Understanding the mechanism of a conjugated ladder polymer as a stable anode for acidic polymer-air batteries

Aqueous polymer-air batteries have several advantages, such as improved safety, lower cost, higher ionic conductivity, and sustainability. However, their electrochemical performance is still limited by the polymer anode’s structural stability, kinetics, and electrical conductivity. Here, we propose a conjugated ladder polymer, poly(benzimidazobenzophenanthroline) (BBL), as a stable anode for acidic polymer-air batteries. The rigid ladder structure, fast kinetics, and high electrical conductivity enable its functional performance. The quantified real-time charge transfer mechanism indicates a fast hydronium ion charge compensation process. Also, self-standing BBL anodes were prepared with carbon nanotubes and coupled with Pt/C cathodes to assemble full BBL-air batteries, exhibiting notable rate capabilities (201 mAh·g−1 at 30 A·g−1) and cycling stability (capacity retention of 98.8% compared with the initial value). This work highlights the potential application of conjugated ladder polymers as anode materials for polymer-air batteries.