One of the most important components of new energy electric vehicles is through the battery, and one of the reasons hindering the development of China's new energy automobile industry is the charging technology problem of the battery. Battery management is of vital importance to the development of China's new energy electric vehicles. What are the types of batteries carried out by vehicles? What are the performance and price of various types of vehicle batteries? This article will be a comprehensive and systematic introduction to the company's current vehicle battery different types of problems.

Five types of car batteries

Types of automotive batteries include lead-acid, nickel-cadmium and nickel hydride, lithium,lithium battery cell machine lithium iron phosphate and fuel cells.

Lead-acid batteries

Lead-acid batteries, a relatively mature technology among the types of automotive batteries, remain the only electric vehicle battery that can be mass-produced due to their low cost and fast discharge rate. During the Beijing Olympics, 20 electric vehicles used lead-acid batteries to provide transportation for the Games. However, the specific energy, specific power and energy density of lead-acid batteries are all very low, so it is impossible for electric vehicles powered by lead-acid batteries to have good speed and range.

Nickel-cadmium and nickel-metal hydride batteries

Although their performance is better than lead-acid batteries, they contain heavy metals and will pollute the environment if they are discarded after use. Among the types of batteries used in vehicles, nickel-metal hydride batteries are just entering a stage of maturity. Among the battery systems used in hybrid vehicles,car battery manufacturers it is the only one that has been practically proven and commercialized and scaled up.

Existing enterprises hybrid learning power battery to carry out 99% of the market share is nickel-metal hydride power battery. Currently, the world's major automotive design major elements as power battery manufacturers include a Japanese PEVE and Sanyo. PEVE occupies 85% of the global market share of nickel-metal hydride battery technology for economic hybrid vehicles. China's nickel-metal hydride battery application in automobiles is still in the stage of social research and development and construction.

Lithium Battery

Traditional lead-acid batteries, nickel-cadmium batteries and nickel-metal hydride batteries are relatively mature, but there are still many problems with their use as automotive power batteries. At present, more and more automobile manufacturers choose to use lithium-ion batteries as the type of power battery for automobile batteries.battery coating Because this lithium-ion battery has the advantages of high operating voltage, high specific energy, small size, light weight, long cycle life, low self-discharge rate, no memory effect, no pollution and so on.

At present, the bottleneck hindering the development of power lithium-ion batteries is: the safety performance of automotive power battery and management system. In terms of safety performance, due to the high energy density of lithium-ion power batteries, high operating temperature, harsh working environment, coupled with the human-oriented safety concept, the user has put forward high requirements for battery safety.

In automotive power battery management system, since the working voltage of automotive power battery is 12V or 24V, and the working voltage of a single power lithium-ion battery is 3.7 V, it is necessary to increase the voltage by connecting multiple batteries in series.

However, because it is difficult to achieve completely uniform charging and discharging of the battery, the single battery after multiple battery packs are connected in series will have an unbalanced state of charging and discharging, and the battery will be undercharged and over-discharged. This situation will lead to rapid deterioration of battery performance, and ultimately lead to the failure of the entire battery pack, or even scrap, thus greatly affecting the service life and reliability of the battery.

Lithium iron phosphate battery

Lithium iron phosphate battery development is also a kind of Chinese lithium battery. Its specific energy is less than half of the lithium cobalt oxide battery, but it has high security, the number of cycles up to 2000 times, discharge stability, low price and cost. It has become a new choice for different types of power batteries for automobiles in China.

Fuel Cell

In short, a fuel cell is a device that converts the chemical energy in fuels and oxidizers directly into electrical energy. The most promising vehicle is the proton exchange membrane fuel cell. It works by sending hydrogen gas to an anode where two electrons in the hydrogen atom are separated by a catalyst.

The two electrons are attracted to the cathode and an electric current is generated through an external circuit. The hydrogen ions that have lost their electrons can recombine with oxygen atoms and electrons at the cathode through a proton exchange membrane to form water. Since oxygen can be obtained from the air, the fuel cell can continue to provide electrical energy as long as hydrogen continues to be supplied to the anode and water is taken away in time.

Since the fuel cell converts the chemical energy of the fuel directly into electrical energy, there is no combustion process, so it is not limited by the Carnot cycle. The fuel electric conversion efficiency of fuel cell system is currently 45% to 60% of all types of vehicle batteries, while the fuel electric conversion efficiency of thermal and nuclear energy is about 30% to 40%.

The trend of new energy vehicle battery

In the development of new energy vehicles, nickel-metal hydride battery management technology is the most mature application, and will remain the mainstream cultural type of China's automotive power battery in the next three years. Thereafter, nickel-metal hydride batteries to carry out the technology can will compete with lithium iron phosphate and hydrogen fuel cell market, and gradually replaced by lithium batteries and fuel cells within five years.

From the price trend point of view, the current price of fast-charging lithium-ion battery type car battery in about 1600 yuan / kWh, ordinary lithium-ion battery prices in about 500 yuan / kWh. Based on current U.S. gasoline and electricity price trends, over the life of a car, a fast-charging lithium-ion electric car with a battery life of 100 kilometers costs 25% more than a gasoline-powered car with an equivalent internal combustion engine .

Once the price of power batteries for electric vehicles drops to $200-300 u002F kWh, the cost of using an electric vehicle will be comparable to that of a conventional car. It is predicted that under the encouragement of relevant policies of various countries, the global demand for lithium-ion for electric vehicles will be close to 50 Gwh in 2020, and the cost of fast-charging batteries is expected to drop to 400-500 USD u002Fkwh in 2020, and the price of ordinary power batteries can drop to 200-300 USD u002Fkwh.

New energy vehicles choose lithium ternary battery or lithium iron phosphate battery

For new energy vehicles, the most central is the battery, the battery accounts for 40% to 60% of the cost of the whole car. At present, there are a wide variety of car batteries, and the main technical routes are lithium ternary battery route and lithium iron phosphate battery route. As a consumer, how should I choose? The battery not only affects the battery life of new energy vehicles, but also directly affects many properties. Among them, consumers are most concerned about safety, range and charging.

Safety is the basic theoretical premise of any enterprise's other social activities. In these two aspects, compared with LFP and NMC, lithium iron phosphate battery development has very obvious advantages. When the temperature reaches 180 ° C, ternary materials for the cathode of the battery begins to work to decompose and produce the need for a large amount of oxygen, these oxygen will be with the solvent within the battery to occur some chemical reactions, and then students produce to provide a large amount of heat, forming a chain reaction. However, due to the lithium iron phosphate battery car cathode can withstand a temperature of 800 ℃ by itself, so for the fire conditions as well as relatively harsh, the cost of time is relatively long, leaving the owner with plenty of time to escape.

In terms of battery life, ternary lithium batteries have a higher energy density undoubtedly has more advantages. But for new energy vehicles, the cruising distance is enough, depending on its use. Otherwise, too much power and too heavy batteries will only increase the purchase cost and power consumption of the car, which is very cost-effective. The core is fast charging.

In terms of the chemical properties of the battery itself, lithium ternary batteries charge faster because they have a higher voltage and more charging power at the same current. Lithium iron phosphate batteries can make up for this deficiency through technology. The on-board voltage of the lithium ternary battery vehicle is very high, but if the charging pile voltage is low, its charging power cannot be increased.