Abstract
Magnesium batteries are superior to all the known battery systems owing to its substantially larger volumetric capacity, environmental benignity, electrochemical stability and lower cost. This study is focused on the improving the electrochemical characteristics of Magnesium based batteries.
In initial study, the nano engineering were applied in developing electrode material of optimum dimensional and surface properties for dominant Mg storage. TiO2 rutile nanowires having extreme small dimensions of 5-7/100 nm dimeter to length ratio and tremendous surface oxygen vacancies were
solvothermally prepared for enhanced Mg storage controlled by pseudo capacitive mechanism. While tested as Mg battery cathodes, It showed a specific reversible discharge capacity of 232 mAh/g at a current density of 50 mA/g and retained a capacity of 84 mAh/g at 1 A/g current density, which outperformed all the previous reports of TiO2 based Mg battery formulations. The system showed very long cycling stability, more than 2000 cycles without much capacity degradation. Post cycling studies evidenced the excellent structural stability of the nanowire against extended mg charge/discharge cycles. The pseudocapacitance
led charge storage mechanism owing to extreme small dimension and surface defects of the TiO2 nanowires results to mechanically stable electrode having excellent galvanostatic rate as well as cycling performance.
The second study is a comparative analysis of the variation in the Mg/Li hybrid battery performance with respect to different polymorphs of TiO2 nanosheet cathodes. Solvothermally synthesized nanosheets were bronze, anatase and bronze-anatase hybrids of varying ratios. The bronze – anatase hybrid with a relative ratio of 1:2 outperformed the other nano sheet variants in galvanostatic rate performance and over all specific discharge capacity irrespective of the current density. Bronze – anatase hybrid (1:2) showed 233 mAh/g specific capacity at the current density of 25mA/g, which was at least twice than the other polymorphs. It showed extremely superior cycling stability, more than 3000 cycles without significant capacity degradation, which is competent with the most of the reported TiO2 cathodes. Galvanostatic as well as post cycling ex situ analysis reviled the pseudo capacitive type charge storage mechanism of the hybrid nano sheet electrode, which exhibited an excellent structural stability against the extended electrochemical cycles.