Ultrathin carbon boosted sodium storage performance in aqueous electrolyte

The sodium-based aqueous energy storage devices possess the advantages of low cost, high safety and wide application. However, the low energy density of traditional carbon-based sodium storage materials limits their large-scale application. Besides, other sodium storage materials, such as transition metal oxides, polyanionic compounds and Prussian blue analogues (PBAs), cannot achieve high capacity and stable energy storage performance due to their poor conductivity and instability. Ultrathin carbon with unique characteristics, such as high electrical conductivity, excellent chemical stability, can compensate for the shortcomings of these sodium storage materials. Besides, the arising synergistic effect among ultrathin carbon and active materials is capable of further boosting the performance to achieve robust microstructure, stable electrode/electrolyte interface, high reaction kinetics for obtained composite electrode. This paper summarizes the recently developed strategies to incorporate ultrathin carbon with electrode materials, followed by a discussion of the important role of ultrathin carbon in enhancing sodium storage properties, as well as the future research direction.