Se-Regulated MnS Porous Nanocubes Encapsulated in Carbon Nanofibers as High-Performance Anode for Sodium-Ion Batteries

• Developed an efficient and scalable strategy to prepare single-phase ternary MnS0.5Se0.5-carbon nanofiber composite with defect-rich microstructure. • Thoroughly investigated Na+ storage mechanism of manganese-based sulfides after Se incorporation via electrochemical characterization and theoretical calculations. • MnS0.5Se0.5@N-CNF anode exhibits excellent reversible capacity, rate capability, and cycling stability in sodium-ion batteries. • Full cell with MnS0.5Se0.5@N-CNF anode and NVP@C cathode achieves high energy density of 254 Wh kg−1.