The heart of the new energy automotive vehicle battery technology
The heart of the internal combustion engine vehicles, power systems, the heart of the new energy vehicles is the battery system, is directly related to the mileage of the vehicle, ease of use, whatever the merits of the battery system, and the current new energy dynamic models of technical the bottleneck is precisely the limit in the battery system, such as charging time, charging efficiency, energy density and volume, materials, safety or quality, etc..
Battery three classification
Car battery is divided into three categories, namely, chemical batteries and physical batteries as well as biological cells, namely: chemical batteries, chemical batteries, the battery system of the use of the chemical reaction to generate electricity, which is divided into primary cells, batteries and four kinds of fuel cells and reserve cells.
A primary cell, in fact, disposable batteries, refers to the general charge the battery put the point of active substances to recover and continue to use batteries, such as zinc - manganese dioxide batteries, lithium manganese batteries, zinc air batteries, as well as the first zinc silver battery, etc. are such a disposable battery.
The original battery works
Batteries, also known as secondary batteries means the battery discharge through the charging of the active material recovery continue to use the battery, in fact, is the most common rechargeable batteries, such as lead-acid batteries, nickel cadmium batteries nickel-metal hydride batteries and lithium-ion battery.
The battery is the most common type of battery in the car
3, fuel cells, fuel cells, also known as contact battery, refers to participate in the continuous input reflect the activity of substances from the battery external battery, or it can be said in fact, is a fuel cell power plants, such as proton exchange membrane fuel cell, the basic dye cell phosphoric acid fuel cell, and so on.
4, the reserve battery, the battery is the battery positive and negative electrodes and electrolyte is not in direct contact during storage prior to use into the electrolytic solution to the positive and negative contacts, since the battery into the status of the pending discharge, such as magnesium batteries, thermal batteries and so on.
Physical battery, battery of physical battery of light, heat, physical adsorption, physical energy generation such as solar cells, supercapacitors and flywheel battery.
Biological cells, biological cell generation battery of biochemical reactions, such as microbial fuel cells. Enzymes, cells and biological solar cells, and so on.
Microbial cell works
The requirements of the new energy vehicle battery system
As for the diesel locomotive for the various requirements of the engine, the new energy vehicle battery pack also has a harsh, which several requirements for the battery pack is directly related to the performance of new energy vehicles in electric drive:
Than the energy, the battery pack to power battery on the car need to maximize the stored energy in order to improve the mileage of the electric drive, but the premise is not too much to increase body weight, space, so you need high The specific energy.
Than power, in order to make electric drive accelerated performance. Climbing performance and load performance comparable to diesel locomotives, so the specific power of the battery pack will have a very high demand.
3, the charge-discharge efficiency of battery energy must be charge - discharge - charge cycle, high moral charge and discharge efficiency has a crucial role in driving efficiency of the electric drive.
4, the stability of the battery pack should be to maintain the stability of the performance of reciprocating conditions of rapid charge and discharge conditions of the power system to achieve a sufficient number of discharge cycles.
5, the cost, in addition to lower initial purchase cost of the battery, but also improve the battery life.
, Security, the battery can not be caused by spontaneous combustion or burning, not the occupants in the event of vehicle collision causing bodily harm.
Since the invention of the lead-acid batteries since 1958, its use and development has been 100 years of history, its widely used in diesel locomotive power end, and new energy vehicles used in lead-acid batteries because of the need to provide power for the vehicle, so it the main development direction is to improve energy, increase the life cycle use. Lead-acid battery is the most mature new energy battery systems, in 1881, an electric tricycle in the world to use lead-acid batteries hesitate to lead-acid battery is mature, reliable, inexpensive raw materials, at the same time basically to meet the specific power electric drive power requirements, so widely used in the new energy vehicles.
The advantages of lead-acid batteries:
1 In addition to the lithium-ion battery, the presence of batteries, lead-acid batteries the maximum voltage is 2.0V;
2, the manufacturing cost;
3, can be made as small as 1Ah up to several thousand Ah a variety of size and structure of the battery;
4, the high rate discharge performance, can be used for engine starting;
5, energy efficiency can reach 60%;
6, the high and low temperature performance, -40 ℃ ~ 60 ℃ under the conditions of work;
7, easy to float use, no "memory" effect, and easy to identify the state of charge.
The disadvantage of lead-acid batteries:
1, lower than the energy in the overall quality and volume occupied by the weight of the new energy, a charge can travel the course is relatively short;
2, short life, and late use of high cost;
3, the charging time is long;
4, lead, heavy metals, there is pollution, and new energy-powered car concept runs counter to.
The nickel-metal hydride battery is developed in the 1990s a new type of battery, the cathode active material mainly composed of nickel-made negative electrode active material by hydrogen alloy support, an alkaline battery. Nickel-metal hydride batteries with high specific energy, high power, suitable for high current discharge, can charge and discharge cycles, no pollution, is a form of green energy, many models of new energy power battery pack will choose the nickel-metal hydride batteries.
