A Microscopic Heterogeneous LiBO₂-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 (LiBO₂)-mediated electrolyte (LBME) that leverages colloid interfacial chemistry to regulate the Li⁺ solvation structure. Stable LiBO₂ 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_0.5Mn_1.5O₄ (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_0.8Co_0.1Mn_0.1O₂ (NCM811) and 5 Ah silicon-graphite (Si-C) || LiNi_0.91Co_0.06Mn_0.03O₂ (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.