• Title/Summary/Keyword: Intercalation

Search Result 388, Processing Time 0.028 seconds

Stage transformation characteristice of Li, K and Na-graphite intercalation compounds (Li, K과 Na-흑연 층간화합물의 stage 전이특성)

  • 오원춘;임창성;오근호;고영신
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.8 no.1
    • /
    • pp.83-90
    • /
    • 1998
  • Stage transformation characteristics of Li, K and Na-graphite deintercalation compounds (GDICs) were studied under consideration of a deintercalation mechanism of the intercalants between carbon layers. Li-graphite intercalation compounds (GICs) synthesized by a controlling temperatures and pressures have been spontaneously decomposed in the atmosphere. By X-ray differaction analysis the $d_{001}$-values of stage 1 and 2 were identified to be 3.71 and 7.06 $\AA$, respectively. After 6 weeks, the deintercalation reaction of the Li-GICs ceased and only residual compounds could be observed. K-GICs were synthesized by the modified two-bulb method resulting in structural stabilities and stage transitions. By X-ray diffraction analysis the very stable K-graphite residue compounds were observed after 10 weeks. Na-GICs with stage 1 and 2 were synthesized using the high temperature and pressure technique. The temperature dependence of a deintercalation reaction and a thermal stability of Na-GICs were discussed. The structure changes of the Na-GDICs depending on heating rates were identified by X-ray diffraction. According to the deintercalation process, the stage transformations could be attributed to irregular deintercalations of the GDICs with disordered stage.

  • PDF

Preparation of Expanded Graphite using Perchloric Acid and It's Application as Anode Materials for High Power Li-ion Secondary Battery (과염소산을 이용한 팽창흑연의 제조 및 고출력 리튬이온전지 음극재로의 응용)

  • Park, Yul-Seok;Zheng, Hua;Kim, Myung-Soo
    • Journal of the Korean Applied Science and Technology
    • /
    • v.28 no.1
    • /
    • pp.85-94
    • /
    • 2011
  • Expanded graphites were used as anode materials of high power Li-ion secondary battery. The expanded graphite was prepared by mixing the graphite with $HClO_4$ as a intercalation agents and $KMnO_4$ as a oxidizing agents. The physical and electrochemical properties of prepared expanded graphites through the variation of process variables such as contents of intercalation agent and oxidizing agent, and heat treatment temperature were analyzed for determination of optimal conditions as the anode of high power Li-ion secondary battery. After examing the electrochemical properties of expanded graphites at the different preparing conditions, the optimal conditions of expanded graphite were selected as 8 wt.% of oxidizing agent, 400 g of intercalation agent for 20 g of natural graphite, and heat treatment at $1000^{\circ}C$. The sample showed the improved charge/discharge characteristics such as 432 mAh/g of initial reversible capacity, 88% of discharge rate capability at 10 C-rate, and 24 mAh/g of charge capacity at 10 C-rate. However, the expanded graphite had the problems of potential plateaus like natural graphite and lower initial efficiency than the natural graphite.

Electrorefining Characteristics of Uranium by Using a Graphite Cathode (흑연 전극을 이용한 우라늄 전해정련 특성)

  • Kang, Young-Ho;Lee, Jong-Hyeon;Hwang, Sung-Chan;Shim, Joon-Bo;Kim, Eung-Ho
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
    • /
    • v.5 no.1
    • /
    • pp.1-7
    • /
    • 2007
  • Electrorefining experiments were successfully carried out in LiCl-KCl eutectic molten salt with a graphite cathode. It was found that the formation of Uranium-Graphite intercalation compound(U-GIC) helped the self-scraping mechanism of the uranium dendrite and the efficiency of the electrorefiner increased due to an elimination of the stripping step. The contaminations of the uranium deposit by rare earth elements was negligible while about 300 ppm of carbon was observed. The carbon contamination is believed to be eliminated by further purification by yttrium reaction. The morphology characteristics of the recovered U deposit was compared to that of steel cathode. These are only qualitative preliminary experimental results, but we believe that further research on this type of activity change the direction of the electrorefining research on spent nuclear fuel.

  • PDF