What are the battery types of pure electric vehicles?

From the big category, there are two major types of batteries for electric vehicles: batteries and fuel cells. The battery is suitable for pure electric vehicles, including lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries, sodium-sulfur batteries, secondary lithium batteries and air batteries. Among them, lead-acid batteries, nickel-cadmium batteries and nickel-hydrogen batteries have appeared relatively early, and are also the types of batteries that have been generally eliminated. Today, mainstream pure electric vehicles are basically lithium batteries, mainly including lithium cobalt oxide batteries, such as Tesla products; lithium manganese oxide batteries such as Toyota Prius, Nissan Leaf; lithium iron phosphate batteries such as BYD products, ZINORO 1E and so on.

Lead-acid batteries are the most commonly used new energy vehicle batteries. The plates of lead-acid batteries are grids made of lead alloy, the electrolyte is dilute sulfuric acid, and both plates are covered with lead sulfate. However, after charging, the lead sulfate on the positive electrode plate is converted into lead dioxide, and the lead sulfate at the negative electrode is converted into metal lead. When discharging, a chemical reaction in the opposite direction occurs. The advantage of the lead-acid battery is that the electromotive force is relatively stable during discharge, and the disadvantage is that the specific energy is small and the environment is corrosive.

Nickel-metal hydride batteries have a wide range of applications in hybrid new energy vehicles. They have a large energy density ratio and can effectively extend the travel time of vehicles. Moreover, nickel-metal hydride batteries have stable discharge characteristics, smooth discharge curves and low heat generation. The volume is too large and there is pollution.

Lithium-ion batteries have advantages such as high operating voltage, large specific energy, small volume, light weight, long cycle life, low self-discharge rate, no memory effect, no pollution, etc. compared with lead-acid batteries and nickel-hydrogen batteries. The more car manufacturers choose to use lithium-ion batteries as the power battery for pure electric vehicles.

There are three kinds of lithium ion batteries, which are lithium cobalt oxide batteries, lithium manganese oxide batteries, and lithium iron phosphate batteries. Lithium cobaltate battery has high efficiency, large discharge current, high charging speed and light weight; but the disadvantage is that the stability is relatively poor, which is why this battery technology is difficult to manufacture large-capacity battery cells. The lithium manganate battery has a slightly lower cost and is not as radical as lithium cobalt oxide, and has good low temperature performance, and is more suitable for use in cold regions, but the high temperature stability is not excellent enough, and it is easy to bulge, and the cycle life is attenuated faster.

lithium iron phosphate battery is called the safest vehicle battery technology, because the stability of lithium iron phosphate battery, especially at high temperature, is stable compared to lithium cobalt oxide battery and lithium manganese oxide battery. Many, the chance of an accident such as a fire in an unexpected situation is also smaller. However, lithium iron phosphate batteries are not as efficient as the two battery technologies mentioned above. The weight required to store the same energy is about twice that of lithium cobalt oxide batteries. It is no wonder why this new battery technology is difficult to become a high-performance electric sports car.

According to the types of electric vehicle batteries currently used in the market, it can be roughly divided into: lead-acid batteries, lithium-ion batteries, and nickel-hydrogen batteries. However, a large number of sealed lead-acid colloid batteries are now in the electric vehicle field, and lithium batteries are also due to its volume. Small, long life and flexible charging methods are also favored by the majority of users, but the high price makes many customers stay away from it.

Lead-acid batteries have the lowest price, good safety and are most commonly used. China is the world's largest producer of lead-acid batteries. It contains less contaminated components and is recyclable. The disadvantage is that the volume is small. That is to say, under the same capacity, the battery is heavy and bulky. Colloidal batteries are a developmental classification of lead-acid batteries. The simplest method is to add a gelling agent to the sulfuric acid to make the sulfuric acid electro-hydraulic into a colloidal state. A battery in which electro-hydraulic is colloidal is often referred to as a colloidal battery. Broadly speaking, the difference between a colloidal battery and a conventional lead-acid battery is not only that the electro-hydraulic is changed to gelatinous. For example, non-solidified aqueous colloids are the same colloidal battery from the electrochemical classification structure and characteristics.

The specific volume of a lithium-ion battery is better than that of a nickel-metal hydride battery. For a lead-acid battery of the same capacity, the weight of a lithium-ion battery is equivalent to a laptop, so that both old and weak women and women can use it. However, there is the possibility of explosion and burning, which is a problem that needs to be solved with lithium ion batteries.

