- Colloidal lead-acid battery
Lead-acid batteries have been the most widely used chemical power sources in military and civilian fields since their inception to the present. Since it uses sulfuric acid electrolyte, acid will flow out during transportation, and acid mist will be precipitated during charging, which will cause damage to the environment and equipment. People try to “fix” the electrolyte and “seal” the battery. So the lead-acid battery using colloidal electrolyte came into being. A colloidal lead-acid battery is simply a battery that uses a colloidal electrolyte. The colloidal lead-acid battery is a kind of lead-acid battery. The simplest method is to add a gelling agent to the electrolyte to make the electrolyte into a colloidal state.
The difference between colloidal lead-acid batteries and ordinary lead-acid batteries is not only that the electrolyte is changed to gel, but also that it is further developed to study the electrochemical characteristics of the electrolyte basic structure, as well as its application in grids and active materials. For example, the non-solidified water-based colloidal lead-acid battery is the same as the colloidal lead-acid battery in terms of electrochemical classification and characteristics. For another example, the use of polymer materials in the grid, commonly known as ceramic grid, is a feature of colloidal lead-acid batteries. Recently, some laboratories have added a targeted coupling agent to the plate formula, which greatly improves the reaction utilization rate of the active material of the plate.
The colloidal lead-acid battery is a sealed structure, and its electrolyte is gel, no leakage, no acid mist and no pollution when charging and discharging. It is an environmentally friendly product that is vigorously promoted and applied by the country. The most important features of colloidal lead-acid batteries are: the discharge curve is flat, the inflection point is high, the specific energy, especially the specific power, is more than 20% larger than that of ordinary lead-acid batteries, and the service life is generally about twice as long as that of ordinary lead-acid batteries. Strong capacity; small self-discharge, resistant to storage; good over-discharge recovery performance, high-current discharge capacity increased by more than 30% compared with ordinary lead-acid batteries: good low-temperature performance, stable high-temperature characteristics, and meet the environmental requirements of 65 ℃ or higher; Long cycle life, can reach 800~1500 charge and discharge times, the industrial cost per unit capacity is lower than that of ordinary lead-acid batteries, and the economic benefit is high. (We also provide high quality Tycorun Battery for you to choose)
The quality of the colloid and the filling process have an important influence on the quality of the colloidal lead-acid battery, and the design, manufacturing process and application conditions (especially the charging and discharging process) of the colloidal lead-acid battery restrict the performance of the colloidal lead-acid battery. The properties of the gel must be compatible with the structure and usage conditions of the battery. The structure and use conditions of the sealed battery are conducive to the stability of the colloid, and the characteristics of the colloid make the performance of the sealed battery more perfect. Modern high-quality colloidal lead-acid batteries are VRLA batteries, and colloidal lead-acid batteries made from semi-finished products of ordinary lead-acid batteries without modification are also controversial issues recently.
Colloidal filling, gel stability and ensuring battery capacity are the three key technologies for colloidal lead-acid batteries. The colloidal lead-acid batteries produced by German Sunshine Company have very low colloidal viscosity. Even large colloidal lead-acid batteries are filled with colloidal lead-acid batteries like dilute sulfuric acid. The colloid is fully gelled in the battery, and it is a uniform paste-like gel inside and outside the pole group. During the entire life of the colloidal lead-acid battery, there is no liquefaction phenomenon at all, which is difficult for the colloidal lead-acid battery produced in my country. . Sunshine’s technology is the most advanced in the world. Its Dryfit series gel lead-acid batteries are safe, reliable, and have a long service life. They are the best gel lead-acid batteries in the world. However, the specific energy and high current discharge of the colloidal lead-acid battery produced by Sunshine Company are not as good as that of the AGM-VRLA battery (that is, the valve-regulated sealed lead-acid battery with ultra-fine glass fiber diaphragm). In addition, Sunshine Company’s polar plate formation process is complex and the production cycle is long. Some varieties of colloidal lead-acid batteries need to go through 10 charge-discharge cycles before leaving the factory, which reduces production efficiency and increases product costs, which is not conducive to large-scale product development. compete with the market.
