Dihydrophenazine-Based Conjugated Microporous Polymer Cathodes with Enhanced Electronic and Ionic Conductivities for High-Performance Aluminum Dual-Ion Batteries

It is fundamentally challenging for cathode materials to achieve long life, high capacity, and fast kinetics in rechargeable aluminum batteries, due to the strong electrostatic interaction between Al3+ and the host materials. Herein, the redox-active dihydrophenazine (Pz) is coupled with pyrene (Py) or biphenyl (Ph) to develop two conjugated microporous polymers of PyPz and PhPz as AlCl4--hosting cathodes for aluminum dual-ion batteries (ADIBs). It is revealed that the planar Py unit endows PyPz with an extended conjugated skeleton and a higher surface area than PhPz produced from the Ph unit with a twisted structure, thus leading to a higher redox activity for PyPz. Hence, the PyPz cathode delivers a much higher capacity of 231 mAh g(-1) than PhPz (137 mAh g(-1)). Its porous structure and insolubility also ensure PyPz shows a superior rate performance and exceptional cyclability over 100 000 cycles. Meanwhile, the feature of fast kinetics for AlCl4- storage also allows PyPz to operate well at not only a low temperature (-30 degrees C) but also a high areal capacity of 2.53 mAh cm(-2). These findings suggest that redox-active conjugated polymers are promising advanced organic cathodes for sustainable ADIBs, where the electrochemical performance can be significantly enhanced by rational structural design.