Double-Shelled Hollow SiO2@N-C Nanofiber Boosts the Lithium Storage Performance of [PMo12O40]3-

Polyoxometalates (POMs)-based materials, with high theoretical capacities and abundant reversible multi-electron redox properties, are considered as promising candidates in lithium-ion storage. However, the poor electronic conductivity, low specific surface area and high solubility in the electrolyte limited their practical applications. Herein, a double-shelled hollow PMo12-SiO2@N-C nanofiber (PMo12-SiO2@N-C, where PMo12 is [PMo12O40](3-), N-C is nitrogen-doped carbon) was fabricated for the first time by combining coaxial electrospinning technique, thermal treatment and electrostatic adsorption. As an anode material for LIBs, the PMo12-SiO2@N-C delivered an excellent specific capacity of 1641 mA h g(-1) after 1000 cycles under 2 A g(-1). The excellent electrochemical performance benefited from the unique double-shelled hollow structure of the material, in which the outermost N-C shell cannot only hinder the agglomeration of PMo12, but also improve its electronic conductivity. The SiO2 inner shell can efficiently avoid the loss of active components. The hollow structure can buffer the volume expansion and accelerate Li+ diffusion during lithiation/delithiation process. Moreover, PMo12 can greatly reduce charge-resistance and facilitate electron transfer of the entire composites, as evidenced by the EIS kinetics study and lithium-ion diffusion analysis. This work paves the way for the fabrication of novel POM-based LIBs anode materials with excellent lithium storage performance.

Automated summary

This study successfully fabricated double-shelled hollow PMo12-SiO2@N-C nanofiber materials through a unique preparation method, demonstrating excellent performance as an anode material for lithium-ion batteries. This paves the way for the development of novel POM-based LIBs anode materials with outstanding lithium storage performance.