Temperature-Inert Weakly Solvating Electrolytes for Low-Temperature Lithium-Ion Batteries with Micro-Sized Silicon Anodes.

Cost-effective micro-sized silicon (μSi) anodes with high specific capacity are promising for high-energy-density lithium-ion batteries but face significant volume changes during cycling. Constructing anion-derived, inorganic-rich solid-electrolyte interphase by electrolyte engineering is considered a viable strategy for stabilizing μSi anodes. However, at low temperatures, temperature-dependent anion-dominated solvation and sluggish Li desolvation hinder cyclability and capacity retention. Here we introduce a unique temperature-inert weakly solvating electrolyte (TIWSE) that preserves the anion-dominated solvation sheath and has weak solvent coordination capability, enabling stable cycling of μSi anodes in subzero environments. The crucial role of NO anions with a high donor number in regulating competitive coordination in TIWSE is unveiled. As a result, μSi||LiNiCoMnO full cells with TIWSE demonstrate impressive capacity retention of 91.8 % at -20 °C and 80.8 % at 30 °C after 100 cycles, along with a high specific capacity of 137.4 mAh g at 6 C. Furthermore, a 1-Ah pouch cell of Si-C||LiNiCoMnO shows remarkable cycling stability with 89.3 % capacity retention over 300 cycles at 30 °C and 77.3 % retention at -20 °C, demonstrating the practical applicability. This work highlights the importance of solvation chemistry in addressing low-temperature challenges and offers new insights into high-energy μSi-based lithium-ion batteries operating under harsh conditions.