Battery Warring States Period
"I am willing to invest all the assets in Yinlong today." Dong Mingzhu said at the "China Manufacturing Summit Forum" on December 15 last year. It is reported that Yinlong is a young new energy technology company. In 2011, Yinlong Holdings held the United States Titanium Nanotechnology Co., Ltd. to master the production technology of lithium titanate materials in lithium batteries for electric vehicles.
"And electric vehicle batteries are the core of the development of electric vehicles, but also a key combination point between the power industry and the automotive industry." Wang Binggang, head of the National New Energy Vehicle Innovation Engineering Expert Group, said. At present, there are many types of batteries for electric vehicles (including low-speed electric vehicles, hybrids, etc.), such as Toyota's hybrid models with nickel-metal hydride batteries, Honda hybrids, Buick hybrids with lithium batteries, Dong Mingzhu optimistic about Yinlong lithium titanate Battery, BYD new energy uses lithium iron phosphate battery.
It can be seen that the core of new energy development is battery technology. Lu Guanqiu, chairman of Wanxiang Group, also said that "the progress of the battery is often a breakthrough, and it is the problem of choosing which material to use. This leads to a strong disruptiveness, so the investment risk is great. Now the battery is not only It is the most difficult problem for Wanxiang, and it is also the bottleneck that the industry can't break through now."
So what are the mainstream battery types used in the new energy market? What is the difference between their applications? Here is the "Car Watch" to lead everyone into the mystery of the battery world.
Representing enterprises or models: Changan Automobile, Beiqi Group, Great Wall Motor, Geely Automobile, SAIC GM and other traditional fuel vehicles, generally using lead-acid batteries as vehicle power supply devices, most of the low-speed electric vehicles currently on the market The car also uses lead-acid batteries.
The first generation of electric vehicles EV1 used lead-acid batteries, which were produced by General Motors in 1996, and lead-acid batteries were invented by Gaston Plante in 1859, from invention to application in electric vehicles for 137 years. . The so-called lead-acid battery uses lead oxide as a positive electrode plate, sponge lead as a negative electrode plate, and sulfuric acid aqueous solution as an electrolyte solution. Lead-acid batteries are currently the most widely used batteries in the automotive field, mainly as power supplies for various electrical and electronic devices inside internal combustion engines.
Lead-acid batteries are divided into closed and non-closed. The enclosed type requires no maintenance, allows deep discharge, can be recycled, and is inexpensive, and has become the power supply device for most conventional fuel vehicles. For example, the maintenance-free lead-acid battery used by Buick Weilang. However, the low energy and low power of lead-acid batteries are their Achilles heel.
Industry experts pointed out that the nominal voltage of a single-battery lead-acid battery is 2.0V, which can be discharged to 1.5V and can be charged to 2.4V. 12V lead-acid batteries, as well as 24V, 36V, 48V, etc., the service life is generally 3 years.
"Power, density can be increased by increasing the surface area of ??the electrode, but it will increase the erosion speed and shorten the battery life." Hu Zechun, an associate professor of electrical engineering at Tsinghua University, said, "The charging and discharging methods will also seriously affect it." The long service life, long-term overcharge and over-discharge will lead to shortened battery life."
The reason why lead-acid batteries have been widely used in the past 50 years, in addition to mature technology, can be mass-produced, low production costs, Changeability and low prices are also dominant factors. Despite the continuous generation of new battery technology, lead-acid batteries are still used as power sources, mainly for tourist vehicles, electric forklifts or some short-distance buses.
Representing companies or models: FAW Toyota Hybrid, Changan Ford Hybrid, Lexus RX400h, Porsche Cayenne, etc., generally use NiMH batteries as the power source.
The so-called alkaline battery consists of nickel-based and alkaline solution electrolytes, mainly nickel-cadmium battery, nickel-zinc battery and nickel-hydrogen battery. Among them, nickel-hydrogen battery is compared with nickel-cadmium and nickel-zinc batteries. High and no pollution to the environment.
Experts in the industry pointed out that nickel-metal hydride batteries are synthesized by hydrogen ions and metallic nickel. The disadvantage of nickel-metal hydride batteries is that they are much more expensive than nickel-cadmium batteries, and their performance is worse than that of lithium batteries. It is reported that the second generation of electric vehicles developed by General Motors in 1999 was based on nickel-metal hydride batteries, but eventually it was withdrawn from the market due to lack of competitiveness. However, Toyota Motor Corporation of Japan has used the nickel-hydrogen battery technology to manufacture a third-generation electric vehicle that combines an internal combustion engine and an electric motor, that is, a hybrid electric vehicle (HEV).
