Self‐Charging Aqueous Zn//COF Battery with Ultra‐High Self‐Charging Efficiency and Rate

Abstract Self‐charging zinc batteries that combine energy harvesting technology with batteries are candidates for reliable self‐charging power systems. However, the lack of rational materials design resulted in unsatisfactory self‐charging performance. Here, a covalent organic framework containing pyrene‐4,5,9,10‐tetraone groups (COF‐PTO) is reported as a cathode material for aqueous self‐charging zinc batteries. The ordered channel structure of the COF‐PTO provides excellent capacity retention performance and ultra‐fast ion transfer, with a capacity retention of up to 98% after 18000 cycles at 10 A g −1 . To visually assess the self‐charging performance, two parameters, namely self‐charging efficiency (self‐charging discharge capacity/galvanostatic discharge capacity, η) and average self‐charging rate (total discharge capacity after cyclic self‐charging/total cyclic self‐charging time, ν), were proposed for performance evaluation. COF‐PTO achieved an impressive η of 96.9% and an ν of 30 mAh g −1 self‐charge capacity per hour in 100 self‐charging cycles, surpassing the previous reports. Mechanism studies reveal that COF‐PTO contains abundant C = O functional groups, enabling the co‐insertion of Zn 2+ and H + double ions in aqueous zinc ion batteries to achieve self‐charging performance. In addition, the C = N and C = O (on the benzene) in COF‐PTO are ortho structures to each other, which can easily form metal heterocycles with Zn ions, thereby driving the forward progress of the self‐charging reaction and enhancing the self‐charging performance. This work broadens the application scope of COF materials in aqueous zinc batteries and paves the way for designing high‐efficiency self‐charging batteries. This article is protected by copyright. All rights reserved