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

This work develops an organic–inorganic-bilayer protective layer for improving Li⁺ transport, provide insulation, and isolating CO₂ and H₂O. Deep eutectic solvents are used as electrolyte additives to promote stable inorganic solid electrolyte interfaces consisting of Li₃N, LiF, and LiCl, which result in improved ionic conductivity, reduced surface energy, and inhibited dendrite growth. At the same time, an elastic LiNafion buffer layer is introduced to mitigate the volume expansion during cycling. This dual protection mechanism provides valuable insights to improve the stability and lifetime of 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.