Triple-Anion Coordination Design for Tuning Li+ Transport Energy Barrier and Promoting the Performance of Li-Ion Battery.

Abstract

The complex phase transitions of lithiated phosphorus (P) species-derived interfacial side reactions can be substantially mitigated through a triple-anion coordination design within the solvation sheath. Our results indicate that the triple-anion electrolyte exhibits an expanded energy level distribution of solvation sheaths, a low barrier for migrating Li+ solvation sheath, a high Li+-anion coordination number, a low Li+-ether solvent coordination number and an effective NO3 --FSI--TFSI- adsorption-decomposition-sustained release cooperative mechanism that generates a robust rigid-soft coupled SEI layer during the cycling process. When coupled with a LiFePO4 cathode, the full cell utilizing the triple-anion ether electrolyte demonstrates superior stability compared to cells using commercial LiPF6-EC/DEC electrolytes. More importantly, we establish a universal principle governing P/ether electrolyte compatibility, driven by anion-rich configurations: a higher Li+-FSI- coordination number and a lower Li+-solvent coordination number in the triple-anion electrolyte not only broaden the electrochemical window but also enable a remarkable 94% capacity retention at 50 mA g-1 after 200 cycles for P-based NCM523 full cells.