Anion modification for stable solid electrolyte interphase in anode-free lithium metal batteries. (January 2023) - Qin, Kaiqiang
Abstract: The durability of anode-free Li metal batteries is largely limited by the undesired Li plating/stripping irreversibility on the current collector due to the infinite volume change, uncontrollable Li dendrite growth, and continuous parasitic reactions between Li metal and the electrolyte. To address these challenges, the formation of a stable and robust solid electrolyte interphase (SEI) with high ionic conductivity and strong mechanical strength is critical. Here, we developed an advanced electrolyte by introducing LiNO3 into the localized high concentration electrolyte (LHCE) with lithium bis(fluorosulfonyl)imide (LiFSI) salt, 1, 2-dimethoxyethane (DME) solvent, and 1, 1, 2, 2-tetrafluoroethyl-2, 2, 3, 3-tetrafluoropropylether (TFTE) diluent to in situ construct a LiF and Lix Ny Oz co-enriched passivation layer on the Cu current collector. The synergetic effect of the high mechanical strength of LiF and high ionic conductivity of Lix Ny Oz endows the Li metal anode with a high Coulombic efficiency (CE) of 99.35%. An anode-free Li metal pouch cell using LiFePO4 (LFP) as a cathode holds an exceptionally improved capacity retention under the charging/discharging rate of 1/3 C, demonstrating great promise for developing dendrite-free and safe Li metal batteries. Graphical abstract: Here, we developed an advanced electrolyte by introducing LiNO3 into the localized high concentration electrolyte (LHCE) with lithium bis(fluorosulfonyl)imide (LiFSI) salt, 1, 2-dimethoxyethane (DME) solvent, and 1, 1, 2, 2-tetrafluoroethyl-2, 2, 3, 3-tetrafluoropropylether (TFTE) diluent to in situ construct a LiF and Lix Ny Oz co-enriched passivation layer on the Cu current collector. The Li metal anode with a high Coulombic efficiency (CE) of 99.35% was achieved and used in anode-free Li metal pouch cells. Image 1 Highlights: A contact ion pair (CIP) solvation structure dominated electrolyte was achieved. A LiF and Lix Ny Oz co-enriched SEI was in situ constructed in the new electrolyte. Li metal anode delivers a high average CE of 99.35% over 600 cycles. Anode-free LiFePO4 -based pouch cells with superior capacity retention were achieved.