Progress has been made in the preparation of silicon nanowire electrodes by "one-step method" of photovoltaic silicon waste

Silicon wafers are the basic material of crystalline silicon solar cells, but silicon waste is generated during their manufacturing process, resulting in waste of resources and environmental pollution. The preparation of lithium-ion battery anode materials using photovoltaic silicon waste is an important direction to achieve green, collaborative and sustainable development of photovoltaic and lithium battery industries. Recently, Lu Jijun, a doctoral student in the Green Metallurgy and Product Engineering Research Group of the Institute of Process Engineering of the Chinese Academy of Sciences, under the guidance of researcher Wang Zhi and associate researcher Liu Junhao, using the controllable electrothermal shock method, innovatively realized the catalyst-free preparation from photovoltaic silicon waste to high-silicon content nanowire electrodes, and the energy density of lithium-ion batteries was significantly improved, providing a new idea for the efficient and low-cost preparation of silicon nanowire materials for lithium-ion batteries. The results of the study were published in Advance Energy Materials under the title of Millisecond Conversion of Photovoltaic Silicon Waste to Binder-Free High Silicon Content Nanowires Electrodes.

In recent years, under the guidance of carbon neutrality targets, the photovoltaic solar energy industry has developed rapidly. However, silicon waste is generated during the wafer manufacturing process and can only be downgraded at this time. To this end, the team of researcher Wang Zhi of the Institute of Process Engineering proposed a green and efficient value-added recycling strategy for the problems of fine particle size (~1 μm), oxide film wrapping and trace impurity entrainment causing its high value utilization, giving full play to the limitation of the silicon waste oxide film and the induction of defects, and providing a large gradient thermal field (~105K/s) to drive the directional diffusion of silicon atoms in a restricted space through flash heating and quenching to achieve the rapid growth of silicon nanowires, with a first effect of 89.5% of the electrode. The capacity of more than 500 cycles is still greater than 2300 mAh g-1, reaching the international advanced level.

Wang Zhi's team has made a series of progress in the field of high-value recycling of photovoltaic silicon waste, developed a number of characteristic technologies and equipment, established a demonstration project of short-range high-value recycling of 10,000 tons of silicon-based solid waste, and the research results have been published in ACS Sustainable Chem. Eng.DOI: 10.1021/acssuschemeng.1c03381；ACS Sustainable Chem. Eng., 2021, September, 2962-2974 (cover article); Energy Mater. Sol. Cells, 2021, 230, 111213；J. Hazard. Mater., 2021, 403, 123598；J. Alloys Compd., 2021, 874, 159914；J. Alloys Compd., 2020, 820, 153300；J. Mater. Chem. A, 2019, 7, 11347-11354；Chem. Eng. J., 2019, 370, 565-572。

The research work is supported by the National Key R&D Program, the National Natural Science Foundation of China and the Beijing Municipal Natural Science Foundation.

Electrothermal shock synthetic silicon nanowire products and their electrochemical properties

Source: Institute of Process Engineering, Chinese Academy of Sciences