Analysis: The rapid development of battery technology and the classification of new energy batteries

The official opening of the Beijing Motor Show with the theme of "Define a New Life for Cars" also attracted automotive companies and brands from around the world.

This year's auto show shows a total of 1,022 vehicles, of which 174 are new energy vehicles, accounting for 17 % of them. It can be seen that new energy vehicles have become the focus of attention of major car companies, and technologies, concepts, and innovative products on new energy vehicles will also be fully displayed. To the public.

According to foreign media reports, the Northwest Pacific National Laboratory has developed a new battery electrolyte formula aimed at extending the battery life and battery capacity, thereby increasing the mileage of electric vehicles.

The researchers added a fluorinated solvent to the electrolyte, and the lithium salt will become a salinization cluster, which can form a local spherical high concentration lithium salt in the solution to prevent the electrolyte from being corroded, thus avoiding the formation of lithium crystal branches.

When lithium crystal branches are crystallized, the crystal branches or branching structures formed by the crystals resemble snowflakes and frost flowers. Lithium crystal branches can easily lead to short circuit of the battery, which affects the service life of the battery.

And the battery's electrolyte concept has been tested on the laboratory battery core, but the size of the core is only the size of a watch battery. Compared to traditional electrolyte batteries that can maintain battery capacity after 100 recharges, newly developed electrolytes can withstand 700 charge and discharge processes, making the battery life more than seven times.

The range of electric vehicles has always been a major obstacle to their development. Although the new concept of electrolytes can not be applied to electric vehicle batteries for the time being, we have seen the rapid development of battery technology.

Battery as an important part of new energy, its performance to a large extent determines the comprehensive performance of vehicles, so what kinds of mainstream new energy batteries on the market, and what characteristics? Let's take stock.

Lithium-iron phosphate batteries. Many vehicles used lithium-iron phosphate batteries as energy storage devices before electric vehicles switched to three-dimensional lithium batteries in 2017.

The service life of lithium iron phosphate batteries is relatively long. Under normal circumstances, its recycling service life can reach 2,000 times. And its thermal stability is best among all lithium batteries. Its electric peak can reach 300-500 °C, and after 500 °C, the internal chemical composition begins to dissolve, which also ensures its safety.

Moreover, the cost of lithium iron phosphate batteries is low, and the cost of batteries accounts for a large proportion of a pure electric car. Reducing the cost of batteries has a very significant role in improving the cost-effectiveness of vehicles.

Although lithium iron phosphate batteries have quite a few advantages, but it also has some shortcomings, so that electric car companies have turned to ternary lithium batteries. Its energy density is relatively low. If it wants to achieve a certain mileage, it needs a higher vehicle weight, which is obviously unfavorable for controlling energy consumption.

In particular, the subsidies for China's new energy policy have different subsidy amounts for different mileage. However, due to the limitations of its own characteristics, lithium iron phosphate batteries are difficult to increase in energy density, so they are gradually replaced by ternary lithium batteries.

A lithium ternary battery is a lithium battery that uses a nickel cobalt manganese potassium ternary cathode material for a positive electrode material. Its greatest advantage is its high energy density, which can reach 200 kWh / kg, which is a great help for the lightweight design of the car body. And with the rapid development of the battery industry, its price has come to a place that manufacturers can generally accept.

However, the disadvantages of the ternary lithium battery are also very obvious. Its decomposition temperature is about 250-350 °C. The decomposition of internal chemical components releases oxygen molecules. Under the action of high temperature, the internal electrolytes will burn rapidly. Therefore, the battery is in danger of spontaneous combustion or explosion. However, with the Advancement of technology and the wide application of ceramic diaphragm, the safety problem of three-element lithium batteries has been effectively improved.

Although nickel-metal hydride batteries are rarely mentioned now, it used to dominate the electric car market. The total sales volume of HEV equipped with nickel-metal hydride batteries in the world has also reached 10 million vehicles. At present, with the exception of Toyota's models, few other models carry such batteries.

Nickel-metal hydride batteries are a kind of battery with good performance. They are mainly divided into high-voltage nickel-metal hydride batteries and low-voltage nickel-metal hydride batteries. At present, the new energy vehicles we are in contact with are low-voltage nickel-metal hydride batteries.

Its energy density is not much different from that of ordinary lithium cells, but because the cell's monomer pressure is only 1.2 V, the battery's volume is much larger than that of lithium cells when a certain voltage is required.

In the end, it has to be said that hydrogen fuel cells are based on the principle of the reverse reaction of electrolytic water. Hydrogen fuel cells have the advantages of high energy conversion efficiency, no pollution, long life and smooth operation, and it has no pollutant emissions because the product it reacts with is water.

Although hydrogen fuel cells have so many advantages, its disadvantages are also obvious. Its storage and transportation requirements are relatively high, and due to the flammable and explosive properties of hydrogen, the transportation process requires the laying of special pipelines.

However, at present, the supporting facilities for the transportation and transfer of hydrogen fuel cells are still not perfect, so hydrogen fuel cells have not been widely used.

The rapid development of new energy vehicles can not be separated from the support of battery technology, and the ability to solve battery life has become the key to the problem.

With the development of new electrolyte technology at the Northwest Pacific National Laboratory, it is believed that more battery technology will be developed and battery range will no longer be the point of pain in the development of new energy vehicles.

The page contains the contents of the machine translation.