Electrochemical studies on Na2FeP2O7 pyrophosphate enhanced with SWCNT as intercalation compounds for Na-ion batteries: An insight into sensitive mode operations

A sol-gel assisted method followed by post calcination is utilized here to synthesize polyanionic type Na2FeP2O7 (NVP) material as a cathode for Na-ion batteries. The NVP with super carbon black (SCB) as a conducting agent delivers a specific discharge capacity of 68 mAh g−1 at 0.1C in the initial cycle. To improve the specific capacity, stability and reversibility the different carbon sources such as Single-Walled Carbon Nanotube (SWCNT) and Multiwalled Carbon Nanotube (MWCNT) are physically mixed with the as-synthesized NVP material. The SWCNT mixed material shows a better specific discharge capacity of 73 mAh g−1 at the initial cycle at 0.1C rate. The structure modification with the SWCNT addition fastens the reaction kinetics, diffusion and the movement of the Na-ions, which leads to better capacity and rate performance.