Types of new energy vehicle batteries
One, lead-acid batteries
Lead-acid batteries as a more mature technology, because of its lower cost, and can be discharged at a high rate, is still the only available for mass production of batteries used in electric vehicles. For the Beijing Olympics, there were 20 electric cars using lead-acid batteries to provide transportation for the Games.
But lead-acid batteries have very low specific energy, specific power and energy density, making it impossible for electric vehicles to have good speed and range.
Two, nickel-cadmium batteries and nickel-metal hydride batteries
Although the performance is better than lead-acid batteries, but contains heavy metals, the use of the environment will cause pollution after abandonment.
Nickel-metal hydride power battery has just entered the maturity period, is currently the only hybrid car battery system used in the battery system has been verified and commercialized, the scale of the battery system, 99% of the market share of the existing hybrid batteries nickel-metal hydride power batteries, the representative of the commercialization of Toyota's Prius. At present, the world's major automotive power battery manufacturers mainly include Japan's PEVE and Sanyo, PEVE occupies 85% of the global market share of nickel-metal hydride batteries for hybrid vehicles, and currently the major commercialized hybrid vehicles such as Toyota's Prius, Alphard and Estima, as well as Honda's Civic, Insight, etc. are all adopting PEVE's nickel-hydrogen power packs. NiMH power battery packs. In China, Changan Jiexun, Chery A5, FAW Pentium, GM Grand Hyatt and other brands of sedans have been in demonstration operation, they also use nickel-metal hydride batteries, but the battery is mainly purchased from abroad, the domestic nickel-metal hydride batteries in the automobile is still in the research and development of matching stage.
Three, lithium batteries. Traditional lead-acid batteries, nickel-cadmium batteries and nickel-metal hydride batteries itself is more mature technology, but they are used in automobiles as a power battery is a big problem. At present, more and more automobile manufacturers choose to use lithium batteries as the power battery of new energy vehicles.
Because lithium-ion power battery has the following advantages: high operating voltage (nickel-cadmium batteries hydrogen-nickel batteries 3 times); specific energy (up to 165WH/kg, is nickel-hydrogen batteries 3 times); small size; lightweight; long cycle life; self-discharge rate is low; no memory effect; non-polluting and so on.
Currently, many well-known automobile manufacturers are committed to the development of power lithium battery cars, such as the United States Ford, Chrysler, Japan Toyota, Mitsubishi, Nissan, South Korea's Hyundai, France Courreges, Ventury and so on. And domestic automakers such as BYD, Geely, Chery, Lifan, ZTE and others have also been carrying lithium power batteries in their hybrid and pure electric vehicles.
The current bottlenecks hindering the development of lithium-ion power batteries are: safety performance and automotive power battery management system. Safety performance, due to the lithium-ion power battery has a high energy density, high operating temperature, harsh working environment and other aspects, coupled with the people-oriented safety concept, therefore, the user has put forward very high requirements for the safety of the battery. As for the management system of automobile power battery, since the working voltage of automobile power battery is 12V or 24V, and the working voltage of single power lithium-ion battery is 3.7V, it is necessary to increase the voltage by connecting multiple batteries in series, but it is difficult for batteries to achieve completely uniform charging and discharging, which results in the imbalanced charging and discharging of single batteries in multiple battery packs connected in series, and the batteries will be charged and over-discharged, while the charging and over-discharging phenomena will occur. Insufficient charging and over-discharging phenomenon, and this situation will lead to a sharp deterioration of the battery performance, and ultimately lead to the whole group of batteries can not work properly, or even scrap, thus greatly affecting the service life of the battery and the reliability of the performance.
Four, lithium iron phosphate
Lithium iron phosphate is also a lithium battery, its specific energy is less than half of the lithium cobalt acid battery, but its high security, the number of cycles can reach 2000 times, discharge stability, cheap, become the new choice of automotive power.
BYD proposed "iron battery", the industry believes that the possibility of its lithium iron phosphate batteries.
Fifth, the fuel cell
Simply put, the fuel cell (Fuel Cell) is a kind of chemical energy present in the fuel and oxidizer is directly converted into electrical power generation device. Fuel and air are fed into the fuel cell separately, and electricity is wonderfully produced. From the outside, it looks like a storage battery with positive and negative electrodes and electrolyte, but in essence it is not a "power storage" but a "power plant".
The most promising type of fuel cell for automobiles is the proton exchange membrane fuel cell. Its working principle is: the hydrogen to the negative pole, after the role of the catalyst (platinum), hydrogen atoms in the two electrons were separated out, the two electrons in the positive pole of attraction, by the external circuit to produce electric current, the loss of electrons of hydrogen ions (protons) can be passed through the proton exchange membrane (i.e., the solid electrolyte), in the positive pole and oxygen atoms and electrons recombined into water. Since oxygen can be obtained from the air, as long as the negative electrode is constantly supplied with hydrogen and the water (vapor) is taken away in time, the fuel cell can constantly provide electrical energy.
Because the fuel cell directly converts the chemical energy of the fuel into electrical energy without going through the combustion process, it is not limited by the Carnot cycle. The fuel-electricity conversion efficiency of the current fuel cell system is 45% to 60%, while the efficiency of thermal and nuclear power generation is about 30% to 40%.
According to the database data of China Business Industry Research Institute, the domestic production and sales of new energy vehicles in August were 72,000 and 68,000 respectively, an increase of 67.3% and 76.3% year-on-year; the production and sales of new energy vehicles in January-August were 346,000 and 320,000 respectively, an increase of 33.5% and 30.2% year-on-year. New energy vehicle production and sales volume growth, the upper and lower industrial chain have been developed. Among them, the power battery, which is an important part of new energy vehicles, has also seen rapid development. According to statistics, in August 2017, the installed capacity of domestic lithium batteries for new energy vehicles was 2,924.8Mwh; the cumulative installed capacity from January to August was 8,653.7Mwh.
In August, in the domestic new energy vehicle market, the sales of pure electric vehicles accounted for more than 80% of the overall new energy vehicle market. At present, the domestic new energy models are mainly concentrated in the field of new energy vehicles, new energy buses, new energy logistics vehicles, etc. The installed capacity of power battery from January to August 2017 is as follows. According to statistics, in August, CATL power battery installed capacity ranked first, amounting to 1,262.41Mwh, and is the only enterprise with an installed capacity of more than 1,000Mwh. Cumulatively, from January to August, the first enterprise of power battery installed capacity is still CATL, with a cumulative installed capacity of 3,265.7Mwh, accounting for 28.2% of the market share.
The development trend
In the development of new energy vehicle batteries, nickel-metal hydride (NiMH) battery technology is the most mature, the next three years will still be the mainstream of new energy vehicles, after which nickel-metal hydride (NiMH) battery technology will be three-way split with lithium iron phosphate (LiFePoP) and hydrogen fuel cell (HFC), and will gradually be replaced by lithium batteries and fuel cells after five years.