Diphenyl Azidophosphate as a Functional Electrolyte Additive for High-Conductivity Film Construction over Lithium Metal Battery

Lithium metal batteries (LMBs) with high loading and high current density can be achieved by tailoring electrolyte components. As an effective film-forming electrolyte additive, diphenyl azidophosphate (DPPA) has been proposed here to construct high conductive solid electrolyte interphase (SEI) layers on the Li metal anode surface enriched with Li 3 N and P–O compounds. Compared with cells without DPPA additive, the Li∣∣Cu cells with 1% DPPA demonstrate evaluated accurate Coulombic efficiency (CE) from 77.9% to 93.8%, and Li∣∣Li symmetric cells are able to cycle for more than 250 h at the current density of 2 mA cm −2 . The high conductive SEI layer increases the exchange current density of Li metal anode from 0.247 mA cm −2 to 0.760 mA cm −2 . The Li∣∣LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cell maintain 80.8% capacity retention after 250 cycles in the DPPA-containing electrolyte. Discharge capacity of the Li∣∣NCM811 cell can reach 142 mA h g −1 at a high discharge current of 13.2 mA cm −2 . Further theoretical calculations indicate that the DPPA additive can be preferentially reduced to form a stable SEI layer with high conductivity.