A process of purification of coal-based coke powder as anode the treatment of coke powder with dilute hydrofluoric acid solution, for Li-ion batteries was attempted. The process started with followed by united-acid-le...A process of purification of coal-based coke powder as anode the treatment of coke powder with dilute hydrofluoric acid solution, for Li-ion batteries was attempted. The process started with followed by united-acid-leaching using sulfuric acid and hydrochloric acid. The effects of altering the hydrofluoric acid addition, hydrofluoric acid concentration, contact time, temperature and acid type were investigated. A minimum ash content of 0.35% was obtained when proper conditions were applied. The electrochemical performance of purified coke powder shows greatly improved electrochemical performance. The as-purified coke powder presented an initial reversible capacity of 257.4 mAh/g and a retention rate of 95% after 50 cycles. The proposed purification process paves a way to prepare a promising anode material with good performance with low cost of coke powder for Li-ion batteries.展开更多
Numerical simulation of the electrical field distribution helps in-depth understanding of the mechanisms behind the responses and the benefits of the high voltage pulse comminution. The COMSOL Multiphysics package was...Numerical simulation of the electrical field distribution helps in-depth understanding of the mechanisms behind the responses and the benefits of the high voltage pulse comminution. The COMSOL Multiphysics package was used to numerically simulate the effect of ore compositions in this study. Regarding phosphate ore particles shape and composition, the effects of mineral composition, particle size, particle shape and electrodes distance were investigated on the electrical field intensity and distribution. The results show that the induced electrical field is significantly dependent on the electrical properties of minerals,the feed particle size and the location of conductive minerals in ores. The angle of material contact surface with the discharge electrode is also an important factor in the intensity of electrical field. Moreover,it is found that the specific liberation effect at the disintegration of phosphate ore by electrical pulses is due to the locality of the electrical field at the interface of mineral components of the phosphate ore aggregates with different permittivities. However, the intensity of the electrical field increases with sharpening the contact angle. Besides, the electrical discharge in the samples is converted to the electrohydraulic discharge across the surrounding water by changing the distance between the discharge electrode and sample surface.展开更多
The main aim of this paper is to investigate the properties of Cu-TaC electrodes produced by Powder Metallurgy （PM） method. The design of Experiment （DOE） method was used to plan the investigation. Two different c...The main aim of this paper is to investigate the properties of Cu-TaC electrodes produced by Powder Metallurgy （PM） method. The design of Experiment （DOE） method was used to plan the investigation. Two different compositions of the powders （Cu-TaC with 30 and 55 % wt TaC） were used. The major properties which determine suitability of electrodes for Electro Discharge Machining （EDM） are electrical conductivity, therrnal conductivity and to some extent density. These properties were measured for the green compacted electrodes, analyzed and compared with their sintered counterparts. This is the initial stage to determine the suitability or otherwise of the compacted electrodes. The results showed that the compacted electrodes in green form can be suitable for EDM, since the electrical conductivities are very high （94.96-189.92Ω^-1m^-1）. The thermal conductivity is good （29.70-33.20W/m K）. The density ranges between 6.13 and 9.80 g/cm3. The sintered electrodes were found to be unsuitable at the specified conditions, because they became non-conductive electrically after sintering. Current efforts are geared towards improving these properties for the sintered ones and also determining their optimum levels.展开更多
Study of electrochemical behavior of chromium （molybdenum, tungsten） and silicon containing melts allowed defining conditions for synthesis of silicides of chromium, molybdenum and tungsten in the form of fine powde...Study of electrochemical behavior of chromium （molybdenum, tungsten） and silicon containing melts allowed defining conditions for synthesis of silicides of chromium, molybdenum and tungsten in the form of fine powders by electrolysis of halide-oxide melts. Sequence of stages of electrosynthesis of silicides of molybdenum and tungsten was found as follows： deposition of more electroposifve metal （molybdenum or tungsten）, deposition of the second component （silicon） on the surface of metal deposited previously, and reaction diffusion of silicon into the deep of the metal-salt ＂pear＂ with the formation of silicide phases of different compositions up to the higher silicides. In contrast, during the electrodeposition of chromium silicides, one of the components （chromium） is deposited not in elemental form, but in oxide form, and the other （silicon） acts as a reducing agent for this oxide to form binary compounds. Duration of the synthesis first stage （deposition of refractory metal or of its oxide） depends on the refractory metal compound content in the system and on the cathode current density. Synthesis of silicides is possible due to retention of powders of molybdenum （tungsten） or chromium oxide at the cathode without scaling. Optimal values of concentrations ratio, current density, temperature, and duration of electrosynthesis were found. Phase composition of products were obtained, as well as their chemical and thermal stability, were studied.展开更多
基金Projects(51274240,51204209) supported by the National Natural Science Foundation of ChinaProject(2012M521545) supported by the National Postdoctoral Science Foundation of China
文摘A process of purification of coal-based coke powder as anode the treatment of coke powder with dilute hydrofluoric acid solution, for Li-ion batteries was attempted. The process started with followed by united-acid-leaching using sulfuric acid and hydrochloric acid. The effects of altering the hydrofluoric acid addition, hydrofluoric acid concentration, contact time, temperature and acid type were investigated. A minimum ash content of 0.35% was obtained when proper conditions were applied. The electrochemical performance of purified coke powder shows greatly improved electrochemical performance. The as-purified coke powder presented an initial reversible capacity of 257.4 mAh/g and a retention rate of 95% after 50 cycles. The proposed purification process paves a way to prepare a promising anode material with good performance with low cost of coke powder for Li-ion batteries.