The specific volume of nickel-metal hydride batteries is much better than that of lead-acid batteries. The life of single-cell batteries is also good, and the high-current charge-discharge characteristics are better than lead-acid batteries. The problem is that there are many management problems in the series of nickel-hydrogen battery series. Once the charging occurs, the problem of melting of the single-cell separator will be formed, resulting in rapid failure of the entire battery. Therefore, the key technical problem of the domestic nickel-metal hydride battery is the problem of the charger and the battery management system, and this problem has not caused enough attention of the battery manufacturers and the manufacturers. Therefore, the development of nickel-hydrogen batteries has received great constraints.

Electric vehicle batteries include lead-acid batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lithium-ion batteries, polymer lithium batteries, zinc-air batteries, and fuel cells. Among them, the battery is divided into valve-regulated lead-acid maintenance-free battery, colloidal lead-acid battery, nickel-metal hydride battery and lithium-ion battery.

The main use of lead-acid batteries and lithium batteries, lead-acid batteries are cumbersome, but the price is cheap, the performance is stable, the technology is relatively mature; lithium batteries, the price is more expensive, but the use time is longer, portable. I bought a Tianneng lead-acid battery from Daoyixing Mall in April of last year. Now I feel that it is still good. The battery still needs more maintenance.

Electric vehicle battery is the power source on electric vehicles. Most of the current electric vehicles are equipped with lead-acid batteries. The lead-acid batteries are low in cost and cost-effective. Because this battery can be charged and can be used repeatedly, it is called a “lead-acid battery”.

In 1860, France's Plante invented a battery using lead as an electrode, which is the precursor of a lead-acid battery. ,

The following four types of power batteries can be used by electric bicycles, namely valve-regulated lead-acid maintenance-free batteries, colloidal lead-acid batteries, nickel-metal hydride batteries, and lithium-ion batteries.

Lead-acid batteries

Lead-acid batteries are widely used and widely studied by various electric vehicles in various countries because of their low price, abundant material sources, high specific power, mature technology and manufacturing processes, and high resource recovery rate. As a labor-saving, convenient, fast, comfortable, inexpensive, zero-emission personal vehicle, electric bicycles have been widely accepted and valued by relevant state departments. The Research Group on the Development Strategy of Light Electric Vehicle Industry, which was participated by the Development Research Center of the State Council, the National Development and Reform Commission, the Ministry of Construction, and the Ministry of Science and Technology, put forward the report on the “Study on the Development Strategy of Light Electric Vehicle Industry”. The number of electric bicycles in the country 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 reaction is: PbO2+2H2SO4+Pb←Charging, Discharging→2PbSO4+2H2O

When the lead-acid battery is charged, the spongy lead of the yttrium-yang pole which becomes lead sulfate releases the sulfuric acid component fixed therein into the electrolyte, and becomes sponge lead and lead oxide, respectively, and the concentration of sulfuric acid in the electrolyte is continuously increased; The lead oxide in the anode during discharge and the spongy lead on the cathode plate react with sulfuric acid in the electrolyte to become lead sulfate, and the concentration of sulfuric acid in the electrolyte is continuously lowered. When the lead-acid battery is not fully charged, the lead sulfate in the yin and yang plates cannot be completely converted into spongy lead and lead oxide. If the battery is insufficient for a long period of time, the lead sulfate will crystallize, the plate will be vulcanized, and the battery quality will be deteriorated; When the battery is overcharged, the amount of oxygen generated by the anode is greater than the adsorption capacity of the cathode, so that the internal pressure of the battery increases, causing gas to overflow, the electrolyte is reduced, and the active material may soften or fall off, and the battery life is greatly shortened.

Comprehensive performance has been greatly improved

In the past 10 years, the comprehensive performance of valve-regulated lead batteries for electric bicycles has been greatly improved. Take the 6-DZM-10 battery as an example. In 1997, this type of battery has insufficient capacity. The 2h rate (5A) discharge capacity is less than 10Ah; the specific energy is low, the specific energy of 2h rate is less than 30Wh/kg; the life is short, and the cycle life of 100% discharge depth is only 50~ 60 times (before the capacity dropped to 8Ah; the same below), the service life is only 3~5 months.

By 2003, the 2h rate (5A) discharge capacity reached 11~13Ah; the 2h rate specific energy reached 33~36Wh/kg; the 100% discharge depth cycle life reached 250~300 times, and the service life could reach more than 12 months. The problems with valve-regulated lead-acid batteries for electric bicycles have basically been solved.

