Unraveling the compatibility of ether-based solvents with Li-metal anodes under O2 atmosphere
image: A deeper understanding of the compatibility between Li-metal anode and ether-based (G2, G3 and G4) solvents in O2-rich environment from the perspective of Li/Li symmetric cells and Li-O2 cells can be obtained. Among three ether-based electrolytes (G2, G3 and G4), G2 is more effective in enhancing the cycling stability of Li/Li symmetric cell under O2-rich condition, while G4 is more conducive to the reversibility of Li-O2 cell compared to G3 and G2.
Credit: ©Science China Press
Unstable Li-metal anode/electrolyte interface and excessive dendrite growth have been considered as main issues which seriously plagues the Li-metal anode stability in Li-O2 cells. The involvement of O2 makes the electrochemical environment faced by Li-metal anode more complex than that in an inert Ar atmosphere. The composition of the solvent in the electrolyte has a significant impact on the electrochemical performance of Li-metal in an O2 atmosphere. For fabricating long-term stable cycling Li-metal anode under harsh O2 atmosphere, the compatibility of ether-based solvents with Li-metal anodes under severe O2 environment remain a subject of ongoing investigation and intrigue.
Recently, Professor Jiang Chunhai and Qiao Yu reported a study on the compatibility of ether solvents with Li-metal anodes in an O2 atmosphere, and the experimental results show that electrolyte with G2-based solvent can promote the formation of a thin and uniform solid electrolyte interphase (SEI) film, facilitating dendrite growth suppression and rechargeability of Li/Li symmetric cells under O2 atmosphere. However, its poor oxidative stability under high voltage impedes further long-term cycling of the Li-O2 cell. The evolution of SEI film with fragmentation accumulation and reconstruction during cycling leads to poor reversibility of both Li/Li symmetric cells and Li-O2 cells in G3-based electrolyte. In G4-based electrolyte, a relatively uniform SEI film and side reaction suppression resulting from the oxidative stability of the electrolyte together contribute to long-term stable cycle life of Li-O2 cells. This work provides new insights for suitable solvent selection of stable Li-metal anode under O2 environment and has also paved a novel research avenue for other metal-based batteries in a harsh O2 atmosphere.