Durable and Self‐Charging Aluminum‐Organic Battery Based on Conjugated Ladder Polymer

ABSTRACT Organic materials are highly promising to construct Aluminum (Al)‐organic batteries (AOBs) due to their low‐cost, sustainability, and structural flexibility. However, key challenges like high solubility and over‐reliance on conductive additives largely constrain their implementation. Herein, we propose a conjugated ladder polymer, poly(benzimidazo‐benzophenanthroline) (BBL), as a stable cathode for durable AOBs. The rigid skeleton from a double‐stranded fused‐ring structure and extensive π–π intermolecular interactions endow BBL with insolubility and fast charge transfer kinetics. With moderate addition of carbon nanotubes (20%) in the electrode, the freestanding BBL cathode exhibits impressive cycling stability and rate performance under a wide range of temperatures (−20°C–100°C). Specifically, the BBL electrode delivers a reversible capacity of 117 mAh/g and stable cycling over 10000 cycles, as well as an excellent anti‐self‐discharge behavior. A series of characterizations confirmed AlCl 2 + as the charge carrier and C═O groups of BBL as the redox active sites. Interestingly, without any form of energy input, a room‐temperature self‐charging function is also noticed with at most 82% capacity self‐charged. Our work highlights the significance of advanced structure design for Al‐organic batteries.