A Photoresponsive Battery Based on a Redox‐Coupled Covalent‐Organic‐Framework Hybrid Photoelectrochemical Cathode

Abstract Photoresponsive batteries promise flexible and low‐cost solar‐to‐electrochemical energy storage (SES), but suffer from a limited SES efficiency due to rapid charge recombination and sluggish redox. Here, we present a porous‐shell/core hybrid of covalent organic framework@carbon nanotube. This hybrid ensures long‐lived separated charges (τ ave =3.0 ns) by an electron transfer relay starting from the donor‐acceptor molecules to the nanoscale heterojunction. These charges are further allowed to drive high‐rate redox of −C=O/−C−O − and −C−N/−C=N + with facile kinetics. Equipped with this photoelectrochemical cathode, a photoresponsive aqueous battery shows a 5‐fold enhancement in SES efficiency (1.1 % at 1 sun) over their counterparts. It is unveiled that the electron relay favors the formation of electron‐enriching −C−O− and hole‐enriching −C=N + groups responsible for photoelectrochemical Zn 2+ and OTf − storage cascade; and further, the general photo coupled ions transfer (PCIT) process is proposed. This work presents an inspiring photoelectrochemical cathode design and theoretical insight for photoresponsive batteries.