The trend of electrification is intensifying. China has become the world's largest new energy vehicle market through policy guidance and support. As we all know, the important bottleneck of new energy vehicles is the battery life. In this context, the state has issued the "Promoting Action Plan for Promoting Automotive Power Battery Development" and "Technology Roadmap for Energy Saving and New Energy Vehicles" to encourage the use of high energy density batteries. The recent "Guidance Catalogue for Foreign Investment Industries (2017 Practice)" The policy proposes to lift the restrictions on pure electric vehicle joint ventures and to eliminate the restrictions on the ratio of automotive electronics and power battery stocks. This is also an important measure to promote the application of high energy density batteries in the new energy vehicle market. The battery is a very deep subject, because this thing has been very widely used in our lives since its invention, such as 3C, such as energy storage. Power battery refers to a battery with large electric energy capacity and output power, which can be equipped with electric bicycles, electric vehicles, electric equipment and tool drive power. It usually includes military (submarine, advanced intelligent robot, etc.) and energy storage used by enterprises and institutions. The standing power supply of the equipment communication command system. With the development of new electric bicycles, electric vehicles and commercial production, new submarines and unmanned underwater vehicles (UUV), the demand for new green power batteries has increased dramatically. At present, the most widely used power batteries in the world mainly include lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries, lithium batteries, fuel cells, and solar cells. These power batteries have their own advantages and have been widely used in different fields. The lead-acid battery was invented by RG. Plante in 1859 and was the first battery to be used. The Plante battery uses two lead plates as electrodes, which are placed in a sulfuric acid solution for electrolysis. By continuously changing the current direction of the electrolysis, the storage capacity of the lead plate is gradually increased, but the specific energy of the battery is low. The traditional lead-acid battery has two main disadvantages: one is to maintain water maintenance during the service life; the other is that the rich liquid cannot be placed in any direction due to the risk of acid leakage. After continuous research, in the mid-20th century, the invention of colloidal electrolyte technology and maintenance-free sealing technology was invented: in 1955, German Sunshine Company first applied gel electrolyte technology to lead-acid batteries and put them on the market. In the mid-1960s, the company developed the "Dryfit" practical colloidal electrolyte sealed lead-acid battery series. In 1968, Desai submitted the first patent describing a gas-sealed lead-acid battery, which was officially released in 1974. In 1972, DH McLelland and JLDevitt of Gates Company of the United States invented the adsorption-type ultra-fine glass fiber separator (AGM), which solved the problem of the composite circulation of oxygen inside the battery in practice, and developed a cylindrical AGM valve-regulated sealed lead-acid battery. (VRLAB), the electrolyte of this battery is adsorbed in the glass fiber membrane, the electrolyte can not flow freely, compared with the traditional liquid-rich lead-acid battery (the electrolyte can flow freely), the valve-regulated lead-acid battery is the poor liquid. Battery. In the following 30 years, VRLAB batteries have been rapidly developed and widely used in various professional departments such as electric power, railways, ships, and communications. The emergence of VRLA technology has promoted the development of lead-acid batteries, which has entered a period of prosperity and development. Lead-acid battery is the most mature battery in all chemical power sources. It has the advantages of low price, high safety, high current discharge performance and high battery recovery rate. It has been widely used in electric bicycles, electric motorcycles, communication industry, electric power. Industrial backup power, railway diesel locomotives and other fields. However, due to the shortcomings of low specific energy and environmental protection, new materials, new structures and new technologies of lead-acid batteries are still being studied, such as corrosion-resistant lead alloy positive grids, foam lead grids, foam carbon grids, and new anodes. Additives, super lead acid batteries, etc. The alkaline nickel-based battery mainly includes a nickel-cadmium battery, a nickel-zinc battery, and a nickel-hydrogen battery. Among them, nickel-cadmium batteries have been widely used in many fields, but the risk of cadmium pollution in used nickel-cadmium batteries has greatly limited their application. EU countries have banned the use of nickel-cadmium batteries for power batteries, which are basically on the verge of elimination; nickel-zinc When the battery is charging, the negative zinc is prone to dendrites, which causes the diaphragm to puncture and affect the service life of the battery. In contrast, the nickel-hydrogen battery is the best comprehensive power battery. At present, nickel-hydrogen batteries have been widely used in commercial electric vehicles. The nickel-hydrogen battery is a battery composed of hydrogen ions and metallic nickel. The positive electrode active material is nickel hydroxide, the negative electrode active material is a hydrogen storage alloy, and the electrolyte solution is a 6 M potassium hydroxide solution. Its electrochemical formula can be expressed as: (-)M/MH-KOH-Ni(OH)2/NiOOH(+) When charging, hydrogen ions (H+) in the KOH electrolyte are released, absorbed by the hydrogen storage alloy, and the positive electrode is changed by Ni(OH)2 NiOOH and H2O are formed; hydrogen is consumed on the negative electrode during discharge, and the positive electrode is changed from NiOOH to Ni(OH)2. Ni-MH batteries have high specific energy and high specific power, and their specific energy is three times higher than that of lead-acid batteries; the specific power is nearly 10 times higher than that of lead-acid batteries. In addition, nickel-metal hydride batteries have better overcharge and discharge resistance and thermal properties, so they have higher safety and reliability. Fast charging, environmental pollution, long life, etc. are also advantages of