How to Eliminate Vulcanization of Batteries

First let us know what is called battery vulcanization, what is the cause of vulcanization and its hazards and characteristics. Xiaobian here to give you a brief introduction:

1. What is battery vulcanization?

White and hard lead sulfate crystals are formed on the plate, and it is very difficult to convert lead sulfate into active substance when charging. This is lead sulfate salting, referred to as "sulfurization". The main reason for the formation of such lead sulfate crystals is that the lead sulfate particles dissolve in the electrolyte and are saturated when they are placed for a long time after overdischarge or discharge. These lead sulfate crystallizes again at low temperature, and lead sulfate precipitates during crystallization. In this way, the precipitated particles grow and develop again and again because of the temperature change, which enlarges the crystalline grains. The lead sulfate has poor conductivity, high resistance, low solubility and dissolution rate, and it is difficult to recover during charging. Therefore, it is the reason for the reduction of capacity and the shortening of service life.

2. What are the causes of vulcanization?

Normal lead-acid batteries form lead sulfate crystals when discharged, which can be easily reduced to lead when charged. If the battery is not properly used and maintained, such as under-charged or over-discharged frequently, a thick and hard lead sulfate will gradually form on the negative electrode. It is difficult to recover the lead sulfate by conventional charging method, which requires a high charging voltage. Because of the poor charging acceptance, a large number of gases are emitted. This phenomenon usually occurs at the negative pole and is called irreversible sulfation. It leads to the decrease of battery capacity, and even causes the end of battery life.

It is generally believed that the reason for this irreversible sulfation is the recrystallization of lead sulfate and the decrease of solubility after the formation of coarse crystals. The recrystallization of lead sulfate enlarges the crystal because of the tendency of polycrystalline system and the decrease of surface free energy. According to the law of crystallization process, the solubility of small crystalline size is greater than that of large crystalline size. Therefore, when long-term charge-discharge or over-discharge occurs, a large amount of lead sulfate exists, coupled with the fluctuation of sulfuric acid concentration and temperature, individual lead sulfate crystals can grow up depending on the dissolution of small crystals.

3. What are the hazards of battery vulcanization?

Mild vulcanization of batteries will reduce the capacity of batteries, increase the internal resistance of batteries, and in serious cases, the electrodes will fail to charge. For mild battery vulcanization, some methods can be used to recover it. In severe cases, the general charging method can not recover the capacity.

4. What are the characteristics of battery vulcanization?

The most obvious external characteristic of vulcanized batteries is that the capacity of batteries decreases and the internal resistance increases. Of course, if the battery loses water and the positive plate softens, it also has this external characteristic. The method of identifying whether the battery is vulcanized or not is usually to use the pulse repair instrument to repair the battery. If the capacity increases, it is vulcanized. If there is no little capacity increase, the decrease of the battery capacity may be caused by other reasons.

5. Method of eliminating battery vulcanization

There are several ways to eliminate battery vulcanization, specifically:

1) High Current Charging Repair

If the adsorption is considered to be the cause of sulfation, it can be charged with high current density (up to 100 mA/c). Under such current density, the negative electrode can reach a very negative potential value. At this time, it is far from the zero charge point, which changes the charged symbols on the surface of the electrode. The surface active substance will desorb, especially the anionic surface active substance. This harmful surface active substance will be desorbed from the surface of the electrode. Afterwards, the charging can proceed smoothly. At present, almost no one in China uses this method to treat irreversible sulfation. It may be due to the following considerations: polarization and ohmic pressure drop increase at high current density, this part of energy is converted into heat, which increases the temperature of the battery, and a large number of gases are released, especially positive gases, which wash away. Active substances fall off easily. But the disadvantage of this method is that it is easy to cause water loss, and it is also easy to break down the plates of some batteries that could be repaired in the process of charging at high current, causing unnecessary trouble.  Rehabilitation rate and effect are greatly reduced.

2) Pulse Repair

According to the principles of atomic physics and solid state physics, sulfur ions have five different states of energy. Usually, ions in the metastable state tend to migrate to the most stable covalent bond level. At the lowest level (i.e. covalent bond state), sulfur exists in the form of a ring molecule containing eight atoms, which is a stable combination and is difficult to be broken down to form an unparalleled sulfation-sulfuration of batteries. When this happens many times, a layer of lead sulfate crystals similar to the insulating layer is formed. To break the bonds of these sulfate layers, it is necessary to raise the energy level of the atoms to a certain extent, when the electrons added to the outer atoms are activated to the next higher energy band, so that the bonds between the atoms are released. Each particular energy level has a unique resonance frequency, and some energy must be provided to enable the activated molecules to migrate to a higher energy level. Too low an energy can not meet the energy requirement for the transition. However, too high an energy will unstable the atoms that have been out of bond and transition. The state falls back to its original level. In this way, it is necessary to make one of them break away from the bond and reach the most active level without falling back to the original level through multiple resonances. In this way, free ions dissolved in the electrolyte are converted to participate in the electrochemical reaction. Very high voltage