Green proton reservoirs of PANI for disposable high-performance zinc-ion batteries

Rechargeable batteries are widely used to power various electronic devices. However, their toxic components cause serious environmental pollution when discarded. To date, the toxicity characteristics of rechargeable batteries do not meet the requirements for implantable medical devices. Herein, we report an organic cathode using tannin-protonated polyaniline (Tannin-PANI). As "green proton reservoirs", plant-derived tannins continuously supply H+ to maintain high electrochemical activity and excellent reversibility of Tannin-PANI. Hence, the Tannin-PANI-based cathode exhibited a capacity of 92.8 mAh g-1 after 1500 cycles at 10.0 A g-1. Moreover, it demonstrated long-term stability for more than 10,000 cycles in bacterial cellulose-based gel electrolyte. Further, the Tannin-PANI-based cathode showed excellent in vitro biocompatibility, and a pouch cell composed of the Tannin-PANI electrode had no significant impact on plant growth. This study provides further insights into the design of implantable batteries with high stability, excellent biocompatibility, and high environmental compatibility.