DFT-Guided Synthesis of High-Performance Ni₃Sn₂S₂/Ni₃S₂ Anodes on Graphite Nanosheets for Sodium-Ion Batteries

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Metal sulfides are promising anode materials for sodium-ion batteries (SIBs) due to their high theoretical capacity, multiple redox sites, and ease of preparation. However, their use is limited by significant volume expansion, slow Na + diffusion, and low electronic conductivity. In this study, guided by DFT calculations, a 3:1 molar ratio mixture of Ni and SnS 2 was calcined and then anchored on graphite nanosheets (Gn) after ball milling to create NSS-3/Gn (Ni 3 Sn 2 S 2 /Ni 3 S 2 /Gn). The Ni 3 Sn 2 S 2 /Ni 3 S 2 heterostructure enhanced electron transfer and Na + diffusion, while Gn improved the conductivity and mitigated volume changes during cycling. The different crystal phases of the constructed NSS and the contact model with Gn indicate that the NSS interface forms chemical bonds with Gn, thereby ensuring the uniform dispersion and anchoring of active materials on Gn. As a result, NSS-3/Gn demonstrated exceptional electrochemical performance. It achieved specific capacities of 466.1 to 279.4 mAh g –1 at current densities from 0.1 to 10.0 A g –1, and retained a reversible capacity of 365.6 mAh g –1 after 300 cycles at 1.0 A g –1 . This study presents a simple and effective method for synthesizing high-performance anode materials with broad applicability in energy storage.