Carbon materials with well-dispersed SnOx particles exhibit excellent lithium-storage performance. However, the volume change of SnOx and the weak interaction between SnOx and carbon induce an unsteady SnOx-C interface during the lithiation/delithiation process. This phenomenon results in enhanced charge transfer resistance and reduced electrical contact of active materials, which leads to low reversibility of tin oxidation, restricted capacity, sluggish kinetics, structural deterioration, and rapid capacity decay. Herein, tin oxide/carbon composites with a metaphosphate-bridged interface are synthesized to construct a robust interfacial contact between tin oxides and carbon. The metaphosphate group functions as a bridge between SnOx and carbon and results in excellent electrochemical stability during the charge/discharge process, which is favorable for electrode structural integrity. The formation of the metaphosphate-bridged interface provides a steady transport channel for e-/Li+ and thus improves the reversibility of the conversion reaction. The enhanced charge transfer and interaction can also boost the charge transfer between SnOx and carbon, which leads to higher SnOx utilization. Thus, the prepared P-SnOx/C anode exhibits enhanced lithium-storage performance in terms of specific capacity, cycling stability, and rate performance.
Keywords: charge transfer; chemical bond; lithium storage; metaphosphate-bridged interface; reversibility.