Lidan Xing

The insufficiently protective cathode electrolyte interphase (CEI) remains a critical challenge for sodium-ion batteries, particularly under wide temperature conditions. Conventional CEI-forming additives rely on potential-driven decomposition during charging, leaving the cathode surface vulnerable before polarization. Here, we develop a dual-driven CEI regulation strategy using N-fluorobenzenesulfonimide (NFSI), integrating contact-driven preformation with potential-driven reinforcement. Upon contact with Na4Fe3(PO4)2P2O7 (NFPP), NFSI induces spontaneous interfacial redox reactions to generate a NaF-rich inner layer, while the intermediate NaNSI is subsequently oxidized to form an N/S-containing outer layer during charging. This bilayer CEI suppresses electrolyte decomposition, transition-metal dissolution, and interfacial degradation while improving Na+ transport. With 1.0 wt % NFSI, NFPP/Na cells retain 79.9% capacity after 500 cycles, compared with 45.8% for the base electrolyte, and maintain cycling capability from –20 to 80 °C. The strategy is further validated in other cathodes and NFPP||HC full cells, providing a programmable approach for durable sodium-ion batteries.

Graphite anodes dominate commercial lithium‐ion batteries (LIBs), yet fast charging is limited by interfacial polarization that drives resistive SEI growth and lithium plating. Borate additives such as lithium bis(oxalato)borate (LiBOB) can boost rate performance, but often produce thick, resistive interphases and gas‐induced swelling in practical cells; nevertheless, they are still used because comparable, manufacturable alternatives remain scarce‐highlighting the urgency for new interphase chemistries. Here, an anhydrous lithium bis(catecholato)borate (LiBCB) additive is enabled by a one‐step non‐aqueous synthesis that eliminates water of crystallization, an often‐overlooked factor that can obscure intrinsic interphase function. LiBCB first enriches at the graphite surface via preferential adsorption and then undergoes interfacial reduction to form a thin, compact, ionically conductive SEI, thereby reducing polarization, delaying sub‐0 V plating, and suppressing dead‐lithium accumulation. In 1.7 Ah graphite||LiFePO ₄ pouch full cells, 2 wt.% LiBCB retains 92% of initial capacity after 1000 cycles at 2.6 A with the smallest pouch‐volume change among the tested electrolytes, vastly outperforming the base electrolyte (13% rentention). These results identify salt form (hydration state and purity) as a decisive variable in SEI engineering and position anhydrous LiBCB as a practical alternative to LiBOB for fast‐charging graphite‐based batteries.

Methyl and tert -butyl groups at ether oxygen bond ends weaken ether oxygen groups and Li ⁺ interaction via steric hindrance. This induces anions into the solvation sheath to construct a LiF-rich interphase and achieve stable Li metal anode cycling.