Sb₇₀Ag₃₀ Alloy Cathode: Lithiation-Induced Li₂AgSb/Li₃Sb Interpenetrating Network Enables High Energy/Power Density...

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 Li₃Sb layer. Herein, we propose a novel low-melting-point Sb₇₀Ag₃₀ cathode, which undergoes an ingenious lithiation mechanism with reversible formation of the ternary Li₂AgSb compound at a high voltage (~1.08 V). Crucially, the generated intermetallic compounds show a unique bi-continuous and mutually interspersed "Li₂AgSb+Li₃Sb" interpenetrating-phase architecture. The Li₂AgSb phase, with a lower lithium migration energy barrier and a much-reduced bandgap compared to Li₃Sb, 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||Sb₇₀Ag₃₀ 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.