Robust Solid Electrolyte Interphase Engineered by Catalysis Chemistry Toward Durable Anode-Free Sodium Metal Batteries

Abstract

Anode-free sodium metal batteries (AFSMBs) are considered one of the most promising large-scale energy storage systems due to their extremely high energy density. Nonetheless, their practical application is hindered by the uncontrolled growth of sodium dendrites. Constructing a mechanically robust solid electrolyte interphase (SEI) is an effective strategy to suppress dendrite formation. Herein, we report a catalysis chemistry approach to construct an ultra-thin (∼ 5 nm), NaF-rich and high-strength (203 MPa) SEI layer by introducing Ru catalytic sites on the current collector, which promotes rapid Na⁺ diffusion and effectively inhibits dendrite growth. Benefiting from this design, the Ru modified-Cu//Na asymmetric cells exhibit exceptional cycling stability over 2000 h (1000 cycles at 2 mA cm−2, 2 mAh cm−2). Furthermore, the AFSMBs with Ru modified-Cu current collector also deliver excellent cycling performance and maintains nearly 98.1% capacity retention after 100 cycles at 0.5 C. The results demonstrate great potential of catalysis chemistry in developing advanced sodium metal anodes and provide a new perspective to engineering efficient SEI toward battery applications.