Whether it is AGM sealed lead storage battery using glass fiber membrane, or a gel electrolyte gel sealed lead storage battery, the battery is sealed by the principle of cathode absorption.

　　When the battery is charged, oxygen will be released from the anode and hydrogen will be released from the cathode. When the positive electrode charge reaches 70%, the positive electrode begins to evolve oxygen. The precipitated oxygen reaches the negative electrode and reacts with the negative electrode as described below to achieve the purpose of cathode absorption. The hydrogen evolution of the negative electrode should start when it is charged to 90%, plus the reduction of oxygen on the negative electrode and the increase of the hydrogen overpotential of the negative electrode itself, so as to avoid a large amount of hydrogen evolution reactions.

　　For AGM sealed lead-acid batteries, although most of the battery’s electrolyte is stored in the AGM separator, 10% of the separator’s pores must not enter the electrolyte. The oxygen generated by the anode reaches the cathode through this part of the pores and is absorbed by the cathode.

　　For the gel-sealed lead-acid battery, the silica gel in the battery is a three-dimensional porous network structure with SiQ particles as the skeleton, and the electrolyte is wrapped inside. After the silica sol filled in the battery becomes a gel, the skeleton will shrink further, causing cracks in the gel to penetrate between the positive and negative plates, providing a channel for the oxygen released from the positive electrode to reach the negative electrode. It can be seen that the sealing principles of the two batteries are the same, the difference lies in the "fixing" method of the electrolyte and the method of supplying oxygen to the negative electrode channel.

　　AGM sealed lead-acid batteries use pure sulfuric acid aqueous solution as the electrolyte, with a density of 1.29-1.3lg/cm3. Except for a part of the electrolyte absorbed in the plate, most of the electrolyte is present in the glass fiber membrane. In order to provide a channel for the oxygen precipitated from the anode to the cathode, it is necessary to keep 10% of the pores of the diaphragm not occupied by the electrolyte, which is a lean solution design. In order to make the electrode plate fully contact the electrolyte, the polar groups are tightly assembled.

　　In addition, in order to ensure sufficient battery life, the electrode plate should be designed to be thicker, and the positive grid alloy is Pb'-Q2w-SRR-A1 quaternary alloy.

　　The electrolyte of a sealed lead-acid battery is composed of silica sol and sulfuric acid. The concentration of sulfuric acid solution is lower than that of AGM batteries, usually 1.26 ~ 1.28 g/cm3. The amount of electrolyte used is 20% more than that of AGM batteries, which is equivalent to that of flooded batteries. This electrolyte exists in a colloidal state and is filled in the separator and between the positive and negative electrodes. The sulfuric acid electrolyte is surrounded by gel and will not flow out of the battery.

　　Since the battery adopts a liquid-rich and not tightly assembled structure, the positive grid material can be a low antimony alloy or a tubular battery positive plate. At the same time, in order to increase the battery capacity without reducing the battery life, the plate can be made thinner. The internal space of the battery unit can also be expanded.