1. True colloid battery: When preparing sulfuric acid electrolyte, 98% concentrated sulfuric acid, silica sol and water are used to prepare the electrolyte. The content of sulfuric acid in the electrolyte is 35-40%. The amount of silica sol added should be controlled to make the mass of pure silicon dioxide account for 5-11% of the mass of the entire electrolyte (the smaller the particle size, the less the amount added). After a certain period of time, the electrolyte undergoes a gel change, from the original liquid to a non-flowing colloid (like jelly), but the colloid has the same conductive properties as the electrolyte. This method requires high technical requirements, because the gel must be appropriate, not too light, and not too much. If the gel is too light, the strength is insufficient; and excessive gel will increase the resistance of the colloid, and it is not suitable to produce colloid cracks, which affects the performance of the battery. Therefore, only some companies with technical strength can use it well.
This method can extend the service life of the battery by more than 1 times, greatly improve the various performance of the battery, and can also make the electrolyte gel, so that the electrolyte will not spill out when the battery is tilted, making the battery a maintenance-free battery.
After gelation, the liquid electrolyte becomes a colloid, and the silica particles of the silica sol are cross-linked to form a three-dimensional network structure, but the gaps between the silica sol particles contain electrolyte (aqueous sulfuric acid solution), so the colloid can still conduct electricity.
After the colloid is formed, it takes a certain period of time to reach the best use effect (after 3-6 months). At this time, the colloid cracks, and the cracks provide a channel for the oxygen generated during the battery charging process, so that the oxygen can pass through the cracks from the negative electrode to the positive electrode and be absorbed, achieving a maintenance-free effect.
2. Pseudo-colloid battery: Adding a small amount of silica sol to the sulfuric acid electrolyte, generally about 1% of the total amount of the electrolyte, can slow down the corrosion rate of the electrode, thereby extending the service life of the battery by more than 50%.