SnO₂-decorated three-dimensional carbon nanotubes as aluminophilic skeleton for anode-less aluminum-ion batteries

The inherently non-uniform and non-planar microscale morphology of metallic aluminum during plating significantly impedes the long-cycle performance of aluminum-ion batteries (AIBs). To address these challenges, a coral-like aluminophilic CNT@SnO₂ three-dimensional self-supporting material has been synthesized via a straightforward impregnation process. This composite comprises spherical SnO₂ nanoparticles, which also form an Al_xSnO₂ interfacial layer during plating. The aluminophilic properties of SnO₂ reduce the nucleation overpotential, facilitating nucleation-directed deposition and resulting in nanoscale Al deposits. Furthermore, the Al_xSnO₂ interfacial layer inhibits side reactions between the electrode and electrolyte, thereby reducing the local current density and promoting uniform deposition while suppressing dendrite formation. The symmetric cell incorporating CNT@SnO₂ demonstrates stable cycling for over 400 h at 5 mA cm⁻² and 1 mAh cm⁻², with the overpotential reduced to 38 mV. Additionally, the assembled anode-less full cell exhibits a Coulombic efficiency (CE) of 99.6 % over 5000 cycles at a current density of 1 A g⁻¹. This study provides valuable insights into the control of nanoscale Al deposition and advances the development of more efficient Al-ion batteries.