Acid- and Gas-Scavenging Electrolyte Additive Improving the Electrochemical Reversibility of Ni-Rich Cathodes in Li-Ion Batteries.

In view of their high theoretical capacities, nickel-rich layered oxides are promising cathode materials for high-energy Li-ion batteries. However, the practical applications of these oxides are hindered by transition metal dissolution, microcracking, and gas/reactive compound formation due to the undesired reactions of residual lithium species. Herein, we show that the interfacial degradation of the LiNiCoMnAlO (NCMA, + + = 0.1) cathode and the graphite (Gr) anode of a representative Li-ion battery by HF can be hindered by supplementing the electrolyte with -butyldimethylsilyl glycidyl ether (tBS-GE). The silyl ether moiety of tBS-GE scavenges HF and PF, thus stabilizing the interfacial layers on both electrodes, while the epoxide moiety reacts with CO released by the parasitic reaction between HF and LiCO on the NCMA surface to afford cyclic carbonates and thus suppresses battery swelling. NCMA/Gr full cells fabricated by supplementing the baseline electrolyte with 0.1 wt % tBS-GE feature an increased capacity retention of 85.5% and deliver a high discharge capacity of 162.9 mAh/g after 500 cycles at 1 C and 25 °C. Thus, our results reveal that the molecular aspect-based design of electrolyte additives can be efficiently used to eliminate reactive species and gas components from Li-ion batteries and increase their performance.