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

Abstract

Abstract 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 Al 3+ and cathodes. Herein, a concept of hybrid Al−Li‐ion batteries is proposed to circumvent the poor Al 3+ 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/cm 3 at 100 mA/cm 3 , based on the total volume of cathode), enhanced rate capability (21.5 mAh/cm 3 at 1000 mA/cm 3 ) 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]/AlCl 3 /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.