Abstract
The role of lignosulfonate constituent of the lead‐acid battery expander on the negative electrode performance is analyzed. Two quantitative electro‐chemical techniques have been developed to monitor the expander activities on constant current discharge and capacity maintenance behavior of the electrode during cycling. Both these techniques are based on small electrodes and proved effective in evaluating expander candidate materials outside the test battery. Test results agree closely with the reported expander's influence on the pasted electrode. The plausible mechanisms of expander action during high rate discharge and deep discharge cycling are elucidated.