Dual-additive chemistry induced robust electrode-electrolyte interphases for high-performance lithium metal batteries

Lithium metal batteries (LMBs) are considered as the most promising high-energy storage devices due to the high specific capacity and the lowest reduction potential of lithium (Li) metal anode. However, the uncontrolled Li dendrite growth, structural collapse of cathode and electrolyte oxidation significantly limit the practical applications of LMBs in terms of high voltage or rapid charge-discharge operation. Herein, an advanced carbonate-based electrolyte is rationally designed by adding lithium difluoro(oxalato)borate-tris(trimethylsilyl)borate (LiDFOB-TMSB) dual additives. Density functional theory (DFT) calculations and experiments reveal that unique dual additives work synergistically to form robust solid electrolyte interphases on the anode and cathode. Implementation of such dual additives can suppress Li dendrite formation, improve the compatibility of electrode-electrolyte interphases, and enhance the structural stability of LiNi0.5Co0.2Mn0.3O2 (NCM523) at high-voltage of 4.4 V. The dual-additive electrolyte enables Li||Cu cell to achieve a high average coulombic efficiency (CE) of 97.7 % at the current density of 1 mA cm−2 with an areal capacity of 1 mAh cm−2 and Li||NCM523 cell to deliver 74.4 % retention at 1 C and a cut-off voltage 4.4 V after 300 cycles. This work provides an effective dual-additive strategy for the feasibility of high-voltage LMBs towards the practical application. [Display omitted] •A dual-additive electrolyte with LiDFOB-TMSB is proposed.•The combination of TMSB and PF6− inhibits the transfer of PF6−.•TMSB-PF6− and LiDFOB preferentially decompose at the cathode to form a robust CEI.•LiDFOB preferentially decomposes at the anode to form a robust SEI film.•TMSB-PF6− can inhibit the reaction between PF6− and the Li anode.