Thiophene-rich conjugated microporous polymers as anode materials for high performance lithium- and sodium-ion batteries

Abstract

4,8-Di(thiophen-2-yl)benzo[1,2-b:4,5-b’]dithiophene was employed to construct thiophene-rich conjugated microporous polymer anode materials for reversible Li+/Na+ storage. The assembled batteries from the as-synthesized polymers display remarkable electrochemical performances, including high reversible Li+/Na+ storage capacity, superior rate behavior, and stable circulation due to the stable structure, high redox activity of thiophene module, low LUMO energy level as well as narrow band gap, and a fully conjugated skeleton that favors charge transport. In particular, the assembled LIBs from DBD-CMP2 with the higher cross-linked degree and thiophene content present an outstanding reversible Li+ ion storage capacity of 1167 mAh g−1 at 50 mA g−1 and an excellent cycle stability with a specific capacity remain of 595 mAh g−1 at 100 mA g−1 after 300 charge-discharge cycles. The assembled SIBs also show a reversible Na+ ion storage capacity of 414 mAh g−1 at 50 mA g−1 as well as an outstanding stability with a stable capacity of 241 mAh g−1 at 100 mA g−1 after 100 cycles. These achievements reveal that it is a rational design to enhance the electrochemical capability by increasing the cross-linked degree and/or the content of the active thiophene unit of conjugated microporous polymer electrodes.