Recovery of valuable and toxic metals from crystalline-Si modules
Valuable and toxic metals including Ag, Pb, Sn and Cu can be recovered from end-of-life Si solar modules. This study presents the recovery of Ag, Pb, Sn and Cu from a simulated leach solution of crystalline-Si modules. 11.4% HNO3 is used as the leach solution. Ag, Pb, Sn and Cu pellets are dissolved in the solution to simulate the metals from front contacts and soldered wires in Si modules. Sn precipitates in the solution as SnO2, which can be separated by filtration or sedimentation. Voltammetry reveals the reduction potentials for Ag and Cu. It is demonstrated that 3-electrode sequential electrowinning can extract Ag and Cu one by one from the solution. The recovery rates of Ag and Cu are 74% and 83%, respectively. Toxic Pb is deposited on the anode as PbO2 during Cu recovery. The purity of the extracted metals is above 99%.
Electroplated Al as the front electrode in crystalline-Si solar cells
This paper reports aluminum (Al) electroplating as the metallization technique for the front finger electrode on n-type silicon (Si) in crystalline-Si solar cells. The development of the Al electroplating process is motivated by the limited reserves of silver (Ag) on this planet and the industry-wide push to reduce Ag usage for cost control. The new metallization process consists of: (1) patterning the silicon nitride (SiNx) layer for front electrode; (2) depositing a nickel (Ni) seed layer into the opening; (3) electroplating self-aligned Al onto the Ni seed layer and (4) annealing the Al/Ni electrode in air at ~200°C. This temperature is far below the typical firing temperatures for commercial Al pastes. The new metallization process has been integrated into commercial p-type monocrystalline Si solar cells from Hareon Solar. An all-Al Si solar cell, with an electroplated Al front electrode and a screen-printed Al back electrode, has been demonstrated. The cell has a size of 2.54×2.54 cm2, with efficiencies approaching 15% demonstrated.
Barbarians, Gentlemen and Players : A Sociological Study of the Development of Rugby Football
Part I: Folk Antecedents and Transitional Forms of Football in the Public Schools 1. The folk antecedents of modern rugby and their decline 2. Football in the early 19th century public schools Part II: The Modernisation of Rugby Football 3. The preconditions for modernization: embourgeoisement and public school reform 4. The incipient modernization of rugby football 5. The 'civilising process' and the formation of the RFU. 6. The democratization of rugby football. 7. Professionalisation and the amateur response. 8. The split. 9. The class structure and the professionalisation of British sport. Part III: The Development of Rugby Football as a Modern Sport 10. The professionalisation of rugby league. 11. Rugby union as a modern sport: bureaucracy, gate-taking clubs and the swansong of amateurism. Conclusion: Sociological Reflections on the Crisis in Modern Sport