There is a new and breakthrough in the deep cycle life performance of this type of battery. The main performances are as follows: 2h rate (5A) initial discharge capacity reaches 14Ah; 2h rate specific energy reaches 38Wh/kg; 100% discharge depth has a cycle life of more than 400 times, total discharge capacity is 4500Ah, and the corresponding cumulative mileage is about 18000km (to 4km) /Ah, the same as below). The highest deep cycle life is more than 600 times, and the total discharge capacity is 6151 Ah, and the corresponding accumulated mileage is about 24,600 km. If the capacity is less than 7Ah as the end of life mark, the deep cycle life is 943 cycles, the total discharge capacity is 8710Ah, and the corresponding cumulative mileage is about 34800km. If you press the deep cycle life of 250 times or release the total capacity of 2250Ah, the corresponding accumulated mileage of 9000km can be guaranteed for 1 year.

Pay attention to the match with the charger

In the practice of many years of use, the whole vehicle manufacturers and battery manufacturers of electric bicycles have gradually recognized the importance of matching between the battery and the electric drive system related equipment, especially the matching with the charger. Manufacturing quality is a prerequisite for battery quality, but it can only be used with its matching charger to achieve the superior performance of high-quality batteries, otherwise high-quality batteries cannot fully exert their potential superior performance.

The storage parameters of different manufacturers' batteries are different due to differences in formulation, structure, acid concentration and the like. For example, we found in the study that the charging parameters of different manufacturers' batteries in the constant voltage stage can differ by 1.5~2.0V (for 36V battery pack). The basic requirements for proper charging parameters are: to ensure that the battery can be fully charged, and that the battery capacity will not be attenuated due to under-charging; and to ensure that the battery will not be seriously dehydrated and thermally run out of control due to over-charging during the whole life.

Pure electric vehicle lead storage battery

The open lead storage battery used in the early pure electric vehicles adopted the research results during the “August 5th” planning period, and has achieved successful experience of 19 months (120,000 km). The key is to accumulate the control charging mode and depth of discharge. And timely hydration and other system matching work experience and meticulous maintenance experience. In recent years, four-wheeled miniature electric vehicles (including tour buses, patrol cars, golf carts, short-distance road vehicles, etc.) have developed rapidly, and most of the cars used are open lead batteries. The battery of the corresponding model is favored by the battery manufacturer.

The electric vehicle adopts a new valve-regulated sealed lead storage battery. Its performance is: 3h rate capacity 55Ah; specific energy is 33Wh/kg and 84Wh/L at 3h; the cycle life of 75% discharge depth is more than 400 times. It is believed that the successful experience of valve-controlled lead storage batteries for electric bicycles can be extended to valve-controlled lead storage batteries for pure electric vehicles, and the performance will be further improved.

Lead battery for hybrid electric vehicles

Hybrid electric vehicles are now divided into three categories: lightly hybrid (ie, electric systems are mainly used to start and recover braking energy, 42V electric systems that will be promoted in all cars belong to this type), moderately mixed (ie electric) The system is used to start, recover braking energy and medium and short distance travel), heavy hybrid (ie electric system for starting, recovering braking energy and driving over longer distances, also known as "Plug-in").

It has been clarified in domestic and foreign literatures that in lightly mixed electric vehicles, valve-regulated lead storage batteries are advantageous, mainly because of their low cost, mature technology and reliable performance; valve-controlled lead storage batteries for medium-mixed electric vehicles. ALABC (Advanced Lead-Acid Battery Complex) is being developed to prepare for the market of moderate hybrid electric vehicles with MH-Ni batteries. Roll-on bipolar batteries and TMF (metal) have been introduced and tested on the vehicle. Thin film) battery; in the field of heavily mixed electric vehicles, the lead battery has a low specific energy and cannot meet the driving requirements of the electric system for a long distance.

Colloidal battery

It is an improvement of ordinary lead-acid batteries for liquid electrolytes. It adopts gelatinous electrolyte, and there is no free liquid inside. In 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 that is easy to be generated in general batteries; the electrolyte concentration is low, and the corrosion of the plates is weak. The concentration is uniform and there is no acid stratification.

