  The study shows the importance of moving towards hollow nanostructures for
obtaining next-generation supercapacitors and batteries. Amongst various
sodium-based electrode materials, NaFePO4 is one of the most promising cathodic
material because of its high electrochemical potential, structural, and thermal
stability. To use this material in high performance Na-ion based energy storage
device, it is imperative to combine it with a suitably optimized carbon
structures and a redox additive modified electrolyte. This strategy is
unequivocally established in the paper. On addition of redox additive, the
performance can be improved by 50%. This makes the Na-ion supercapacitor
competitive with other metal ion based systems. the performance by as high as
50%. This makes the Na-ion supercapacitors competitive with other metal ion
based systems.
