Porous Carbon@Ferric Silicate Hollow Spheres for Enhanced Lithium and Sodium Storage

The intrinsic poor conductivity and large volume variation of ferric silicate severely hinder its practical application. Herein, a unique double-shell-structured amorphous porous carbon@ferric silicate hierarchical hollow sphere (PC@FS) is designed to improve its electrochemical performance. The amorphous feature of PC@FS is favorable for Li+/Na+ diffusion and avoids the structure collapse. FS nanosheets shorten the transport path of lithium/sodium ions. The hollow carbon spheres not only boost the conductivity but also accommodate volume variation. Besides, the heterointerface of PC@FS exhibits interfacial lithium/sodium storage. The synergistic effects bestow PC@FS enhanced lithium and sodium storage with high reversible capacity, excellent rate performance, and remarkable cycling stability. It manifests a capacity as high as 625.7 mAh g(-1) at 5 A g(-1) after 1000 cycles for lithium-ion batteries and 315.7 mAh g(-1) at 0.05 A g(-1) after 50 cycles for sodium-ion batteries.