Preparation and electrochemical properties of benzothiadiazole-benzotriazole donor-acceptor conductive polymer lithium-ion anode materials

Abstract

The specific capacity of conventional conducting polymer composite electrodes is small. Based on the characteristics of donor-acceptor (D-A) conducting polymers with a wide range of π-electron leaving domains, narrow band gap, high conductivity and excellent electrochemical properties, D-A polymer monomers OTTBT (4, 8-Bis(3,4-ethylenedioxythiophene-2-yl)-6-(2-ethylhexyl)-[1,2,5]thiadiazolo[3,4-f] benzotriazole) and TTBT (4, 8-Bis(thiophen-2-yl)-6-(2-ethylhexyl)-[1,2,5]thiadiazolo[3,4-f] benzotriazole) were synthesized by Stille cross-coupling reaction using benzothiadiazole-benzotriazole as the acceptor unit and EDOT (3,4-ethylenedioxythiophene) or thiophene as the donor unit. Each monomer was polymerized in situ on the surface of activated carbon (AC) to obtain POTTBT@AC and PTTBT@AC composite electrode materials, respectively. The results showed that the charge storage behavior of both composites was controlled by the pseudocapacitance process. POTTBT@AC had better specific capacity, rate performance and cycling stability than PTTBT@AC. The lithium-ion storage performance of POTTBT was significantly higher than that of PTTBT, probably due to the former's higher electron supply capacity, rigidity and co-planarity. Both electrode materials had good specific capacity and rate performance and were suitable as anode materials for lithium batteries. D-A conductive polymer provides a new idea for the synthesis of electrode materials for high-capacity lithium batteries.