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

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 AlCl₂ ⁺ 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.