Self-assembling solid Sb electrode enables high-capacity, low-cost Ca-Sb battery
Sanghyeok Im, Peyman Asghari‐Rad, Kelly Varnell, Alex T. Vai, Jianyi Cui, R. C. J. Howland, David Bradwell, Hojong Kim
Abstract
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. The capacity of Ca-based liquid metal batteries is limited by Ca solubility in liquid metals. Here, authors pair a Ca-based liquid metal negative electrode with a solid Sb positive electrode to achieve high capacity and low energy cost.