Cascading use of barley husk ash to produce silicon for composite anodes of Li-ion batteries

Silicon is a promising alternative anode material for LIBs because it has ten times higher capacity than the currently used graphite giving the possibility to even double to capacity of the total battery cell. The high specific capacity is essential in the electric vehicles and portable electronic devices. However, silicon anodes are unstable during the charge/discharge cycles due to the large volume change of silicon leading to cracking of the silicon particles, which results in poor conductivity between the particles and unstable solid electrolyte interface layer. Mesoporous silicon structures can solve the stability issue and provide stable high capacity anodes for LIBs. In the present study, porous silicon anode material was prepared from barley husk ash, an agricultural residue. The production of the silicon material was carried out through a simple magnesiothermic reduction process, which is a cost-effective method compared with the conventional production method. To improve the performance of the biogenic silicon as anode material, carbon nanotubes were conjugated on the particles to connect the particles to each other. The developed porous silicon composite delivered the average discharge capacity of 2049 mAh g−1 and 472 mAh g−1 at the rate of 0.1 C and 1 C, respectively. [Display omitted] •Barley husk ash served as new raw material for porous silicon LIB anodes.•Magnesiothermic reduction method was used to synthesize mesoporous silicon.•CNTs were conjugated with mesoporous silicon to improve the electrical conductivity.•The composite anode enhanced essentially the rate capability performance.