Achieving Practical High-Energy-Density Lithium-Metal Batteries by a Dual-Anion Regulated Electrolyte.

ABSTRACT

Lithium-metal batteries (LMBs) using lithium-metal anodes and high-voltage cathodes have been deemed as one of the most promising high-energy-density battery technology. However, its practical application is largely hindered by the notorious dendrite growth of lithium-metal anodes, the fast structure degradation of the cathode, and insufficient electrode-electrolyte interphase kinetics. Here, a dual-anion regulated electrolyte is developed for LMBs using lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and lithium difluoro(bisoxalato)phosphate (LiDFBOP) as anion regulators. The incorporation of TFSI- in the solvation sheath reduces the desolvation energy of Li+ , and DFBOP- promotes the formation of highly ion-conductive and sustainable inorganic-rich interphases on the electrodes. Significantly enhanced performance is demonstrated on Li||LiNi0.83 Co0.11 Mn0.06 O2 pouch cells, with 84.6% capacity retention after 150 cycles in 6.0 Ah pouch cells and an ultrahigh rate capability up to 5 C in 2.0 Ah pouch cells. Furthermore, a pouch cell with an ultralarge capacity of 39.0 Ah is fabricated and achieves an ultrahigh energy density of 521.3 Wh kg-1 . The findings provide a facile electrolyte design strategy for promoting the practical utilization of high-energy-density LMBs.