The lifespan models of commercial 18650-type lithium ion batteries （nominal capacity of 1150 mA-h） were presented. The lifespan was extrapolated based on this model. The results indicate that the relationship of capacity retention and cycle number can be expressed by Gaussian function. The selecting function and optimal precision were verified through actual match detection and a range of alternating current impedance testing. The cycle life model with high precision （〉99%） is beneficial to shortening the orediction time and cutting the prediction cost.
In order to extract gallium from a high-silica-content flue dust generated in corundum production,a mixed acid solution of H2SO4 and HF was used for leaching,and test parameters of the leaching process were optimized.Experimental results show that the leaching rate of gallium was only 38%when H2SO4 was used as leaching agent.Composition analysis results of micro areas in this corundum flue dust indicate that the content of gallium in silica-enriched phases was high;this portion of gallium was insoluble in H2SO4 solution.The leaching rate of gallium increased significantly with addition of HF due to corrosion of silica.Effects of reaction time,temperature,and concentrations of HF and H2SO4 on leaching rates of gallium were investigated.The leaching rate of gallium reached 91%when this corundum flue dust was leached in a mixed acid solution of H2SO4 and HF for 4 h,at a temperature of 80°C,with a liquid-to-solid ratio of 5:1(mL/g).The optimal concentrations of H2SO4 and HF in the mixed acid solution were 1.5 and 6.4 mol/L,respectively.
An efficient synthesis of carbon nanofibers by pyrolysis of as-prepared polypyrrole nanowires was reported. Under the subsequent KOH activation, a significant morphology variation was detected and the obtained sample took on a ribbon-like structure. The morphology and structure of the carbon nanofibers and carbon nanoribbons were characterized. When the as-prepared one-dimensional carbon nanostructures were used as anode materials in lithium ion batteries, both of them exhibited superior cyclical stability and good rate properties. After 50 cycles, the reversible capacity of carbon nanofibers electrode maintained 530 mA·h/g. Concerning carbon nanoribbons, the reversible capacity is always larger than 850 mA·h/g and the reversible capacity retention after 23 cycles is 86%.
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.
Alloy anodes were studied for pursuing Sn-based microcomposite synthesis, assembly and performance for lithium ion batteries. The self-assembled Sn-Co-C composites with nano-scaled microstructures were prepared via solution method and carbothermal technology. The morphology and physical structure were investigated with scanning electron microscope (SEM) and X-ray diffraction (XRD). The as-prepared materials were assembled to half cell coin for the purpose of discussing the galvanostatic cycling, cyclic voltammetry and rate-capability performance. Results reveal that nanoscaled CoSn 2 alloys covered with Sn and C layer by layer are wrapped by cross-linked porous carbon network to form spherical microstructure. This distinguishing feature of Sn-Co-C composites provides a possible solution to the problems of Sn particle aggregation and poor electron transport, and has strong effect on improving electrochemical performance.
