The contribution of the development of the catalyst technology to the VRLA battery
After 150 years of service for the standard flooded battery technology, people began to develop VRLA battery technology, and it has been extensively verified in long-term use. Like any other new technology, VRLA battery technology will inevitably have problems in the development of technology. To the problems in the development of VRLA battery technology, many countries in the world have made efforts and carried out a lot of basic research. These results finally let people understand why the current design of many VRLA batteries has been significantly improved by the addition of catalyst.
In 1982, the stationary VRLA battery was introduced. The large valve-regulated lead~acid battery (VRLA) was developed in 1985 by GNB (now part of Exide). Telecom users immediately liked the new battery design because it was maintenance~free, safer and compact. Over the next decade, every major battery manufacturer in the United States, Europe, and Asia raced to make VRLA batteries and sell them in the fixed/backup power market. Ten years later, in 1995, the VRLA battery exposed many major problems.
Dr. David Feder presented a controversial paper on the results of 24, 000 batteries (at the 1995 International Conference on Energy in Telecommunications). The 24,000 batteries, which range in age from one to nine years, are made by nine different well~known battery manufacturers around the world and put into use in a controlled temperature environment. But it turns out that 68 percent of those batteries don't meet their capacity requirements. Even more worrying is that the three year old battery has a 35 percent failure rate. Also in the same year, American PS company published a paper, in order to achieve the design life of VRLA batteries for 20 years, This paper established the water loss standard for VRLA batteries that meets the battery performance.
By 1995~1996, complaints from the use site were increasing. Users' complaints about the unreliability of VRLA battery are increasing day by day, and the battery defects include higher floating charging flow, positive grid corrosion, negative plate group strap corrosion, capacity loss, thermal runaway and electrolyte drying up. In fact, all of these seemingly different battery defects were closely related, but it was not understood at the time.
At the 1996 International Telecommunications Energy Conference, the problems in the 1995 paper were further discussed, and for the first time, the long-standing central problem in VRLA battery technology was the depolarization of negative plate. Meanwhile, this paper also proved the beneficial role of catalyst on negative plate polarization.
It was not until 1997, at the E~conference in Budapest, that the whole problem of the negative plate depolarization was solved, accurately explained and experimentally demonstrated that it was the electrochemical properties of VRLA batteries that masked this serious problem. As we know, many such batteries have a tendency to produce the negative plate self~discharge, which is an unexpected failure mode loss, because the VRLA battery becomes a maintenance~free battery oxygen cycle, causing the self~discharge of the negative plate and battery capacity loss. Most people in the battery industry were not yet aware of the problem. This problem is presented by comparison with the well~known flooded single battery design. In fact, in the flooded single battery, all the floating charging flow is charged into the negative plate so keep the negative plate remains fully charged; but in the VRLA battery, little current is charged into the negative plate, so the negative plate starts to self~discharge slowly when the battery is floating charged, even when the plates of both batteries use the same purity material.
At this meeting, three solutions were proposed to the problem of negative plate self-discharge:
1. Improve the purity of the negative plate material and minimize its self~discharge rate, which requires the use of extremely pure lead to make the plate grid. Not only can using this method be extremely expensive, but the manufacturing process is quite difficult, which is also contrary to the social responsibility of battery recycling.
2. Improving the corrosion rate of positive plates is an acceptable method for short life batteries, but obviously not for long-life batteries.
3. Use a small internal catalyst to remove excess oxygen in the battery and allow the negative plate to replenish electricity naturally.
It was not until 1998, when the birth of the VRLA catalyst product, that it changed this situation. In 1998, American PS company began making the catalyst used for VRLA batteries. A large VRLA battery manufacturer has incorporated catalyst into one of their production lines. In the 1998 international telecom energy conference, the PS company announced the decisive test results, and impressed people show how high quality VRLA battery in less than 2 years of accelerated test time suffered almost 50% of the capacity loss, and installed the catalyst battery maintains 100% capacity, and the polarization of the negative plate more "healthy".
By year of 2000, a second generation of catalyst, called MicrocatTM by Philadelphia Technology, was on the market. The obvious advantages of this generation of catalyst were the addition of gas filtration, temperature limitation, and a more robust construction. At the 2000 International Conference on Telecommunications and Energy, the paper published by PS company clarified the purity standards of lead and active materials required for high quality VRLA batteries. Because spectrometric tests do not have the ability to measure this low level of impurity, the purity standard is based on the Chloride test of the 1980s, which provides battery manufacturers with a simple, reliable, and inexpensive measure of final product purity.
The MicrocatTM catalyst, now mass~produced and supplied is the third generation product, These catalyst are suitable for a variety of 2 V and 12 V VRLA batteries.
