SDF-based conjugated microporous polymers cathode materials with high cycle stability for lithium-ion batteries

Conjugated microporous polymers (CMPs) are promising electrode materials in lithium-ion batteries due to their advantages such as highly cross-linked structures, large specific surface areas, pi-conjugated frameworks, and high chemical and thermal stabilities. Herein, conjugated microporous polymers namely CMPs-B and CMPs-By based on spirodifluorenyl and phenyl with different linkages are synthesized, respectively. Compared with CMPs-By, CMPs-B with richer microporous structure shows a lower bandgap (2.75 eV) and larger specific surface area (45 m(2) g(-1)). When applied as cathode material for Lithium-ion batteries (LIBs), CMPs-B exhibited a high discharge potential (3.8 V vs Li/Li+), reversible redox activity and enhanced electrochemical performance, including stable cycling (36.6% capacity retention after 100 cycles at 50 mA g(-1)) and high rate capability. Furthermore, the kinetic behavior of Li+ storage in CMPs-B is also analyzed, of which the charge storage process of CMPs-B is controlled by capacitance and diffusion synergistically. At higher current densities, there is a gradual trend towards capacitive control, which is important to facilitate fast charge-discharge process and improve rate performance.