Battery is a nickel-metal hydride battery used by the public of the Hybrid version of the Touareg
Ni-MH battery features:
Nickel-metal hydride battery is non-polluting, high specific energy, high power, fast charge and discharge, and durable and so many features, compared with lead-acid batteries, nickel metal hydride batteries with high energy, light weight and long cycle life characteristics, but also has the following characteristics:
A high specific power, the commercialization of nickel-metal hydride battery power can reach 1350W/kg;
2, the number of cycles, a nickel-hydrogen battery packs in electric vehicles in the current application, 80% to put some depth circulation can reach more than 1,000 times, more than three times that of the lead-acid battery, 100% DOD cycle life is also more than 500 times in the hybrid car can use more than five years;
Pollution-free, nickel-metal hydride battery is no lead, cadmium and other harmful metals;
4, overcharge and over discharge, no memory effect;
5, temperature range, the normal temperature range of -30 ~ 50 ℃ Storage Temperature Range -40 ~ 70 ℃
6, safe and can withstand short circuit, crush, acupuncture, drops, heat, vibration, etc., and not an explosion or combustion phenomena.
Lithium ion battery
As early as 1990, the lithium-ion battery to market by Sony of Japan is the world's latest generation of rechargeable battery systems, want more than other batteries, the high voltage, high specific energy, charge and discharge long life, no memory effect , non-polluting, faster charging, self-discharge rate and an operating temperature range models and safety advantages, compared to the nickel-metal hydride batteries, hybrid vehicles using lithium-ion battery, but the decline in the quality of the battery system by 40% to 50% volume is reduced by 20% to 30%, energy efficiency has been raised.
Working principle of lithium-ion battery (lithium iron phosphate is only the lithium-ion battery, a branch)
Lithium-ion battery according to the different cathode materials can be divided into the manganese lithium-ion batteries, iron phosphate batteries and nickel-cobalt lithium-ion battery (nickel-cobalt-manganese-ion battery), the majority of new energy models used in the first generation of lithium-ion battery manganese lithium-ion battery are its lower cost, safe, but poor cycle life under high temperature, short life cycle, and even the dissolution of manganese ions at high temperature, most of the new energy models The second-generation battery pack used for the iron phosphate batteries, the future direction of development of the lithium-ion battery is located.
Advantages of lithium-ion battery
1, high voltage, its operating voltage of 3.6V, Ni-MH, Ni-Cd battery operating voltage 3 times;
2, high specific energy, specific energy reach to 150Wh/kg, is three times that of nickel-cadmium batteries, nickel metal hydride battery is 1.5 times;
3, long cycle life cycle life can reach more than thousand times in the low depth of discharge can reach several
Million times more than several other secondary batteries;
4, low self discharge rate, lithium-ion battery self-discharge rate of only 6 to 8 percent, well below the nickel-cadmium batteries and nickel metal hydride batteries.
5, no memory, non-polluting, free shaping.
Lithium-ion battery Disadvantages
1, high costs, mainly the high cost of the cathode material of LiCoO, but to calculate the price when the unit watt, in fact, lower than the nickel-metal hydride batteries and nickel cadmium batteries were flat, but higher than lead-acid batteries.
2, there must be special protection circuitry to prevent overcharging phenomenon.
Fuel cells (Fuel Cell, FC) is a chemical battery, the energy released when it directly to the chemical reaction into electrical energy, and work continuously to its supply of living material (material) starting to reflect the fuel and oxidizer. The hesitated It is to fuel the energy released by a chemical reaction into electrical energy, so the fuel cell. The development of fuel cell is based on electrochemistry, electro-catalytic electrode process dynamics, materials science, chemical processes and automation disciplines, and the first fuel cell hydrogen and oxygen generated by electrolysis of water use in 1839 Glover to produce the first fuel cell.
Fuel battery advantages and disadvantages
In fact, according to the working principle of fuel cell vehicles, the battery in the works of the so-called fuel cell is actually like series hybrid, the fuel cell is not a pure sense, but a transmission of electrical energy "engine" chemical energy into electrical energy delivery to the battery and then, then the power transmission to the motor, or in fact call it a series hybrid is also something that has not, but its advantages:
1, for example, its energy conversion efficiency. Over hydroxide and the role of the chemical they release energy into electrical energy, rather than through a heat process, are not subject to the limitations of the Carnot cycle;
2, no pollution. Its emissions of only pure water, edible or car does not need to take too much drinking water.
3, the structure is simple. Fuel cell vehicles (proton exchange membrane fuel cell) battery module is a building block of the structure, making the battery pack assembly and maintenance are very convenient, because their work is misunderstood some moving parts, and the work will only produce water, lower running noise.
4, the full hydrogen energy sources. Hydrogen is a very wide range of sources of energy, and is a renewable resource, such as oil, natural gas, methanol, methane reforming for hydrogen production, photolysis of water into hydrogen and other methods to get the hydrogen.
But the drawback is the same, its cost and other new energy power will still be very high, the hydrogen purity requirements are very high, and because hydrogen is the active substance, so also quite stringent requirements for its storage appliances, resulting in scientific and technological content and cost no less than other new energy power is low, but is also restricted to a major bottleneck for the development of fuel cell, while Mercedes-Benz fuel cell has a good development, but the bottleneck is still stuck in the battery power density, the manufacturing cost of the problem above.
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