Abstract
For renewable energy technologies to decarbonize the power grid without compromising its reliability, low-cost grid-scale energy storage with resilient long-term performance is required. Here, we report a new type of high-temperature liquid metal battery (LMB) that achieves unprecedented capacity, low electrode costs, and strong cycling performance by replacing the traditional liquid LMB cathode with one based on solid particles. Through the combination of a liquid calcium (Ca) alloy anode, a cathode based on solid antimony (Sb) particles, and an all-chloride electrolyte, the Ca||Sb(s) system achieved 318% higher discharge capacity per unit mass of the cathode (715 mAh g-1 vs. 171 mAh g-1) and 76% lower electrode cost (15.5 $/kWh vs. 65 $/kWh) than the lowest cost LMB chemistry yet published. These Ca||Sb(s) batteries cycled with high Coulombic (>98.4%) and energy efficiencies (79–84%) at C-rates relevant for daily cycling applications. The remarkable increase in specific capacity is due to the self-assembly of Sb into a micro-structured, electronically connected cathode network, which enables nearly complete utilization of Sb. Despite using a solid cathode, the Ca||Sb(s) system retains the characteristic minimal capacity fade of LMBs, with no meaningful degradation observed over ~4000 full depth-of-discharge cycles. Additionally, the liquid Ca alloy anode mitigates the formation of solid Ca dendrites which would be detrimental to stable cycling performance.