In Situ Construction of (NiCo)Se Nanobeads Embedded in N-Doped Carbon 3D Interconnected Networks for Enhanced Sodium Storage.

Transition metal selenides, boasting remarkable specific capacity, have emerged as a promising electrode material. However, the substantial volume fluctuations during sodium ion insertion and extraction result in inadequate cyclic stability and rate performance, impeding their practical utility. Here, we synthesized N-doped carbon three-dimensional (3D) interconnected networks encapsulating (NiCo)Se nanoparticles, denoted as ((NiCo)Se/N-C), exhibiting a bead-like structure and carbon confinement through electrospinning and subsequent thermal treatment. The N-doped carbon 3D interconnected networks possess high porosity and ample volume buffering capacity, enhance conductivity, shorten ion diffusion paths, and mitigate mechanical stress induced by volume changes during cycling. The uniformly distributed (NiCo)Se nanoparticles, featuring a stable structure, demonstrate rapid electrochemical kinetics and numerous available active sites. The distinctive structure and composition of the optimized (NiCo)Se/N-C material showcase a high specific capacity (656.2 mAh g at 0.1 A g) and an outstanding rate capability. A kinetic analysis confirms that (NiCo)Se/N-C stimulates the pseudocapacitive Na storage mechanism with capacitance contributing up to 89.2% of the total capacity. This unique structure design and doping approach provide new insights into the design of electrode materials for high-performance batteries.