As a new generation of high performance integrated energy storage battery system, the key factor in the development and application of sodium-ion batteries (SIBs) are the high-performance electrode materials. As a kind of hard carbon, the biomass-derived carbon has attracted much attention from experts and scholars due to the characteristics of rich-resource, low-cost and simple preparation process. It also can maintain the natural properties of biomass precursors, which contribute to the improvement of electrochemical performance. In the present work, cherry petals were used as precursors to prepare a hard carbon (CP) by a facile preparation. When it was used as an anode material for SIBs, CP exhibits high storage capacity with a high initial reversible capacity (310.2 mAh g^-1), outstanding cyclic stability (the capacity retention rate was 99.3% after 100 cycles at 20 mA g^-1) (Figure 1), favorable rate capability (146.5 mAh g^-1, even at a very high current density of 500 mA g^-1) and a high initial coulomb efficiency of 67.3%. In particular, approximate 45% of the capacity from CP is contributed by sodiation below 0.1 V (vs. Na⁺/Na). This low potential plateau makes CP energetically favorable as an anode material. The excellent electrochemical properties of CP can be attributed to its "open" lamellar structure-associated the nanoscale mesoporous, the presence of nitrogen/oxygen functional groups on the surface, and expanded interlayer distance (~0.44 nm) (Figure 2).

Figure captions

Figure 1. Cycling performance of CP (at 20 mA g^-1).

Figure 2. (a) HRTEM and SAED images of CP; (b) Contrast profiles along the arrows indicate interlayer distance of CP.

References

[1] Qiu S, Xiao L, Sushko M L, Han K S, Shao Y, Yan M, et al. Manipulating adsorption-insertion mechanisms in nanostructured carbon materials for high-efficiency sodium ion storage. Adv. Energy Mater. 2017; 7: 1700403.

[2] Liu, P, Li, Y, Hu, Y. S, Li, H, Chen, L, Huang, X. A waste biomass derived hard carbon as a high-performance anode material for sodium-ion batteries. Journal of Materials Chemistry A 2016; 4: 13046-13052.