Synthesis of high capacity anode materials for lithium-/potassium-ion batteries (LIBs/PIBs) is still a big challenge. Here we report a highly active electrode material, which is synthesized by heat treatment of mixtures of iron(III)hexacyanoferrate (HCF), dicyanamide (DCA) and SiO₂ spheres and then etching engineering. The samples possess three-dimensional (3D) interconnecting carbon architectures coupled with Fe/Fe₅C₂ and large specific surface area. The highlights can be attributed to three points: (i) as far as we know, the study on Fe/Fe₅C₂ in carbon hybrids as anodes for LIBs and/or PIBs has not been reported yet, (ii) the strategy using DCA/HCF can increase the amount of N–C/Fe active sites, and can promote the formation of Fe/Fe₅C₂ and abundant Fe-N_x, and (iii) the results manifest that Fe/Fe₅C₂ NPs and Fe-N_x-C might also serve as efficient catalysts to activate/promote the formation of the stronger and stabler SEI film on the electrode surfaces in the first cycle. Therefore, 3DM Fe/Fe₅C₂@NC presents the outstanding lithium/potassium storage properties. As for LIBs, 3DM Fe/Fe₅C₂@NC exhibits an initial discharge capacity of 1513 mAh g⁻¹ at 0.1 A g⁻¹. At 1 A g⁻¹, it presents the high reversible capacity of 1024 mAh g⁻¹ after 550 cycles and the reversible capacity sustains 839 mAh g⁻¹ (81.9% retention of the maximum capacity) after a long span of 1000 cycles. As for PIBs, 3DM Fe/Fe₅C₂@NC exhibits high reversible capacity of 460 mAh g⁻¹ at 0.05 A g⁻¹ and high cycling stability of 205 mAh g⁻¹ at 0.5 A g⁻¹ after 1000 cycles with an extremely slow capacity decay of only 0.013% per cycle from the 10th to 1000th cycle. Finally, the strategy to fabricate 3DM Fe/Fe₅C₂@NC nanocrystal can synthesize other nanocomposites with metallic nanoparticles and abundant active sites as anodes electrodes toward high-performance LIBs/PIBs in future.

用于锂/钾离子电池（LIB / PIB）的高容量阳极材料的合成仍然是一个巨大的挑战。在这里，我们报告了一种高活性电极材料，该材料是通过对三氰合铁酸亚铁（HCF），双氰胺（DCA）和SiO ₂球体的混合物进行热处理，然后进行蚀刻工程合成的。样品具有与Fe / Fe ₅ C ₂耦合的三维（3D）互连碳结构和较大的比表面积。重点可以归结为三点：（i）据我们所知，关于Fe / Fe ₅ C _2的研究碳杂化物作为LIB和/或PIB的阳极的报道尚未报道，（ii）使用DCA / HCF的策略可以增加N-C / Fe活性位的数量，并可以促进Fe / Fe ₅ C的形成₂和大量的Fe-N _x，以及（iii）结果表明，Fe / Fe ₅ C ₂ NPs和Fe-N _x -C还可作为有效的催化剂来活化/促进在表面上形成更强和更稳定的SEI膜。在第一个循环中电极表面。因此，3DM Fe / Fe ₅ C ₂ @NC具有出色的锂/钾存储性能。对于LIB，3DM Fe / Fe ₅ C ₂@NC 在0.1 A g ^-1时显示出1513 mAh g ^-1的初始放电容量。在1 A g ^-1时，它在550次循环后呈现出1024 mAh g ^-1的高可逆容量，在经过1000次循环后，可逆容量维持了839 mAh g ^-1（最大容量的81.9％保留）。对于PIB，3DM Fe / Fe ₅ C ₂ @NC 在0.05 A g ^-1时表现出460 mAh g ^-1的高可逆容量， 在0.5 A g ^-1时表现出205 mAh g ^-1的高循环稳定性在1000次循环后，从第10次循环到第1000次循环，每循环的容量衰减非常缓慢，仅为0.013％。最后，制备3DM Fe / Fe ₅ C ₂ @NC纳米晶体的策略可以在将来合成具有金属纳米颗粒和丰富活性位点的其他纳米复合材料，作为高性能LIB / PIB的阳极电极。