Flower-like Cu0.18V2O5·0.72H2O/Ketjen black composite as high performance cathode material for sodium-ion batteries

The abundant sodium resources makes sodium ion batteries have the potential to be an alternative to lithium-ion batteries. Due to the large ionic radius of sodium ion, suitable cathode materials have a significant impact on the electrochemical performance of sodium ion batteries. Herein, Cu0.18V2O5•0.72H2O/ Ketjen black, a double modification strategy of groups (Cu2+/H2O) intercalation and Ketjen black composition materials was successfully synthesized. Copper ions and water molecules co-inserted into the V2O5 interlayer to increase its spacing, thus increasing the active sites of Na+ ions intercalation and deintercalation. Meanwhile, the interlayer groups serve as “pillars” to improve the structural stability of the material. Ketjen black not only reduces particle aggregation but also enhances electrical conductivity of the material. As the cathode of sodium-ion batteries, the combination of these factors allows the cathode to exhibit high reversible specific capacity (up to 155 mA h g−1 at 50 mA g−1) and superior cycle performance. The fast and highly reversible Na+-ion intercalation/deintercalation mechanism was revealed by in situ XRD.