Robust cement-graphite thick electrode enables high-performance molten salt aluminum batteries.

Abstract

Molten-salt aluminum batteries are promising for grid-scale energy storage, leveraging the abundance and recyclability of aluminum along with the intrinsic safety, non-flammability, and high ionic conductivity of chloroaluminate electrolytes. However, conventional polymeric binders lack stability in high-temperature, corrosive molten-salt environments, leading to electrode structural degradation and premature battery failure. Here we propose thick cement-graphite electrodes for molten salt aluminum batteries that feature a self-supporting structure, high mechanical strength, high thermal tolerance, and resistance to chemical corrosion. In this design, graphite provides continuous electron-conducting pathways, while hydrated cement phases encapsulate and interconnect graphite, forming an inorganic skeleton with measurable mechanical properties, chemically inert, and hierarchically porous. Operating at 150 °C, the Al| |cement-graphite cells achieve a long cycle life of over 11,000 cycles at 16 mg cm^-2 and 10 A g^-1, rate capability (retaining nearly 80 mAh g^-1 at 15 A g^-1) and stable cycling performance under high mass loadings up to 100 mg cm^-2. After extended cycling, the cement-graphite electrode retains its structural integrity. Multi-cell assemblies demonstrate scalability, while cost analysis shows cost savings associated with cement binders for molten-salt batteries.