Recent advances of electrode materials for low-cost sodium-ion batteries towards practical application for grid energy storage

Energy storage plays an important role in the development of portable electronic devices, electric vehicles and large-scale electrical energy storage applications for renewable energy, such as solar and wind power. Lithium-ion batteries (LIBs) have dominated most of the first two applications due to the highest energy density and long cycle life. Room-temperature sodium-ion batteries (SIBs) have re-attracted great attention recently, especially for large-scale electrical energy storage applications. This is on one hand due to the abundant and widely distributed sodium resources and on the other hand due to the predicted lower cost from using Na, as well as Al current collectors for both cathode and anode. One of the important advantages as well as challenges in SIBs is to use low-cost materials as active electrodes to compete with LIBs in terms of cost/kWh. In this review, both cathode and anode materials for SIBs are reviewed, with focus on the latest development of electrode materials from 2013. Advantages, disadvantages and future directions on the existing electrode materials will be discussed based on the literature and our experience. Although a large number of electrode materials have been reported in the literature, SIBs are still facing grand challenges, which can be overcome by continuing the research efforts to search for new electrode materials with better performance, lower cost, higher safety and more stable interface with electrolyte. Once the right electrode materials are discovered throughout a fundamental understanding of the intimate relationships between its structure and performance, we believe that SIBs with low cost and long life will have promising prospects in low-speed electric vehicles (e.g., bicycle, quadricycle, etc.) and large-scale energy storage in the future.