The synthesis of the conjugated polymers based on phenanthroline-5,6-dione and thiophene derivatives, their composites with carbon and the lithium storage performances as anode materials

Abstract

• Linear polymer@AC composites are prepared, used as anode materials in lithium ion batteries. • Thiophene derivatives and 1,10-phenanthroline-5,6-dione are used as the alternating monomers. • The polymers have a donor–acceptor structure, low redox potentials, be suitable as anode materials. • PBTPD@AC composite has a capacity of 410 mAh g −1 at a current density of 100 mA g −1 . • PBTPD has the most extended conjugation length, give rise to the highest capacity for the PBTPD@AC composite. Three linear conjugated polymers, including poly[(thiophene-2,5-yl)-((1,10-phenanthroline-5,6-dione)-2,7-yl)] (PTPD), poly[((2,3-dihydrothieno[3,4-b][1,4]dioxine)-5,7-yl)-((1,10-phenanthroline-5,6-dione)-2,7-yl)] (POTPD) and poly[(thieno[3,2‐ b ]thiophene-2,5-yl)-((1,10-phenanthroline-5,6-dione)-2,7-yl)] (PBTPD) have been synthesized. Three composites (PTPD@AC, POTPD@AC and PBTPD@AC) are made by introducing active carbon (AC) in the polymerization reaction. The composites are adopted as anode materials, and evaluated their electrochemical parameters in lithium-ion batteries (LIBs). After 300 cycles of running, the specific discharge capacities (at 100 mA g −1 ) of PTPD@AC, POTPD@AC and PBTPD@AC are 318.7 mAh g −1 , 319.5 mAh g −1 and 410 mAh g −1 , respectively. Subtracting the capacity of AC to that of the composites, the actual capacities of pure polymers are 726.3, 729 and 1030.7 mAh g −1 for PTPD, POTPD and PBTPD at 100 mA g −1 , respectively. The structure–activity relationships of the composites are discussed in detail in terms of the electron donating properties of the donor units. This work may pave a way to the exploration of high-capacity electrode materials based on conjugated polymers for LIBs.