Research Of Improving Deep Cycle Life For The VRLA Battery

The development history and present situation of research for VRLA battery industry were reviewed in this paper,especially for the battery for electric vehicle (EV).This study investigates how curing temperature affects the material structure ,the content of PbO₂,the active material ratio,the capacity,the deep cycle life,charge efficiency and self-discharge of lead/acid positive plates. According to experimental results, the major morphology in positive active-material crystals is tribasic lead sulfate(3BS) at a low temperature and tetrabasic lead sulfate(4BS) at a high curing temperature.Obviously, different curing conditions influence heavily electrode composition and cell performance Systematically.The results demonstrate that the plates cured at the higher temperature contain less initial capacity but have a longer cycle life under test conditions.And the active material ratio is low. The primary cause is the high temperature curing and high humidity can produce the thick crystal of 4BS,whose interior is to unify strongly, can provide a rigid for the pole plate network skeleton, and causes the pole plate to be more solid. Thus it has provided a long life.After formation 4BS crystal becomeα-PbO₂. The low temperature curing and high humidity can produce 3BS. Aperture in 3BS is small, the surface area is big, the area contacted between the pellet and the corrosion level is small, the union function is unreliable, the cycle life is short,. After formation the 3BS crystal becomeβ-PbO₂. Because the discharge capacity ofβ-PbO₂ are higher thanα-PbO₂, the capacity of the high temperature curing plate is lower than the low temperature curing.The experimental proved that the temperature is 70℃and 75℃and the apparent density is 4.1g/cm³ and 4.0g/cm³ is the most proper curing for VRLA battery of EV.The plates cured at the lower temperature contain more initial capacity but have a less cycle life under test conditions. The plates cured at the higher temperature contain more initial capacity and have a longer cycle life,so it is the suitable curing temperature for VRLA battery for electric vehicle (EV). The pole plate joined the silicon dioxide in colloid battery experiment have not remarkable influence on the pole plate lead peroxide content and the deep cycle life aspect, but it can improve the initial capacity. The reason is when the battery starts to charge and discharge, the electrode reaction begain, silicon dioxide in the pole plate and the sulfuric acid meet, and the silicon dioxide enters the electrolyte from the pole plate.this causes the porosity in the positive plate increase, so the active material ratiois improved and the capacity of the pole plate increase. Joining silicon dioxide into the plate can improve the initial capacity, but aligning the pole plate/electrolyte contact surface the influence is not . Therefore joining the silicon dioxide into the plate have no remaskable influence on the surface in positive plate in colloid battery.