“Charging anxiety” and “mileage anxiety” are a major obstacle to the large-scale industrialization of pure electric vehicles. At the 2019 World New Energy Car Conference, a “high-proportionable fast-charged lithium-ion battery” has received the global new energy automotive innovation technology award..
The technology breaks through the technical bottleneck of the graphite system that cannot be quickly charged, on the basis of maintaining high energy density, high security, long-service life, can complete 100% charging within 15 minutes to ensure 300 kilometers of electric vehicles.. What is the secret of this technology, how can it be able to make new energy users feel the same “charging for five minutes, call two hours” in the same “charging five minutes, call two hours” similar to the mobile phone.
At present, the current express delivery method has a disadvantage. About pure electric cars, the charging and discharge performance of the battery system is an important indicator for determining the actual use of vehicles..
High-energy density and fast charging capacity is not only the technical direction of various powered lithium battery manufacturers, but also the core of new energy technology.. “Lithium-ion battery is also called a rocker battery.
“CATL New Energy Technology Co., Ltd. (hereinafter referred to as CATL) Research Project Supervisor Cheng Xiaoyan told the reporter, the two ends of the rocking chair are the two poles of the battery, and the lithium ions run back in both ends of the rocking chair.
. When charging, the lithium ion moves from the battery of the battery to the negative electrode. As the graphite of the negative electrode is laminated, the lithium ion is embedded in the graphite through the interlayer, the more lithium ions embedded, the higher the charging capacity.
. A key indicator for measuring electric vehicle charging efficiency is charge and discharge rate (c). The charge and discharge rate can be simply understood as the rate of charging and discharging.
The charge and discharge rate of the lithium-ion battery determines how much can we store a certain energy to the battery, or to release the energy in the battery in the battery.. For example, when the rated capacity is 100-time battery, the discharge magnification is 0.
2c, and the capacity used is 1 hour, referred to as 1C discharge; 5 hours of discharge, referred to as 0.2C discharge. The industry generally believes that electric car fast charge refers to a charging method greater than 1.
6C, which is a technology that charges from 0% to 80%.. As the name suggests, to shorten the charging time, it is necessary to continuously improve the charge and discharge rate.
. The core of the fast charge technology is to optimize the chemical system and design, accelerate the speed of lithium ions in the positive and negative poles..
However, in the development of fast charge technology, the speed is not good.. When the fast charge, the lithium ion should accelerate instantaneous embedding into the negative electrode.
. This ability to quickly receive lithium ions in the negative electrode is very large. The battery of the ordinary chemical system, the lithium, which will produce a by-product such as lithium, affecting the circulation and stability of the battery, can only use the negative electrode material that can withstand the fast charge.
. Cheng Xiaoyan said that in order to achieve rapid charging, the industry generally uses lithium titanate and amorphous carbon as an negative electrode active material, but the presence of lithium titanate and amorphous carbon in practice are severely insufficient, high-cost defects The design of the usual new conductive material is also affecting the energy density of the battery..
“In recent years, some manufacturers have begun to explore graphite as an active material, but the chalk faces when as fast charge materials, how to make lithium electron quickly release from the positive electrode, and quickly go in. “Cheng Xiaoyan explained that graphite is more like a highway, although energy density is higher, lithium electron can only pass. That is to say, graphite is not natural material suitable for fast charge technology.
. “But we use technology to break through the material itself, its killer is the ‘fast ion ring’ and ‘super electronic network’. “Cheng Xiaoyan sighs.
The charging acceleration of the fast ion ring and ultra-electronic mesh “We use graphite as an negative electrode main material, innovative use of aperture optimization and ‘fast ion ring’ technology, to create a circle of high-speed channels on the surface of graphite, so that lithium ions can quickly embed graphite Location, greatly increase lithium ions in the embedding speed of the graphite negative electrode, and the modified graphite takes into account the characteristics of super fast charge and high energy density, and will not appear by-products in the negative electrode, affect the circulation and stability of the battery. sex. Cheng Xiaoyan said.
In addition, the technical team has developed the “ultra-electronic network” technology to modify the positive material, combined with the design parameters of the crystal orientation of the positive and negative pole sheet, and optimize the electrolyte, the dynamics of the electrolyte, the positive and negative electrical performance, enabling the chemical system and Battery design parameters achieve optimal match. “Popularity, ‘fast ion ring’ and ‘super electronic network’ are used for negative electrodes and positive electrodes, and the lithium ions are poured into the negative circuit to establish a fast passage, improve lithium ion diffusion rate..
Cheng Xiaoyan said. In addition, in terms of the design of the machine, the team creatively simplifies the battery cell top cover, set the electrode terminal to the side surface of the top cover and reduce the thickness of the terminal, significantly reduces internal resistance, effectively controls fast-fashioned heat, guarantee fast The re-reliability increases more than 5% energy density. “Our fast charge technology has 4C-5C fast charging ability, realizing fast charging of 10-15 minutes, with a significant energy density and cost advantage compared to the fast charge system of lithium titanate, and the same graphite in the industry.
Compared with other fast charge techniques of the negative electrode, maintain the energy density conditions of the same battery, can increase the charging speed of 20% -30%, and have better cyclic and weather resistance.. Cheng Xiaoyan said.
Successfully applied to more than 5,000 businesses, CATL developed with fast-moving graphite as a negative electrode main material, which has been applied to more than 5,000 electric bus, and the bus operates in good operation and gets the vehicle company and bus. The user is praised, the battery is also rated as “New Energy Bus Best Kyoko Battery” by the Ministry of Communications..
The battery has a large advantage in the energy density, in terms of circulating life, a bus that is more demanding in application conditions, with an average of about 2 times a day, coarse calculates, meets 8 years of operational demand, battery cycle More than 5,600 times. Super ferrithium ion battery cell cycle life can reach 10,000 times, not only fully meet the operational needs of electric vehicles, but also used to use ladder and other ladders and other ladders after electric vehicles, create more economic value. “In order to ensure the safety and reliability of the fast charging core, we also developed specialized technologies to identify the chemical system ‘health charging area in different temperatures and SOCs, and then faster in this’ healthy charging area’.
You can achieve fast charging, but also damage to fast charge, fast charge, long cycle, and safety reliability. Cheng Xiaoyan said. In terms of weather resistance, in order to meet the requirements of Northern Winter Low Temperature Charges and Southern Summer High Temperature Status, the technical team specializes in the high-efficiency thermal management system to ensure that the battery is in a reasonable temperature range.
. When low temperature, the battery can be heated, the temperature can be required to turn on the fast charge mode; when the temperature is high, the system will cool the battery, and the fast charge “. “We are developing single energy density greater than 160 watts of 2C-2.
5C high-energy density long life (cycle greater than 6000 times) fast-filled iron-free iron battery, is expected to produce at the end of 2019. The technology has also achieved 350 kilometers of battery life, and the charging is completed within 15 minutes..
“Cheng Xiaoyan said that the company also plans to launch a three-dimensional lithium battery product of up to 255 watts of energy densities in the next 1-200, which can complete fast charging within 18 minutes.