| 摘要 |
PURPOSE:To increase the life and overdischarge characteristic of a battery by employing a separator which contains either on its surface or in itself a compound whose water-absorbing property varies according to its pH. CONSTITUTION:The separator of a battery contains a compound, for example, a starch or the like which is a graft copolymer of either an acrylic-acid-system monomer or a methacrylic-acid-system monomer either in itself or on its surface; the compound has a water-absorbing property which varies according to its pH. The above-mentioned starch has a water-absorbing property around 200-300 folds (in ratio by weight) at the pH value around neutrality, which decreases as the pH changes to become more acidic or more alkaline. For instance, 1kg of water is added to 10g of the starch which is a graft copolymer of acrylic acid, preparing a paste. This paste is filled in a glass mat in such a way that 0.2g/cm<2>. Through the means mentioned above, the rise of pH at the last stage of discharge is prevented by the water-absorbing property of the starch, thus the corossions of a grid is minimized in a lead battery. While, water is discharged by the starch if alkali concentration becomes large because of water consumption through discharge thus rise in concentration is obviated in an alkaline battery. As a result of this, the life of a battery can be increased with both types of battery. |
