Aluminum vacancy-rich MOF-derived carbon nanosheets for high-capacity and long-life aqueous aluminum-ion battery

Eco-friendly and safe aqueous aluminum-ion batteries as energy storage devices with low economic burden, high stability and fast ion transport have been lucubrated deeply in response to the call for sustainable development. However, the poor cycle performance caused by difficult (de-)intercalation hinders the development prospect. In this work, the aluminum vacancy-rich MOF-derived carbon is constructed to achieve reversible aluminum storage during the charge-discharge cycles. The MOF-derived carbon with anti-stacking waxberry-like structure exhibits high capacity (282.1 mAh g⁻¹ at 50 mA g⁻¹) and long cycle performance (84.4% capacity retention rate at 1 A g⁻¹ after 5000 cycles). Further investigations demonstrate that (de-)intercalation occurs among the vacancies of carbon nanosheets in the form of hydrated aluminum ions. Meanwhile, the introduced nitrogen as energy storage sites contributes part of the capacity. The proposed aluminum vacancy engineering improves the current situation of the capacitive energy storage mode for 2D carbon materials, which may exploit an advanced theoretical model for the design of aqueous batteries.