An electric vehicle with a motor of more than 500W is called an electric motorcycle or an electric motorcycle, and its battery is always fixed on the vehicle, which is inconvenient to disassemble and charge. Anything below 500W is called an electric car. Most batteries are fixed in a box, which can be disassembled for charging.
The battery of electric vehicle is the power source of electric vehicle. Most electric vehicles are equipped with lead-acid batteries, which have low cost and high cost performance. Because this kind of battery can be used repeatedly, it is called "lead-acid battery".
1860, Plante of France invented the battery with lead as the electrode, which is the predecessor of lead-acid battery.
Extended data:
Electric vehicle battery type:
There are four kinds of power batteries that can be used for electric bicycles, namely valve-regulated lead-acid maintenance-free batteries, colloidal lead-acid batteries, nickel-hydrogen batteries and lithium-ion batteries.
Lead-acid battery:
Lead-acid batteries are widely used and studied by all kinds of electric vehicles in various countries because of their low price, rich material sources, high specific power, mature technology and manufacturing process and high resource recovery rate.
As a labor-saving, convenient, fast, comfortable, cheap and zero-emission personal means of transportation, electric bicycle has been widely accepted by people and paid attention to by relevant state departments. The light electric vehicle industry development strategy research group, which is attended by the State Council Development Research Center, National Development and Reform Commission, Ministry of Construction and Ministry of Science and Technology, has put forward the "Light Electric Vehicle Industry Development Strategy Report".
The number of electric bicycles in China has reached more than 30 million. More than 95% of electric bicycles use VRLA batteries.
The vast majority of commercial electric bicycles are sealed lead-acid batteries, which do not need to be replenished frequently and are maintenance-free. The main chemical reactions are: PbO2+2H2SO4+Pb← charge and discharge → 2PbSO4+2H2O.
Sponge lead, which becomes the cathode and anode of lead sulfate when the lead-acid battery is charged, releases the sulfuric acid component fixed in it into the electrolyte, which becomes sponge lead and lead oxide respectively, and the sulfuric acid concentration in the electrolyte keeps increasing; On the contrary, lead oxide in the anode and sponge lead on the cathode plate react with sulfuric acid in the electrolyte to generate lead sulfate, and the concentration of sulfuric acid in the electrolyte decreases continuously.
When the lead-acid battery is under-charged, the lead sulfate of the positive and negative plates cannot be completely converted into sponge lead and lead oxide. If it is not charged for a long time, lead sulfate will crystallize, which will sulfide the electrode plate and deteriorate the quality of the battery.
On the other hand, if the battery is overcharged, the amount of oxygen produced by the anode is greater than the adsorption capacity of the cathode, which will increase the internal pressure of the battery, lead to gas overflow, reduce electrolyte, and may also lead to softening or shedding of active substances, thus greatly shortening the battery life.
The comprehensive performance is greatly improved:
In recent 10 years, the comprehensive performance of VRLA batteries for electric bicycles has been greatly improved. Take 6-DZM- 10 battery as an example. 1997 battery capacity is insufficient, and the discharge capacity at 2h rate (5A) can't reach 10Ah. The specific energy is low, and the specific energy of 2h rate is less than 30 wh/kg; Short life, the cycle life of 100% discharge depth is only 50~60 times (before the capacity drops to 8Ah; The same below), the service life is only 3 to 5 months.
By 2003, the discharge capacity at 2h rate (5A) will reach11~13ah; 2h rate specific energy reaches 33 ~ 36 wh/kg; The cycle life of 100% discharge depth reaches 250~300 times, and the service life can reach 12 months or more. The problem of VRLA battery for electric bicycle has been basically solved.
The deep cycle life performance of this kind of battery has made a new breakthrough. The main performance is as follows: 2h rate (5A) the first discharge capacity reaches14ah; 2h rate specific energy reaches 38 h/kg; The cycle life of 100% discharge depth exceeds 400 times, the total discharge capacity is 4500Ah, and the corresponding cumulative mileage is about 18000km (calculated by 4km/Ah, the same below).
The maximum deep cycle life is over 600 times, the total discharge capacity is 665,438+0,565,438+0 Ah, and the corresponding cumulative mileage is about 24600km. If the capacity below 7Ah is used as the end of life mark, the deep cycle life is 943 cycles, the total discharge capacity is 87 10Ah, and the corresponding cumulative mileage is about 34800km.
