This paper presents supercapacitors utilizing new redox-active electrolytes with bromine species. Two sources of Br specimen were investigated, i.e. dibromodihydroxybenzene dissolved in KOH and potassium bromide dissolved in KOH with hydroxybenzene additive. KOH-activated carbon, exhibiting a well-developed porosity, was incorporated as an electrode material. The tested systems revealed a capacitance enhancement explained by Br− and partial BrO3− redox activity. The optimisation of the electrolyte concentration resulted in a capacitance value of 314 F g−1 achieved at 1.1 V voltage range. Good cyclability performance (11% capacitance loss) combined with a high capacitance value (244 F g−1) were obtained for the system operating in 0.2 mol L− 1 C6H4Br2O2 in 2 mol L− 1 KOH electrolytic solution

This comprehensive review highlights the hydroelementation reactions of conjugated and separated diynes to various products including enynes, dienes, allenes, polymers or cyclic compounds, and their further transformation to valuable compounds.