Li2CO3/LiF-Rich solid electrolyte interface stabilized lithium metal anodes for durable Li-CO2 batteries

Abstract

Lithium carbon dioxide (Li-CO₂) batteries are considered a promising next-generation energy storage device due to their high theoretical energy density and potential carbon neutralization. Despite numerous iterative advancements in cathode catalysts for Li-CO₂ batteries, the cycling stability still to be hindered by the growth of lithium dendrites during cycling, primarily due to uneven deposition and the side reaction of sufficient CO₂ with the Li metal anode. In this work, bisalt electrolyte (BE) consisting of LiPF₆ and LiTFSI is used as a localized anode surface stabilizer to achieve durable Li-CO₂ batteries. The introduction of PF₆^- promotes the decomposition and reduction of TFSI⁻, leading to the formation of LiF-rich inorganic SEI (Li₂CO₃/LiF-rich) with enhanced Li⁺ affinity and good electronic insulating properties. This effectively inhibits lithium dendrite formation while also insulating CO₂ and electrolytes from contacting the lithium anode. Consequently, the Li symmetric battery incorporating the novel BE exhibits a long cycling life of 912 h (∼3.8 times of the cell with a single-salt electrolyte (SE)). The BE based Li-CO₂ battery achieves an ultra-long cyclelife of 2720 h (∼2.6 times of SE battery) and outstanding rate capability. In addition, the assembled belt-shaped Li-CO₂ batteries could stably power a digital watch for 1267 h.