Up to now, the number of new energy vehicles in the country has reached 8.91 million, with a growth rate of nearly 20%. New energy vehicles are undoubtedly the trend of the times, but the frequent occurrence of spontaneous combustion accidents, charging for 1 hour queuing for 4 hours, endurance pit daddy and other issues always make new energy vehicles punch themselves in the face.
When will people buy a new energy vehicle without any worries? This may depend on when the solid-state battery is available for use.
Compared with the current mainstream lithium batteries, solid-state batteries have a longer range, safer and longer service life, so they are regarded by many as the ceiling of power batteries.
Many voices have pointed out that "once the solid-state battery is popularized, it is the time when the traditional fuel vehicle is eliminated", but is the solid-state battery really such a god?
The difference between solid-state batteries and the current mainstream on-board lithium batteries is that the former uses solid materials as electrolytes, simple storage, stable chemical structure, and thermal decomposition temperature of up to more than 500 °C, which can reduce the risk of lithium-ion battery fire.
At the same time, due to the higher energy density of solid-state batteries, the endurance is stronger, while also shortening the charging time and reducing vehicle costs.
On the contrary, the latter will lead to repeated deposition and precipitation of lithium ions when repeatedly charged, generate lithium dendrites on the surface of the negative electrode, continuously shorten the battery life, and even penetrate the diaphragm in severe cases, causing leakage and short circuit, and eventually lead to spontaneous combustion of the vehicle.
Lithium dendrites
In the low temperature environment, the electrolyte of liquid lithium batteries will also become viscous, making the lithium ion migration rate slower, resulting in reduced battery activity, which explains why the current new energy vehicles have such a "pit daddy" phenomenon.
How good the solid-state battery is, all depends on the liquid lithium battery as a peer. At present, Volkswagen, BMW, Toyota, Nissan and other car companies, as well as the Ningde era, are also making every effort to establish technical barriers for solid-state batteries.
In China, the hot land of new energy vehicles, semi-solid-state batteries have begun to gradually move towards the commercialization of automobiles. I still remember that a year ago, Weilai released the ET7 equipped with a semi-solid-state battery, with an energy density of 360kWh/kg, and claimed that the subsequent mileage of a single charge can reach more than 1,000 kilometers.
NIO ET7
Even if the battery on the WEI ET7 is not a solid-state battery in the true sense, it still makes the solid-state battery popular overnight, and the lithium battery concept stock has almost plummeted across the board.
In contrast to the crazy investment boom, there is no all-solid-state battery in the world that has been mass-produced in cars. It is still a laboratory product, and car companies are only in the stage of drawing cakes for the development of solid-state batteries.
In April 2021, Zeng Yuqun, chairman of CATL, publicly stated that "what can be done in the car in 3-5 years is not an all-solid-state battery."
As early as 2011, Toyota threatened to launch solid-state batteries from 2015 to 2020, but it has not been seen yet, and finally changed its mouth to 2025 before it can achieve small-scale mass production; BMW is roughly the same, and launches a prototype car using solid-state batteries by 2025.
Why can solid-state batteries bring down Toyota, the world's number one car company? Mainly in terms of materials, preparation, cost, etc., there are many difficult bottlenecks.
First of all, the material, the electrolyte of the solid-state battery is generally divided into oxides, sulfides, polymers three kinds, representing three different technical routes, in terms of conductivity, energy density, cost, safety performance have their own advantages.
There is no unified answer to which material to choose, and there is no mature material system.
In addition, the preparation process is complex. First, the ion diffusion rate in the solid electrolyte is only one-tenth of that of the electrolyte, and if the energy density is increased, the solid particles should be nanoscaled, which forms a problem of process preparation. Second, the system and interface of solid-state batteries are different from liquid lithium batteries, and the architecture and system need to be redesigned.
Finally, the manufacturing cost is too high. According to earlier public information, the manufacturing cost of all-solid-state batteries reached 15,000 US dollars / kWh (about 970,000 yuan), while the current cost of ordinary liquid lithium batteries is only 200-300 US dollars / kWh, on the cost, the two are still difficult to compete on the same stage.
But no matter how many bottlenecks there are, solid-state batteries that combine many advantages have become an important watershed in the power battery industry. Whoever can land first will be able to command the technological high ground.
As a solid-state battery in this "military preparation race", Japan can be regarded as a pioneer. In addition to Toyota, Nissan is also actively promoting the landing of solid-state batteries, and plans to pilot production in 2024 and launch the first model equipped with solid-state batteries in 2028.
Unlike Toyota, which has only announced some sporadic news at present, Nissan recently held a low-key conference for solid-state batteries, which directly spoiled the news of many technological breakthroughs.
The first is the use of materials. For example, the use of fibrous adhesives instead of traditional adhesives, so that the movement of the cathode active lithium ion without obstacles, thereby reducing the cell impedance.
As mentioned earlier, the solid-state battery material system is not yet mature, which means that the R&D verification process is long and complex. Nissan uses big data and artificial intelligence to verify materials, improve the efficiency of material selection, and reduce the research and development time from the traditional 5-20 years to 2-3 years.
For example, cathode coating materials that prevent performance degradation, materials that inhibit the formation of lithium dendrites, etc.
The second is the production process, Japan through the cathode active and solid electrolyte uniform, high-density mixing, combined with fibrous adhesives, to further reduce the battery impedance. They also invented a design that allows the electrolyte and electrode layers to expand and contract repeatedly without separating.
Third, by 2028, it is expected to reduce the cost of the battery pack to $75 / kWh, shorten the charging time to one-third, and charge from 15% to 80% in 15 minutes at 25 ° C.
In simple terms, the battery impedance is low, the charging efficiency is high, and the cost is low. This short dozen words are the ultimate goal of car companies to continue to explore the development of solid-state batteries in the next few years or even more than ten years, and they are also the foundation for standing in the new energy era.
In the global realization of carbon neutrality in this new energy revolution, the battery is like a core weapon, determining the mileage, determining the convenience and safety of electric vehicles, and deciding whether it can truly "kill" the life of fuel vehicles.
Among them, solid-state batteries with higher safety, higher energy density and longer life are extremely beautiful and ideal forms.
According to the guidance on battery technology in the "Made in China 2025" issued by the Ministry of Industry and Information Technology, by 2025 and 2030, the energy density of power battery cells needs to reach 400Wh/kg and 500 Wh/kg.
However, from the current situation of the industry, the mainstream level of liquid lithium batteries is 160wh/kg, and the 300kWh/kg of Tesla's 4680 battery is the industry ceiling. In contrast, solid-state batteries can achieve an energy density of 400Wh/kg in minutes.
Therefore, it is not difficult to understand why the world's large car companies are developing or investing in solid-state batteries, after all, no one wants to be stuck in the near future.
With the advancement of technology, the future solid-state battery will follow the "liquid - semi-solid - quasi-solid - all-solid" technology evolution path, the liquid electrolyte content gradually declined, and the all-solid-state battery is likely to become the final form.
But no matter what kind of battery it is, the most critical thing is to achieve a perfect balance in terms of energy, safety and cost. If other technical routes can achieve a balance between the three aspects faster in the process of advancing with solid-state batteries, they can also stand in the C position.
Just as lithium iron phosphate was abandoned a few years ago because of low energy density, just when everyone decided that ternary lithium batteries were the protagonists, BYD made up blade batteries, once again allowing lithium iron phosphate batteries to return to the mainstream line of sight.
BYD's new energy vehicle sales in March 2022
Therefore, killing fuel vehicles is not necessarily a solid-state battery, but it must be a battery suitable for market development and has both low cost and high energy.