Designing on solvent composition of dual-salt low concentration electrolyte for inhibiting lithium dendrite growth at-20?

Lithium metal batteries (LMBs) are expected to become a new generation of energy storage technology based on the high theoretical specific capacity and low potential of lithium metal anode. In order to promote the com-mercial application of LMBs, lithium dendrite has become an urgent issue to be resolved to improve the battery safety. Since temperature is a key factor on dendrite growth kinetics, it is of great significance to design novel electrolytes for LMBs to inhibit lithium dendrite growth at low temperature conditions. In this work, gamma-butyr-olactone (GBL) with low melting point, ethyl propanoate (EP) with high wettability and low viscosity, and fluoroethylene carbonate (FEC) with excellent film-forming performance are chosen as the electrolyte compo-nents (GBL/EP/FEC, 7:3:1 w/w/w). Lithium tetrafluoroborate (LiBF4) and lithium difluorophosphate (LiDFP) are used as dual salts to reformulate a low-concentration electrolyte (LCE) of 0.5 mol L-1 (M), i.e., 0.4 M LiBF4 + 0.1 M LiDFP. The solvent compositions of the LCE electrolyte are optimally designed for Li||LiNi0.8Co0.1Mn0.1O2 (NCM811) cells, resulting in good low-temperature cycling performance without affecting the room-temperature performance. The electrolyte enables the Li||NCM811 cells to maintain both 97% capacity after 100 cycles at room temperature and obviously suppress lithium dendrite growth at-20 ?degrees C.

Automated summary

Lithium metal batteries (LMBs) are a promising energy storage technology due to their high capacity and low potential. However, the growth of lithium dendrites limits their commercial application. In this study, a novel electrolyte was designed to inhibit dendrite growth at low temperatures while maintaining good performance at room temperature.