Enhanced\nLithium-Ion Diffusion Kinetics and Inhibition\nVolume Expansion via Sn-Bridged N‑Doped Carbon and SiO<sub><i>x</i></sub> for Highly Reversible Lithium-Ion Storage

Silicon oxide (SiO<sub><i>x</i></sub>) is becoming\na\nhot spot in the research of anode materials for lithium-ion batteries.\nHowever, the low initial coulombic efficiency (ICE), weak conductivity,\nunsatisfied rate performance, and significant volume changes during\ncycling of SiO<sub><i>x</i></sub> have hindered its commercial\napplication. Herein, a silicon–carbon composite material (SiO<sub><i>x</i></sub>/C–Sn@NC) was synthesized, featuring\nmetal tin that is embedded within and on the surface of the SiO<sub><i>x</i></sub> framework. Additionally, a nitrogen-doped\ncarbon layer was incorporated into the material to further mitigate\nvolume changes. Benefitted from the discrepant lithiation/delithiation\npotentials of Sn and Si, the formed structure significantly limits\nthe volume changes of the formed anode during the cycle, enhancing\nthe cycle life and stability of the SiO<sub><i>x</i></sub>/C–Sn@NC material. Additionally, multiple nodes are provided\nin the part where the bridged Sn is in contact with the N-doped carbon\nto enhance the Li<sup>+</sup> diffusion during charge and discharge\nand overall conductivity, promoting the lithium-ion diffusion kinetics.\nThe SiO<sub><i>x</i></sub>/C–Sn@NC anode displays\nan ICE of 73.42% at 0.5 A g<sup>–1</sup>, retaining a capacity\nof 680 mAh g<sup>–1</sup> after 500 cycles. In addition, this\nanode also exhibits excellent cycle performance of 591 mAh g<sup>–1</sup> after 500 cycles, with an ICE of 70.37% at a current of 2 A g<sup>–1</sup>. The prominent cycle performance and electrochemical\nstability of SiO<sub><i>x</i></sub>/C–Sn@NC far surpass\nthose of commercial silicon–carbon and graphite, offering a\nnew pathway for the commercial application of silicon oxide-based\nanodes.