Battery technology is a great invention with a wonderful and long history. The battery "Battery" first appeared in 1749. It was first used by American inventor Benjamin Franklin, who used a series of capacitors in series to conduct electricity. experiment. He used dilute sulfuric acid as the electrolyte to solve the problem of battery polarization, and produced the first zinc-copper battery, also known as the "daniel battery", which was not polarized and could maintain a balanced current.
In 1860, France's Plante invented the battery with lead as the electrode, which is also the predecessor of the battery; at the same time, France's Lakeland invented the carbon-zinc battery, making the battery technology into the field of dry batteries.
Battery technology began with dry batteries, which was invented by British Hellssen in 1887 and mass produced in the United States in 1896. At the same time, Thomas Edison invented rechargeable iron-nickel batteries in 1890, also realized in 1910. Commercial mass production.
Since then, thanks to commercialization, battery technology has ushered in an era of rapid growth. Thomas Edison invented alkaline batteries in 1914, Schlecht and Akermann invented nickel-cadmium battery sintered plates in 1934, and Neumann developed sealed nickel in 1947. Cadmium batteries, Lew Urry (Energizer) developed a small alkaline battery in 1949, which ushered in the era of alkaline batteries.
After entering the 1970s, battery technology was gradually affected by the energy crisis and gradually developed toward physical power. In addition to the continuous improvement of solar cell technology that emerged in 1954, lithium batteries and nickel-hydrogen batteries were gradually invented and commercialized.
What is a power battery?
The difference between it and ordinary batteries
The power source of new energy vehicles is generally based on power batteries. A power battery is actually a power source that provides a source of power for transportation. The main difference between it and ordinary batteries is:
A power battery is a battery that powers a transportation vehicle, generally compared to a small battery that supplies energy to a portable electronic device. An ordinary battery is a lithium metal or lithium alloy as a negative electrode material, and a nonaqueous electrolyte solution is used. The primary battery is different from the rechargeable battery lithium ion and lithium ion polymer battery.
2、Different battery capacities
In the case of new batteries, the battery capacity is tested by a discharge meter. The capacity of a general power battery is about 1000-1500 mAh; while the capacity of an ordinary battery is above 2000 mAh, and some can reach 3400 mAh.
3、Different discharge power
A 4200mAh power battery can discharge the power in just a few minutes, but the ordinary battery can not do it, so the discharge capacity of the ordinary battery can not be compared with the power battery. The biggest difference between a power battery and a normal battery is that it has a large discharge power and a high specific energy. Since the main use of the power battery is the vehicle energy supply, it has a higher discharge power than the ordinary battery.
The battery that provides driving power for electric vehicles is called a power battery, including traditional lead-acid batteries, nickel-hydrogen batteries, and emerging lithium-ion power lithium batteries, which are divided into power-type power batteries (hybrid vehicles) and energy-type power batteries. (Pure electric vehicles); Lithium batteries used in consumer electronics such as mobile phones and notebook computers are generally referred to as lithium batteries, which are different from those used in electric vehicles.
The main types of power batteries
At present, mainstream technologies on the market still focus on lead-acid battery technology, nickel-hydrogen battery technology, fuel cell technology, and lithium battery technology.
Lead-acid batteries have the longest application history and the most mature technology. They are the lowest cost and best-selling batteries, and have been mass-produced. Among them, valve-regulated sealed lead-acid batteries (VRLA) once became an important vehicle power battery, applied to EVs and HEVs developed by many European and American automobile companies, such as Saturn and EVI developed by GM in the 1980s and 1990s. Electric cars, etc.
However, lead-acid batteries have lower specific energy, shorter endurance time, higher self-discharge rate, and lower cycle life; the main raw material lead has a large weight, and may cause environmental pollution of heavy metals during production and recycling. Therefore, current lead-acid batteries are mainly used for ignition devices when the car is started, and small devices such as electric bicycles.
Nickel-hydrogen (Ni/MH) batteries have good resistance to overcharge and overdischarge, and there is no problem of heavy metal pollution, and there is no phenomenon of electrolyte increase and decrease during the work process, which can realize seal design and maintenance-free. Compared with lead-acid batteries and nickel-cadmium batteries, nickel-hydrogen batteries have higher specific energy, specific power and cycle life.
