Influence of Zinc Addition and Solution Heat Treatment on the Electrochemical Behavior of Magnesium Anodes for Biodegradable Battery Applications

Biodegradable magnesium-based batteries are promising power sources for transient and implantable electronic devices, yet their broader application is limited by the inherently high corrosion rate of Mg anodes. Although casting is a cost-effective and scalable method for producing Mg alloys, its use in biodegradable battery electrodes has received little attention. In this work, pure Mg and Mg–1 wt.% Zn anodes were fabricated by conventional casting, and the effects of Zn alloying and solution heat treatment on microstructure, corrosion behavior, and electrochemical performance were systematically examined. Unlike many previous studies that rely on complex fabrication routes or protective coatings, this work demonstrates that a simple casting–solution treatment approach can effectively improve Mg anode stability through microstructural homogenization. Microstructural observations showed that adding 1 wt.% Zn refined the as-cast dendritic structure and introduced intermetallic particles, while solution treatment at 400 °C dissolved these particles and promotes a more homogeneous matrix. Electrochemical tests in phosphate-buffered saline (PBS) revealed that Zn alloying and heat treatment significantly improved corrosion resistance, with the solution-treated Mg–Zn alloy exhibiting a markedly lower apparent corrosion current density than as-cast pure Mg. At a current density of 0.2 mA cm -2 , the combined treatment extended battery lifetime more than eightfold and delivered the highest areal capacity (5.16 mAh cm -2 ) and energy output (2.23 mWh) with stable discharge behavior. These results show that minor Zn alloying combined with conventional heat treatment offers a simple and scalable strategy for improving Mg anodes for biodegradable batteries.