To maximize the performance of lead-acid batteries, particularly in EFB, AGM start-stop, deep-cycle, and energy storage applications, enhancing the negative plate’s charge acceptance—especially under partial state-of-charge conditions—and mitigating side reactions such as hydrogen evolution are critical. Various approaches have previously been proposed to improve charge acceptance, including the use of high-conductivity carbon, increasing carbon loading, employing high-surface-area carbon, and carefully selecting surface functional groups. While these methods have achieved notable success, they have also significantly increased water loss, thus compromising the benefits of enhanced charge acceptance.

Borregaard has reported that lignin can be adsorbed onto carbon materials, reducing the effective lignin content in the negative active material (NAM). By further investigating the interactions between NAM components, Hammond Group developed novel negative expander formulations. Cell and battery testing of one such formulation demonstrated significant improvements in both higher charge acceptance and lower water loss. Interestingly, changes in the negative formula were also observed to substantially influence the performance of the positive plate.