Rechargeable aluminum-ion battery based on interface energy storage in two-dimensional layered graphene/TiO2 electrode

Abstract

Rechargeable aluminum-ion batteries (AIBs) are expected to be one of the most concerned energy storage devices due to their high theoretical specific capacity, low cost, and high safety. At present, to explore the positive material with a high aluminum ion storage capability is an important factor in the development of high-performance AIBs. This paper proposes an AIB using two-dimensional layered graphene/TiO2 nanosheets composite as the highly reversible positive electrode and chloroaluminate ionic liquid as the electrolyte. AlCl4− and Al2Cl7− are proven to be the main anionic carriers in the charge storage. The AIBs exhibit excellent electrochemical performances in the voltage range of 0.1–0.9 V. A discharge specific capacity of 313.2 mAh/g at 0.1 A/g is achieved. Moreover, a high specific capacity of 40.0 mAh/g is still maintained at 1.0 A/g after 100 cycles. The superior electrochemical properties for the AIBs are attributed to the interfacial energy storage mechanism in the layered graphene/TiO2 nanosheets composite, providing the unique two-dimensional interface charge storage layer for the insertion/de-insertion of the AlxCly−. These meaningful results have important guiding significance for the development of high-performance AIBs.