In Situ Construction\nof CoSn/N-Doped Carbon/SnNb<sub>2</sub>O<sub>6</sub> Heterojunctions\nfor Lithium-Ion Storage

SnNb<sub>2</sub>O<sub>6</sub> (SNO) has garnered significant\ninterest\nas a lithium storage anode material primarily because of its typical\nlayered structure and large specific surface area. However, its poor\nelectrical conductivity and substantial volume expansion greatly limit\nits applications. Here, we propose a straightforward in situ polymerization\nstrategy to prepare CoSn/N-doped carbon (NC)/SNO heterojunctions derived\nfrom ZIF-67 for Li-ion batteries. The CoSn nanoalloys are encapsulated\nwithin the NC/SNO framework, which effectively maintains the structural\nstability and mitigates volume expansion. Furthermore, the alloy/intercalation\nhybrid mechanism is integrated into CoSn/NC/SNO to enhance performance\nand ensure long-term stability. The dual catalytic centers provided\nby SNO and CoSn nanoalloys facilitate the rapid transfer of charges\nand promote the diffusion kinetics of Li<sup>+</sup>. As a result,\nCoSn/NC/SNO-2 heterojunctions provide high reversible capacities of\n610.4 and 377.3 mAh g<sup>–1</sup> at 200 and 5000 mA g<sup>–1</sup>, respectively, much greater than those of pure SNO\nand pure Co@NC. At 5000 mA g<sup>–1</sup>, a low capacity decay\nrate of 0.0053% per cycle has been achieved in 3000 cycles, demonstrating\nexceptionally long cycling stability.