| Abstract [eng] |
In this study the possibility of replacing heavy lead grids in lead acid battery electrodes with graphite felt was investigated. Graphite felt is a material which is light, has low specific electrical resistance (2,710-3 m), high specific surface area (0,8-2,8106 m2/m3) and high tensile strength (2,21-3,58 GPa). Also, suggestions for production scheme and parameters of such electrodes were proposed. Two types of modification were investigated: electrochemical deposition from lead nitrate electrolyte and chemical-thermal using saturated solutions of lead acetate and formate. Electrochemical deposition was carried out using galvanostatic or potenciostatic modes in a stirred bath or flow-through reactor. Electric current impulse effect on efficiency and morphology of crystals during electrochemical deposition was also determined. For chemical-thermal deposition, impregnation was carried out in a saturated solution of lead acetate and farmate at 20 and 60 °C temperature. Second step – thermal decomposition was done at 300 or 350 °C temperature. Produced electrodes were analyzed using x-ray diffraction analysis method, scanning electron microscope, simultaneous thermal analysis and electrochemical analysis methods. It was determined that electrochemical modification of graphite felt in flow-through reactor and using electric current impulses did not increase deposited material on the inner filaments of graphite felt while also decreasing total deposited material. On the other hand, electrodes produced using chemical-thermal method showed high amount of deposited material (up to 86 % of the total mass of electrode) and production simplicity. A rechargeable battery made from 2 same size electrodes had specific electrical capacity of 16,11 mAh/g. |
