A stable Zn anode for mitigating dendritic growth, corrosion, and byproducts is vital for exhibiting high-performance electrochemical properties in aqueous Zn-ion batteries. An artificial solid/electrolyte interphase is an effective protective strategy for Zn anodes. Herein, a uniform layer of zinc hydroxide sulfate (ZHS) derived in situ from a ZIF-8 membrane was developed on a Zn anode. The ZHS layer inherited a well-ordered structure and porous channels from the ZIF-8 membrane and exhibited high ionic conductivity, low electronic conductivity, and strong interactions with Zn²⁺ ions, which facilitated the regulation of homogeneous Zn²⁺ flux and deposition for dendritic inhibition. The strong interactions between H₂O molecules and SO₄ ²⁻ ions in the ZHS layer could alter the solvation structure of hydrated Zn²⁺ ions to facilitate the desolvation process, thus mitigating H₂O-induced side reactions during Zn plating/stripping processes. The ZHS layer-coated Zn anode exhibited a remarkably long cycling lifespan of over 2800 h at a low current density of 1 mA cm⁻² (1 mA h cm⁻²) and over 1100 h at a high current density of 10 mA cm⁻² (5 mA h cm⁻²). This study provides a facile and feasible strategy to achieve the interfacial stability of Zn anodes for use in rechargeable aqueous Zn-ion batteries.

Metal–organic frameworks (MOFs) with intramolecular pores have been widely explored as promising active materials in supercapacitor electrodes. Nevertheless, low conductivity of general MOFs is the major bottleneck hindering their capacitance. In this study, a facile strategy has been designed to construct a three-dimensional hybrid architecture of flexible polypyrrole hollow foam with high loading of conductive Ni-CAT MOF nanowires (PPy HF/Ni-CAT-NWs) as a self-standing electrode free of any substrates, conductive agents and binders. The PPy foam with hollow skeletons provides high surface area and efficient conductive networks as well as inherent capacitance, acting as a flexible matrix in the electrode. The Ni-CAT-NWs are deposited onto both the exterior and interior surfaces of PPy foam skeletons to achieve high MOF loading, which could afford decent conductivity and high porosity for enhanced electron/ion accessibility. The PPy HF/Ni-CAT-NW electrode exhibits a satisfactory areal capacitance of over 1050 mF cm⁻² (at 0.5 mA cm⁻²). The assembled symmetric solid-state supercapacitor demonstrates superior electrochemical energy-storage properties as well as excellent mechanical flexibility and working temperature tolerance, and could be fabricated into a wearable wristband to drive an electronic watch, displaying strong potential for wearable electronics. This study provides some valuable insights into MOF-based composite electrodes for wearable energy-storage devices.

In this work, the effects of the microstructure and phase constitution of cast magnesium alloy ZK60 (Mg-5.8Zn-0.57Zr, element concentration in wt.%) on the corrosion behavior in aqueous NaCl (0.1 mol dm⁻³) were investigated by weight-loss measurements, hydrogen evolution tests, and electrochemical techniques. The alloy was found to be composed of α-Mg matrix, with large second-phase particles of MgZn₂ deposited along grain boundaries and a Zr-rich region in the central area of the grains. The large second-phase particles and the Zr-rich regions were more stable than the Mg matrix, resulting in a strong micro-galvanic effect. A filiform corrosion was found. It originated from the second-phase particles in the grain boundary regions in the early corrosion period. The filaments gradually occupied most areas of the alloy surface, and the general corrosion rate decreased significantly. Corrosion pits were developed under filaments. The pit growth rate decreased over time; however, it was about eight times larger than the general corrosion rate. A schematic model is presented to illustrate the corrosion mechanism.