Super-wetting interface engineering of space-confined micron-sized alloying anodes for high-performance sodium-based dual-ion batteries

Abstract

Poor electrolyte wettability on micron-sized alloying anodes causes uneven interfacial reactions and stress distribution. To address this issue, we present a super-wetting interface engineering strategy to foster reaction homogeneity and accelerate reaction kinetics during alloying. As a proof of concept, micron-sized Sn particles are deposited into the space-confined three-dimensional aluminum current collector and encapsulated with amorphous carbon. By combining experimental and theoretical analyses, we confirm an electrolyte-philic interface with a near-zero contact angle, employing the Wenzel wetting model. Simultaneously, the high elastoplastic deformation of the aluminum cage ensures stable electrical contact during the cycling process. The optimized Sn anode paired with a graphite cathode exhibits excellent cycling stability and rate performance in sodium-based dual-ion batteries, maintaining a capacity of 90 mAh g⁻¹ over 2,000 cycles at 5 C and retaining 52% capacity at 100 C. This investigation provides a feasible interfacial and structural engineering strategy for micron-sized alloying anodes in sodium-ion batteries.