The vehicle power battery mainly has two categories of battery and fuel cells. As the name suggests, the battery is to use chemicals to perform reversible charge and discharge reactions and release electrical energy in battery positive and negative poles. The fuel cell is an irreversible combustible combustible reaction (oxidation reaction) to generate electrical and voltage between the positive negative poles. Release the electrical energy. Therefore, the battery needs to be charged, and the fuel cell needs to be added "fuel", such as the hydrogen fuel cell needs to be added hydrogen fuel. Battery discharge reactions typically have no emissions, while fuel cell discharges typically discharge their oxides, such as hydrogen fuel cell discharge water (2H2 + O2 = 2H2O).
The fuel cell technology and industry development has not yet reached the scale application stage, and there are only some small-scale applications such as hydrogen fuel cell vehicles or experimental research phases. The power battery currently applied in the market is all battery class, in which the performance indicators and application verification are also the most applicable most widely used lithium-ion batteries.
Lithium ion battery composition:
Positive material
It is usually made of a metal material such as lithium, cobalt, nickel, and is processed with a conductive agent, a binder, and is a major material that determines the performance of the battery.
Negative electrode material
Mainly used as the main body of the lithium, the embedding and escalation of lithium ions in the charge and discharge process, the current lithium battery negative electrode material is mainly graphite.
Diaphragm
Through the specially formed polymer film, the film has a microporous structure, and the lithium ion can be passed without letting electron pass, and the migration between the lithium ions between the lithium ions during the charge and discharge process can be achieved.
Electrolyte
A good ion migration conductor is formed between the internal and negative electrodes of the battery, generally consisting of an organic solvent, an electrolyte, an additive, or the like.
shell
The housing of the packaging battery is mainly divided into: cylindrical, square, soft bag.
Lithium-ion battery charge and discharge principle:
When the battery is charged: The lithium atom of the positive electrode is ionically ionically charged lithium ions and electrons with positively charged lithium ions from the positive electrode, pass through the film to the negative electrode, and synthesized a lithium atom in the negative electrode.
When the battery is discharged: the lithium atom is ionized from the surface of the negative electrode material to lithium ions and electrons, and the positively charged lithium ions are started from the negative electrode to the positive electrode, and the electron synthesis of lithium atoms.
Types of lithium ion batteries:
The lithium-ion battery is primarily named according to the nature of the positive material. At present, the main lithium batteries are: three-dimensional lithium (NCM / NCA), lithium iron phosphate (LFP), lithium manganate, and lithium titanate.
Various different lithium-ion batteries have a large difference, the energy density of the three-dimensional cells is the highest, the battery capacity is up to the battery, and the battery life is most suitable for lifting the electric vehicle. Due to its significant advantage of its energy density, the requirements of new energy car subsidies on battery life, it is considered to be the mainstream technical direction of the future of electric passenger cars, but due to poor security, it is in the rear of the industrial in several fire accidents. Development of returning to rationality, but with the continuous improvement of the technical level, safety is also effective, and is still one of the main battery technology of electric passenger cars. Representative factory: Tesla.
Lithium iron phosphate battery energy density is lower than the ternary lithium battery, but the safety is good, it is considered to be one of the safest lithium battery technology, and the cost of cost is lower than the ternary lithium battery, but the low temperature performance is poor. The comprehensive performance is At present, two mainstream electric vehicle battery technology for three-dimensional lithium batteries.
Due to the limited space and load of electric passenger cars, the battery is small, light, large, and the capacity is mainly based on three-dimensional lithium and lithium iron phosphate technology; large vehicles such as large bus, truck, mud car, Engineering vehicles, etc., there is a larger space carry heavier battery, taking into account safety and cost factors, using a lithium iron phosphate battery. Representative factory: BYD.
Lithium manganate battery is earlier, and the famous Nissan Harmony (LEAF) electric vehicle is lithium manganganate battery. Since 2010, it has been sold to 49 countries around the world, and it is said that the accumulated sales exceeded 300,000 records of no battery safety accidents. However, due to the low energy density, it has gradually left the mainstream technology, and there is less application.
The lithium titanate battery has several significant excellent features: good safety, especially high-power fast charge, long cycle life, low temperature adaptability. But there is also a large defect: low energy density, high production cost (lithium titanate is more expensive). At present, the main applications of vehicles in some special uses and scenes, such as bus or engineering vehicles in the cold area in the north. Representative car factory: Zhuhai Yinlong.
After the previous description, the small partners should have a certain understanding of the current few main electric vehicle lithium battery technology. I will know that they have the types:
Tesla mainly uses Panasonic Sanyi Lithium Battery BYD E6 using self-producing phosphate battery Zhuhai Yinlong new energy passenger car uses self-producing titanate battery BYD mud car using self-producing iron phosphate battery, the above, the following can come Talking about the safety of lithium battery systems and fasting. Charge and discharge of lithium batteries is a series of very complex chemical response processes, which affects safety factors, most important and critical is the lithium bodies produced by battery negatives during charging process.
According to the preceding the lithium battery charge and discharge principle, the lithium atomic ionization of the positive electrode is ionized as lithium ions and electrons, and the lithium ions are processed from the positive electrode, and the lithium atom is synthesized in the negative electrode.