nickel-metal hydride batteries. However, since the raw material nickel and the hydrogen storage alloy are very expensive, the cost of the nickel-hydrogen battery is high, and the price becomes a major factor restricting the development of the nickel-hydrogen battery. The application of nickel-metal hydride batteries in the field of electric vehicles has shown limitations. Lithium-ion battery research began in 1990 by Nagoura et al., a lithium-ion battery with petroleum coke as the negative electrode and lithium cobaltate as the positive electrode. In the same year, Japan and Canada's Moli two battery companies announced that they will introduce lithium with carbon as the negative electrode. Ion battery; In 1991, Japan's Sony Energy Technology Co., Ltd. and the Battery Division jointly developed a lithium-ion battery with a glycan pyrolysis carbon (PFA) as a negative electrode; in 1993, Bellcore Corporation of the United States first reported a polymer lithium-ion battery. A lithium ion battery refers to a high energy secondary battery in which Li+ is repeatedly embedded and deintercalated into a positive and negative electrode material. Usually consists of the following components: (1) The negative electrode, which undergoes an oxidation reaction during discharge, and the carbon material is used more; (2) The positive electrode, the reduction reaction occurs during discharge, and more transition metal oxides such as LiCoO2 are used; (3) an electrolyte that provides a transport medium for ion motion; (4) Diaphragm, providing electronic isolation for the positive and negative electrodes. Aluminum foil is usually used as the cathode current collector, and copper foil is used as the anode current collector. Compared with other power batteries, the advantages of lithium-ion batteries are obvious: 1) The energy density is large, the volume specific energy and mass specific energy can reach 300 Wh/cm3 and 125 Wh/kg, respectively, up to 350 Wh/cm3; 2) The average output voltage is high (about 3.9 V), which is 3 times that of Ni-Cd and Ni-MH batteries; 3) The output power is large; 4) Self-discharge is small, less than 10% per month, less than half of Ni-Cd\Ni-NH self-discharge; 5) no memory effect like Ni-Cd\Ni-NH battery; 6) can be quickly charged and discharged; 7) High charging efficiency. Up to 100%; 8) Wide operating temperature range, -25Co~70Co; 9) There is no environmental pollution, called green battery; 10) Long service life, up to 1200 times, up to 3000 times. Therefore, lithium ion batteries are widely used in consumer electronics, military products, and aviation products. However, with the explosion of lithium-ion batteries, fires and other accidents, safety issues have become a key problem in the development of lithium-ion battery technology. There are a series of potential exothermic reactions inside lithium-ion batteries, which are the root cause of lithium-ion battery safety problems. The ability to effectively solve the safety problems caused by thermal runaway has also become a key factor to promote or restrict the further development of lithium-ion batteries. A fuel cell is a power generation device that directly converts chemical energy stored in a fuel and an oxidant into electrical energy by an electrochemical reaction. Like conventional batteries, it is also a power generation unit that operates on the principle of electrochemistry. The difference is that as long as the fuel source is continuously supplied, the fuel cell can continuously supply electric energy. There is no heat engine process in the fuel cell, that is, it is not limited by the Carnot cycle, so the energy conversion efficiency is high, and no pollution occurs during the reaction, and the product is only water. There are many kinds of fuel cells, and based on their different electrolyte properties, they can be divided into proton exchange membrane fuel cells, phosphoric acid fuel cells, solid oxide fuel cells, molten carbonate fuel cells and alkaline fuel cells. . As a new type of power generation technology, fuel cells have the following characteristics: 1) High energy conversion efficiency: The fuel in the fuel cell is directly converted into electric energy without combustion, and is not restricted by the Carnot cycle. Therefore, the fuel cell is more efficient than the ordinary heat engine, and the theoretical value of the energy conversion efficiency is as high as 60% or more. The actual use efficiency is 2 to 3 times that of ordinary internal combustion engines. 2) Environmentally friendly: the fuel directly reacts with the fuel cell and generates water with the air. In the process, almost no environmental pollutants such as nitrogen oxides (NOx) and sulfur oxides (SOx) are emitted, and the fuel cell structure is simple. There are no moving parts and the noise level is low. 3) Fuel diversity: fuel cell fuel sources are wide, it can be gaseous fuels such as hydrogen, natural gas and biogas, liquid fuels such as gasoline, diesel, methanol, ethanol and formic acid, which are in line with the trend of energy diversification, and should deal with oil and coal. The depletion of fossil energy. 4) Wide range of applications: Unlike ordinary batteries, fuel cells allow for arbitrary scaling between power (determined by fuel cell size) and capacity (determined by fuel storage size), making it easy to achieve MW from 1 W It is used in portable power sources, distributed power stations and centralized power stations, as well as in aerospace, marine, automotive and other vehicles. It is precisely because of these outstanding advantages that the research and development of fuel cell technology is favored by governments and companies of all countries, which will detonate the green revolution of new energy and environmental protection in the 21st century. Fuel cells provide the most efficient and environmentally-friendly vehicle power for power vehicles, but there are still many problems to be solved in order to achieve widespread use of fuel cells, such as high battery development costs (using precious metal platinum as a catalyst), hydrogen storage and transportation. The problem, as well as the short battery life. These power batteries have their own advantages and have been widely used in different fields. The main technical characteristics of common power batteries are shown in Table 1. Ultra-Fast Scanning External Cavity Tunable Laser Ultra-Fast Scanning External Cavity Tunable Laser,Tunable Diode Laser Analyzer,Applications Tunable Laser,Tunable O-Band Laser AcePhotonics Co.,Ltd. , https://www.acephotonics.com