In Situ Construction of CoSn/N-Doped Carbon/SnNb₂O₆ Heterojunctions for Lithium-Ion Storage

SnNb2O6 (SNO) has garnered significant interest as a lithium storage anode material primarily because of its typical layered structure and large specific surface area. However, its poor electrical conductivity and substantial volume expansion greatly limit its applications. Here, we propose a straightforward in situ polymerization strategy to prepare CoSn/N-doped carbon (NC)/SNO heterojunctions derived from ZIF-67 for Li-ion batteries. The CoSn nanoalloys are encapsulated within the NC/SNO framework, which effectively maintains the structural stability and mitigates volume expansion. Furthermore, the alloy/intercalation hybrid mechanism is integrated into CoSn/NC/SNO to enhance performance and ensure long-term stability. The dual catalytic centers provided by SNO and CoSn nanoalloys facilitate the rapid transfer of charges and promote the diffusion kinetics of Li+. As a result, CoSn/NC/SNO-2 heterojunctions provide high reversible capacities of 610.4 and 377.3 mAh g–1 at 200 and 5000 mA g–1, respectively, much greater than those of pure SNO and pure Co@NC. At 5000 mA g–1, a low capacity decay rate of 0.0053% per cycle has been achieved in 3000 cycles, demonstrating exceptionally long cycling stability.