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Colloidal Gel And Liquefaction Contradictions Of Gel Batteries

2022-07-22

    Gel batteries are basically valve-regulated sealed batteries, and their main features are safety, reliability and long service life. Its electrolyte is fixed in a gel state that does not flow and the battery does not leak acid. It can be used in any orientation and can be used as a safety item for air and sea transportation. The gel-state electrolyte has semi-solid properties, low vapor pressure, and very little acid mist is generated during charging.

    The gel electrolyte eliminates acid stratification, and also makes the gel battery a flooded design, prolonging the service life, preventing early capacity decay and thermal runaway, and making the battery safe and reliable. The gel is a safe and reliable gel battery that must be stable, that is, the electrolyte in the battery is always solid and there should be no apparent liquid (free acid). However, gel batteries generally have the phenomenon that the gel is easy to liquefy (also known as hydration). Although the gel liquefaction has no obvious adverse effect on the electrical performance and the service life of the battery, it will cause the battery to leak liquid. People initially developed gel batteries to prevent leakage and to be safe.

    The gel is stable and does not liquefy, which is a must-have for gel batteries. Colloidal electrolytes are mainly prepared by adding gelling agents (such as sodium silicate, silica sol, and gas-phase s) to dilute sulfuric acid. The gelling agent first generates polysilicon acid colloidal particles in dilute sulfuric acid, and the colloidal particles gradually form a spatial network mainly through hydrogen bonds to form a hydrophilic gel. The bond energy of hydrogen bonds is very low, and the gel is thixotropic, that is, the gel will be destroyed by external forces such as stirring or shaking, and it will become a liquid; the liquid will gradually become a gel after resting. The thixotropy of the gel indicates that its strength is low, it is a metastable state, and it is easy to liquefy. It can be seen that the gelation and liquefaction of colloids are a pair of contradictions, and it is difficult to fundamentally eliminate its liquefaction from the gel formation mechanism.