Building Hierarchical Microcubes Composed of One‐Dimensional CoSe2@Nitrogen‐Doped Carbon for Superior Sodium Ion Batteries

Designing and synthesizing highly stable anode materials with high capacity is critical for the practical application of sodium ion batteries (SIBs), however, to date, this remains an insurmountable barrier. The introduction of hierarchical architectures and carbon supports is proving an effective strategy for addressing these challenges. Thus, we have fabricated a hierarchical CoSe2 @nitrogen-doped carbon (CoSe2 @NC) microcube composite using the Prussian blue analogue Co3 [Co(CN)6 ]2 as template. The rational combination of the unique hierarchical construction from one to three dimensions and a nitrogen-doped carbon skeleton facilitates sodium ion and electron transport as well as stabilizing the host structure during repeated discharge/charge processes, which contributes to its excellent sodium storage capability. As expected, the as-prepared CoSe2 @NC composite delivered remarkable reversible capacity and ultralong cycling lifespan even at a high rate of 2.0 A g-1 (384.3 mA h g-1 after1800 loops) when serving as the anode material for SIBs. This work shows the great potential of the CoSe2 -based anode for practical application in SIBs, and the original strategy may be extended to other anode materials.