Sulfur-Anion-Modulated Electron Configuration of Manganese Selenide for High Performance Sodium Ion Storage

Manganese selenide (MnSe), as a typical electrode material, has garnered significant attention due to its high theoretical specific capacity and cost-effectiveness. However, persistent challenges, including sluggish reaction kinetics and inadequate cycling stability, remain to be addressed. Anion-doping-induced defect engineering is regarded as a promising strategy to achieve superior sodium storage performance by modulating the electronic configuration of MnSe. In this work, electronegative sulfur (S) is incorporated into nitrogen-rich metal-organic framework-derived MnSe via sulfuration treatment. Various characterizations and theoretical calculations reveal that doping of S into the MnSe lattice can introduce defect levels, optimize ion diffusion pathways, and reduce Na⁺ diffusion barrier, thereby enhancing the electrochemical performance of the MnSe anode. As expected, the optimal material exhibits excellent rate performance and long-term cyclability, delivering a specific capacity of 402.7 mAh g^-1 at 2.0 A g^-1 after 300 cycles and retaining 353.1 mAh g^-1 after 800 cycles at 5.0 A g^-1. Furthermore, ex situ X-ray diffraction patterns and X-ray photoelectron spectroscopy are employed to analyze the sodium storage mechanism.