Solid-state lithium-ion batteries will achieve mass production, will the status of ternary lithium-ion batteries really be replaced?

by:CTECHi     2021-08-11

On November 19th, the 2nd Li-ion Battery Technology and Industry Development Forum was held in Kunshan. At the opening ceremony of the forum, Qingtao (Kunshan) Energy Development Co., Ltd. invited guests to visit the first solid-state lithium-ion battery production line in China. It is reported that this production line can produce 10,000 solid-state batteries per day, and the energy density of the batteries can reach more than 400Wh. At present, the products will be mainly used in special power supply, high-end digital and other fields, and it is expected to enter the power lithium battery field in 2020. Car companies supply batteries. As soon as this news came out, it was almost a sensation in the industry.

Power lithium batteries are like the heart of electric vehicles, and the price also occupies more than half of the entire vehicle. Therefore, battery technology is very important for the development of the new energy industry. If the current bottleneck of water-based lithium-ion battery capacity cannot be broken, the entire industry is likely to fall into a more difficult situation. In the future, not only family cars, but even transportation vehicles may have to use electric energy, and the requirements for batteries will be even higher. Therefore, solid-state batteries with higher plasticity have become the direction of many companies' efforts, including internationally renowned car companies such as Toyota, BMW, Mercedes-Benz, and Volkswagen, as well as major companies funded by the Ministry of Economic Affairs of Japan, have begun to deploy in this field.

In this production line display of Kunshan Qingtao Company, people saw this: the battery pack with only the thickness of the fingernail was cut by scissors, not only did not explode , And even the normal power supply. In addition, even if it was bent tens of thousands of times, the battery capacity did not decay by more than 5%, and the battery did not burn or explode after acupuncture. In fact, solid-state lithium-ion batteries do have many advantages. Because solid electrolytes are non-flammable, non-corrosive, non-volatile, and non-leakage, they will not cause spontaneous combustion events in the vehicle, which greatly enhances safety. An ideal battery material for electric vehicles.

Currently, the ternary lithium-ion battery commonly used in mainstream electric vehicles has certain defects, because no matter from the chemical structure or the battery structure, the ternary lithium material is very Easy to heat. If the pressure cannot be transmitted in time, the battery may explode. This is also due to most of the spontaneous combustion incidents of electric vehicles that have occurred this year. And in terms of battery life, the single energy density of ternary lithium-ion batteries is currently facing a bottleneck, and it is difficult to break through. If you want to increase the energy density, you can only increase the content of nickel or add CA, but the thermal stability of high nickel is very poor, and it is prone to violent reactions. Therefore, at present, only a trade-off can be made between battery capacity and safety.

Even Toyota, who is very good at technology and technology research and development, said that solid-state batteries can only be mass-produced in 2030. It can be seen that there are still some problems in the research and development of solid-state batteries. In fact, since solid-state batteries do not require liquid infiltration and only require solid electrolytes to separate the positive and negative plates, the choice of metal materials becomes very critical. The biggest challenge of the current technology is that the overall conductivity of the solid electrolyte is lower than that of the liquid electrolyte, which leads to the overall low rate performance of the current solid-state battery and large internal resistance, so the solid-state battery cannot meet the requirements of fast charging temporarily. Claim. However, the electrical conductivity has a very large relationship with temperature, so working at a higher temperature will make the battery perform better. In addition, the conductivity of the battery must be maintained at a normal level, and the current too high or too low may cause other problems.

Nowadays, the research and development technology of ternary lithium-ion batteries by companies led by Panasonic and Ningde Times is already well-established, even if solid-state lithium-ion batteries are developed in a short period of time. It is also difficult to achieve mass production. After all, when a new technology goes to the world, it is always necessary for the company to have the corresponding product volume and output capacity in order to achieve large-scale promotion and application. Although the current solid-state lithium-ion batteries still face many problems and do not have much advantage in energy density for the time being, they do have very high safety. If suitable metal materials can be developed, perhaps the entire power lithium The battery industry will usher in new breakthroughs. This is what we hope to see. After all, unremitting research is the true scientific research spirit. The energy density ratio refers to the capacity of the battery per unit weight. Cylindrical monomers are calculated according to the current domestic mainstream 18650 (1.75AH), and the energy density ratio can reach 215WH/Kg, and the square monomers can reach 205WH/Kg according to 50AH. The system group rate is around 60% for 18650, and the square is around 70%. (The grouping rate of the system can be imagined by putting ham in the box. The gap between the square hams is smaller, so the grouping rate of the system is higher.)

This is how the 18650 battery pack is calculated. The system energy density ratio is about 129WH/Kg, and the square battery system energy density ratio is about 143WH/Kg. When the energy density ratio of 18650 and square cells reaches the same in the future, square lithium-ion battery packs with higher grouping rate will have more obvious advantages.

Rateness

Charge/discharge rateu003dcharge/discharge current/rated capacity, the higher rate the battery supports The faster the speed. The domestically manufactured mainstream horizontal energy cell 18650 is around 1C, and the square can reach around 1.5-2C (with good thermal management), and there is still some distance from the policy target of 3C. However, it is entirely possible that the square manufacturing process will become more and more perfect to achieve the established target 3C.

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