Amide-Functional, Li3N/LiF-Rich Heterostructured Electrode Electrolyte Interphases for 4.6 V Li‖LiCoO_2 Batteries

摘要

Enhancing the charge cut-off voltage of LiCoO_2 at 4.6 V can improve thebattery density, however, structural instability is a critical challenge (e.g., electrolytedecomposition, Co dissolution, and structural phase transition). Here,robust electrode electrolyte interphases (EEIs) with the high Li+ conductivityoffered by polar amide groups and a Li3N/LiF heterostructure is constructed.3-(trifluoromethyl) phenyl isocyanate (3-TPIC) is rationally designed as anelectrolyte additive for sustaining a 4.6 V Li‖LiCoO_2 battery with such CEI,which can effectively address the challenge of structural instability. The polaramide group can achieve Li+ de-solvation and increase Li~+ transport. Li_3N/LiFheterostructure in the cathode electrolyte interphase (CEI) can speed up theLi+ insertion/extraction for improving Coulombic efficiency and weakeningpolarization of LiCoO_2 at 4.6 V. In addition, the solid electrolyte interphase(SEI) with a similar structure on the Li anode surface contributes to the uniformLi deposition for suppressing the Li dendrite growth. As expected, 4.6 VLi‖LiCoO_2 batteries with superior EEIs can deliver excellent electrochemicalperformance.