Preparation of heterostructured MnSe/FeSe@C nanorods for high-performance Na-ion storage

Abstract

The large radius of sodium ions causes an increase in anode volume during charge/discharge cycles, which can damage the electrode structure and deteriorate the battery's cycling performance. The conductivity of electrode materials and sodium-ion diffusion rate can be improved through materials morphology control, composite material construction, and doping, consequently boosting the performance rate and cycling stability of Na⁺ batteries. In this work, Mn/Fe bimetallic oxalate nanorod templates were prepared using liquid-phase precipitation techniques, followed by calcination in air and coating with resorcinol-formaldehyde resin. Subsequently, carbon-coated MnSe/FeSe (MnSe/FeSe@C) nanorods were obtained through carbonization-selenization reactions. A reversible capacity of 263.1 mAh g⁻¹ was retained by MnSe/FeSe@C nanorods after 3800 cycles at 10.0 A g⁻¹ when utilized as an anode for Na⁺ batteries. The electrochemical characteristics are primarily attributed to the interactive effect of carbon coating and heterostructured MnSe/FeSe. The aggregation of MnSe/FeSe nanoparticles was effectively mitigated by the outer carbon coating, while the volume expansion during the reaction of MnSe/FeSe@C with sodium ions was effectively mitigated by the internal voids within the carbon layer of the nanorods. Furthermore, the bimetallic composition of the anode materials formed a well-defined phase interface, optimizing sodium-ion transport channels and enhancing the battery's charge-discharge rate performance. Electrolyte penetration was facilitated, the electrolyte contact area was increased, and the sodium ion transport pathway was shortened by the carbon-coated one-dimensional porous rod-like structure, contributing to improved energy efficiency, anode performance rate, and cycling stability. The results highlight the potential of MnSe/FeSe@C nanorods as an efficient anode material for next-generation Na⁺ battery.