Framework structured Na4Mn4Ti5O18 as an electrode for Na-ion storage hybrid devices

In this study, framework structured Na4Mn4Ti5O18 possessing S-shaped tunnels for sodium intercalation is reported as an electrode for hybrid sodium ion batteries. Galvanostatic cycling of Na4Mn4Ti5O18vs. Na in the voltage region from 1.5 V to 3.95 V exhibits a capacity of 102 mA h g(-1) at 0.1C rate corresponding to a specific capacitance of 149 F g(-1) with a capacity retention of 90% over 50 cycles. The electrochemical analysis using CV measurements revealed the charge storage involving intercalation and pseudocapacitance. For instance, total charge storage of 345 C g(-1) is observed at 0.01 mV s(-1), which is attributed to 63% intercalation and 37% capacitance. Na4Mn4Ti5O18 was also studied for sodium ion storage in an aqueous medium. It delivered a capacity of 36 mA h g(-1) (144 F g(-1)) in the voltage window of 0-0.8 V.