Diatom Frustules Decorated with Co Nanoparticles for the Advanced Anode of Li-Ion Batteries

Silica is regarded as a promising anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity. However, large volume variation and poor electrical conductivity are limiting factors for the development of SiO2 anode materials. To solve this problem, combining SiO2 with a conductive phase and designing hollow porous structures are effective ways. In this work, The Co(II)-EDTA chelate on the surface of diatom biosilica (DBS) frustules and obtained DBS@C-Co composites decorated with Co nanoparticles by calcination without a reducing atmosphere is first precipitated. The unique three-dimensional structure of diatom frustules provides enough space for the volume change of silica during lithiation/delithiation. Co nanoparticles effectively improve the electrical conductivity and electrochemical activity of silica. Through the synergistic effect of the hollow porous structure, carbon layer and Co nanoparticles, the DBS@C-Co-60 composite delivers a high reversible capacity of >620 mAh g(-1) at 100 mA g(-1) after 270 cycles. This study provides a new method for the synthesis of metal/silica composites and an opportunity for the development of natural resources as advanced active materials for LIBs.

Automated summary

Silica is a promising anode material for LIBs due to its high theoretical capacity, but its large volume variation and poor electrical conductivity limit its development. This study presents a new approach by combining SiO2 with a conductive phase and designing hollow porous structures. The DBS@C-Co composite, decorated with Co nanoparticles, exhibits a high reversible capacity of >620 mAh g(-1) after 270 cycles, thanks to the synergistic effect of the unique three-dimensional structure of diatom frustules, carbon layer, and Co nanoparticles. This work offers a new method for synthesizing metal/silica composites and provides new opportunities for the development of advanced active materials for LIBs.