Nucleation-Mediated Aluminum Deposition/Stripping for Long-Life Molten Salt Aluminum Batteries

Abstract

Molten salt aluminum batteries (MSABs) hold significant promise for grid-scale energy storage due to the low cost and high capacity of the aluminum anode. However, an aluminum dendrite stemming from nonuniform electrodeposition leads to safety and stability issues. Here, we describe a membrane electrode with predeposited aluminum metal featuring surface-mediated nucleation and growth behavior for operation in alkali chloroaluminate melt electrolytes. The introduction of TiN, as aluminophilic sites, facilitates the initial growth of aluminum on TiN by forming Al-N bonding, thereby enabling uniform aluminum nucleation and mediated growth along the TiN/C fiber, resulting in reversible and dendrite-free aluminum plating/stripping. The TiN/C@Al electrode enables symmetric cells to maintain stable cycling for over 850 h (10.0 mA cm-2; 5.0 mA h cm-2) and shows high rate performance at up to 30.0 mA cm-2. The Al-graphite cell using a TiN/C@Al anode demonstrates long-term stability over 7000 cycles at 2.0 A g-1 and enhanced rate capability with 72.2 mA h g-1 even at 5.0 A g-1. To validate practical scalability, we designed an Ah-level TiN/C@Al-based molten salt Al-graphite pouch cell. This approach offers a scalable pathway for overcoming the limitations of state-of-the-art anodes in MSABs, enabling high-performance and cost-effective energy storage solutions.