Gel lead-acid batteries are an improvement over conventional lead-acid batteries with liquid electrolytes. They replace sulfuric acid with a gel electrolyte, offering improvements over conventional batteries in terms of safety, capacity, discharge performance, and service life.

Gel lead-acid batteries utilize a gel-like electrolyte with no free liquid inside. This allows for high electrolyte capacity, high heat capacity, and strong heat dissipation for a given volume, preventing thermal runaway, a common problem in conventional batteries. The low electrolyte concentration reduces corrosion to the plates, and the uniform concentration eliminates electrolyte stratification.

Operating Principle

Gel lead-acid batteries offer superior performance to valve-regulated sealed lead-acid batteries. They offer stable performance, high reliability, long service life, strong adaptability to both high and low ambient temperatures, and the ability to withstand long-term, cyclic, deep, and high-current discharges. They also provide self-protection against overcharge and overdischarge.

Domestic colloidal lead-acid batteries used in electric bicycles utilize a vacuum infusion process, injecting a silica gel and sulfuric acid solution between the positive and negative plates of the battery. Initially, colloidal lead-acid batteries are unable to circulate oxygen. This is because the colloidal material encloses both the positive and negative plates. Oxygen generated on the positive plate cannot diffuse to the negative plate, preventing it from reducing the active lead there. Instead, oxygen must escape through the exhaust valve, similar to flooded batteries.

After a period of use, the colloidal material begins to dry out and shrink, forming cracks. Oxygen then flows directly through these cracks to the negative plate, allowing oxygen to circulate. The exhaust valve then becomes less frequently opened, rendering the battery nearly sealed and resulting in minimal water loss. Therefore, considering water loss is a key failure mechanism in e-bike batteries, using colloidal lead-acid batteries can achieve excellent results. Colloidal electrolytes are made by adding a gelling agent to the electrolyte to solidify the sulfuric acid electrolyte into a colloidal substance. Usually, colloidal stabilizers and compatibilizers are also added to the colloidal electrolyte. Some colloidal formulas also add agents to delay the coagulation of the colloidal and retardants to facilitate the filling of the colloidal.