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 NO3− anions with a high donor number in regulating competitive coordination in TIWSE is unveiled. As a result, μSi||LiNi0.8Co0.1Mn0.1O2 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−1 at 6 C. Furthermore, a 1‐Ah pouch cell of Si‐C||LiNi0.8Co0.1Mn0.1O2 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.