CoNiSe2 Nanoparticles Embedded in Pod-Like N-Doped Carbon Nanofibers for High-Performance Sodium-Ion Batteries

Sluggish kinetics and severe volume expansion critically limit the electrochemical performance of sodium-ion batteries (SIBs). Herein, a novel material combining CoNiSe₂ nanoparticles with pod-like N-doped carbon nanofibers (CoNiSe₂/PCNFs) is designed and fabricated. The bimetallic selenide of CoNiSe₂ combines the redox characteristics of Co and Ni, which offers more redox active sites for Na⁺ adsorption. The nanocubes show large surface areas, which contribute to faster Na⁺ diffusion kinetics. Unique pod-like N-doped carbon nanofibers not only serve as reinforcing frameworks to inhibit volume change but also improve the conductivity of CoNiSe₂/PCNFs. Herein, the CoNiSe₂/PCNFs electrode achieves a high capacity of 395.8 mAh g⁻¹ at a current density of 0.1 A g⁻¹ after 100 cycles and exhibits excellent cycling stability for 1000 cycles at a current density of 1.0 A g⁻¹ with a capacity of 284.3 mAh g⁻¹. The novel structure and high electrochemical properties of CoNiSe₂/PCNFs shed new light on developing high-performance bimetallic selenides as SIB anodes.