Abstract
Lignin-basis polymers obtained from plants have been used as additives for the negative plates of lead-acid batteries in order to improve the performance of the negative plates. Most of lignins for additives are made of by-products of pulping-processes. Since their molecular structure is complicatedly changed by high-energy treatment in pulping-processes, its detail remains unclear. Therefore, the effects on the molecular structure of lignins on the performance of the negative plates of batteries have hitherto been ambiguous. Then authors obtained lignophenols with controlled molecular structure from native lignins using the phase-separation system, and investigated the relationships between the molecular structure of lignins and the performance of batteries by adding lignophenols to negative plates. It was found that the discharge performance of the negative plates of batteries improved because the active materials of the negative plates got finer, leading to larger surface area. It was considered that dimethoxyphenol units contribute to the improvement of both the initial performance and the life performance of batteries. Then, it was found that there exists a suitable molecular weight of lignins for uses in batteries.
