cycling life and environmental benignity. However, the scarce (0.0017% in weight) and uneven distribution of lithium in the earth's crust limits the sustainable development of LIBs. [1-4] Therefore, it is necessary to explore alternative energystorage systems with the sufficient resource. Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have the notable advantages due to the abundance of sodium (2.36 wt%) and potassium (2.09 wt%) in the earth's crust. [5-7] Meanwhile, SIBs and PIBs have similar electrochemical principles with that of LIBs. [8-10] Therefore, SIBs and PIBs have recently received considerable attention as the next-generation promising energy storage systems. However, the radii of Na + (1.02 Å) and K + (1.37 Å) are larger than that of Li + (0.76 Å), which can easily cause serious structure damage and sluggish kinetics of electrode material during the repeated Na + /K + intercalation/extraction processes. [11-13] The common anode materials (graphite, metal oxides) for LIBs suffer from low capacity for SIBs and PIBs. [14,15] Thus, it is desirable to fabricate the suitable electrode materials to alleviate the huge volume expansion during the charge/discharge processes. Recently, transition-metal selenides (TMDs, M = Co, Zn, Fe, V, Mo) have attracted significant attention as promising anode materials for SIBs and PIBs owing to their high theoretical capacity, low cost, and fascinating physicochemical properties. [16-20] Among them, zinc selenide (ZnSe) combining the conversion and alloying reactions is considered as a promising anode material owing to its high theoretical specific capacity, suitable discharge/charge platform, and low toxicity. [21,22] Nevertheless, as similar as other TMDs, the performance of ZnSe still suffers from low intrinsic conductivity and dramatic volume variation during the charge-discharge processes, which eventually result in poor cycling stability and rate performance, although obvious progresses have been made up to date. [23,24] To overcome these issues, some promising strategies have been explored to enhance the electrochemical performance. On one hand, incorporation of ZnSe within carbon matrix could improve the electronic conductivity and alleviate huge volume expansion. For example, ZnSe-reduced graphene oxide has been fabricated via a ZnSe is regarded as a promising anode material for energy storage due to its high theoretical capacity and environment friendliness. Nevertheless, it is still a significant challenge to obtain superior electrode materials with stable performance owing to the serious volume change and aggregation upon cycling. Herein, a willow-leaf-like nitrogen-doped carbon-coated ZnSe (ZnSe@NC) composite synthesized through facile solvothermal and subsequent selenization process is beneficial to expose more active sites and facilitate the fast electron/ion transmission. These merits significantly enhance the electrochemical performances of ZnSe@NC for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). The obtained ZnSe@NC exhib...

To date, the fabrication of advanced anode materials that can accommodate both Na+ and K+ storage is still very challenging. Herein, we developed a facile solvothermal and subsequent annealing process to synthesize SnS2/RGO composite, in which SnS2 nanosheets are bonded on RGO, and investigated their potential as anodes for Na+ and K+ storage. When used as an anode in SIBs, the as-prepared SnS2/RGO displays preeminent performance (581 mAh g−1 at 0.5 A g−1 after 80 cycles), which is a significant improvement compared with pure SnS2. More encouragingly, SnS2/RGO also exhibits good cycling stability (130 mAh g−1 at 0.3 A g−1 after 300 cycles) and excellent rate capability (520.8 mAh g−1 at 0.05 A g−1 and 281.4 mAh g−1 at 0.5 A g−1) when used as anode for PIBs. The well-engineered structure not only guarantees the fast electrode reaction kinetics, but also ensures superior pseudocapacitance contribution during repeated cycles, which has been proved by kinetic analysis.