original research article
Electrochemical Evaluation of Lithium-Ion Battery with Anode of Layer-Reduced Biocarbon and Cathode of LiFePO4
Nirwan Syarif, Dedi Rohendi, Nyimas Febrika Sya'baniah
The application of reduced carbon anode layer and LiFePO4 cathode was conducted in laboratory-scale battery. Both electrodes were fabricated into lithium - ion battery with LiCl electrolyte in both gel and liquid based. The carbon was prepared by using Hummer method and solvent sonification to exfoliate the carbon layer from biocarbon. The battery performance tests were carried out in potentiostat for Cyclic Voltammetry (CV) and galvanostatic measurements. The highest current of CV measurement can be obtained in the battery with reduced carbon layer anode and 20% of liquid electrolyte. It was calculated that the same battery produced the highest energy and power. Current - Voltage profile is relatively stable in CV of batteries with 40% electrolytes in both gel and liquid media. All batteries have two peaks in both anodic and cathodic. The reduction peaks show in around 0.5 and 1.5 volts. The cathodics show in around –0.5 and –1.5 volts. The best power and energy values are given by battery with rCNSO anode and 20% liquid electrolyte. Galvanostatic profiles show that the 40% electrolytes in the batteries produces a slower discharging process. It was revealed that applying anode of layer reduced biocarbon as the battery electrode caused the discharging to run faster. The highest slope value of the galvanostatic curve can be found in the battery with the electrode of oxidized starting material and 40% of gel electrolyte, while the lowest can be found in 20% gel electrolyte with the same electrode.
original research article
The Effects of Grain Size, Oxidizers and Catalysts on Band Gap Energy of Gelam-Wood Carbon
Nirwan Syarif, Dedi Rohendi, Sri Haryati, Claudia Kartika Sari Dewi
The research of the effects of grain size, oxidizers, and catalysts on band gap energy of gelam-wood carbon has been conducted in which the carbons were produced from gelam-wood pyrolysis in high temperatures. The instrumentations used in this study were UV-Vis, FTIR spectrophotometer, and SEM. SEM and FTIR were used to characterize the morphology and the functionality of the carbon surface. UV-Vis spectrograms showed that the electronic property of carbon such as band gap was affected when grain size and surface area were changed. The increase of the functional groups in carbon occurred as the surface area of the carbon was increased. Band gap energy of crystalline carbon became much lower along with the increase in grain size due to the effects of bands-broadening. FTIR spectrograms showed that the carbon contained of hydroxyl and carboxylic groups. The hydroxyls were derived from steam-oxidized carbon that was provided narrower in the interlayer distance and lower-set band gap energy. Carboxylic groups were derived from acid nitric oxidation causing flat layer to become curved. The layers were wider and the band energy was higher. The main factor that affects the electronic structure of metal oxide in carbon/metal oxide composites was atomic alignments. The band gap energy increased along with the increase of the asymmetry alignments in metal oxide.