Core–Shell Solvation Structure Engineering Enables Practical Lithium Metal Batteries With 475 Wh Kg ⁻¹

ABSTRACT

Lithium metal batteries (LMBs) offer extremely high theoretical energy densities, but face significant challenges in terms of electrolyte compatibility and interface stability. Existing low‐concentration electrolytes struggle to form a robust solid‐electrolyte interface to maintain stable cycling. Here, we designed a low‐concentration electrolyte based on a functionally partitioned core–shell solvation strategy. Methyl sulfone, possessing a relatively high donor number, dominates the primary Li ⁺ coordination domain, while fluoroethylene carbonate, with a low donor number and low viscosity, primarily regulates the outer solvation environment and interfacial chemistry. This design facilitates rapid desolvation, high ionic conductivity (4.42 mS cm ⁻¹ ), and an exceptionally high Li ⁺ transference number (0.74). The core–shell structure induces a gradient SEI, promoting uniform lithium deposition. Consequently, the LiFePO ₄ (LFP)||Li cell achieved capacity retention of 85.9% after 5000 cycles at 1 C, along with cycling stability from −10°C to 50°C. Practical application was further confirmed by stable cycling of NCM811||Li pouch cells (200 cycles, 95.7%) and NCM811||graphite pouch cells (650 cycles, 88.5%). Furthermore, a 2.2 Ah NCM811||Li pouch cell achieves a gravimetric energy density of 475 Wh kg ⁻¹ . This work presents a scalable approach to engineering solvation chemistries for high‐voltage and high‐energy‐density LMBs.