In recent years, thanks to the implementation of environmental protection, energy saving and emission reduction policies, new energy vehicles have experienced unprecedented development and are gradually become a new sales star in the automobile market.
But for new energy vehicles, battery life, charging and safety are the three issues that consumers worry about most, and their performance largely depends on the source of energy. energy of electric vehicles: the battery.
So, what are the differences between the batteries used in new energy vehicles currently on the market? What is the difference between them? Which is the most reliable? Today the teacher will talk about these aspects, see if there is anything you don't understand.
There are many types of batteries, which can be divided intothree categories: chemical, physical and biological batteries According to the type and according to the structure, they can be divided into two categories: storage batteries and fuel cells.
In terms of type, the batteries used in new energy vehicles are all chemical batteries. The most common batteries include lead acid, lithium titanate, lithium cobalt oxide, lithium iron phosphate, nickel cobalt manganese, and nickel cobalt. Aluminum five types of power batteries.
Among them, lithium iron phosphate and lithium ternary batteries with higher energy density and more stable performance are the two most widely distributed batteries in the battery market and are also the source of he most widely used consumer energy for electric vehicles. .
Since lithium iron phosphate batteries and bedternary hium are currently mainly circulating on the market, in the following we will focus on these two batteries and explain the differences between the two batteries.
What is the difference between the two batteries? Let's talk about the results first. In terms of safety, service life and manufacturing cost, lithium iron phosphate batteries have advantages over ternary lithium batteries, but in terms of energy density, ternary lithium batteries are slightly better than ternary lithium batteries. lithium iron phosphate.
Energy density: Is ternary lithium battery larger than lithium iron phosphate battery?
Energy density is an important indicator to evaluate battery performance. Generally speaking, the higher the energy density, the higher the electrical energy contained in the battery per unit of weight or volume and the greater the autonomy.The cruising time it can offer the vehicle is long.
No need to say more. Let's give an example. For example, if two pieces of ore have the same weight and size, one contains more impurities and the other less impurities and a higher content of extracted ingredients, then there is no doubt that the one with the higher content will have more value. Therefore, under the same volume, the higher the energy density, the stronger the capacity to store electrical energy.
Due to their inherent chemical properties, lithium iron phosphate batteries have a low voltage and energy density of approximately 140 Wh/kg while ternary lithium batteries have a high voltage and density energy of essentially 240 kWh/kg; This means that for the same battery weight, the energy density of ternary lithium is 1.7 times higher than that of lithium iron phosphate batteries.
CurrentBasically, there are three types of ternary lithium batteries: NCM523, NCM622 and NCM811, among which NCM811 battery is the main application battery. What is little known is that the naming of these three types of batteries is derived from the proportion of nickel, cobalt and manganese in the cathode material. For example, in the 811 battery, the cathode material is mainly 80% nickel and 10% cobalt. and 10% manganese. Simply put, based on the previous ternary lithium battery, the electrode material has been changed to .8:1:1.
It is worth noting that due to the increasing requirements for battery life, high nickel NCM811 is a key advancement in battery development. The main reason for its choice is that increasing the nickel content will increase the specific capacitance of the ternary cathode material (nickel-cobalt-manganesis), which can further increase the energy density of the battery core, and the electrical energy storage capacity will increase with the increase of energy density.
In fact, before the emergence of ternary lithium batteries, NCA batteries were the main power source for new energy vehicles. After testing NCA and NCM811 batteries by an organization, it was found that only NCA batteries contained 5% cobalt. is necessary. It has more performance advantages than NCM811 batteries with 10% cobalt content. However, because the production process and cost of nickel-cobalt-aluminum batteries are high, and the technology is in the hands of Japanese and Korean companies. companies now mainly develop nickel-cobalt-manganese batteries.
Safety: Is the lithium iron phosphate battery larger than a bternary lithium battery?
For material reasons, the lithium iron phosphate battery has the best thermal stability. The maximum value of electric heating is greater than. 350℃. When temperature rises, the internal chemical components will begin to decompose at 500-600°C. However, its resistance to low temperatures is poor. A battery with a capacity of 3500 mAh will be discarded after 100 charge and discharge cycles when working in minus 10°C environment.
In comparison, ternary lithium battery materials are unstable and often break down easily at around 200 degrees. The electrolyte burns quickly at high temperatures, triggering a chain reaction and even causing the vehicle to spontaneously combust! Therefore, many new energy vehicles equipped with ternary lithium batteries now need to add overheating protection and overheating protection systems.battery management to protect batteries.
However, the low temperature performance of ternary lithium batteries is better than that of lithium iron phosphate batteries. At low temperatures, the lower limit of charging and discharging of lithium iron phosphate batteries is -20°C, while the lower limit of ternary lithium batteries is -30°C, and the low temperature discharge performance is best. According to tests, under the same low temperature conditions, the low temperature range of ternary lithium batteries is reduced by less than 15%.
Lifespan: Is lithium iron phosphate battery longer than ternary lithium battery?
Battery life is the power loss of the battery after several complete charges and discharges. Generally, the effective power of a battery. the electric vehicle battery is deteriorating. If the capacity ofIf the original battery is less than 80%, it means the battery needs to be replaced. Replacement standards are the same as those for cell phone batteries.
Normally, the number of complete charge and discharge cycles of a lithium iron phosphate battery can reach 3,500 times. After that, the power will decrease once every charge and discharge. will reach less than 80% of the original power. Converted to time, if charged and discharged once a day, the lithium iron phosphate battery will begin to decompose in almost 10 years, so the battery needs to be replaced.
Unlike lithium iron phosphate batteries, ternary lithium batteries have a shorter lifespan than lithium iron phosphate batteries. They will begin to disintegrate after more than 2,000 complete charge and discharge cycles, which typically takes about 6 years. However, battery life pcould be slightly extended through methods such as battery management, but only with a slight delay.
Of course, battery life is not simply the life of a single battery. The sum of the singles. As a combination, only when the performance of multiple battery cells in the battery pack is very consistent can the life of the battery pack be close to that of a single battery.
Manufacturing cost: Is ternary lithium battery larger than lithium iron phosphate battery?
In terms of battery cost, lithium iron battery Phosphate also has a huge advantage. It does not contain precious metals. (nickel and cobalt metal elements). The production cost is therefore lower. Ternary lithium batteries use a variety of materials such as nickel, cobalt and manganese, and the production of hHigh nickel content requires a relatively strict process environment, and the current cost is relatively high.
Second, in recent years, lithium, cobalt and other metal resources have faced shortage problems, especially metal cobalt, with prices skyrocketing, with quotations above 200,000 yuan/ton. The price of a ton of electrolytic nickel is now only about 110,000 yuan. Therefore, many battery manufacturers need to move towards 811, increasing the nickel content and reducing the cobalt content, thereby reducing costs.
Back to main story, considering battery energy density, low temperature performance, safety, life and cost, lithium iron phosphate batteries and Ternary lithium batteries have their own advantages, but if we have to say who loses It's really difIt's hard to decide who wins.
However, Tesla is now developing solid-state batteries, to paraphrase the words of Li Xiang, founder of Li Auto: lithium iron phosphate batteries belong to buses, ternary lithium batteries belong to passenger cars and solid-state lithium iron phosphate batteries belong to buses. -state Batteries are the future.
This article is from the author of Autohome Chejiahao and does not represent the views and positions of Autohome.