Elemental properties make lithium hot.
The reason why new energy vehicles can pass in deep water is actually very easy to explain: because there is no need to obtain oxygen from the outside air as an oxidant for energy release reaction like fuel vehicles. In the battery pack of new energy vehicles, ions shuttle between the cathode and anode, generating current to release energy. Therefore, the "high-voltage system" of new energy vehicles can be completely isolated from the external environment, which generally meets the waterproof standard of IP67, that is, it can ensure no water leakage for 30 minutes under the condition of water depth 1 meter.
However, the "low-voltage system" of new energy vehicles is often not so excellent in waterproof performance, and it is prone to short circuit and other problems in water, so it is still not suitable for driving in deep water without tires.
New energy vehicles show their talents in front of the public by virtue of their better wading performance than fuel vehicles. Just like a famous saying circulating in the industry, "Whoever gets the battery wins the world", the power battery, which accounts for about 40% of the manufacturing cost of new energy vehicles, is also at the cusp of great changes.
This makes contemporary Ampere Technology Co., Ltd., which has won the global champion of power battery market share for four consecutive years, still dare not relax, and recently released the newly developed sodium ion battery. Then, as a lithium-ion battery giant, contemporary Amperex Technology Co., Ltd., why should it release sodium ion batteries at this time? What are the advantages compared with traditional lithium-ion batteries? Where is the future of power batteries?
In fact, the research of sodium battery started almost at the same time as lithium battery. Both of them began in the background of the cold war and oil crisis in the late 1960s, and people urgently needed new energy storage materials.
The first generation lithium battery belongs to lithium metal battery, which is different from the current lithium ion battery. Its crystallization effect is extremely serious when charging, and it is easy to cause internal short circuit, so it is basically a non-rechargeable battery.
The essence of ion battery is that metal elements shuttle back and forth between positive and negative electrodes in ionic state, and electrons are gained and released in this process, thus forming current. Metal ions are only "porters" of electrons, so that there is almost no loss of anode and cathode materials and a very high cycle life is realized. This is the main idea of charging the battery now.
The ideal rechargeable battery needs to achieve as small a volume and weight as possible, and store and carry more energy. Therefore, from the periodic table of elements, to be a good energy carrier, the relative mass of atoms should be small, the ability to gain and lose electrons should be strong, and the proportion of electron transfer should be high. Lithium is the lightest metal on the earth and has become the most ideal material for manufacturing batteries.
At the same time, sodium and potassium, the same family elements of lithium, have also become the research objects. However, because sodium atoms have eight more electrons than lithium atoms, the atomic radius of sodium is much larger than that of lithium. This makes it occupy more space when it is embedded and detached between the anode and cathode materials, and it needs to use larger and stronger materials than the anode and cathode embedding holes of lithium ion batteries.
And it is much heavier than lithium, which makes the energy storage density of sodium battery lower than that of lithium battery. This series of problems made sodium ion battery once forgotten by people in the wave of battery research. Lithium battery ushered in a technological breakthrough in the late1980s. The "rocking chair battery" based on lithium ion replaced the previous lithium metal battery system, and completely occupied the consumer electronics market in just a few decades, becoming the mainstream solution for power batteries of new energy vehicles.
Worried about "exhaustion of energy storage"
But the first scientists who studied lithium batteries 50 years ago probably wouldn't have thought that the earth is not a planet rich in lithium resources. The content of lithium in the earth's crust is only 0.0065%, and 70% is in South America, which has the problem of uneven distribution.
Similarly, the situation of cobalt, another indispensable element of lithium-ion battery anode, is not optimistic. Mainly distributed in Congo (DRC) (52%) and Australia (17%), with an area of 0.005438+0%. On a global scale, the output of lithium batteries keeps hitting new highs, and the overall price of lithium batteries has dropped sharply, but the price of raw materials used to produce lithium battery electrodes has soared rapidly. "Depletion of reserves" is becoming a real concern of many people in the industry.
Lithium-ion batteries face a challenge that most commodities will never encounter: with the increase of output, the price can not continue to decline, but may rise sharply. In this situation, new energy vehicle companies that use hundreds of mobile phone battery materials to build a car are on pins and needles.
Therefore, in recent years, in addition to building cars, the biggest possibility for major new energy vehicle companies is to reduce the lithium and cobalt content in battery packs, acquire shares of upstream mining companies, and vigorously develop the next generation energy storage system other than lithium.
Under this background, the sodium ion battery, which was neglected in the early years, became a research hotspot after 20 10 years. Different from rare lithium, the mass ratio of sodium in the earth's crust is 2.75%, which is 400 times that of lithium. As the main component of salt, the price of sodium chloride is less than that of lithium carbonate110.
