Detection of Metal Impurity Particles in Lead‐Acid Battery Electrolyte Based on Lens‐Free Digital Holography Technology

Abstract Lead‐acid batteries, widely used in energy storage and power systems, are susceptible to performance degradation due to metal impurities such as iron, copper, and tin. Traditional methods like ICP‐OES are accurate but costly and complex. Therefore, this study proposes a new method based on lens‐free digital holography (LDH) to detect and distinguish metal impurities in lead‐acid battery electrolytes. The study uses a compact setup with a green LED light source and a CMOS camera to capture holographic images of impurities. The technique reconstructs clear particle images using angular spectrum algorithms and analyzes their reconstruction distances and gray‐scale differences for identification. Results show that copper particles have a reconstruction distance of 1406.4 µm and a total gray‐scale difference of 4.4681; tin particles have a reconstruction distance of 1414.85 µm and a total gray‐scale difference of 0.5344; iron hydroxide has a reconstruction distance of 1647.85 µm and the total gray‐scale difference of 13.5789. By combining these parameters, the method effectively distinguishes between copper, tin, and iron particles, even in mixed solutions. This cost‐effective and efficient method offers a promising alternative for rapid and accurate detection of metal impurities in lead‐acid battery electrolytes, with potential applications in battery maintenance and quality control.