Investigations on Novel Cathode Materials for Sodium-based Storage System

Since the development of various forms of renewable energy such as solar, wind and tidal energy, burning scarce fossil fuel is no longer the only option for electricity. Manufacturing inexpensive and efficient energy storage systems on a massive scale is fundamentally important for our society due to the intermittency of the renewable energy. Recently, sodium-ion batteries (SIBs) have been considered as a promising alternative to their lithium-ion battery counterparts for next-generation energy storage because of the abundant and cost-effective nature of sodium resources. Based on the success of commercial layered oxide cathodes in LIBs, NaxTMO2 (with TM representing Ni, Co, Mn, and other transition metals) has been regarded as one of the most promising cathodes for commercial SIBs. Nevertheless, the introduction of expensive transition metals (Ni and Co) in layered oxide cathode, and their inevitably complicated phase transitions, and weak kinetics during the charge/discharge process have greatly limited the practical application of SIBs. The cost of raw materials and the electrochemical reversibility of the cathode are key factors in the SIB systems. Low-cost layered oxides free of Ni and Co with reversible mechanisms are considered to be the most promising cathode materials for future SIBs...