Update on anode materials for Na-ion batteries
Na-ion batteries have emerged in recent years, due to their advantages of natural abundance, low cost and environmental friendliness. In this article, we review the up-to-date research progress on anode materials for Na-ion batteries from five respects: carbon-based materials, alloy-based materials, metal oxides and sulfides based on conversion reaction, titanium-based compounds with insertion mechanism, and organic composites. In particular, we not only summarize the Na-storage mechanism of these anodes, but also discuss the failure mechanism. The problems and challenges associated with these anodes are pointed out. Furthermore, on the basis of extensive reports and our experimental studies, feasible strategies are suggested for designing high performance anode materials. After further in-depth exploration and investigation, we believe that Na-ion batteries are promising alternative to lithium-ion batteries for low cost and large-scale energy storage systems in the near future.