyte maintained 77.6% of its initial discharge capacity. Moreover, the Li 1.17 Ni 0.17 Mn 0.5 Co 0.17 O 2 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°C, whereas a full cell charged in the LiBOB-added electrolyte exhibited superior retention of the OCV.