context: Therefore, the above results demonstrate the superior energy/power densities and high efficiency of the DBHF sample, which, based on the above discussions, are associated with the “fiber-in-tube” hierarchical structure, hollow and defective oxide bubbles and conductive and porous carbon network of the DBHF fibers. The combined effects of the features are favourable for the generation of more active sites, superior catalytic activities and enhanced kinetics of the DBHF cathode in the hybrid batteries.
answer: DBHF 