Tailored silicon hollow spheres with Micrococcus for Li ion battery electrodes

The porous Si hollow spheres (p-Si HSs), which feature interconnected Si nanostructures decorated with spherical-type Micrococcus bacteria, were synthesized by a combination of magnesiothermic reduction and byproduct removal and were subsequently studied as an anode material for lithium-ion batteries (LIBs). The p-Si HSs offer a high lithium-ion storage capacity because of their numerous active sites and large electrolyte contact area stemming from their large specific surface area (∼313.7 m² g⁻¹); in addition, their large pore volume (∼0.927 cm³ g⁻¹) buffers large volume changes during the lithiation/delithiation processes, which is important for improving the cycle stability of anode materials. Furthermore, carbon coating resulted in the formation of a stable solid electrolyte interface through minimization of the Si/electrolyte contact area and also offered an efficient electronic conduction pathway, corresponding with improved lithium reactivity of the active Si materials. The lithium-ion diffusion coefficient of the non-clogging carbon-coated p-Si HSs was approximately five times greater than that of the p-Si HSs. As a result, the designed composite nanostructured electrodes demonstrated excellent cycle stability and superior rate capability.