At present, there are three most important lithium-ion batteries for electric vehicles, in order: lithium iron phosphate battery, lithium cobalt oxide battery and ternary material battery
1.1.1 Lithium iron phosphate battery:
Lithium iron phosphate battery belongs to lithium ion secondary battery, which is mainly used as power lithium battery, and its discharge efficiency is high, and the charge and discharge efficiency can reach more than 90% under the condition of rate discharge, while the lead-acid battery is about 80%. Among the batteries, the safety of lithium iron phosphate batteries is also higher than other batteries, the theoretical life can reach 7~8 years, the actual service life is about 3~5 years, and the performance-price ratio is theoretically 4 times that of lead-acid batteries. above.
Let's talk about its shortcomings. The price of lithium iron phosphate batteries is higher than other types of batteries, and the battery capacity is small, the continuation mileage is short, and it is basically impossible to recycle after being scrapped, so it has no recyclable value. In summary, the application of lithium iron phosphate batteries in electric vehicles will increase the overall cost, and the batteries cannot be recycled, which will cause waste and consumption of resources.
1.2 Lithium-ion cobalt oxide battery: TESLA's exclusive battery
The battery of the TESLA electric vehicle adopts the NCA series (nickel-cobalt-aluminum system) 18650 cobalt-acid lithium-ion battery supplied by Panasonic, with a single battery capacity of 3100 mAh. TESLA adopts the strategy of battery pack. The battery unit of 85kWh MODELS uses a total of 8142 18650 lithium-ion batteries. The engineers firstly distribute these batteries one by one in bricks and slices to form a whole battery pack. The battery pack is located on the underbody.
Lithium-ion cobalt oxide batteries have stable structure, high capacity ratio and outstanding comprehensive performance, but their safety is poor and the cost is very high. It is mainly used for small and medium-sized batteries with a nominal voltage of 3.7V. TESLA combines such batteries together, and safety has become a very important issue. TESLA engineers distribute the safety device in the battery pack to each 18650 lithium cobalt oxide battery, and each 18650 lithium cobalt oxide battery. There are fuses at both ends of the ion battery. When the battery is overheated or the current is too large, the fuse will cut off, so as to prevent the entire battery pack from being affected by an abnormal condition (overheating or excessive current) of a certain battery. So, from this point of view, although the lithium-ion cobalt oxide battery itself has its own defects, the safety can be basically ignored in the packaging of TESLA engineers. Obviously, such a solution is still very suitable for the development of pure electric vehicles.
1.3 Ternary material battery:
Taking the positive electrode material of the battery as the naming method, the full name of the ternary lithium ion battery is the ternary polymer lithium ion battery, which refers to the lithium ion battery using the nickel cobalt lithium manganate ternary polymer as the positive electrode material. Ternary lithium-ion batteries are mostly used in electronic products such as notebook computers, and later in the field of electric vehicles. Among the pure electric vehicles using ternary lithium-ion batteries, perhaps the most familiar to the public is Tesla's Model S.
Wang Chuanfu, chairman of BYD, said that BYD's newly researched lithium iron manganese phosphate battery breaks through the energy density limit of traditional lithium iron phosphate battery, reaching the level of ternary materials, and is better than ordinary lithium iron phosphate in cost control. , the battery life has been greatly improved.
2.1
A lithium-air battery is a battery that uses lithium as the anode and oxygen in the air as the cathode reactant. Discharge process: Lithium at the anode releases electrons to become lithium cations (Li+), Li+ passes through the electrolyte material, and combines with oxygen and electrons from the external circuit at the cathode to form lithium oxide (Li2O) or lithium peroxide (Li2O2), and remain at the cathode. The open circuit voltage of the Li-air battery is 2.91V.
Lithium-air batteries have higher energy density than lithium-ion batteries because their cathodes (mainly porous carbon) are light and oxygen is taken from the environment instead of being stored in the battery. Theoretically, since oxygen is not limited as a cathode reactant, the capacity of this cell depends only on the lithium electrode, with a specific energy of 5.21 kWh/kg (including oxygen mass), or 11.14 kWh/kg (excluding oxygen). Compared with other metal-air batteries, Li-air batteries have higher specific energy (see table below) [1], therefore, it is very attractive.
Scientists are very hopeful that lithium-air batteries will one day replace the lithium-ion batteries we currently use. Lithium-ion rechargeable batteries have been in use for nearly 25 years, Professor Clare P. Grey, from the University of Cambridge's Department of Chemistry, said on the phone. Twenty-five years ago, more compact lithium-ion batteries paved the way for portable electronics, enabling The electronic devices we carry around have become lighter and more portable. Lithium-ion battery technology was more suitable for consumers at the time, and now, it is time for lithium-air batteries to replace it.
No chemist or engineer would say that lithium-ion batteries are perfect. With the increasing popularity of electric vehicles, researchers have also begun to focus their efforts on lithium-air batteries. Because lithium-air batteries are much lighter than lithium-ion batteries, lighter cars mean longer range. To be sure, lithium-air batteries ideally have higher energy densities. In theory, only this type of battery could allow electric vehicles to have a range comparable to gasoline and diesel vehicles without having to carry huge and bulky battery packs.
