Self-assembling solid Sb electrode enables high-capacity, low-cost Ca-Sb battery

To decarbonize the power grid using renewable technologies without compromising its reliability, low-cost grid-scale energy storage with resilient long-term performance is required. We report a liquid metal battery that achieves high capacity, low electrode costs, and strong cycling performance by replacing the traditional liquid positive electrode with solid particles. The Ca||Sb(s) system described herein achieved 318% higher discharge capacity (715 mAh g⁻¹ Sb) and 71% lower electrode cost (19.1 $ kWh⁻¹) than the most competitive liquid metal battery chemistries yet published. The remarkable increase in specific capacity results from the self-assembly of a micro-structured electronically connected Sb network at the positive electrode during cycling while the formation of a liquid Ca-Li alloy at the negative electrode mitigates the growth of solid Ca dendrites. We demonstrate minimal capacity fade of the Ca||Sb(s) battery over ~4000 full depth-of-discharge cycles and high coulombic (>98.4%) and energy efficiencies (79–84%) at C-rates (C/8–C/10) relevant for daily storage applications coupled with intermittent renewable energy technologies.