Electrical properties of cathodic material of lithium power sources based on polyaniline synthesized at various perox excesses of peroxidisulphate

Abstract

Polyaniline was synthesized with a different molar excess of sodium peroxide disulfate relative to aniline. Materials based on polyaniline and thermally exfoliated graphite Superior Graphite ABG-81 were used as electroactive masses of the positive electrode in secondary lithium batteries. The synthesis of polyaniline was carried out from an aqueous solution containing 1 M aniline, 2 M hydrochloric acid, and 15 wt. % (by the sum of the masses of aniline and graphite) of thermally expanded graphite by adding sodium peroxide disulfate with constant stirring. In the synthesis of the polymer for element 1 was used sodium peroxide disulfate taken in a molar excess of 1.5, compared with the amount taken for the synthesis of aniline. In the synthesis of polyaniline for element 2, the molar excess of peroxide disulfate was 2. The electrical characteristics of the elements were designed and studied, discharging them at a constant resistance of the outer circuit. The discharge current and voltage of the element 1 decrease rapidly during the discharge of the power sources. There are no plateaus on the discharge curves. During the initial discharge, the internal resistance of the element was slightly higher, but after recharging the resistance decreased significantly. This can be explained by the destruction and reduction of passivating films on lithium electrodes during the discharge and charge of the element. In the first and second charge − bit cycles, the characteristics of the element do not actually change. This indicates a good reversibility of the electrochemical process. On the discharge curve of the second element there are two small voltage plateaus − at about 3.1 and 2.3 V, which may correspond to the transitions pernigranilin-emeraldin and emeraldin-leukoemeraldin. Thus, the use of more oxidant during the synthesis of polyaniline significantly increased the bit characteristics of the element. It should also be noted the flatter nature of the bit curve and the lower internal resistance of the second element compared to the first. In the following cycles of discharge-charge there is some deterioration of the discharge characteristics and a decrease in the coefficients of recoil for energy and current. The discharge properties of the first element Q sp = 29.85 mA∙h/g, W sp = 36.02 mW∙h/g, internal resistance 84.1 Ohms. The discharge properties of the second element Q sp pit = 38.97 mA∙h/g, W sp = 78.99 mW∙h/g, internal resistance 24.4 Ohms. Keywords: polyaniline, lithium power sources, discharge characteristics.