Ni-MH batteries have become the most concerned battery in the research field and market application of electric vehicle battery technology. Compared with lead-acid batteries, nickel-hydrogen batteries have increased the energy volume density by 3 times and the specific power by 10 times. . The unique advantages of this technology include: higher operating voltage, specific energy and specific power, better overcharge and discharge resistance and thermal performance.
"However, there are certain limitations in the application of nickel-hydrogen batteries. The capacity is reduced at low temperatures and the charging resistance is not good at high temperatures. In addition, the price is also a major factor limiting the development of nickel-hydrogen batteries. Raw materials such as metals Nickel is very expensive. Although nickel-metal hydride batteries store more energy than lead-acid batteries, over-discharge can cause permanent damage. The state of charge must be limited to a small range. Most of the energy stored in the battery is not In actual use, the Toyota Prius can only use 20% of the energy of the battery,” industry experts said.
On behalf of the company or model: Honda mixed, Buick mixed, etc., such as Honda Accord sharp mix, Buick Lacrosse mixed.
Lithium-ion batteries can be divided into lithium ion batteries and lithium polymer batteries. The cathode materials of lithium ion batteries mainly include lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium iron phosphate, etc., and the anode materials mainly include graphite, lithium titanate and the like. The performance of lithium ion batteries with different cathode materials is also different.
"Compared with nickel-metal hydride batteries, lithium-ion batteries have a relatively high operating voltage and a large specific energy, which is three times that of nickel-metal hydride batteries. Lithium-ion batteries are small in size, light in weight, long in cycle life, self-discharge The rate is low, there is no memory effect and no pollution; the value range of the single performance index of the battery is large, because the lithium ion battery has more electrode combinations, and there are certain differences in performance," explains Associate Professor Hu Zechun.
Of course, the large number of lithium-ion batteries used in electric vehicles is also problematic, mainly due to a variety of performance limitations, including lithium-ion battery safety, cycle life, cost, operating temperature and material supply. It is reported that lithium-ion batteries are currently dominated by small-capacity, low-power batteries, and large-capacity, high-power lithium-ion batteries have not yet been mass-produced. In addition, some technologies in the battery management system of the battery pack are still immature (such as balanced charging technology), which is one of the important reasons why lithium-ion batteries have not been widely used in electric vehicles.
Lithium iron phosphate battery
Representing enterprises or models: BYD pure electric vehicles (Qin, Qin EV, Tang, etc.), Yutong New Energy Bus, Xiamen Jinlong New Energy Bus, etc.
At present, in electric vehicles, the lithium ion battery that is used more is lithium iron phosphate battery. BYD New Energy uses lithium iron phosphate batteries. It has a phosphorus-oxygen covalent bond structure, so that oxygen atoms are not released, so the thermal stability and safety are better, and the price is relatively cheap. These factors make lithium iron phosphate batteries the first choice for small electric vehicles and PHEV power batteries.
Industry experts pointed out that lithium iron phosphate battery refers to lithium ion battery with lithium iron phosphate as cathode material. Its characteristic is that it does not contain precious elements such as cobalt, and the raw material price is low, and phosphorus and iron are rich in resources. The working voltage is 3.2V, the capacity is large under unit weight (170mAh/g), high discharge power, fast charging and long cycle life, and high stability under high temperature and high heat environment.
"However, in lithium-ion batteries, the specific energy, specific power and operating voltage of lithium phosphate batteries are relatively low, and lithium cobalt oxide and lithium manganese oxide batteries have advantages in large-scale pure electric vehicle applications." Expressed for this.
ternary lithium battery
Representing a car or model: Tesla, Geely Emgrand, Beiqi EV200, Jianghuai iEV5, Ai Ruize 7e, Roewe Erx5, etc.
The three-lithium battery is a lithium battery using a nickel-cobalt-manganese ternary cathode material as a positive electrode material. According to Professor Ouyang Minggao of Tsinghua University, the so-called "three yuan" means that the positive electrode is ternary and the negative electrode is graphite. The ternary lithium battery has the advantages of high energy density and better cycle performance than normal lithium cobaltate. At present, with the continuous improvement of the formula and the perfect structure, the nominal voltage of the battery has reached 3.7V, and the capacity has reached or exceeded the level of lithium cobalt oxide battery.
