Nanoconfinement effect of nanoporous carbon electrodes for ionic liquid-based aluminum metal anode

Rechargeable aluminum batteries (RABs), which use earth-abundant and high-volumetric-capacity metal anodes (8040 mAh cm−3), have great potential as next-generation power sources because they use cheaper resources to deliver higher energies, compared to current lithium ion batteries. However, the mechanism of charge delivery in the newly developed, ionic liquid-based electrolytic system for RABs differs from that in conventional organic electrolytes. Thus, targeted research efforts are required to address the large overpotentials and cycling decay encountered in the ionic liquid-based electrolytic system. In this study, a nanoporous carbon (NPC) electrode with well-developed nanopores is used to develop a high-performance aluminum anode. The negatively charged nanopores can provide quenched dynamics of electrolyte molecules in the aluminum deposition process, resulting in an increased collision rate. The fast chemical equilibrium of anionic species induced by the facilitated anionic collisions leads to more favorable reduction reactions that form aluminum metals. The nanoconfinement effect causes separated nucleation and growth of aluminum nanoparticles in the multiple confined nanopores, leading to higher coulombic efficiencies and more stable cycling performance compared with macroporous carbon black and 2D stainless steel electrodes.