How to eliminate battery vulcanization

Let us first understand what is the battery vulcanization? What is the cause of vulcanization and its hazards and characteristics?

1. What is battery vulcanization?

It produces white hard lead sulphate crystal on the plate, which is very difficult to convert into active substance lead sulfate when charging. This is the lead sulphate salification, referred to as "vulcanization". The main reason for the formation of such lead sulfate crystals is that the lead sulfate particles are dissolved in the electrolyte in a long-term state after over discharge or discharge, and the lead sulfate is recrystallized at a low temperature, and lead sulfate is precipitated during crystallization. Thus, the particles which are once precipitated grow and develop again and again due to temperature fluctuations, and the crystal grains are enlarged. This lead sulfate has poor conductivity, large electrical resistance, low solubility and dissolution rate, and difficulty in recovery during charging. Therefore, it is a cause of a decrease in capacity and a shortened life.

2. What is the cause of vulcanization?

A normal lead storage battery forms lead sulfate crystals upon discharge, and is relatively easily reduced to lead when charged. If the battery is used and maintained poorly, for example, if it is often undercharged or over-discharged, a coarse and hard lead sulfate will gradually form on the negative electrode. This lead sulfate is difficult to be recharged by a conventional method, and requires a high charging voltage, and a large amount of gas is precipitated due to poor charging acceptance during charging. This phenomenon usually occurs at the negative electrode and is called irreversible sulfation. It causes a drop in battery capacity and even becomes the cause of the end of battery life.

It is believed that this reason for irreversible sulfation is the recrystallization of lead sulfate, which decreases solubility after formation of coarse crystals. The recrystallization of lead sulfate causes the crystal to become larger due to the tendency of the polycrystalline system to decrease its surface free energy. It is known from the law of the crystallization process that the solubility of a small crystal size is greater than the solubility of a large crystal size. Therefore, when a large amount of lead sulfate is present during long-term charge or discharge or over-discharge, and the fluctuation of sulfuric acid concentration and temperature, individual lead sulfate crystals can grow up depending on the dissolution of small crystals.

3. What is the hazard of battery vulcanization?

A slight battery vulcanization will reduce the capacity of the battery, and the internal resistance of the battery will increase. In severe cases, the electrode will fail and the battery will not be charged. Slight battery vulcanization can still be recovered by some methods. In severe cases, the general charging method cannot restore the capacity.

4. What are the characteristics of battery vulcanization?

The most obvious external feature of a vulcanized battery is a decrease in battery capacity and an increase in internal resistance. Of course, this external characteristic is also obtained if the battery loses water and the positive plate softens. The method for identifying whether a battery is vulcanized is often a pulse repair device that uses a pulse repair device to repair the battery. If the capacity rises, it is vulcanized. If there is not a little increase in capacity, the battery capacity may drop for other reasons.

5, the method of eliminating battery vulcanization has the following, specifically:

1) High current charging repair

If adsorption is considered to be the cause of sulfation, it can be charged at a high current density (up to 100mA/cm²). At such a current density, the negative electrode can reach a very negative potential value, at which time away from the zero charge point, so that φ-φ(0) < 0, changing the sign of the surface of the electrode, the surface active material will desorb, especially It is an anionic surface-active substance, and after the detrimental surface-active substance is desorbed from the electrode surface, the charging can be smoothly performed. At present, almost no one in China uses this method to deal with irreversible sulfation, which may be due to the following considerations: polarization and ohmic pressure drop increase at high current density, which is converted into heat, which causes the internal temperature of the battery to rise, and at the same time A large amount of gas is precipitated, especially a large amount of gas is evolved from the positive electrode, and the scouring action easily causes the active material to fall off. However, the disadvantage of this is that it is easy to cause water loss, and it is also easy for some of the batteries that can be repaired to be broken down during the charging of the large current, causing unnecessary trouble. The repair 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 energy levels, and ions that are usually in the metastable energy state tend to migrate to the most stable covalent bond level. At the lowest energy level (ie, the covalent bond level), sulfur exists in the form of a ring molecule containing 8 atoms. The circular molecular pattern of these 8 atoms is a stable combination that is difficult to be broken and cannot form a battery. Quasi-sulfation - vulcanization. When this happens many times, a layer of lead sulphate crystals similar to the insulating layer is formed. To break the bondage of these sulfate layers, it is necessary to raise the energy level of the atom to a certain extent. At this time, the electrons added to the outer atom are activated to the next higher energy band, and the atoms are unbounded. Each specific energy level has a unique resonant frequency. Some energy must be supplied to enable the activated molecules to migrate to a higher energy level. Too low energy cannot meet the energy requirements of the transition. However, Excessive energy will cause the atoms that have left the bondage to be in an unstable state and fall back to the original energy level. In this way, it is necessary to pass multiple resonances, so that one of them is out of bounds, reaches the most active energy level state, and does not fall back to the original energy level. Thus, it is converted into a free ion dissolved in the electrolyte to participate in the electrochemical reaction. A very high voltage can be achieved, that is, a method of charging a large current and a high voltage, and resonance can also be realized, that is, a method of pulse harmonic resonance. Physically, any insulating layer can break down at a sufficiently high voltage. Once the insulating layer is broken down, the coarse lead sulfate will be in a conductive state. If a high voltage is applied to the high-resistivity insulation, a large lead crystallization can also be broken. If the high voltage is short enough and the current is limited, the charging current is not large under the condition of breaking through the insulating layer, and a large amount of gassing is not formed. The strong gas evolution rate of the battery is positively related to the charging current and the charging time. If the pulse width is sufficient, under the condition of ensuring the breakdown of the coarse sulphate crystal, the simultaneous micro-charging cannot form the gassing. In this way, pulse elimination vulcanization is achieved. The disadvantage of this is that the effect achieved after the repair is not satisfactory, and the repair time will be very long.

3) Adding repair agent combined with pulse repair

After the addition of the repairing agent, the lead acid crystal particles are decomposed by the active material under the action of the applied electric field, and the active material (pb/pbo2) on the surface of the crystal is activated and regenerated, and the sulfate ion is returned to the electrolyte; Lead sulfate crystals, these micro-particles will be uniformly adsorbed on the electrode under the action of an applied electric field, so that the lead sulfate crystal will never be produced at the interface of the electrode. Moreover, it can avoid the water loss caused by the usual overcharge. Effectively improve the utilization rate of the active material of the entire battery, and the electrode of the battery is in a new battery state for a long time. Fundamentally overcome the battery because of lead sulfate salinization caused by the battery capacity decline shortcomings, prolong the life of the lead-acid battery, it can make any one of the physical damage of the lead-acid battery can fundamentally solve the short life, capacity decline fast fatal weakness.

Based on the above comparison, it can be concluded that neither simple high-current repair nor pulse repair can fundamentally inhibit the sulfudation, so that the effect and duration of the repair cannot reach the desired effect. In general, it can be said that instrumental repair belongs to physical therapy, and the addition of repair agent belongs to chemotherapy. Only the combination of the two can achieve better results. It's like a combination of Chinese and western medicine.

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