Sb ₇₀ Ag ₃₀ Alloy Cathode: Lithiation‐Induced Li ₂ AgSb/Li ₃ Sb Interpenetrating Network Enables High Energy/Power Density Liquid Metal Batteries

ABSTRACT Liquid metal batteries (LMBs) offer potential for grid‐scale energy storage due to their long lifespan, high safety, and simple manufacturing. Antimony (Sb), as a particularly attractive cathode with high theoretical voltage and earth‐abundant reserves, faces the challenges of its high melting point and the unsatisfactory rate‐capability resulting from the sluggish lithium diffusion kinetics across the generated solid Li ₃ Sb layer. Herein, we propose a novel low‐melting‐point Sb ₇₀ Ag ₃₀ cathode, which undergoes an ingenious lithiation mechanism with reversible formation of the ternary Li ₂ AgSb compound at a high voltage (~1.08 V). Crucially, the generated intermetallic compounds show a unique bi‐continuous and mutually interspersed “Li ₂ AgSb+Li ₃ Sb” interpenetrating‐phase architecture. The Li ₂ AgSb phase, with a lower lithium migration energy barrier and a much‐reduced bandgap compared to Li ₃ Sb, can provide a 3D fast Li/electron transport network in the cathode, significantly facilitating the electrode reaction kinetics and thus improving the rate‐capability and power density. Consequently, the Li||Sb ₇₀ Ag ₃₀ cell displays a superior rate capability (∼0.56 V at 2 A cm ⁻² ) together with a high power density (∼537 W kg ⁻¹ at 2 A cm ⁻² ) and an exceptionally competitive energy density (345.18 Wh kg ⁻¹ at 0.6 A cm ⁻² ). This work provides an effective strategy for simultaneously achieving Sb‐based LMBs with high energy/power density.