If the deep cycle life of the battery pack is 250 times or the total capacity is 2250Ah, and the corresponding cumulative mileage is 9000km, the battery pack can be used 1 year.
Pay attention to the matching with the charger;
In many years' practice, electric bicycle manufacturers and battery manufacturers have gradually realized the importance of matching batteries with related equipment of electric drive system, especially with chargers.
Manufacturing quality is the premise of battery quality, but only when it is used with a matching charger can the superior performance of high-quality batteries be fully exerted, otherwise the potential superior performance of high-quality batteries cannot be fully exerted.
Due to the different formula, structure and acid concentration of batteries from different manufacturers, the applicable charging parameters are also different. For example, in the study, we found that the charging parameters of different manufacturers' batteries in the constant voltage stage can be different by 1.5~2.0V (for 36V batteries).
The basic requirements of appropriate charging parameters are: to ensure that the battery can be fully charged, and the battery capacity will not be abnormally attenuated due to insufficient charging; It is also necessary to ensure that the battery will not be seriously dehydrated and thermally out of control due to overcharge during its entire life.
Lead storage battery for pure electric vehicle;
The open-ended lead-acid batteries used in early pure electric vehicles adopted the research results during the Eighth Five-Year Plan period, and achieved successful experience of 19 months (120,000 kilometers). The key is to accumulate a set of system matching work experience and careful maintenance experience, such as controlling charging mode, discharging depth and timely water replenishment.
In recent years, four-wheeled miniature electric vehicles (including tour buses, patrol cars, golf carts, short-distance road vehicles, etc.). ) has developed rapidly, and most of them are open lead-acid batteries. The corresponding models of batteries are favored by battery manufacturers.
The new product of valve-regulated sealed lead-acid battery is adopted for electric vehicles, and its performance is as follows: the specific energy at 3h rate is 55 a, and the specific energy at h3h rate is 33Wh/kg and 84wh/l respectively; The cycle life of 75% discharge depth reaches more than 400 times.
It is believed that the successful experience of VRLA batteries for electric bicycles can be extended to VRLA batteries for pure electric vehicles, and the performance will be further improved.
Lead storage battery for hybrid electric vehicle;
At present, hybrid electric vehicles are basically divided into three categories: mild hybrid (that is, the electrical system is mainly used to start and recover braking energy, and the 42V electrical system to be popularized on all vehicles belongs to this type), moderate hybrid (that is, the electrical system is used to start and recover braking energy and travel in short and medium distances) and heavy hybrid (that is, the electrical system is used to start and recover braking energy and travel in long distances, also known as "plug-in").
Literature at home and abroad has made it clear that valve-regulated lead-acid batteries have advantages in light hybrid electric vehicles, mainly low cost, mature technology and reliable performance.
ALABC (Advanced Lead-acid Battery Consortium) is organizing the development of valve-regulated lead-acid batteries for moderate hybrid electric vehicles, and preparing to compete with MH-Ni batteries for the market of moderate hybrid electric vehicles. Now, the wound bipolar battery and TMF (metal film) battery have been put on the market and tested in the car. In the field of heavy-duty hybrid vehicles, the specific energy of lead-acid batteries is low, which can not meet the requirements of long-distance driving of electric systems. ?
Colloidal battery:
It is an improvement of common liquid electrolyte lead-acid battery. It uses gel electrolyte and there is no free liquid in it. Under the same volume, the electrolyte has large capacity, large heat capacity and strong heat dissipation ability, which can avoid the thermal runaway phenomenon that is easy to occur in general storage batteries. Low electrolyte concentration, weak corrosion to electrode plate; Uniform concentration, no acid stratification.
Nickel-hydrogen battery:
Ni-MH battery is a new star in the battery family that rose in the 1990s and developed rapidly.
The electrode reaction of Ni-MH battery is as follows:
Positive electrode: Ni(OH)2+OH-= NiOOH+H2O+e-
Negative electrode: m+H2O+e = mhab+oh-ni (oh) 2+m = niooh+mhab.
It belongs to the same alkaline battery as the Ni-cd battery, except that the negative electrode material Cd in the Ni-Cd battery is replaced by hydrogen-absorbing alloy material (mh), and the electromotive force is still1.32v v, which has all the excellent characteristics of Ni-Cd battery and the energy density is higher than that of Ni-Cd battery. The main advantages are: high specific energy (long charging distance).
High specific power, stable discharge even under high current (good climbing acceleration); Good low temperature discharge performance; Long cycle life; Safe and reliable, maintenance-free; No memory effect; There is no pollution to the environment, and it can be recycled, which conforms to the concept of sustainable development. However, the cost of Ni-MH battery is too high, too expensive.
