High-rate capability of zinc anodes in alkaline primary cells

This work is devoted to the electrochemical aspects of high-power testing of primary alkaline LR6 (“AA”) cells and to the factors influencing cell performance, namely the corresponding zinc anode behaviour under such high-rate conditions. The influence of the high-rate testing regime, such as the discharge mode and the end-potential, on zinc utilisation in alkaline cells has been monitored and its behaviour has been isolated by means of a pseudo-reference electrode. As anticipated, anode formulation, including zinc alloy composition and size distribution, is found to affect the cell’s discharge curve and the corresponding zinc electrode potential and utilisation. The effects of these parameters on the discharge curve are discussed in terms of three stages of discharge. Finally, the high-rate capability of commercial LR6 cells is analysed in terms of zinc anode formulation. It was concluded that zinc electrode polarisation is very small and is relatively independent of manufacturer, of zinc anode formulation and of zinc alloying. On the other hand, metallic zinc utilisation remains very low under high-rate conditions.