(503b) Synthesis of Biorenewable C/Si/SiO2 As the Li-Ion Battery Anode Material

Technological advances in the electronic devises and electro-mobile industries give big challenges energy manufacturers and energy researchers. The aspiration to decrease the cost of traditional rechargeable energy storage and improve the specific energy and power is becoming much more popular. Lithium-ion battery is in great requirement as an energy source for many applications because of its high energy density. With long cycle life and low cost properties, carbon anode material has been used for about 20 years since the graphite used as anode material, however, its Lithium-storage capacity is about 372mAh/g which is much lower than 4200mh/g of silicon lithium-storage. That means carbon anode material could not satisfy future demands of the mobile phone and electric vehicles.

Silicon can alloy with lithium with higher theoretical specific capacity. The material is developed as anode material to replace the current carbon based materials, but it has disadvantages of poor mechanical and cycling stability caused by drastic volume changes in charge and discharge processes. To solve these problems, some matrix outside of the silicon anode need to be constructed to eliminate the impact of  the volume changing and improve the conductivity.

In this project, two innovative fabrication methods were use to prepare the C/SiO₂ composition from biorenewable high silica biomass. The first, sodium silicate, extracted after carbon materials preparation, were mixed with mesoporous activated carbon together, and synthetize nanostructured SiO₂/C composition with certain conditions. The second method, porous SiO₂ structure, which was synthesized using bio-inspired bottom up fabrication method, was coated with porous nano-carbon particles or films. After generation of nanostructured C/SiO₂ structure, by controling the conditions of reduction, such as dosage of reducing agent, react time and react temperature, different C/Si/SiO₂ composites were prepared. The cyclic voltammetry and EIS was measured to evaluate the properties of the innovative bioreneable anode.

The innovative biorenewable C/Si/SiO₂ composites shown higher and more stable electrical energy storage capacity than reported results based on similar composited produced by CVD methods.