COMPARISON OF SEVERAL CARBONACEOUS MATERIALS AS CANDIDATE ACTIVE MATERIALS FOR LI-ION NEGATIVE ELECTRODES

摘要

In this work we wish to report about the comparison study, which was performed on few typical samples each representing one of the three groups of the carbonaceous materials identified above. The structural characteristics of these carbons have been studied using the methods of x-ray diffraction, Raman spectroscopy, emission spectroscopy and high resolution scanning electron microscopy. The methods used to characterize physicochemical parameters of materials included but were not limited to: loss on ignition (LOI), BET surface area, free moisture, volatile and ash content of carbons, moisture by Karl Fischer titration, resiliency, tap & true & apparent densities, particle size distribution by the laser analyzer (Microtrak) as well as sieve analyses, etc. The electrochemical performance has been investigated using the techniques of cycling voltammetry as well as galvanostatic charge/discharge at the following rates: C/20, C/10, C/5 and C/3. Coin cells of the 2016 size equipped with Li foil as a counter electrode were used in the galvanostatic cycling. Most of the study has been performed in the electrolyte system consisting of 1M LiPF_6 in EC:DMC, which is the choice of many for its comparably good conductivity and suppressed carbon "exfoliation" upon prolonged cycling.