But current lithium-air batteries still have some problems. The reduction of the voltage gap and the large capacity of the graphene oxide electrode result in that it can only accommodate a small rate of charge and discharge, and the metal lithium located in the negative electrode of the battery sometimes still forms dendrites that affect the performance of the battery. And, as we mentioned in the previous article, there is not only oxygen in the air, but other compounds in the air can also cause the lithium-air battery to become unstable.
The fact that these problems have not yet been solved also means that lithium-air batteries cannot really be put into commercial use at present. It is easy to develop new battery technology, but many technical hurdles need to be overcome to put it into practical use. The researchers say they are currently working with several companies to advance the technology as quickly as possible
2.2 High temperature resistant lithium-ion battery
Recently, Japan's Daikin Industry and Japan's Advanced Paper Industry have jointly developed high heat-resistant technology for lithium-ion batteries used in electric vehicles. The new technology does not require a battery cooling system, which reduces the weight of the car body while reducing its own power consumption, and the driving distance can be increased by 30% to 40% on a single charge. It can also prevent battery spontaneous combustion accidents and improve driving safety.
Existing vehicle lithium-ion batteries generate heat due to chemical reactions during power generation. When the temperature rises above 45 degrees, the power generation performance is reduced, and a cooling system must be installed. During the high temperature season in summer, the entire operation of the cooling system can reduce the efficiency and shorten the driving distance by about 30%.
The new technology uses fluorine compounds to replace the flammable electrolyte components, and the new electrolyte can work normally even if the temperature rises to 60 degrees; the insulating materials made of finely processed plant fibers are more resistant to high temperature and higher than the current general resin film products. The reduction of the expansion ratio can greatly improve the heat resistance of the insulating component; the binder used for the electrode has been replaced with a high heat resistance material, and the dissolution phenomenon will not occur even at high temperature.
3.1 Status of battery patent technology in important countries around the world
As the only source of power for pure electric vehicles, patents related to batteries and management systems for electric vehicles represented by lithium-ion batteries are attracting the attention of various countries, because this is an effective protection measure for countries to focus on research and development of electric vehicle batteries and achieve results . The following is an analysis of the world's top important countries, including China, Japan and South Korea in East Asia and the United States and Germany in Europe and the United States.
1. Japan: (1) Research focuses on lithium-ion batteries, followed by lead-acid batteries, nickel-metal hydride batteries, and sodium-sulfur batteries; (2) In terms of the number of patents, there are 6,782 patents, ranking first in the world; (3) . From the identity of the patent applicant, more than 90% of the patent applications for batteries and management systems for pure electric vehicles are from Japanese. Therefore, Japan controls most of the patented technologies and is the strongest in the world.
2. The United States: This country is the world's largest automobile producer and consumer, and the earliest country in the world to carry out research on electric vehicle-related technologies. (1) The research focuses on lithium-ion batteries, followed by lead-acid batteries, nickel-metal hydride batteries, air batteries and sodium-sulfur batteries; (2) In terms of the number of patents, it ranked second in the world as of June 2010, second only to In Japan; (3) From the perspective of patent applicants, nearly 60% of the patent applications for batteries and management systems for pure electric vehicles are from Japanese, followed by patents from American applicants.
3. Germany: (1) The research focuses on lithium-ion batteries, followed by lead-acid batteries, nickel-metal hydride batteries, sodium-sulfur batteries and air batteries; (2) In terms of the number of patents, it ranked No. 1 in the world as of June 2010 6th (the whole of Europe ranks 4th in the world), accounting for only 11% of the 6,782 Japanese applications; (3) In terms of the identity of patent applicants, patent applications from Germans account for 43% of the total, followed by Japan people.
4. South Korea: South Korea ranks 5th in the world in terms of automobile production and 4th in the world in terms of export volume. (1) The research focuses on lithium-ion batteries, which is much higher than the subsequent nickel-hydrogen batteries, lead-acid batteries, and sodium-sulfur batteries; (2) In terms of the number of patents, it ranks fourth after Japan, the United States and China. As a market, South Korea is after Europe; (3) From the perspective of patent applicants, Koreans own the most patents, followed by Japanese, and third by Americans.
5. my country: (1) The research focuses on lithium-ion batteries, followed by power nickel-metal hydride batteries, and the status of lead-acid batteries has declined rapidly; (2) In terms of the number of patents, it ranks third after Japan and the United States; ( 3) From the perspective of the identity of the patent applicant, the Japanese are the most, followed by the natives. Among the natives, BYD is the one with outstanding strength. The company focuses on lithium-ion batteries and polymer lithium-ion batteries. In 2003, the company applied for the first domestic patent and US patent.
From the perspective of the entire patent pattern, the patent competition around lithium-ion batteries will be the main battlefield of future patent battles. In terms of trends, Japan will still be at the forefront. Since the electric vehicle industry is in the growth stage, many key technologies have yet to be broken through, so Europe and the United States may have excellent performance based on their strong basic research advantages. At present, China and South Korea have invested the most in the research and development of lithium-ion batteries and their output has risen the fastest. Their participation in the war has further complicated the patent game.