At present, the negative electrode material of the lithium battery is usually graphite, and the main function is to absorb the lithium ions from the positive electrodes from the battery, but since the absorption embedding capacity of the graphite negative electrode is limited, once the amount of lithium ion, the number of lithium ions from the ionization migration exceeds the negative graphite can be embedded A series of factors such as current, ion concentration, and negative surface roughness, the lithium ion will crystallize the surface of the negative electrode, commonly referred to as a lithium lact crystal.
To form a lithium branch crystal is an irreversible process, the lithium ion will not be involved in the ionization reaction once, that is, the capacity and life of the lithium battery have caused the capacity and service life attenuation. If the lithium branch continues to increase, the battery will may have problems such as drums, failure. Thereby, the main cause of electric vehicle failure is caused.
The formation process of lithium dendrites:
Lithium branch micro picture:
Lithium battery structure damage principle:
The lithium titanate battery has good safety, high-power fast charge, and the length of the cycle life. The reason is that the lithium titanate of the lithium titanate battery is replaced by the graphite, and the lithium titanate negative electrode is also in the case of high power. Lithium-studded is not easy to form, thereby avoiding the possibility of risk and problems, and extending the battery life.
Therefore, for current lithium battery technology, high-power fast charge and safety and circulating life are uncomfortable relationships of this, improve charging power shortening the charging time potential to increase the risk of forming lithium-transcammon, affect safety and Circulating life. At the same time, two performances are the direction of lithium battery manufacturers.
On the other hand, scientists are also a problem in trying to solve safety and energy density by changing the basic materials and structures of lithium batteries. Such as solid state batteries, convert the flammable and explosive liquid electrolyte in lithium batteries to non-flammable solid matter, will greatly reduce the risk of combustion explosion. However, since the solid electrolyte and the positive and negative electrode material are low, affecting lithium ion conduction, which in turn affects battery performance, and has not reached the stage of large-scale applications due to cost reasons.
Therefore, it is necessary to ensure the safety of electric vehicles, on the one hand, the lithium battery and the whole vehicle should be selected for manufacturing process and product quality, and on the other hand, the charging equipment that is stable in quality, and the charging equipment interacts with the battery BMS during charging battery. Information, according to the appropriate instructions to provide a matching charging power, while playing a number of important functions such as charging status monitoring, security protection, intelligent management, charging piles provide full range of charging through the monitoring and analysis of the indicators of charging Protection function, including overcurrent protection, overvoltage protection, overheating protection, short circuit protection, reverse protection, leakage protection, insulation protection, etc., ensuring that the battery is accurately distributed and providing high quality stable charging power, it is to ensure the safety of charging Key links. Technical advanced, good quality, stable and reliable charging equipment will be an important guarantee for charging security.
With the continuous improvement of the battery requirements for electric vehicles, the energy density and capacity of the power battery continue to increase, the charging time requirements are constantly shortened, and the high-power DC fast charge has become the trend of the industry development. At present, the mainstream bidding in China has reached the power. 120KW ~ 180KW / Taiwan, Tesla launched the latest generation of super charging pile Super Charger V3, which reached 250 kilowatts for Model 3. Coda, mainstream charging pile manufacturers, also introduced a 240KW DC high-power charging pile and 360kW of a ten-point DC charging pile. It is expected that the charging pile of more than 500kW above 2021 to 2022 is expected to face the city, and the charging power of bicycles is expected to reach 200KW to 250KW.
Caseda 360KW one-point DC charging pile
For the pursuit of improving the use of electric vehicles, it also promotes the development of high-power fast charging direction. In the future, "10 minutes, life is 300 km", "similar to this advertising will be a powerful competition weight of new energy vehicle manufacturers, but In the case of the technical principle and physical structure of the lithium battery, the high-power fast charge still has a certain impact on the cycle life and safety risks of the lithium battery, so it is recommended that even if the technology is reached, it is not necessary to pursue the charging time, after all Battery costs approximately half of the cost of the vehicle. The service life and safety of the battery directly determines the cost and safety of the vehicle. In an optional case, more medium and small power slow recharge, keep the battery life, It also reduces the risk of charging.
In terms of electric vehicle selection, if you look at the long-lived mileage, high performance performance, you can pay more attention to the three-dimensional lithium battery car, usually more high-end models; if you value safety and reliable, you can consider lithium iron phosphate. Battery cars, usually a large low-end model. With the development of lithium batteries, the advantages and disadvantages of the two battery technology are gradually improved and improved, future or will be developed.
At the national policy level, on May 29th, the Ministry of Industry and Information Technology issued a notice on implementing the mandatory national standard for motor vehicles: Implementing "Electric Automotive Safety Requirements", "Electric Passenger Car Safety Requirements", "Electric Automotive Power Battery Safety Requirements "Three mandatory national standards.
Under the common promotion of the new infrastructure and electric vehicle industry, the charging pile will develop in the direction of greater power. The quality and performance reliability of charging piles have higher requirements, and the charging pile products are safe monitoring, safety protection. Aspects also need to continue to increase. Big brand, technology lead, excellent quality, and reliable performance, charging pile manufacturers will gradually play an advantage.
For new energy owners, buy high quality and reliable electric vehicles, choose a reliable quality brand mainstream charging equipment such as Cosda charge pile, forming a habit of expressing quick-fitting, and is also an effective battery life, reducing security risks method.
Editor in charge: GT, read full text
Our other product:
