Application of a densely hydrophobic copper metal layer in-situ prepared with organic solvents for protecting zinc anodes

Herein, a dense and hydrophobic Cu metal protective layer was constructed in-situ on the Zn electrode (Cu@ Zn) through a displacement reaction in an organic solvent. Specifically, CuI powder was dissolved in N-methyl-2-pyrrolidone (NMP) and stirred for 12 h to obtain a uniform solution. Subsequently, the bare Zn was immersed in the solution at 80 degrees C for 6 h, and then washed with absolute ethanol three times to achieve the Cu@Zn electrode. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses confirm a dense Cu protective layer on the surface of the Cu@ Zn electrode. Additionally, the better hydrophobicity of the Cu@Zn electrode was demonstrated through contact angle measurements with a 2 mol center dot L-1 ZnSO4 electrolyte. The dense and hydrophobic Cu metal protective layer can effectively isolate the direct contact between the Zn electrode and electrolyte, suppressing side reactions such as hydrogen evolution and corrosion at the electrode/electrolyte interface. Furthermore, the Cu layer possesses zincophilicity, reduced interfacial resistance, and a lower nucleation energy barrier, thereby promoting uniform Zn deposition and effectively inhibiting dendritic growth. As a result, Cu@ Zn symmetric cells exhibited continuous stable performance for 1 700 and 1 330 h at 1 mA center dot cm(-2), 1 mAh center dot cm(-2) and 3 mA center dot cm(-2), 1 mAh center dot cm(-2), respectively, which were higher than those of bare Zn symmetric cells (204 and 120 h). Furthermore, the Cu@Zn||MnO2 full cell delivered a specific capacity of 168.5 mAh center dot g(-1) at 1 A center dot g(-1) respectively, maintaining stability for over 2 000 cycles.