Nickel-metal hydride battery

(Ni-MH)

Nickel-metal hydride batteries are a newcomer to the battery family that emerged in the 1990s and are growing rapidly. The electrode reaction of the Ni-MH battery is:

Positive electrode: Ni (OH)2+OH-=NiOOH+H2O+e-

Negative electrode: M+H2O+e=MHab+OH-Ni(OH)2+M=NiOOH+MHab

It is the same alkaline battery as the nickel-cadmium battery. It only replaces the cadmium cd of the negative electrode material in the nickel-cadmium battery with the hydrogen storage alloy material (MH), and the electromotive force is still 1.32v. It has all the excellent characteristics of nickel-cadmium batteries, and its energy density is higher than that of nickel-cadmium batteries. The main advantages are: higher specific energy (longer distance for one charge); higher specific power, smooth discharge during high current operation (good ability to accelerate climbing); good low temperature discharge performance; long cycle life; safe and reliable, Maintenance-free; no memory effect; no pollution problems to the environment, renewable, consistent with the concept of sustainable development. However, Ni-MH batteries are too expensive and expensive.

Lithium Ion Battery

The lithium-ion battery is a new high-energy battery that was first introduced to the market by Sony Corporation of Japan in 1990. The advantage is that it has higher specific energy and is the current battery with the highest energy. It has been promoted and applied 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; fast discharge, high efficiency; wide operating temperature range; no environmental pollution, etc. It is expected to enter the ranks of the best power supply in the 21st century. It is expected that during the period of 2006-2012, when lithium-ion batteries are further developed, the market share of MH/Ni batteries will shrink. The lithium ion market share will expand. Electric bicycle products using lithium ion batteries have been sold.

Driven by the development of new and inexpensive cathode materials with good safety, good cycle performance and high specific capacity, lithium ion batteries for electric bicycles are close to practical. Several lithium-ion batteries for electric bicycles with a battery management system (BMS) are available. There are also electric bicycle manufacturers specializing in the production of lithium ion batteries. The author believes that the lithium-ion battery for electric bicycles will be the first commercialized, high-volume power-type battery in the car; it will be a practical battery after the lead battery, and will also be used for high-end electric The battery for bicycle products. There have been many reports on large-scale lithium-ion batteries in pure electric cars and electric buses, as well as trials on hybrid electric vehicles. According to the current development level and experience of lithium-ion batteries, it is considered that the safety of 48V10Ah battery packs for electric bicycles is guaranteed, but the use of large-scale lithium-ion batteries for commercial electric vehicles still requires a lot of hard work. Mainly: pure electric cars and electric buses, as well as hybrid electric vehicles, the number of batteries used, the system is complex, the safety is more difficult, the requirements for reliability and consistency are higher, the price is too high. It has been reported that Shenzhen BYD will provide 200 taxi cars with lithium-ion batteries as the power source in 2005. It has been postponed until 2007.

The fuel cell

The fuel cell directly converts chemical energy into electrical energy to supply the motor to drive the vehicle. Its main advantages are: high efficiency, fuel saving; zero emissions; low noise, etc., especially suitable for vehicle power source. Hydrogen fuel cell vehicles will be ideal for replacing cars that are fueled by petroleum products.

Zinc-nickel battery (Zn-Ni)

Zn-Ni batteries have been considered as batteries for electric vehicles that should be promoted. From the market screening of 4 to 5 years, it is almost never used on commercial electric vehicles. This is mainly due to the high price of Zn-Ni battery (2.5 to 4 Yuan per VAH, 4 to 6 times that of lead storage battery); during the cycle, the initial capacity attenuation rate is large, which affects the actual usable life of the battery pack. In addition, the rapid development and price reduction of lithium ion batteries make Zn-Ni batteries less competitive in electric vehicles.

Zinc air battery

Zinc air battery is a kind of metal-air battery and belongs to the category of semi-fuel battery. It has the advantages of high energy, abundant raw materials, low price, no pollution, and is considered to be a competitive candidate for batteries for electric vehicles.

American Chinese have set up Power Zinc in Shanghai to produce mechanically rechargeable zinc batteries, and have built demonstration workshops. The manufactured electric bicycles and electric motorcycles were loaded with zinc-air batteries for driving mileage tests, reaching 150km and 250km respectively, and a large number of promotion and application work were carried out, and 50 battery replacement points were established in Shanghai. However, in less than one year, the promotion of the trial work stopped, and the results of the market screening were not accepted by the users. Later, with the support of some leaders, an electric bus with the zinc-air battery manufactured by the manufacturer was used as the power source. However, due to the poor power performance of the zinc-air battery, the starting and acceleration performance of the vehicle was significantly worse. Much work has been done at home and abroad in the development of zinc-air batteries for electric vehicles. In recent years, the development of zinc-air batteries for electric vehicles in China has re-emerged, but the practice has confirmed the superiority of zinc-air batteries, and also exposed some problems that have been reported abroad, such as zinc electrode replacement service system and regeneration cost, life of the oxygen electrode, leakage of the electrolyte of the battery, leakage or overflow.

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