Solvation Chemistry Reimagined: LiPF6‐Enabled Suppression of Gas Evolution for Ultra‐Stable 200 Ah Anode‐Free Lithium‐Metal Batteries

Abstract

ABSTRACT Anode‐free lithium‐metal batteries (AFBs) offer an attractive pathway to achieve cell‐level energy densities >500 Wh kg −1 but suffer from rapid degradation driven by parasitic electrolyte decomposition, gas evolution, and unstable interphases. Here, we report a solvation‐structure engineering strategy using trace LiPF 6 additive in localized high‐concentration electrolytes (LHCEs) to regulate homogeneous Li deposition and stabilize electrode‐electrolyte interfacial chemistry. Molecular dynamics simulations and spectroscopic analyses reveal a synergistic PF 6 − –FSI − coordination that dramatically enriches aggregate (AGG) species in the Li + solvation sheath, increasing AGG populations from 17% to 93% with only 1 wt.% LiPF 6 . Owing to its persistent stability, this LiPF 6 ‐derived AGG‐dominated solvation suppresses ether‐solvent reduction and CH 4 generation, forming an inorganic‐rich solid–electrolyte interphase/cathode‐electrolyte interphase. AFBs with optimized electrolyte achieve substantially improved performance, including a significant reduction in high‐temperature gas evolution alongside increases in cycle life of 64% at 45°C and 28% at 25°C. When scaled to 240 Ah blade cells, this optimized electrolyte delivers stable cycling for nearly 100 cycles at 80% DOD and 45°C with negligible swelling and >1260 Wh L −1 volumetric energy density. This study demonstrates a practical and scalable electrolyte design principle that overcomes the key barriers to commercial deployment of large‐format AFBs.