The effect of additives on the positive lead—acid battery electrode

The effect of the additives carboxymethylcellulose (CMC), carbon black, silica gel, and fibres on the manufacture of positive active material and on the cycle life was investigated by means of porosimetry, inner surface (BET) determination, X-ray diffractometry, chemical analysis, and by measuring the course of the potential, by testing the low rate and high rate capacities and by overcharge cycling tests. It was shown that the additives can be classified, according to their mode of action, into additives (a) increasing the water accumulating capacity of the paste, (b) influencing the crystallization of the mass, (c) increasing the electronic conductivity of the mass, (d) stabilizing the mass. Types (a), (b), and (c) affect the manufacture of active material and the initial capacities, whereas additive (d) improves the cycle life.