Amide-Functional, Li3N/LiF-Rich Heterostructured Electrode Electrolyte Interphases for 4.6 V Li||LiCoO2 Batteries

Enhancing the charge cut-off voltage of LiCoO2 at 4.6 V can improve the battery density, however, structural instability is a critical challenge (e.g., electrolyte decomposition, Co dissolution, and structural phase transition). Here, robust electrode electrolyte interphases (EEIs) with the high Li+ conductivity offered by polar amide groups and a Li3N/LiF heterostructure is constructed. 3-(trifluoromethyl) phenyl isocyanate (3-TPIC) is rationally designed as an electrolyte additive for sustaining a 4.6 V Li||LiCoO2 battery with such CEI, which can effectively address the challenge of structural instability. The polar amide group can achieve Li+ de-solvation and increase Li+ transport. Li3N/LiF heterostructure in the cathode electrolyte interphase (CEI) can speed up the Li+ insertion/extraction for improving Coulombic efficiency and weakening polarization of LiCoO2 at 4.6 V. In addition, the solid electrolyte interphase (SEI) with a similar structure on the Li anode surface contributes to the uniform Li deposition for suppressing the Li dendrite growth. As expected, 4.6 V Li||LiCoO2 batteries with superior EEIs can deliver excellent electrochemical performance.