A mesoporous conjugated polymer based on a high free radical density polytriphenylamine derivative: its preparation and electrochemical performance as a cathode material for Li-ion batteries

Abstract

A novel mesoporous conjugated polymer-poly(4,4′,4′′-tris(N,N-diphenyl-amino)triphenylamine) (PTDATA), which was one of the polytriphenylamine derivatives with high free radical density, has firstly been prepared by chemical oxidative polymerization. Compared to polytriphenylamine (PTPA) with aggregated morphology and relatively low surface area (5.6 m² g⁻¹), PTDATA exhibited a nanofiber-packed mesoporous structure with an obviously improved surface area of 560.58 m² g⁻¹. When explored as the cathode material for organic free radical batteries, PTDATA showed a well-defined multistage discharge voltage plateau and an improved capacity of 133.1 mA h g⁻¹, which was equal to 92.8% of its theoretical capacity (143.5 mA h g⁻¹). Also, PTDATA exhibited an enhanced rate performance of 125.4, 114.1, 97.5 and 90.9 mA h g⁻¹ with a 10 times increase of the current density from 50 to 500 mA h g⁻¹, respectively. The excellent electrochemical performances of the PTDATA electrode were due to its special chemical structure of high free radical density and its high specific surface caused by the nanofiber-packed mesoporous morphology, which made PTDATA a good potential candidate as the organic cathode material for high-performance organic lithium secondary batteries.