Rational Integration of Carbon Nanotubes into Chain-Engineered Bipolar Polyimides as Core-Shell Heterostructured Electrodes for Polymer-Based Symmetrical Full Batteries

Organic redox-active polymers are promising electrode alternatives to Li-ion batteries using transition-metal resources. Such metal-free electrode materials suffer realistically from low electronic conductivities and insufficient utilization of active sites. Herein, thermally imidized polyimides are synthesized by polycondensation between 2,6-diaminoanthraquinone (DAAQ) and anhydrides. A quinone-containing polyimide (PMAQ) derived from pyromellitic dianhydride and DAAQ is found to exhibit the highest capacity and rate performance. Furthermore, carbon nanotubes (CNTs) are encapsulated in densely interlaced PMAQ nanoflakes by in situ polymerization to form core-shell heterostructured composites (CNT@PMAQ). Remarkably, the CNT@PMAQ cathode delivers reversible capacities of 163 mAh g(-1) at 0.05 A g(-1) and 122 mAh g(-1) at 5 A g(-1), respectively. CNT@PMAQ is also employed as an anode with a high capacity of 1158 mAh g(-1) at 0.05 A g(-1). Accordingly, a symmetric full-battery using CNT@PMAQ as bipolar electrodes is assembled that delivers a high energy density of 103 Wh kg(-1) at a power density of 1801 W kg(-1). This study crafts an unusual strategy to engineering macromolecular chains and building core-shell heteroarchitectures to unlock the barrier of low utilization ratio of active sites toward high-rate charge storage. Coupling bipolar electrode materials into symmetric full batteries will further stimulate the development of low-cost sustainable batteries.