Electrolyte Composition for Lithium-Ion Batteries

Lithium bis(fluorosulfonyl)imide (LiFSI, > 99.9%), lithium difluoro(oxalato)borate (LiDFOB, > 99.9%), ethylene carbonate (EC, > 99.95%), and dimethyl carbonate (DMC, > 99.99%) were purchased from DoDo Chem. Lithium nitrate (LiNO₃, > 99.99% metal basis) and cetyltrimethylammonium bromide (CTAB, > 99%) were purchased from Sigma-Aldrich. CTAB was vacuum-dried at 80 °C overnight and all solvents were further dried with 4 Å molecular sieve. Other Li salts were used without further purification. Lithium chips (600 μm) were purchased from China Energy Lithium Co., Ltd., China, and 50 or 100 μm Li was homemade via electric roller in the glovebox. Lithium iron phosphate (LiFePO₄, LFP) and lithium cobalt oxide (LiCoO₂, LCO) cathodes were purchased from Guangdong Canrd New Energy Technology Co., Ltd., China. Electrolytes were prepared in an Ar-filled glove box (Vigor Pte Ltd), in which both the content of O₂ and H₂O were lower than 0.5 ppm. BE electrolyte was prepared by dissolving 1 M LiFSI into EC/DMC 7:3 by volume. Additional 0.3 M LiNO₃ with 30 mM CTAB in the BE electrolyte was denoted as CNE-30.