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 (NO${}_3$${}^{-}$) is proposed and validated to improve the homogeneity of the SEI in practical LMBs. NO${}_3$${}^{-}$ is connected to an ether-based moiety to form isosorbide dinitrate (ISDN) to break the resonance structure of NO${}_3$${}^{-}$ and improve the reducibility. The decomposition of non-resonant -NO${}_3$ in ISDN enriches SEI with abundant LiN${}_x$O${}_y$ 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 LiNO${}_3$ after 55 cycles. Moreover, lithium-sulfur pouch cells with ISDN additives provide a specific energy of 319 Wh kg${}^{-1}$ and undergo 20 cycles. This work provides a realistic reference in designing additives to modify the SEI for stabilizing LMBs. (© 2022 Wiley‐VCH GmbH)