Colloid Electrolyte with Changed Li<sup>+</sup> Solvation Structure for High‐Power, Low‐Temperature Lithium‐Ion Batteries
Xiaoyan Wang, Le Yang, Niaz Ahmad, Leguan Ran, Ruiwen Shao, Wen Yang
Abstract
Abstract Lithium‐ion batteries currently suffer from low capacity and fast degradation under fast charging and/or low temperatures. In this work, a colloid liquid electrolyte (CLE) is designed, where the trace amount of lithium thiocarbonate (LTC) colloids in commercial carbonate electrolyte (1 m LiPF 6 in ethylene carbonate/dimethyl carbonate) not only boosts up σ Li+ but also improves the Li + transfer kinetics at LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) cathode/electrolyte interface. The competitive coordination of LTCs with anions and solvents facilitates the dissociation of lithium salts and Li + decoupling, dramatically enhancing the σ Li+ (15 to 4.5 mS cm −1 at 30 and −20 °C, respectively); meanwhile, the desolvation process is accelerated. It demonstrates that LTC colloids induce an ≈5 nm ultrathin Li 2 CO 3 ‐rich cathode electrolyte interface and infuse the grain boundary of NCA particles, enhancing interfacial Li + transfer and inhibiting the particle cracks during cycling. Consequently, the Li||CLE||NCA battery delivers a maximum capacity of 135 mAh g −1 at a 10 C rate with 80% retention after 2000 cycles. Moreover, the fast‐charging capability under a sub‐zero environment is proved (122 mAh g −1 with 90% retention after 400 cycles at 2 C and −10 °C). This strategy for tailoring the interfacial charge transfer appears generalizable and can practically be extended to next‐generation energy‐storage systems.