Lithium ion battery:
Lithium-ion battery is a new type of high-energy battery first introduced to the market by Sony Corporation of Japan in 1990. Its advantage is high specific energy, which is the battery with the highest specific energy at present. It has been widely used in portable information products.
Lithium-ion batteries are generally considered to have the following advantages: large specific energy; High specific power; Small self-discharge; No memory effect; Good cycle characteristics; Can be discharged quickly with high efficiency; Wide working temperature range; No environmental pollution, etc.
Therefore, it is expected to enter the best power supply ranks in 2 1 century. It is predicted that the market share of MH/Ni battery will decrease with the further development of lithium-ion battery during 2006-2012. The market share of lithium ion will expand. Electric bicycle products using lithium-ion batteries have been sold.
Driven by the development of new cheap cathode materials with good safety, good cycle performance and high specific capacity, lithium-ion batteries for electric bicycles are close to practical use. Several companies can provide mature lithium-ion batteries for electric bicycles equipped with battery management system (BMS). There are also electric bicycle manufacturers specializing in lithium-ion batteries.
Lithium-ion batteries for electric bicycles will be the first power batteries to be commercialized and widely used in automobiles. It will be a practical battery with a large proportion after lead storage battery, and it will also become the battery of high-end electric bicycle products. There have been many reports on large-scale tests, exhibitions and demonstrations of lithium-ion batteries in pure electric vehicles, buses and hybrid electric vehicles.
According to the current development level and experience of lithium-ion batteries, it is considered that the safety of battery packs below 48V 10Ah for electric bicycles is guaranteed, but there is still a lot of hard work to be done for large-scale lithium-ion batteries to be used in commercial electric vehicles. The main reasons are pure electric vehicles and electric buses.
Moreover, the number of batteries used in hybrid electric vehicles is large, the system is complex, the safety is more difficult, the requirements for reliability and consistency are higher, and the price is too high. It is reported that Shenzhen BYD will provide a taxi fleet of 200 electric vehicles powered by lithium-ion batteries in 2005, but the plan has been postponed to 2007.
Fuel cell:
Fuel cells directly convert chemical energy into electrical energy and supply it to motor-driven vehicles. Its main advantages are: high efficiency and fuel saving; Zero emission; Low noise, etc. , especially suitable for automobile power supply. Hydrogen fuel cell cars will be ideal and will eventually replace cars fueled by petroleum products.
Zinc-nickel battery (zinc-nickel);
Zinc-nickel battery was once considered as the battery of electric vehicle. Judging from the market screening in 4~5 years, it is hardly used for commercial electric vehicles. This is mainly due to the high price of zinc-nickel battery (VAh 2.5 ~ 4 yuan per battery, which is 4~6 times that of lead battery).
In the cycle process, the initial capacity decay rate is large, which affects the actual service life of the battery pack. In addition, the rapid development and price drop of lithium-ion batteries make the application of zinc-nickel batteries in electric vehicles even less competitive.
Zinc-air battery:
Zinc-air battery is a kind of metal-air battery, which belongs to the category of semi-fuel battery. It has the advantages of high specific energy, abundant raw materials, low price and no pollution, and is considered as a competitive candidate material for electric vehicle batteries.
Chinese-Americans once set up PowerZinc Company in Shanghai to produce mechanical rechargeable zinc-air batteries, and now a demonstration workshop has been built. The mileage of manufactured electric bicycles and electric motorcycles loaded with zinc-air batteries was tested, reaching 150km and 250km respectively, and a lot of popularization and application work was done, and 50 battery replacement points were established in Shanghai.
But less than 1 year, this promotion and trial work stopped, and the results of market screening were not accepted by users. Later, with the support of some leaders, the electric bus was built with the manufactured zinc-air battery as the power source. However, due to the poor high power performance of zinc-air battery, the starting and acceleration performance of automobile is obviously poor. A lot of work has been done at home and abroad in developing zinc-air batteries for electric vehicles.
In recent years, the research and development of zinc-air battery for electric vehicles in China has revived, but the practice has confirmed the original advantages of zinc-air battery, and at the same time exposed some problems that have been reported abroad, such as the replacement service system and regeneration cost of zinc electrode, the life of oxygen electrode, the leakage, leakage or overflow of battery electrolyte, etc.
Baidu encyclopedia-electric vehicle battery