Cellulose-derived flake graphite as positive electrodes for Al-ion batteries

Due to the renewable nature and rich carbon content, biomass resources provide an adequate source of raw materials for developing carbon materials. Biomass energy is a by-product of agriculture, industry and forestry, and the rational use of biomass is an important issue. For converting biomass into graphitized products, there are some critical problems in the traditional graphitization method, such as high cost, long processing time, addition of catalyst impurities and environmental pollution. For addressing these problems effectively, here, we present a high-efficiency method for graphitizing biomass materials in molten CaCl₂ salt. This method has the advantages of low-temperature, environment-friendly and catalyst-free features, which allow the amorphous carbon to be converted into highly graphitized products. The as-prepared graphite could then be used as the positive electrode in rechargeable aluminum-ion batteries. The results indicate an efficient strategy for sustainably utilizing biomass in a high value-added way.