BaTiO3‐doped silicon nanocomposite anodes capacity enhancement for ultra‐high capacity rechargeable lithium‐ion batteries

Abstract

Silicon anodes are vital for the next generation ultra-high capacity rechargeable lithium-ion batteries. This study investigates ultrasmall silicon nanopowder (30–40 nm) as an anode material. Its high capacity > 3700 mAh/g makes it attractive, given the current theoretical capacity of graphite is ten times lower (370 mAh/g). However, it has severe instability due to volume expansion of silicon particles during charging. Hence, BaTiO3 nanomaterial was used to stabilise the cycling ability and improve the capacity. This study showed that silicon anode with BaTiO3 retained 40% of its original capacity after the 100th cycle where the silicon anode without BaTiO3 lost almost all of its capacity. The silicon anode with BaTiO3 also managed to regain and sustain ∼800 mAh/g of its capacity at slow charging rate compared to the silicon anode without BaTiO3. Water was used as a solvent and the basic changes in oxidation states of the silicon anode were investigated using X-ray photoemission spectroscopy and proved the creation of COx at different rates of repeated cycling. The work also provides detailed mapping of the different stages as the silicon nanopowder undergoes cycling. It provides a simple and effective way of synthesising and testing nearly pure silicon anodes.