Stabilizing Microsized Sn Anodes for Na-Ion Batteries with Extended Ether Electrolyte Chemistry

Electrolytes using ether solvents show great advantages in building robust solid electrolyte interphases (SEIs), which play a pivotal role in stabilizing alloy anodes in Na-ion batteries. Herein, we deviate from the most widely adopted methyl glymes (represented by monoglyme) to enrich the ether-based electrolyte chemistry. Stable cycling of Sn microparticles is realized in two ether electrolytes derived from the linear ethylene glycol diethyl ether (ethyl glyme) and cyclic ether (tetrahydrofuran). We reveal that the formation of thin yet strong SEIs accounts for ameliorated stability and excellent rate capability. The inorganic species in the as-constructed SEIs have low crystallinity and are uniformly distributed among the organic matrix, rendering superb mechanical properties in accommodating the deformation upon sodiation, as confirmed by nanoindentation tests. This study opens the door to exploring the large ether family besides the methyl glymes, and the unraveled mechanics/microstructure correlation of SEIs can help screen the potential candidates.