文摘Numerical simulation of the electrical field distribution helps in-depth understanding of the mechanisms behind the responses and the benefits of the high voltage pulse comminution. The COMSOL Multiphysics package was used to numerically simulate the effect of ore compositions in this study. Regarding phosphate ore particles shape and composition, the effects of mineral composition, particle size, particle shape and electrodes distance were investigated on the electrical field intensity and distribution. The results show that the induced electrical field is significantly dependent on the electrical properties of minerals,the feed particle size and the location of conductive minerals in ores. The angle of material contact surface with the discharge electrode is also an important factor in the intensity of electrical field. Moreover,it is found that the specific liberation effect at the disintegration of phosphate ore by electrical pulses is due to the locality of the electrical field at the interface of mineral components of the phosphate ore aggregates with different permittivities. However, the intensity of the electrical field increases with sharpening the contact angle. Besides, the electrical discharge in the samples is converted to the electrohydraulic discharge across the surrounding water by changing the distance between the discharge electrode and sample surface.
文摘The main aim of this paper is to investigate the properties of Cu-TaC electrodes produced by Powder Metallurgy （PM） method. The design of Experiment （DOE） method was used to plan the investigation. Two different compositions of the powders （Cu-TaC with 30 and 55 % wt TaC） were used. The major properties which determine suitability of electrodes for Electro Discharge Machining （EDM） are electrical conductivity, therrnal conductivity and to some extent density. These properties were measured for the green compacted electrodes, analyzed and compared with their sintered counterparts. This is the initial stage to determine the suitability or otherwise of the compacted electrodes. The results showed that the compacted electrodes in green form can be suitable for EDM, since the electrical conductivities are very high （94.96-189.92Ω^-1m^-1）. The thermal conductivity is good （29.70-33.20W/m K）. The density ranges between 6.13 and 9.80 g/cm3. The sintered electrodes were found to be unsuitable at the specified conditions, because they became non-conductive electrically after sintering. Current efforts are geared towards improving these properties for the sintered ones and also determining their optimum levels.
文摘Study of electrochemical behavior of chromium （molybdenum, tungsten） and silicon containing melts allowed defining conditions for synthesis of silicides of chromium, molybdenum and tungsten in the form of fine powders by electrolysis of halide-oxide melts. Sequence of stages of electrosynthesis of silicides of molybdenum and tungsten was found as follows： deposition of more electroposifve metal （molybdenum or tungsten）, deposition of the second component （silicon） on the surface of metal deposited previously, and reaction diffusion of silicon into the deep of the metal-salt ＂pear＂ with the formation of silicide phases of different compositions up to the higher silicides. In contrast, during the electrodeposition of chromium silicides, one of the components （chromium） is deposited not in elemental form, but in oxide form, and the other （silicon） acts as a reducing agent for this oxide to form binary compounds. Duration of the synthesis first stage （deposition of refractory metal or of its oxide） depends on the refractory metal compound content in the system and on the cathode current density. Synthesis of silicides is possible due to retention of powders of molybdenum （tungsten） or chromium oxide at the cathode without scaling. Optimal values of concentrations ratio, current density, temperature, and duration of electrosynthesis were found. Phase composition of products were obtained, as well as their chemical and thermal stability, were studied.
