The world is undertaking a large scale energy transition away from fossil fuels to renewable system, to combat the effects of climate change. Solar Photovoltaics (PV) has seen rapid deployment since the early 2000s, and cumulative installed capacity is expected to reach 4,500 GW worldwide by 2050. This has lead to vast quantities of End-of-Life (EOL) solar modules entering the waste stream. The key components of solar modules (e.g. silver, silicon, copper and aluminum) are energy intensive to produce and contribute significantly to the lifecycle emissions of the technology. Therefore, effective recycling can not only increase the sustainability of the technology by ensuring that critical materials are diverted from landfill and remain in circulation, but also has the potential to reduce the overall environmental footprint to the technology.
Silver is used as a key current collecting material in the solar cells. While silver only contributes approximately 0.03 % to the weight of a solar module, it account for approximately half the material value. As a result, it is an essential material that could greatly impact the economics of recycling. Once a module has been deframed and delaminated, the solar cells are liberated which allows for silver recovery. Silver extraction is generally performed via nitric acid leaching and then recovered via hydrometallurgical or electrochemical methods. Hydrometallurgical methods have been primarily investigated due to the metal content and solubility parameters. However, these techniques have a large chemical requirement, generate large volumes of wastewater and produce metal salts. Alternatively, electrochemical methods can directly extract pure metals based on different reduction potentials driven by renewable energy.
Despite the advantages of electrochemical methods over hydrometallurgy, there are still significant knowledge gaps. This work aims to investigate the electrochemistry and process optimization of silver nitrate electrolysis. This was performed by varying nitric acid concentration, working electrode material, current density and effect of copper concentration. As a result, the recovery, faradaic efficiency, electrochemical response and deposit were measured and analysed.