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

Abstract

AbstractSelf‐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 results 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 of 98% after 18 000 cycles at 10 A g−1 and ultra‐fast ion transfer. 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), are proposed for performance evaluation. COF‐PTO achieves 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 the co‐insertion of Zn2+ and H+ double ions in COF‐PTO of self‐charging zinc batteries. 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.