Peroxide induced tin oxide coating of graphene oxide at room temperature and its application for lithium ion batteries

We describe a new, simple and low-temperature method for ultra-thin coating of graphene oxide (GO) by peroxostannate, tin oxide or a mixture of tin and tin oxide crystallites by different treatments. The technique is environmentally friendly and does not require complicated infrastructure, an autoclave or a microwave. The supported peroxostannate phase is partially converted after drying to crystalline tin oxide with average, 2.5 nm cassiterite crystals. Mild heat treatment yielded full coverage of the reduced graphene oxide by crystalline tin oxide. Extensive heat treatment in vacuum at >500 °C yielded a mixture of elemental tin and cassiterite tin oxide nanoparticles supported on reduced graphene oxide (rGO). The usefulness of the new approach was demonstrated by the preparation of two types of lithium ion anodes: tin oxide–rGO and a mixture of tin oxide and tin coated rGO composites (SnO2–Sn–rGO). The electrodes exhibited stable charge/discharge cyclability and high charging capacity due to the intimate contact between the conductive graphene and the very small tin oxide crystallites. The charging/discharging capacity of the anodes exceeded the theoretical capacity predicted based on tin lithiation. The tin oxide coated rGO exhibited higher charging capacity but somewhat lower stability upon extended charge/discharge cycling compared to SnO2–Sn–rGO.