Modification-scavenging hydroxyl groups of natural mineral fiber separators to boost initial coulombic efficiency of lithium-ion battery

The recently reported inorganic separator is promising for advanced lithium-ion batteries (LIBs) with excellent electrochemical performance and high safety. However, then with most of inorganic separators suffered from low initial Coulombic efficiency (ICE). In this work, the chrysotile fiber (CF) separator was researched as a hydroxyl-rich inorganic separator, and the relationship between the hydroxyl groups on the surface of the CF separators and the ICE of batteries was studied. It was found that the rich hydroxyl groups on the surface of the CF separators induced the decomposition of LiPF6, thus leading to low ICE. Modified CF separators (LSO) were prepared by acid leaching and lithium ions modification. Modification-scavenging the hydroxyl groups on the surface of the CF separators can effectively promote the ICE of the Li|LiFePO4 cell (93%). Furthermore, the Li|LiFePO4 cell with LSO exhibited an excellent rate performance and high-rate cycle stability (109.4 mAh g−1 at 5C after 1000 cycles). This work provided a new strategy for improving electrochemical performance that reducing the number of hydroxyl groups on the surface of natural mineral fibers is effective to improve the ICE of inorganic separators. [Display omitted] •Rich hydroxyl groups of mineral fiber separator induced the decomposition of LiPF6.•The decomposition of LiPF6 led to low initial coulombic efficiency (ICE).•Modification-scavenging hydroxyl groups of the separators promote ICE (93%).•The cell with the modified separator (LSO) exhibited excellent stability.