Abstract: Hard carbon (HC) is regarded as an ideal anode material for sodium-ion batteries (SIBs) due to its abundant closed-pore structure and large interlayer spacing. However, its practical application was limited by low initial coulombic efficiency , poor fast-charging performance and complicated preparation process. Sugar used as a common precursor of HC is easy to foam by direct high-temperature carbonization, which produces numerous open-pores, insufficient closed-pore volume and uneven distribution, which in turn affects Na+ storage performance. To solve these problems, preparation strategies including hydrothermal, pre-oxidation, molecular cross-linking and template methods have been adopted to increase interlayer spacing and closed pore volume of sugar-based HC materials, for enhancing Na+ storage performance. This review summarizes in detail the related technologies for the preparation of sugar-based HC anode materials. Subsequently, the preparation problems and research focusing on the sugar-based HC materials have been rosed, and a new controllable preparation method of high-performance HC anode materials in SIBs also has been proposed in the further.

Key words: sugar-based hard carbon anodes, controllable preparation technology, sodium-ion battery, microstructure, sodium-ion storage performance