High‐Performance Supercapacitor Afforded by a High‐Connected Keggin‐Based 3D Coordination Polymer

A new coordination polymer, [Ag 5 (brtmb) 4 ][VW 10 V 2 O 40 ] [ 1 , brtmb = 1‐bromo‐4‐(1,2,4‐triazol‐1‐ylmethyl)benzene], has been synthesized by a hydrothermal method. Its structure was determined by single‐crystal X‐ray diffraction analysis and further characterized by scanning electron microscopy, energy dispersive spectroscopy, bond valence sum (BVS) analysis, FTIR spectroscopy, and powder X‐ray diffraction. Each of the [VW 10 V 2 O 40 ] 5– clusters in polymer 1 acts as an octadentate connector, connecting with eight silver–brtmb subunits to generate a three‐dimensional structure. When employed as as the electrode material in supercapacitors, compound 1 showed remarkable electrochemical performances with a high capacitance of 13.3 mF cm –2 at 0.5 mA (206 F g –1 at 110 A g –1 ) and good cycling ability at various currents up to 2.0 mA (440 A g –1 ) with 81.7 % of the initial capacitance remaining after 1000 cycles. The above results reveal that polyoxometalate‐based hybrid coordination polymers may be a new‐generation alternative electrode material for high‐performance electrochemical capacitors.