A Microscopic Heterogeneous LiBO ₂ ‐Mediated Electrolyte for High‐Voltage and Low‐Temperature Lithium‐Ion Batteries

ABSTRACT Conventional electrolytes remain fundamentally constrained by the trade‐offs among high‐voltage stability, low‐temperature operation, and fast ion transport, limiting the practical deployment of advanced lithium‐ion batteries (LIBs). Here, we report a micro‐heterogeneous lithium metaborate (LiBO 2 )‐mediated electrolyte (LBME) that leverages colloid interfacial chemistry to regulate the Li + solvation structure. Stable LiBO 2 colloids competitively coordinate with anions through coordinatively unsaturated surface sites, thereby weakening Li + –solvent/anion interactions and accelerating ligand‐exchange kinetics. Consequently, the LBME exhibits enhanced ionic conductivity and reduced Li + desolvation barrier, enabling uniform lithium deposition at −30°C and facilitating a compact inorganic‐rich cathode‐electrolyte interphase (CEI) during ultrahigh‐voltage operation. Consequently, a 5.0 V Li || LiNi 0.5 Mn 1.5 O 4 (LNMO) cell with LBME achieves exceptional cyclability, retaining 99.1% of its capacity after 5000 cycles at 5 C, and maintaining 72% of its room‐temperature capacity at −30°C. The technological viability is further demonstrated in practical pouch cells, where 1 Ah graphite || LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) and 5 Ah silicon‐graphite (Si‐C) || LiNi 0.91 Co 0.06 Mn 0.03 O 2 (NCM90) pouch cells demonstrate superior stability, achieving 87.8% capacity retention (500 cycles) and a striking energy density of 394 Wh kg −1 (89% retention after 120 cycles), respectively. This work demonstrates a heterogeneous electrolyte strategy promising for stable LIBs under harsh conditions.