The disadvantage is that the battery has a poor memory effect, and as the charge and discharge cycle progresses, the hydrogen storage alloy gradually loses its catalytic ability, and the internal pressure of the battery gradually increases, which affects the use of the battery. In addition, the expensive price of nickel metal also leads to higher costs.
On the key materials, nickel-metal hydride batteries are mainly composed of a positive electrode, a negative electrode, a separator and an electrolyte. The positive electrode is a nickel electrode (Ni(OH) 2 ); the negative electrode is generally a metal hydride (MH); the electrolyte is mainly a liquid, and the main component is hydrogen. Potassium oxide (KOH). At present, the research focus of nickel-hydrogen battery is mainly on the positive and negative materials, and its technology research and development is relatively mature.
The nickel-metal hydride battery for vehicles has been mass-produced and used, and it is the most widely used vehicle battery type in the development of hybrid vehicles. The most typical representative is the Toyota Prius, which has the largest production volume of hybrid vehicles. PEVE, a joint venture between Toyota and Matsushita, is the world's largest manufacturer of nickel-hydrogen battery.
Now that nickel-metal hydride batteries have withdrawn from the ranks of mainstream power batteries, why is Toyota still stubbornly sticking to the nickel-hydrogen battery camp?
This has to say the biggest advantage of NiMH batteries: superior durability!
Once the famous American car media conducted a comparative test on a first-generation Prius that had been used for ten years. The test results show that the first-generation Prius model with Ni-MH battery has been compared with the data of the new car after 10 years of driving for 3 years, and the fuel consumption performance and the dynamic performance are kept at the same level. The hybrid system and the NiMH battery pack are still working properly.
In addition, even after running for 330,000 kilometers in ten years, this first-generation Prius NiMH battery has never had a problem. People questioned a decade ago that battery capacity degradation will greatly affect fuel consumption and power performance. It also did not appear. From this point of view, the Japanese who have always been rigorously conservative have a unique reason for the love of nickel-metal hydride batteries.
3、The fuel cell
A fuel cell is a power generation device that directly converts chemical energy present in a fuel and an oxidant into electrical energy. Fuel and air are fed into the fuel cell separately, and electricity is produced. It looks like a positive and negative electrode and electrolyte, like a battery, but in essence it can't "storage electricity" but a "power plant."
Compared to conventional chemical batteries, fuel cells can be refueled, usually with hydrogen. Some fuel cells can use methane and gasoline as fuel, but are usually limited to industrial applications such as power plants and forklifts. The basic principle of a hydrogen fuel cell is the reverse reaction of electrolyzed water. Hydrogen and oxygen are supplied to the anode and the cathode, respectively. After the hydrogen diffuses through the anode and reacts with the electrolyte, the electrons are released to the cathode through an external load.
Hydrogen fuel cell works by sending hydrogen gas to the anode plate (negative electrode) of the fuel cell. After the catalyst (platinum), one electron in the hydrogen atom is separated, and the hydrogen ions (protons) that lose electrons pass through the proton. The exchange membrane reaches the cathode plate (positive electrode) of the fuel cell, and the electrons cannot pass through the proton exchange membrane. This electron can only reach the cathode plate of the fuel cell via an external circuit, thereby generating electric current in the external circuit.
After the electron reaches the cathode plate, it recombines with oxygen atoms and hydrogen ions into water. Since the oxygen supplied to the cathode plate can be obtained from the air, the electric energy can be continuously supplied as long as hydrogen is continuously supplied to the anode plate, air is supplied to the cathode plate, and the water vapor is taken away in time.
The electricity generated by the fuel cell is supplied to the motor via an inverter, a controller, etc., and then the wheel is rotated by the transmission system, the drive axle, etc., so that the vehicle can travel on the road. Compared with traditional cars, the energy conversion efficiency of fuel cell vehicles is as high as 60-80%, which is 2 to 3 times that of internal combustion engines.
The fuel cell fuel is hydrogen and oxygen. The product is clean water. It does not work to produce carbon monoxide and carbon dioxide, nor does it emit sulfur and particulates. Therefore, hydrogen fuel cell vehicles are truly zero-emission, zero-pollution vehicles, and hydrogen fuel is the perfect vehicle energy!