Hierarchical Sulfide-Rich Modification Layer on SiO/C Anode for Low-Temperature Li-Ion Batteries

The silicon oxide/graphite (SiO/C) composite anode represents one of the promising candidates for next generation Li-ion batteries over 400 Wh kg^-1 . However, the rapid capacity decay and potential safety risks at low temperature restrict their widely practical applications. Herein, the fabrication of sulfide-rich solid electrolyte interface (SEI) layer on surface of SiO/C anode to boost the reversible Li-storage performance at low temperature is reported. Different from the traditional SEI layer, the present modification layer is composed of inorganic-organic hybrid components with three continuous layers as disclosed by time-of-flight secondary ion mass spectrometry (TOF-SIMS). The result shows that ROSO₂ Li, ROCO₂ Li, and LiF uniformly distribute over different layers. When coupled with LiNi_0.8 Co_0.1 Mn_0.1 O₂ cathode, the capacity retention achieves 73% at -20 °C. The first principle calculations demonstrate that the gradient adsorption of sulfide-rich surface layer and traditional intermediate layer can promote the desolvation of Li⁺ at low temperature. Meanwhile, the inner LiF-rich layer with rapid ionic diffusion capability can inhibit dendrite growth. These results offer new perspective of developing advanced SiO/C anode and low-temperature Li-ion batteries.