Acid-free molten salt method recovers 94% of silver from solar cells

Researchers in China have developed an acid-free method to recover silver wires from end-of-life aluminum back-surface-field solar cells using a molten mixture of sodium hydroxide and potassium hydroxide (NaOH-KOH). The molten salt etches the cell's silicon nitride (SiNx) passivation layer and weakens the bond between the silver and the SiNx, allowing the silver wires to detach and be recovered directly as metal, rather than being dissolved into silver ions and recovered later. At 230 C for 150 seconds, the process recovered 94.34% of the silver and effectively removed the SiNx layer, the researchers ...

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