In Situ Synthesis of Porous SnO₂/SnS₂@PC Anode Material with High Capacity Using Calcium Carbonate as Template for Lithium-Ion Batteries

Tin-based materials have emerged as promising anode candidates for advanced lithium-ion batteries (LIBs) due to their high theoretical capacity (e.g., 994 mAh·g⁻¹ for Li₄.₄Sn), moderate operating potential, and natural abundance. However, Tin-based materials suffer from severe volume expansion (>300%) and rapid capacity decay during cycling. To mitigate these challenges, a composite composed of tin-based materials and porous carbon (PC), i.e., SnO₂/SnS₂@PC, was prepared by calcining a mixture of SnO₂, petroleum asphalt and calcium carbonate at high temperature, where petroleum asphalt acted as the carbon and sulfur resource, and calcium carbonate acted as a pore-forming template. The prepared SnO₂/SnS₂@PC composite had a specific surface area of 190 m²·g⁻¹ with total pore volume 0.386 cm³·g⁻¹, and delivered an initial specific capacity of 1431 mAh·g⁻¹ and retained 722 mAh·g⁻¹ at 100th cycle at 0.2 A·g⁻¹, which is nearly three folds that of the actual capacity (~260 mAh·g⁻¹) of commercial graphite. The novelty of this work lies in that the abundant sulfur element in petroleum asphalt was fully utilized to react in situ with nano SnO₂ to generate SnS₂ and form a composite with high specific capacity and good structural stability, along with greatly reducing the emission of the harmful element sulfur into the atmosphere.