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

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.