VRLA batteries use two ways to fix the electrolyte, one is to fix the electrolyte through AGM, and the other is to fix the electrolyte through the colloid structure. But C&D Technologies in the United States combines the two methods to fix the electrolyte, called composite technology. In the definition of colloidal lead-acid battery, it is only mentioned that the electrolyte is gel-like (intuitively, it is jelly-like), and there is no provision for the use of separators, so as long as gel is used to fix the electrolyte, the battery will be It can be called colloidal lead-acid battery.
Regardless of whether liquid SiO2 or gas phase SiO2 is used, the principle of gel formation is the same, and there are differences in particle size and purity between them, so adding a battery will have a greater impact on the performance of the battery. The strength of the gel is proportional to the content of SiO2 and acid, and the greater the strength, the less likely it is to hydrate and crack.
The internal resistance of the colloidal lead-acid battery is proportional to the content of SiO2 in the colloid, so the high-rate discharge (above 3C) of the colloidal lead-acid battery is worse than that of the AGM-VRLA battery of the same structure, but the rated capacity is higher than that of the AGM-VRLA of the same structure. The battery is 5%~10% larger. Colloidal lead-acid batteries using special separators such as PVC-SiO2 or phenolic resin have a smaller rated capacity than AGM-VRLA batteries due to their content. If PVC or PE is used as the separator, the SiO2 content must be quite high to form a stable colloid. The colloidal lead-acid battery produced by composite technology has a floating charge life of 1.5 to 2 times that of the AGM-VRLA battery with the same structure, and the cycle capacity can be increased by 20%.
Almost all the major companies producing lead-acid batteries in the world produce colloidal lead-acid batteries, such as Sunshine, Hagen in Germany, DEKA, Trojan, Exide, SEC in the United States, etc. YUASA in Japan does not produce colloidal lead-acid batteries, but its UXL series There are colloidal components in the battery, and its main function is to reduce the stratification of the electrolyte. In application, it is mainly used in solar energy, power battery, etc. Its market is relatively large, and the price is about 20% higher than that of AGM-VRLA battery.
Among the large enterprises in China, there are Shuangdeng, Shenzhen Xiongtao and other companies that produce colloidal lead-acid batteries. Shuangdeng’s GFM series adopts tubular polar plates, generally PVC-SiO2 separators and phenolic resin separators. Guangdong Panyu Hengda After three years of research, the research group of the battery factory has developed two kinds of colloidal lead-acid batteries, one uses AGM separator, its technology is the same as that of C&D Technology Company, and the other uses PVC-SiO2 separator, its technology is the same as The same as DEKA.
- The structure of colloidal lead-acid battery
The colloidal lead-acid battery is an improvement of the ordinary lead-acid battery with liquid electrolyte. The colloidal electrolyte is used to replace the liquid electrolyte, which is improved compared with the ordinary lead-acid battery in terms of safety, storage capacity, discharge performance and service life. The colloidal lead-acid battery adopts a gel-like electrolyte, and there is no free liquid inside. Under the same volume, the electrolyte capacity is large, the heat capacity is large, and the heat dissipation ability is strong, which can avoid the thermal runaway phenomenon of AGM-VRLA battery. The corrosion effect of the plate is weak; the concentration is uniform, and there is no stratification of the electrolyte.
The performance of the colloidal lead-acid battery is better than that of the AGM-VRLA battery. The colloidal lead-acid battery has stable performance, high reliability, long service life, strong adaptability to ambient temperature (high and low temperature), and can withstand long-term discharge capacity, It has strong cyclic discharge capacity, deep discharge capacity and high current discharge capacity, and has the advantages of overcharge and overdischarge self-protection.
At present, the domestic colloidal lead-acid battery is poured into the AGM separator by vacuum infusion, and the silica gel and sulfuric acid solution are poured between the positive and negative plates of the battery. The colloidal lead-acid battery cannot carry out oxygen circulation in the early stage of use, because the colloid surrounds the positive and negative plates, the oxygen generated on the positive plate cannot diffuse to the negative plate, and cannot achieve lead reduction with the active material on the negative plate. Oxygen can only be discharged by the safety valve, which is consistent with the flooded battery.
