Modification of Nitrate Ion Enables Stable Solid Electrolyte Interphase in Lithium Metal Batteries

The lifespan of high-energy-density lithium metal batteries (LMBs) is hindered by heterogeneous solid electrolyte interphase (SEI). The rational design of electrolytes is strongly considered to obtain uniform SEI in working batteries. Herein, a modification of nitrate ion (NO3-) is proposed and validated to improve the homogeneity of the SEI in practical LMBs. NO3- is connected to an ether-based moiety to form isosorbide dinitrate (ISDN) to break the resonance structure of NO3- and improve the reducibility. The decomposition of non-resonant -NO3 in ISDN enriches SEI with abundant LiNxOy and induces uniform lithium deposition. Lithium-sulfur batteries with ISDN additives deliver a capacity retention of 83.7 % for 100 cycles compared with rapid decay with LiNO3 after 55 cycles. Moreover, lithium-sulfur pouch cells with ISDN additives provide a specific energy of 319 Whkg(-1) and undergo 20 cycles. This work provides a realistic reference in designing additives to modify the SET for stabilizing LMBs.

Automated summary

This study proposes and validates the use of modified nitrate ions (NO3-) to improve the homogeneity of the solid electrolyte interphase (SEI) in lithium metal batteries. By forming isosorbide dinitrate (ISDN), the resonant structure of NO3- is broken and its reducibility is improved. Lithium-sulfur batteries with ISDN additives show improved cycling performance and specific energy.