Sodium-ion batteries are the primary candidate for a low-cost and resource-abundant alternative to lithium-ion batteries for large-scale electric storage applications. However, the development of sodium-ion batteries is hindered by the lack of suitable cathode materials that have sufficient specific energy density and cycle life. Here, we report layered NaVOPO4 as a cathode material that exhibits high voltage (∼3.5 V versus Na/Na+), high discharge capacity (144 mAh g−1 at 0.05 C), and remarkable cyclability with 67% capacity retention over 1,000 cycles. The excellent performances result from the high Na+ ion diffusion rate in the two-dimensional path and the reversible transformation behavior of (de)sodiation. Particularly, this layered structure and its synthetic procedure can be extended to other alkali-metal intercalation materials, leading to other metal-ion battery systems, which opens a new avenue for large-scale energy storage systems with the development of high-energy-density and long-life cathodes for electric storage applications. The growing demand for large-scale energy storage is driving the development of alternative cation batteries beyond lithium, considering the limited resources of Li in the Earth's crust and its uneven distribution. Sodium-ion batteries have become a topic of emerging interest for large-scale energy storage. The wide availability and low cost of sodium resources confer an overwhelming advantage over commercial lithium-ion batteries. Developing advanced sodium storage cathodes with robust structure and enhanced energy density is a great challenge for energy chemists in the pursuit of efficient storage systems. Here, we report a NaVOPO4 cathode with layered structure by facile synthesis routes. The two-dimensional Na+ diffusion path enables an electrode with extraordinary structural stability and outstanding electrochemical performance. The synthetic method could provide inspiration for material synthesis and development at low cost and on a large scale. Sodium-ion batteries have attracted enormous attention as an alternative to lithium-ion batteries because of the abundant resources and low cost of sodium. However, the development of sodium-ion batteries is hindered by the lack of suitable cathode materials that have sufficient specific energy density and cycle life. Here, we report a layered NaVOPO4 material with high voltage, large reversible capacity, and superior cycle life. The layered structure and its synthetic procedure can also be extended to other alkali-metal intercalation materials.
Fang, Y., Liu, Q., Xiao, L., Rong, Y., Liu, Y., Chen, Z., … Ren, Y. (2018). A Fully Sodiated NaVOPO4 with Layered Structure for High-Voltage and Long-Lifespan Sodium-Ion Batteries. Chem, 4(5), 1167–1180. https://doi.org/10.1016/j.chempr.2018.03.006