After the colloidal lead-acid battery is used for a period of time, the colloid begins to crack and shrink, resulting in cracks, and oxygen goes directly to the negative plate through the cracks for oxygen circulation. At this time, the safety valve is no longer opened frequently, the colloidal lead-acid battery enters the sealing work, and the water loss is very small. A colloid stabilizer and a compatibilizer are added to the colloid electrolyte, and some colloid formulations also contain a retarder that delays the coagulation of the colloid, so as to facilitate the filling of the colloid. The colloidal lead-acid battery electrolyte is fixed by gas silica and various additives. It is liquid when injected and can fill all the spaces in the battery.
- Advantages and disadvantages of colloidal electrolytes
Compared with ordinary liquid electrolytes, colloidal electrolytes have the following advantages:
(1) The sulfuric acid is uniformly solidified and distributed by the colloid, and there is no problem of concentration stratification. The colloidal lead-acid battery can be placed vertically or horizontally. Ultra-pure materials and colloids ensure that the colloidal lead-acid battery has a floating service life of more than 10 years under normal conditions, which can significantly extend the service life of the battery. According to the relevant literature, the battery life can be extended by 2 to 3 times.
(2) Good maintenance-free performance. Due to the use of colloidal electrolyte, the self-discharge performance of colloidal lead-acid batteries has been significantly improved. Under the same sulfuric acid purity and water quality, the storage time of colloidal lead-acid batteries can be extended by more than 2 times. It can be stored for two years and can be used without charging, and the capacity of the 2V series remains above 99.9% after standing for two months.
(3) The colloidal lead-acid battery has obvious anti-vulcanization performance in the case of serious power shortage.
(4) There is no memory effect (N times) of charge and discharge, strong recovery ability under severe discharge conditions, large rebound capacity, short recovery time, and can still be used in an emergency after a few minutes of discharge.
(5) The colloidal lead-acid battery has strong charge acceptance ability, and the nano-colloid and special alloy ensure the good charge acceptance ability of the colloidal lead-acid battery. It has strong anti-overcharge ability, good deep cycle ability, and good overcharge and overdischarge ability. After repeated deep discharge to 0V, it can still recover normally, which can reduce the lower limit protection of 1.75V per cell, which is very important for deep cycle batteries.
(6) The late discharge performance of colloidal lead-acid batteries has been significantly improved.
(7) The colloidal lead-acid battery will not have liquid leakage, acid leakage, etc., and the outgassing volume is small, and the environmental damage is very small.
(8) Good low temperature characteristics. Ordinary lead-acid batteries have a sharp drop in capacity when used in an environment below 0°C, while colloidal lead-acid batteries are suitable for a variety of harsh environments. It can be used normally in the environment of -40℃~+70℃. At -20°C, more than 80% of the rated capacity can still be released.
Although colloidal electrolytes have many of the above advantages, they also have certain disadvantages, which are manifested in the following aspects:
(1) Compared with ordinary electrolyte, colloidal electrolyte is more difficult to add, which needs to be changed by changing the colloidal formula and adding retarder.
(2) If the production process is unreasonable or poorly controlled during the preparation of the colloid, the initial capacity of the battery will be relatively small. (3) The colloidal lead-acid battery’s early exhaust gas contains acid, and the colloidal particles are easily attached to the outer casing of the battery, so it reflects the phenomenon of false acid leakage of the battery.
(4) Although the oxygen cycle inhibits water loss, the excellent oxygen cycle also generates heat, which makes the internal temperature rise of the battery higher.
Experience shows that colloidal lead-acid batteries need to formulate a complete set of technological processes in terms of plate production, colloidal electrolyte formulation, filling method, charging process, etc., to ensure better performance of colloidal lead-acid batteries.
Read more: What are the characteristics of the discharge of a VRLA battery?