Innovative recycling of high purity silver from silicon solar cells by acid leaching and ultrasonication

Journal Article · 25 March 2024 · Solar Energy Materials and Solar Cells

DOI: https://doi.org/10.1016/j.solmat.2024.112834 · OSTI ID:2335689

Click, Natalie  ^[1]; Teknetzi, Ioanna  ^[2]; Tam, Eric Pui Lam  ^[3]; Tao, Meng  ^[4]; Ebin, Burҫak  ^[2]

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1. Arizona State University, Tempe, AZ (United States); Arizona State University
2. Chalmers University of Technology, Göteborg (Sweden)
3. Chalmers University of Technology, Gothenburg (Sweden)
4. Arizona State University, Tempe, AZ (United States)

Precious and scarce silver (Ag) is used as a front electrical contact in silicon solar panels. With massive amounts of solar panel waste coming to end-of-life, it is imperative to recover all the Ag from these modules. In this paper, we propose a novel method to easily reclaim Ag from end-of-life silicon solar cells using low concentration sulfuric acid (H₂SO₄) leaching followed by ultrasonication. Our process simplifies the Ag recycling procedure by directly recovering the Ag contacts from solar cells, eliminating the need for secondary precipitation/electrodeposition. First, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) was used to study the leaching and ultrasonication process on rejected solar wafers. Next, a solar panel from landfill was heated in a furnace to burn off the polymer encapsulant. The silicon wafers were then collected from the burning process and leached in 2 M H₂SO₄ at two different shaking speeds for 48 hours at room temperature. Finally, the end-of-life silicon wafer pieces were collected, sonicated in water, and then the sonication water was centrifuged to show a proof-of-concept to recover the Ag contacts. Inductively coupled plasma optical emission spectroscopy (ICPOES) is used to monitor dissolved elements in the leachate as a function of time and shaking speed. XPS is used to evaluate the composition of the silicon cell wafer surface before and after H₂SO₄ leaching. SEM is used to image the recovered Ag contacts morphology and EDX confirms the recovered particles contain high amounts of Ag. Furthermore, a proposed schematic illustrates the authors’ hypothesis for the peeling mechanism.

• Research Organization: REMADE Institute, Henrietta, NY(United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• Grant/Contract Number: EE0007897
• OSTI ID: 2335689
• Alternate ID(s): OSTI ID: 2331514
• Journal Information: Solar Energy Materials and Solar Cells, Journal Name: Solar Energy Materials and Solar Cells Vol. 270; ISSN 0927-0248
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English