Deep Eutectic Solvent Additive Induced Inorganic SEI and an Organic Buffer Layer Synergistic Protected Li Anode for Durable Li-CO2 Batteries

Abstract

Interface instability and safety concerns related to lithium anodes are major barriers to the practical use of Li-CO₂ batteries. To address these challenges, an organic–inorganic dual-layer protective coating is developed to improve Li⁺ transport, provide electronic insulation, and isolate CO₂ and H₂O. Deep eutectic solvents (DESs) are used as electrolyte additives to promote a stable, inorganic solid electrolyte interphase (SEI) composed of Li₃N, LiF, and LiCl, which enhance ionic conductivity, lowers surface energy, and suppresses dendrite growth. Additionally, an elastic Li-Nafion buffer layer is incorporated to mitigate volume expansion during cycling. This dual protection system significantly improves cycling stability, extending the lifespan of Li||Li and Li-CO₂ batteries by 5.19 and 4.62 times, respectively, with a reversible cycle life of 4160 h. A pouch battery using this system also demonstrates exbatteryent stability, with 1400 h of cycling at 50 µA cm⁻² and a cut-off specific capacity of 250 µAh cm⁻². These findings offer valuable insights for enhancing the stability and longevity of Li-CO₂ batteries.