New energy electric vehicle batteries (how much is a group of new energy electric vehicle batteries)
In recent years, with the implementation of environmental protection, energy saving and emission reduction policies, new energy vehicles have achieved unprecedented development, and have gradually grown into a sales rookie in the automobile market.
However, for new energy vehicles, endurance, charging and safety are the three issues that consumers are most concerned about, and their performance depends largely on the power source of electric vehicles-batteries.
So, what is the difference between the batteries used in new energy vehicles on the market now? What's the difference between them? Which is more reliable? Today, the professor will talk about these aspects to see if there is anything you don't understand.
There are many kinds of batteries, which can be divided into three types: chemical, physical and biological batteries. According to the structure, it can be divided into two categories: battery and fuel cell.
In terms of types, the batteries used in new energy vehicles are all chemical batteries, and there are five common power batteries: lead acid, lithium titanate, lithium cobaltate, Ferrous lithium phosphate, nickel cobalt manganese and nickel cobalt aluminum.
Among them, Ferrous lithium phosphate and ternary lithium battery, which have higher energy density and more stable performance, are the two most widely circulated batteries in the battery market, and are also the most widely used mainstream power sources for electric vehicles.
Because Ferrous lithium phosphate and ternary lithium batteries are mainly circulating in the market now, we will mainly aim at these two batteries and interpret the differences between them.
What is the difference between the two batteries? As a result, lithium iron phosphate battery is superior to ternary lithium battery in terms of safety, service life and manufacturing cost, but ternary lithium battery is slightly superior to lithium iron phosphate battery in terms of energy density.
Energy density: ternary lithium battery is larger than lithium iron phosphate battery.
Energy density is an important index to evaluate the performance of batteries. Generally speaking, the higher the energy density, the higher the electric energy contained in the battery per unit weight or volume, and the farther the cruising range can be provided for the vehicle.
It's no use talking more, for example. For example, two pieces of ore with the same weight and size, one with more impurities and the other with less impurities and higher extracted components, will undoubtedly be more valuable. Therefore, under the same volume, the higher the energy density, the stronger the ability to store electric energy.
Because of its inherent chemical properties, lithium iron phosphate battery has a low voltage and an energy density of about 140Wh/kg. The ternary lithium battery has high voltage and energy density of 240kWh/kg. That is to say, under the same battery weight, the energy density of lithium ternary battery is 1.7 times that of lithium iron phosphate battery.
At present, there are three kinds of ternary lithium batteries: NCM523, NCM622 and NCM811, among which NCM811 battery is the mainstream application battery. Little known is that the naming methods of these three types of batteries are all derived from the proportion of nickel, cobalt and manganese as cathode materials, such as 811 battery. The cathode materials are mainly 80% nickel, 10% cobalt and 10% manganese. Simply put, the electrode materials are changed to 8: 1: 1 on the basis of the previous ternary lithium battery.
It is worth noting that because of the rising requirements for battery life, high nickel NCM811 is the key breakthrough direction for battery development. The main reason for choosing it is that the increase of nickel content will increase the specific capacity of ternary cathode material, which can further expand the energy density of the battery, and the energy storage capacity will increase with the increase of energy density.
In fact, before the appearance of ternary lithium battery, NCA battery was the mainstream of power source for new energy vehicles. After testing NCA and NCM811 batteries by a certain institution, it was found that NCA with only 5% cobalt was superior to NCM811 battery with 10% cobalt content in performance. However, because the manufacturing process and cost of nickel-cobalt-aluminum battery are high, and the technology is in the hands of Japanese and Korean enterprises, domestic enterprises are now mainly developing nickel-cobalt-manganese batteries.
Safety: Lithium iron phosphate battery is larger than ternary lithium battery.
Because of the material, the thermal stability of lithium iron phosphate battery is the best, and the electric heating peak is greater than 350℃, and the internal chemical components will begin to decompose when the temperature is 500-600℃. However, its low temperature resistance is poor, and the battery with a capacity of 3500mAh works at MINUS 10℃. After 100 charge and discharge cycles, the battery is in a state of scrapping.
In contrast, the ternary lithium battery material is unstable, and it is easy to decompose at about 200 degrees, and the electrolyte will burn rapidly under the action of high temperature, which will trigger a chain reaction and even cause the vehicle to spontaneously ignite! Therefore, many new energy vehicles equipped with ternary lithium batteries now need to add over-temperature protection and battery management systems to protect the batteries.
However, the low-temperature performance of ternary lithium batteries is better than that of lithium iron phosphate batteries. At low temperature, the lower limit of charge and discharge of lithium iron phosphate battery is -20℃, while the lower limit of ternary lithium battery is -30℃, so the low temperature discharge performance is better. According to the test, under the same low temperature conditions, the low temperature cruising range of ternary lithium battery is attenuated by less than 15%.
Life: Lithium iron phosphate battery is larger than ternary lithium battery.
Battery life is the battery's power decay after many times of full charge and discharge. Generally, the effective power of electric vehicle battery decays below 80% of the original power, which means that the battery needs to be replaced. The replacement standard is the same as that of mobile phone battery.
Normally, the number of complete charge and discharge cycles of lithium iron phosphate battery can reach 3500 times, and after each charge and discharge, the power will be attenuated once, and after several attenuations, it will be below 80% of the original power. Converted into time, the lithium iron phosphate battery will be charged and discharged once a day, and it will take nearly 10 years to start to decay and replace the battery.
Different from lithium iron phosphate battery, ternary lithium battery has a shorter life than Ferrous lithium phosphate, and it will begin to decay after being fully charged and discharged for more than 2000 times, and the time is generally about 6 years. However, battery life can be slightly prolonged by means of battery management, but it is only slightly delayed.
Of course, the life of the battery pack is not the simple sum of the life of the single battery. As an assembly, only when the performance of multiple battery cells in the battery pack is highly consistent, the life of the battery pack can be close to that of the single battery.
Manufacturing cost: ternary lithium battery is larger than lithium iron phosphate battery.
In terms of battery cost, lithium iron phosphate battery also has great advantages. It has no precious metal, so the production cost is lower. The ternary lithium battery uses a variety of materials such as nickel, cobalt and manganese, and the production of high-nickel batteries requires a strict process environment, and the current cost is relatively high.
Secondly, in recent years, lithium, cobalt and other metal resources are facing the problem of scarcity, especially metal cobalt, the price has soared all the way, and the price is more than 200,000 yuan/ton. And the price of a ton of electrolytic nickel is now about 110,000 yuan. Therefore, many battery companies have to develop to 811, increase the nickel content and reduce the cobalt content, thus reducing the cost.
Get to the point, considering the battery energy density, low temperature performance, safety, service life and cost, lithium iron phosphate battery and ternary lithium battery have their own advantages, but it is really difficult to draw a conclusion if it is not to say who wins or loses.
However, now Tesla is developing solid-state batteries, so to paraphrase Li Xiang, the founder of LI, lithium iron phosphate batteries belong to buses, ternary lithium batteries belong to passenger cars, and solid-state batteries belong to the future.