Department of Chemical and Materials Engineering , National Central University , 300 Jhong-Da Road , Taoyuan 32001 , Taiwan.
Department of Materials Science and Engineering , National Chiao Tung University , 1001 University Road , Hsinchu 30010 , Taiwan.
ACS Appl Mater Interfaces. 2019 Nov 13;11(45):42049-42056. doi: 10.1021/acsami.9b12915. Epub 2019 Nov 4.
Electrolyte is a key component in high-voltage lithium-ion batteries (LIBs). Bis(trifluoromethanesulfonyl)imide-based ionic liquid (IL)/organic carbonate hybrid electrolytes have been a research focus owing to their excellent balance of safety and ionic conductivity. Nevertheless, corrosion of Al current collectors at high potentials usually happens for this kind of electrolyte. In this study, this long-standing problem is solved via the modulation of the IL/carbonate ratio and LiPF concentration in the hybrid electrolyte. The proposed electrolyte suppresses Al dissolution and electrolyte oxidation at 5 V (vs Li/Li) and thus allows for ideal lithiation/delithiation performance of a high-voltage LiNiMnO (LNMO) cathode even at 55 °C. The underlying mechanism is examined in this work. Excellent cycling stability (97% capacity retention) for an LNMO cathode after 300 cycles is achieved. This electrolyte shows good wettability toward a polyethylene separator and low flammability. In addition, satisfactory compatibility with both graphite and Si-based anodes is confirmed. The proposed electrolyte design strategies have great potential for applications in high-voltage LIBs.
电解质是高压锂离子电池（LIB）的关键组成部分。基于双（三氟甲烷磺酰基）亚胺的离子液体（IL）/有机碳酸酯混合电解质由于其出色的安全性和离子电导率平衡而成为研究热点。然而，对于这种电解质，铝集流器在高电位下通常会发生腐蚀。在这项研究中，通过调节混合电解质中的 IL/碳酸盐比和 LiPF6 浓度，解决了这个长期存在的问题。所提出的电解质抑制了 5 V（相对于 Li/Li）下的 Al 溶解和电解质氧化，从而使高压 LiNiMnO（LNMO）正极即使在 55°C 下也能实现理想的锂化/脱锂性能。在这项工作中检查了其潜在机制。LNMO 正极在 300 次循环后仍具有出色的循环稳定性（容量保持率为 97%）。该电解质对聚乙烯隔膜具有良好的润湿性和低可燃性。此外，还证实了与石墨和硅基阳极具有良好的兼容性。所提出的电解质设计策略在高压 LIB 中有很大的应用潜力。
