Synergistic Design of Multifunctional Interfacial Zn Host toward Practical Zn Metal Batteries

Abstract

Aqueous Zn metal batteries (ZMBs) are receiving attention as large-scale energy storage systems owing to their high theoretical capacity, low toxicity, and the abundance of Zn. However, Zn anodes still undergo undesired dendrite growth and intrinsic side reactions, thereby hindering the practical application of ZMBs. In this study, a multifunctional porous zincophilic carbon host (FPCH) assisted by a thin ZnO interphase (ZI) on bare Zn (FPCH-ZI/Zn) is rationally designed as the interfacial host for stable Zn deposition/dissolution processes to reduce the limitations of Zn anodes. Hydrophobic FPCH with large specific surface areas and zincophilic oxygen-based functional groups induce a uniform distribution of electric field/Zn2+ flux and low nucleation overpotential and restrain side reactions. Additionally, hydrophilic ZI ensures sufficient quantities of the electrolyte are absorbed into FPCH-ZI/Zn; it complements the shortcomings (low hygroscopicity of the electrolyte) of hydrophobic FPCH, depositing Zn inside the host. Consequently, the symmetric FPCH-ZI/Zn cells exhibit excellent cycling performances with low-voltage polarization, even under harsh operating conditions. Furthermore, in the MnO2 parallel to Zn full-cell tests, the FPCH-ZI/Zn full cells exhibit superb long-term cyclability compared to that of bare Zn under real-world operating conditions (N/P ratio: approximate to 7.3), indicating the availability of FPCH-ZI/Zn for practical ZMBs.