Vanadium Oxide Nanosheets for Flexible Dendrite-Free Hybrid Aluminium-Lithium-Ion Batteries with Excellent Cycling Performance

Aluminum (Al)-ion batteries can be an attractive alternative to lithium-ion batteries because of low costs, high volumetric capacities and dendrite-free formation when Al is used as anode. However, there are limited cathode materials for Al-ion batteries that can deliver satisfactory electrochemical performance, especially cycling stability. The major reason for that is the sluggish kinetics of ion intercalation/deintercalation, resulting from large coulombic attraction between Al³⁺ and cathodes. Herein, a concept of hybrid Al−Li-ion batteries is proposed to circumvent the poor Al³⁺ ions insertion/extraction kinetics in Al-ion batteries, and maintain the dendrite-free characteristics of Al-ion batteries. The high volumetric capacity (32.5 mAh/cm³ at 100 mA/cm³, based on the total volume of cathode), enhanced rate capability (21.5 mAh/cm³ at 1000 mA/cm³) and excellent cycling performance (70.1 % retention after 3000 cycles) have been achieved in the hybrid Al−Li-ion battery composed of vanadium oxide nanosheets on carbon fibers as cathode and Al as anode in a mixed [EMIM][Cl]/AlCl₃/LiCl electrolyte. Combining with the good flexibility of cathode and anode, the hybrid Al−Li-ion battery maintains structural and capacity stability under different bending angles. This study unveils a safe, cost-effective and flexible hybrid Al−Li-ion battery that presents highly competitive advantages among various energy storage devices.