화학공학소재연구정보센터
Journal of Power Sources, Vol.196, No.15, 6412-6418, 2011
Polymer-derived-SiCN ceramic/graphite composite as anode material with enhanced rate capability for lithium ion batteries
We report on a new composite material in view of its application as a negative electrode in lithium-ion batteries. A commercial preceramic polysilazane mixed with graphite in 1:1 weight ratio was transformed into a SiCN/graphite composite material through a pyrolytic polymer-to-ceramic conversion at three different temperatures, namely 950 degrees C, 1100 degrees C and 1300 degrees C. By means of Raman spectroscopy we found successive ordering of carbon clusters into nano-crystalline graphitic regions with increasing pyrolysis temperature. The reversible capacity of about 350 mAh g(-1) was measured with constant current charging/discharging for the composite prepared at 1300 degrees C. For comparison pure graphite and pure polysilazane-derived SiCN ceramic were examined as reference materials. During fast charging and discharging the composite material demonstrates enhanced capacity and stability. Charging and discharging in half an hour lead to about 200 and 10 mAh g(-1), for the composite annealed at 1300 degrees C and pure graphite, respectively. A clear dependence between the final material capacity and pyrolysis temperature is found and discussed with respect to possible application in batteries, i.e. practical discharging potential limit. The best results in terms of capacity recovered under 1V and high rate capability were also obtained for samples synthesized at 1300 degrees C. (C) 2011 Elsevier B.V. All rights reserved.