We present a study of the performance of silicone oil as an environmentally friendly and flame retardant insulating medium for electric power equipment. We have investigated the streaming electrification characteristics for flowing silicone oil for cooling of electric power equipment. As the initial step, the electric charge density accumulated in silicone oil and on the surface of the insulator is investigated simultaneously. We have used 5 types of insulating material for the experiment, including aramid paper. Silicone oil becomes negatively charged by streaming electrification, in contrast to conventional mineral oil, and the magnitude of the electric charge density on the insulating material is influenced by the kind of insulating material. As the second step, the streaming electrification characteristics of silicone oil were further examined using an insulator for which the work function is known. Based on these results, streaming electrification for various kinds of insulator and silicone oil is evaluated with respect to the work function. We consider the optimum combination of silicone oil and insulating material.

This paper describes the surface breakdown characteristics of the silicone oil which has the possibility of the application to innovative switchgear as an insulating medium. At the first step, we have experimentally studied on the impulse breakdown characteristics of the configuration with a triple-junction where a solid insulator is in contact with the electrode. The test configurations consist of solid material (Nomex and pressboard) and liquid insulation oil (silicone and mineral oil). We have discussed the experimental results based on the maximal electric field at a triple-junction. As the second step, we have studied the configuration which may improve the surface breakdown characteristics by lowering the electric field near the triple-junction.

Here, Ni, Co, and Li ions in the leachate obtained from commercial LiCoO2/LiNiO2 cathode materials by hydrothermal leaching with citric acid were precipitated and separated in order using a series of precipitants, dimethylglyoxime (DMG), (NH4)2C2O4, and Na3PO4, respectively. The parameters including the pH value, precipitant amount, and reaction temperature were optimized during the metal separation step. Finally, the recovery rates of Ni, Co, and Li were 97.2, 96.1, and 94.1%, respectively, with the purities of Ni, Co, and Li in the corresponding precipitate being 96.3, 96.2, and 99.9%, respectively. The method of hydrothermal leaching was compared with the method of traditional leaching in terms of the leaching mechanism and the metal separation performance of the obtained leachates. Compared with the traditional leaching with a reductant (e.g., H2O2), hydrothermal leaching is performed at higher temperatures and requires pressure-resistant reactors, but it can reduce the consumption of chemicals such as reductants, promote the reaction rate, and improve industrial applicability. Even though the leaching mechanisms were different, the leachates obtained by hydrothermal and traditional leaching showed comparable performance in the metal separation step, indicating hydrothermal leaching is qualified to produce leachates for lithium-ion battery (LIB) recycling. With the success of isolating metal components from the leachate obtained by hydrothermal leaching, an upgraded hydrometallurgical method, composed of hydrothermal leaching and precipitation separation steps, was officially launched for LIB recycling and is subject to further development.

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This paper describes the surface breakdown characteristics of silicone oil which has the possibility of application to innovative switchgears and transformers as an insulating medium. At the first step, we have experimentally studied the impulse breakdown characteristics of the configuration with a triple-junction where a solid insulator is in contact with the electrode. The test configuration consists of solid material (Nomex ® or pressboard) and liquid insulation oil (silicone or mineral oil). We have discussed the experimental results based on the maximal electric field at the triple-junction. As the second step, we have studied the configuration which may improve the surface breakdown characteristics by lowering the electric field on the insulator surface.Index Terms -Surface breakdown, Electric power apparatus, silicone oil, triple junction, discharge inception voltage.