In situ heating-induced loading of anion-rich vacancy Mo–Fe_1-xS nanoparticles on mesoporous carbon for high-performance sodium-ion batteries

Inspiriting the kinetics of transition metal sulfide-based anodes is key to optimizing rate performance and cycling stability. To this end, the controllable anion vacancy and large specific surface area are considered as powerful means to improve the performance of sodium-ion batteries due to their unique physical and chemical properties and convenient transport paths. Hence, we have generated Fe³⁺/MoO₄²⁻@cystine nanosheets by solvothermal reaction with iron molybdate nanosheets using cysteine as a sulfur and carbon source. in situ environmental transmission electron microscopy demonstrates that the Fe³⁺/MoO₄²⁻@cystine nanosheets calcined under a vacuum state undergo significant structural evolution, consequentially, the decomposition and carbonization of cystine induces the generation of mesoporous structures with increasing temperature. In the half-cell, Mo–Fe_1-xS@mesoporous nitrogen doped carbon-600 showed excellent rate capability at current densities of 0.1–5 A g⁻¹, as well as excellent cycling performance (428.9 mAh g⁻¹ at 2.0 A g-1 after 800 cycles). Mesoporous nitrogen doped carbon and sulfur vacancies induced enhanced conductivity, fast ionic transfer and structural stability, resulting in excellent electrochemical performance of Mo–Fe_1-xS@mesoporous nitrogen doped carbon under calcination at 600 °C (Mo–Fe_1-xS@MCN-600).