Introduction to new energy battery technology and corresponding types
1. New energy lithium battery
The energy storage per unit mass of lithium-ion battery is three times that of lead-acid battery, and the lithium polymer battery is four times that of lead-acid battery. Moreover, lithium resources are abundant and the price is not very expensive. It is a potential vehicle battery.
Lithium battery has the advantages of large specific energy, light weight, small volume, long cycle life, low self discharge rate, no memory effect and low environmental pollution. It is the research hotspot of energy storage technology in various countries.
Lithium is a very active metal and will react strongly with water. Therefore, in order to maintain the long life of lithium battery, the moisture content must be reduced to less than 30ug / g.
New energy lithium batteries mainly include lithium ion batteries, lithium iron phosphate batteries and polymer lithium batteries. There are three main production technologies of these batteries: winding type and laminated type.
Winding type: it is mainly the production method used for cylindrical lithium batteries, which is more suitable for the production of low-capacity batteries, such as 18650 batteries. The winding type has high internal resistance because the winding type cell is usually a single pole lug.
Different internal resistance leads to different heat generation in the charge discharge cycle of the finished battery and different attenuation speed of the battery capacity. It is obvious that the attenuation of the battery capacity of the laminated battery is slower.
Lamination process is equivalent to multi pole pieces connected in parallel, which is easier to complete high current discharge in a short time, which is conducive to the rate performance of the battery. The winding process is just the opposite, and a single polar ear leads to slightly poor magnification performance.
Lamination: the electric core produced by lamination process has low internal resistance, and the laminated electric core can be regarded as multipole lug type, which greatly reduces its internal resistance.
With the continuous charge discharge cycle, heat will be generated in the battery, which will then affect the temperature of the battery. For the laminated battery, the internal temperature distribution is relatively uniform, while for the wound battery, because there is only one-way heat transfer between the pole piece and the diaphragm, the phenomenon of temperature gradient distribution is more serious, resulting in the phenomenon of internal high temperature and external low temperature. The uneven temperature distribution leads to the inactivation of active substances at high temperature during the charging and discharging process of the battery, which can not carry out the function of de intercalation of lithium ions, thus affecting the rapid attenuation at other locations and the performance of the battery.
2. New energy Ni MH battery
At present, nickel metal batteries used in new energy vehicles mainly include nickel cadmium batteries and nickel hydrogen batteries. Nickel cadmium batteries contain heavy metals, which will pollute the environment after being abandoned.
Ni MH battery is a kind of green nickel metal battery, which does not have the problem of heavy metal pollution. It has the advantages of high specific energy, specific power and cycle life.
However, the problems of high price, poor uniformity (especially the large capacity and voltage difference between batteries under high rate and deep discharge), high self discharge rate, performance level and practical requirements affect the wide application of Ni MH batteries in new energy vehicles.
At present, the application of domestic NiMH batteries in automobiles is still in the stage of R & D and matching, mainly purchased from abroad.
3. Supercapacitor
Supercapacitor is an energy storage device proposed to meet the requirements of real-time changes in energy and power of hybrid electric vehicles. It is generally used together with other batteries as the power supply of electric vehicles, which can meet the power requirements of electric vehicles without reducing the service life of batteries.
It is an electrochemical capacitor, which has the advantages of both battery and traditional physical capacitor: the charge and discharge process is highly reversible, high efficiency, fast second charge and discharge, high specific power, long cycle life, maintenance free and so on.
However, the specific energy of supercapacitors is small and the range is short. Improvement methods:
① combined with fuel cell or battery;
② Establish charging stations at both ends of the traffic line.
4. Fuel cell
Fuel cell is a power generation device that directly converts the chemical energy stored in fuel and oxidant into electrical energy through electrode reaction.
It has the advantages of no combustion, no rotating parts, no noise, long operation life, high reliability and good maintenance performance. Hydrogen fuel cell vehicle is a real zero emission and zero pollution vehicle. It is one of the best solutions to today's traffic and environmental problems and represents the future development direction of vehicles.
5. Solar cell
Solar cell is a device that converts light energy into electric energy. However, due to the problems of low photoelectric conversion efficiency, high price and complex battery system configuration, it can not be produced and applied on a large scale in the near future, and can only be used as a supplementary power supply for electric vehicles.
As the cleanest and inexhaustible energy, the research and application of solar energy will make great progress.