"sodium-lithium mixed collocation"
As the largest new energy vehicle market in the world, China is also in a leading position in the research of sodium ion batteries. Before Amperex Technology Co., Ltd., the sodium ion battery researched by Institute of Physics of Chinese Academy of Sciences was put into mass production last year, but the energy density was still low, about 145Wh/kg.
The energy density of the first generation sodium ion battery of Ampere Technology Co., Ltd. reached 160Wh/kg. Although the energy density of 160Wh/kg is really not high in front of the ternary lithium battery with 300Wh/kg, even lower than that of lithium iron phosphate battery, it is already the highest level of energy storage density of sodium ion battery in the world.
In addition, the sodium ion battery of contemporary Amperex Technology Co., Ltd. can be charged for 15 minutes at room temperature, and the power can reach more than 80%; Moreover, in the low temperature environment of -20 degrees Celsius, it also has a discharge retention rate of more than 90%, which is far better than the level of 70% of ternary lithium batteries under this condition.
Sodium ion batteries can also pass the most stringent acupuncture test in the industry, which can basically be regarded as "fast charge" and "enhanced low temperature performance" versions of lithium iron phosphate batteries. Sodium ion battery has high safety and cost advantages, and can be used as a substitute for lithium iron phosphate battery, which is widely used in many fields such as low-end electric vehicles, commercial electric buses and even two-wheeled battery cars.
At the press conference, Contemporary Ampere Technology Co., Ltd. also put forward the technical scheme of mixing sodium ion battery and ternary lithium battery according to the ratio of 2 1. Through excellent BMS (Battery Management System) logic, the discharge level curves of two batteries can be accurately controlled, which makes it possible for sodium ion batteries to be mounted on high-end electric vehicles with more stringent battery life requirements.
Multi-technology solutions emerge.
According to the idea that the country's carbon emissions will peak in 2030 and be carbon neutral in 2060, the demand for clean energy such as solar energy and wind energy in the west is also expanding. But unlike thermal power, clean energy can dynamically adjust the power generation according to the load. If the generated electricity is not used in time, it can only be treated as "abandoned electricity".
It is understood that in 20 18 years, the electricity consumption of light, wind and water in China is 1022 million kwh, which is a huge waste. In order to stably connect the electricity generated by clean energy to the power grid, it is necessary to build a large-scale "energy storage power station".
Take the largest pumped storage power station built in Yangjiang, Guangdong Province some time ago as an example. Its basic principle is to use the surplus electricity in the urban electric wave valley to pump water. After pumping water to a high place, it is released during the peak hours of radio waves to generate electricity. This can be regarded as a giant rechargeable battery, which undertakes the tasks of peak load regulation and emergency standby in the power grid.
Such a task can also be accomplished by providing it to a sodium ion battery with low cost, relatively high energy density and insensitivity to ambient temperature.
So, is sodium ion battery the future of new energy vehicles? In fact, the mainstream power battery solutions for new energy vehicles, including ternary lithium batteries and lithium iron phosphate batteries, all belong to the category of "liquid batteries", that is, liquid "electrolyte" is needed as a medium where ions can flow unimpeded.
In fact, there is another "solid-state battery" scheme for power batteries, which, as the name implies, uses an electrolyte that is solid at room temperature as a medium for ion transfer. It is generally believed that the upper limit of energy storage density of liquid batteries is 350Wh/kg, while the energy density of solid batteries is expected to reach 65,438+0,000 Wh/kg.
Solid electrolyte is very stable, which basically eliminates the risk of thermal runaway explosion, and is considered by the industry as the development direction of future power batteries. Many domestic battery manufacturers have also laid out the track for many years. At present, theoretical research papers on new materials for solid-state batteries are also blooming everywhere. I believe that the era of solid-state batteries is not far away from us.
Previously, there was a bold prediction in the new energy vehicle industry that the turning point of new energy vehicles replacing fuel vehicles in an all-round way would come after the energy density of power batteries reached 400Wh/kg. At present, many countries in the world have also announced that 2030 will be the time node for a total ban on the sale and production of fuel vehicles.
I want to end the article with a sentence from Zeng Yuquan, founder and chairman of contemporary Amperex Technology Co., Ltd. at the sodium ion battery conference: "We believe that the electrochemical world is like an energy cube, and the unknown is far greater than the known." I believe that mankind will eventually overcome the difficulties in the development of power batteries and let the world enter the era of clean energy in an all-round way.
Author | Ma Dianqiu
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