The battery is the source of power for electric vehicles. At present, the key factor restricting the development of electric vehicles is that power batteries are not ideal. The main performance indicators of electric vehicle batteries are specific energy, specific power and service life. In order for electric vehicles to compete with internal combustion engine vehicles, the key is to develop batteries with higher energy, higher specific power, longer service life and lower cost.
01 lead-acid battery
Lead-acid batteries have a history of more than 100 years. The electrodes are mainly made of lead and its oxide. The electrolyte is a kind of storage battery of sulfuric acid solution. English: Lead-acid battery. In the discharge state, the main component of the positive electrode is lead dioxide, and the main component of the negative electrode is lead; in the state of charge, the main components of the positive and negative electrodes are lead sulfate. It is widely used as a starting power source for internal combustion engine vehicles. It is also a mature electric vehicle battery, which has good reliability, easy availability of raw materials and low price; the specific power can basically meet the power requirements of electric vehicles. However, it has two major drawbacks; one is lower than the energy, the mass and volume are too large, and the mileage is short on one charge; the other is the short service life and the use cost is too high.
02 nickel-metal hydride battery
Nickel-metal hydride batteries are alkaline batteries. Nickel-metal hydride batteries have a long service life and no memory effect, but the price is high. Although its initial acquisition cost is high, its long-term practical use cost is not high due to its advantages in terms of energy and service life. At present, the company that produces electric vehicle nickel-metal hydride batteries abroad is mainly a joint venture company of Ovonie, Toyota and Panasonic. Ovonie has 80A·h and 130A·h unit cells with a specific energy of 75-80W·h/kg and a cycle life of more than 600 cycles. The battery is installed on several electric vehicles. One type of vehicle can travel 345km on a single charge, and one vehicle travels more than 80,000 kilometers a year. Due to the high price, it has not yet been mass-produced. Domestically developed 55A·h and 100A·h unit batteries, with a specific energy of 65 W·h/kg and a power density greater than 800 W/kg nickel-metal hydride storage batteries.
03 lithium ion battery
As a new high-voltage, high-energy-density rechargeable battery, lithium-ion secondary batteries have unique physical and electrochemical properties and have broad prospects for civil and defense applications. Its outstanding features are: light weight, large energy storage, no pollution, no memory effect, and long service life. Under the same volume weight, the lithium battery has 1.6 times the storage capacity of nickel-metal hydride batteries and 4 times that of nickel-cadmium batteries. At present, humans only use 20% to 30% of their theoretical power, and the development prospects are very bright. . At the same time, it is a true green battery that does not pollute the environment. It is the best battery that can be applied to electric vehicles. Since the 1990s, China has developed and utilized lithium-ion batteries, and has made breakthroughs so far, and has developed lithium-ion batteries with independent intellectual property rights.
04 nickel-cadmium battery
The application of nickel-cadmium batteries is second only to lead-acid batteries, and its specific energy can reach 55W?h/kg, and the specific power exceeds 190W/kg. It can be quickly charged and has a long cycle life. It is more than twice as long as lead-acid batteries, and can reach more than 2,000 times, but the price is 4 to 5 times that of lead-acid batteries. Although its initial acquisition cost is high, its long-term practical use cost is not high due to its advantages in terms of energy and service life. The disadvantage is that there is a "memory effect", which is easy to reduce the available capacity of the battery due to poor charging and discharging. It must be fully charged and discharged after about ten times of use. If there is already a "memory effect", it should be continuously charged and discharged 3 to 5 times to release the memory. In addition, cadmium is toxic, and it is necessary to pay attention to recycling work during use to avoid environmental pollution caused by cadmium.
05 sodium sulfur battery
Advantages of sodium-sulfur batteries: One is higher than energy. Its theoretical specific energy is 760W?h/kg, which is actually more than 100W?h/kg, which is 3-4 times that of lead-acid batteries; the other is high-current, high-power discharge. The discharge current density is generally up to 200-300 mA/mm2, and it can release three times of the intrinsic energy instantaneously; the other is high charging and discharging efficiency. Since a solid electrolyte is used, there is no self-discharge and side reaction which usually employs a liquid electrolyte secondary battery, and the charge and discharge current efficiency is almost 100%. The disadvantage of sodium-sulfur battery is that its working temperature is 300-350 °C. Therefore, the battery needs certain heating and heat preservation when working. The high temperature corrosion is serious and the battery life is short. High-performance vacuum insulation technology has been used to solve this problem effectively. There are also problems such as poor performance and poor safety. In the 1980s and 1990s, foreign countries focused on the development of sodium-sulfur batteries as a fixed application (such as power storage), and increasingly showed its superiority. Japanese companies have made the most significant progress in this regard. As a recently optimistic electric vehicle battery, it has been listed as a medium-term electric vehicle battery by the US Advanced Battery Association (USMABC). The B240K type sodium-sulfur battery produced by ABB Company of Germany has a mass of 17.5kg and a storage capacity of 19.2Kw. h; specific energy up to 109W?h/kg, cycle life of 1200 times, the best one in the loading test was 2300km without fault.