The electric vehicle produced by Tesla is the ternary lithium battery. The selection reason for the Tesla battery technology director Kurt Kelty is: higher energy density, better stability and consistency; can effectively reduce The cost of the battery system; small size, controllability and safety can be continuously improved.
However, some insiders pointed out that "the ternary lithium battery mainly has nickel-cobalt lithium aluminate battery and nickel-cobalt-manganese lithium battery. Due to the high temperature structure of nickel-cobalt aluminum, the high-temperature safety is poor, and the pH value is too high. Gao Yi makes the monomer flatulent, which in turn causes danger, and the current cost is higher."
It is reported that if the existing ternary lithium battery is internally short-circuited or the positive electrode material is in contact with water, there will be an open flame. Therefore, the general ternary lithium battery will have a layer of steel shell protection, because Tesla's battery pack is composed of 7000 or so 18650 batteries, so Tesla gives the battery pack a full range of protection, but in In the event of an extreme collision, there is still a fire hazard.
"The lithium iron phosphate battery is much more stable. The battery board will not explode and burn even if it is puncture or short circuit. It will not catch fire when it is heated at 350 °C (the ternary lithium battery will not be fired at 180-250 °C) Lived.) So in terms of safety performance, lithium iron phosphate battery is slightly better." Industry insiders told reporters.
Lithium Titanate Battery
On behalf of the company: Zhuhai Yinlong, the battery technology application is currently in the experimental stage.
In the actual research and development application, there is a lithium ion secondary battery with a positive electrode of ternary and a lithium iron titanate composition of 2.4V or 1.9V, which is often called "lithium titanate", and its performance is relatively safe and long-lived. It is relatively long and does not belong to the "three-dimensional material".
"The so-called lithium titanate battery uses lithium titanate as the negative electrode material for the battery. This technical route is different from the mainstream using graphite as the negative electrode material." Industry insiders pointed out.
Dong Mingzhu, Chairman of Gree Electric, said, “Lithium titanate is one of the most mature products of American Titanium Nano.” Some insiders pointed out that “the advantages and disadvantages of using lithium titanate as the anode material are very obvious. The advantages are long battery cycle life, fast charging, wide temperature resistance and good safety. The disadvantage is that the cost is high and the energy density is low. Correspondingly, the battery is bulky. Among them, the energy density is low ( In general, it is very low in electricity. It is widely believed that the energy density (90 wh/kg) of lithium titanate batteries is lower than that of other types of power batteries (110-120 wh/kg of lithium iron phosphate). Subject to this factor, the technology is difficult to apply to new energy passenger vehicles (light vehicles).
Wei Yincang, chairman of Zhuhai Yintong New Energy, also admitted that “the lithium titanate battery developed by Yinlong is indeed small. The public, and the economic benefits are also at the end, but he stressed that Yinlong valued the green and environmental protection of this technology throughout its life cycle. It is reported that this technology is mainly used in energy storage systems, robotics industry and a small number of buses. Because of the limited application range, lithium titanate batteries account for only 2% of the global lithium batteries. In addition to energy density, The price of lithium titanate is more than two times more expensive than lithium iron phosphate and ternary materials. At present, only two companies in the world have a leading position in the field of lithium titanate batteries, one is Toshiba in Japan and the other is Zhuhai Yinlong. Br\u003e Prospects
There are advantages and disadvantages in all things, how different types of power battery performance, after all, the market needs long-term verification. In the current market, lithium-ion batteries (lithium-ion batteries and lithium polymer batteries) in addition to In addition to being inferior in terms of price and safety, other aspects are in an absolute leading position, with prospects for further research and development and large-scale application. Currently in the hybrid models, the major automotive companies use nickel-metal hydride batteries and various lithium-based batteries. Technical battery, battery capacity is 3 ~ 60 kW · h or more. In traditional fuel vehicles, the main application of lead-acid batteries as equipment power supply Lithium titanate batteries are still in the research and development stage and have not yet been mass-produced.
Therefore, the competition for different technical routes of batteries and the breakthrough of core technology performance have just begun.