Versatile Zn hosting Lewis-basic interfacial layer for high-performant Zn reversibility in aqueous Zn ion battery

Owing to the urgent demand for high-energy and high-power Zn batteries, achieving excellent cycling performances of Zn electrodes under high current density and areal capacity conditions remains a critical challenge. Herein, we show that a surface layer of phosphorus (P)-doped g-C3N4 particles remarkably improves the reaction kinetics and cyclability of the Zn electrode. The Lewis basic P-doped g-C3N4 surface strongly interacts with Zn ions, reducing Zn2+–H2O interactions and consequently suppressing the hydrogen evolution reaction. Furthermore, P-doped g-C3N4 near the Zn surface serves as a Zn intercalation host, improving the diffusion kinetics of Zn adatom and the distribution of the Zn reaction site. The evident disparity of the electronic/chemical environment on the Zn electrode surface induces uniform Zn redox reaction at a low overpotential. The combination of these merits enables Zn||Cu half-cells to achieve a high average Coulombic efficiency of 99.9% at 3 mA cm−2/3 mAh cm−2 and Zn||Zn symmetric cells to achieve 550 h of cycles at 5 mA cm−2/5 mAh cm−2. A Zn|PANI full cell operates for 2300 cycles with an accumulative discharge capacity exceeding 95 times the theoretical capacity of the Zn metal electrode, highlighting the potential of P-doped C3N4 for use in Zn-ion batteries.