For the first time, the effects of designed siloxane derivative N-triethoxysilylpropyl 3,4,5-tris(tetradecyloxy) benzamide (Compound 1) as an electrolyte additive on the electrochemical properties of gelled electrolyte valve-regulated lead-acid (VRLA) battery were investigated. Results show that Compound 1 decreased gelled electrolyte resistance and possibly triggered the formation of large inorganic crystals due to the poly-condensation reaction. In addition, the hydrogen evolution process was inhibited and the stability of gelled electrolyte by the experiment of released liquid was significantly improved by addition of Compound 1.