06 nickel zinc battery
The new sealed nickel-zinc battery offers the advantages of high quality, high quality power and high current discharge. This advantage allows nickel-zinc batteries to meet the energy needs of electric vehicles in terms of charging trips, hill climbing and acceleration. The nickel-zinc battery is a product developed and produced by the National Energy Research Corporation (ERC), and the Xiamen Battery Factory has cooperated with it to introduce this product. Nickel-zinc batteries are very competitive batteries. Its advantages: its specific energy reaches 50Wh / k or more, the volume energy has exceeded the nickel-cadmium battery, less than the nickel-hydrogen battery. High current discharge, the battery voltage will be balanced over a wide range, and has a long service life, cycle life ≥ 500 times. Charging time ≤ 3.5h, fast charging ≤ 1h. It is particularly worth mentioning that the self-discharge resistance of the self-discharge is very good. At room temperature, the self-discharge amount is less than 30% of the rated charge. At 50 ° C high temperature, with C / 3 discharge, the battery charge amount is ≤ 10% of the rated charge, and at -15 ° C, C / 3 discharge ≤ 30%. Nickel-zinc batteries have good compatibility with lead-acid batteries. Any vehicle that uses lead-acid batteries can be replaced with nickel-zinc batteries. From the current price point of view, nickel-zinc is also slightly more expensive, but I believe that after the application of the amount, the price will naturally fall. The compatibility with the outline of the lead-acid battery makes the nickel-zinc battery more convenient to replace the lead-acid battery and becomes the ideal power source for the electric vehicle.
07 zinc air battery
Zinc air battery, also known as zinc oxide battery, is a kind of metal air battery. The theoretical value of the specific energy of zinc-air battery is 1350W?h/kg, and the current specific energy has reached 230Wh/kg, which is almost 8 times that of lead-acid batteries. It can be seen that the development space of zinc air battery is very large. Zinc air batteries can only be "mechanically charged" by replacing the zinc electrode. The time to replace the electrode can be completed in 3 minutes. With a new zinc electrode, the "charging" time is extremely short and very convenient. If such batteries are developed, the construction of social security facilities such as charging stations is eliminated. Zinc electrodes can be purchased in supermarkets, battery operating points, auto parts stores, etc., which is very beneficial to the popularization of this battery electric vehicle. The battery has the advantages of small volume, large charge capacity, small mass, normal operation over a wide temperature range, no corrosion, safe and reliable operation, and low cost. The charge capacity of the test battery is now only five times that of the lead-acid battery, which is not ideal. However, the charge of 5 times that of lead-acid batteries has attracted the attention of the world. The United States, Mexico, Singapore and some European countries have already tried on postal vehicles, buses and motorcycles. It is also a promising electric vehicle. battery.
08 flywheel battery
The flywheel battery is a new concept battery that was introduced in the 1990s. It breaks through the limitations of chemical batteries and uses physical methods to achieve energy storage. When the flywheel rotates at a certain angular velocity, it has a certain kinetic energy. The flywheel battery is converted into electrical energy by its kinetic energy. The high-tech flywheel is used to store electrical energy, much like a standard battery. There is a motor in the flywheel battery. When charging, the motor runs in the form of a motor. Under the drive of the external power supply, the motor drives the flywheel to rotate at a high speed. That is, the “charge” of the flywheel battery increases the speed of the flywheel to increase its function; The motor is operated in the state of the generator, and the electric energy is outputted by the flywheel to complete the conversion of mechanical energy (kinetic energy) to electric energy. When the flywheel battery is powered out, the speed of the flywheel gradually decreases. The flywheel of the flywheel battery operates in a vacuum environment with a very high speed (200000r/min). The bearings used are non-contact magnetic bearings. It is said that the flywheel battery can reach 150W?h/kg, the specific power is 5000~10000W/kg, and the service life is up to 25 years, which can be used for electric vehicles to drive 5 million kilometers.