What is a "solid state battery"?

　　Solid state battery is known as the black technology in power battery. It can double the endurance of electric vehicles. New energy vehicles that can run 350 kilometers now can run 700 kilometers with solid state battery. This prospect is undoubtedly very attractive. Major companies not only invest heavily in research and development, but also promote the commercialization of solid-state batteries. Want to seize the market as soon as possible. Despite the fierce competition, the insiders poured cold water on the solid state battery: there are still many problems to be solved, and the industrialization process has a long way to go!

　　1、 Introduction to the development status of black technology solid state battery

　　Volkswagen Group predicts that if all solid state batteries are used, the range of the company's electric vehicle model "e-Golf" can be increased from the existing 300 km to 750 km. Solid state battery technology is the next competitive highland of the company. Many automobile companies, power lithium-ion battery companies and scientific research institutions around the world are committed to the scientific research of solid-state batteries. BMW Group has cooperated with solidpower to develop solid state batteries as early as 2017; Toyota is a car company that uses solid-state batteries in the late stage, and is expected to launch models equipped with solid-state batteries in 2022; At the beginning of this year, Daimler announced that it would cooperate with the Canadian Quebec Hydropower Company to develop solid-state battery technology. Once the solid state battery reaches the mass production state. Since 2017, Japan has invested a lot of R&D funds to develop the next generation of solid-state batteries. The United States and Europe are also developing in an all-round way. Although China's battery industry has gained temporary advantages in this field, the international competition pressure is huge, and we need to make every effort to catch up with cutting-edge technologies such as solid-state batteries. In China, companies such as Ningde Times and Beijing Satellite Blue are at the forefront of research and development. Tianji Automobile, a new force in the automobile manufacturing industry, launched the first me7 prototype vehicle equipped with solid state batteries in early 2019, and announced that it will achieve mass production in 2021; Recently, Hezhong and Qingdao Energy have reached a comprehensive and in-depth cooperation to jointly promote the research, development and application of solid-state batteries. Wang Kefeng, R&D director of Hezhong, revealed that the second mass production vehicle "Nezha u" of Hezhong would become the first mass production vehicle equipped with solid state batteries in the world. At present, the two sides have carried out joint research and development and testing for nearly two years, and plan to apply to the Ministry of Industry and Information Technology for announcement in October, and produce 500 sets in batches by the end of the year. Be ready to subvert the existing product system,

　　2、 Solid state battery is expected to solve the two pain points of power lithium battery

　　The reason why the company introduced solid state battery is that it is expected to solve the two major challenges plaguing the power lithium ion battery industry - potential safety hazards and low energy density. As the name implies, the so-called solid state battery is a lithium ion battery that uses solid electrolyte. In terms of working principle, all solid state batteries are no different from traditional lithium ion batteries. The traditional lithium ion battery is composed of positive pole, negative pole, diaphragm and electrolyte. The electrolyte contains flammable organic solvents. In case of external short circuit, sudden rise of temperature is easy to cause combustion and even explosion. Solid electrolyte materials are non combustible, non corrosive, non volatile and non leaking. It is safe to use solid electrolyte instead of electrolyte. In addition, the all solid state battery uses lithium metal as the cathode, and the battery energy density is expected to reach 300-400whkg or even higher. It is widely believed in the industry that all solid state batteries are expected to become the technical route of the next generation of power lithium-ion batteries. In recent two years, the technical route of power lithium ion battery has become increasingly diversified. Ningde Times launched CTP technology, BYD announced blade batteries, and Honeycomb Energy also launched the first cobalt free battery. Is there any conflict between related technical reserves? "Blade battery and CTP technology have only made some structural optimization, which is not contradictory to the development of solid state battery." Liu Yanlong, secretary-general of the China Chemical and Physical Power Industry Association, told reporters. In fact, the research and development of solid-state batteries has risen to the national strategic level. In December 2019, the Ministry of Industry and Information Technology issued the New Energy Vehicle Industry Development Plan (2021-2035) (draft for comments), which puts forward requirements for improving technological innovation capabilities, including "accelerating the research and development and industrialization of all solid state power lithium ion battery technology" Huajing Industrial Research Institute believes that new technological revolution such as solid-state battery is preparing to overturn the existing entire product system framework. With the continuous development of R&D and industrial technology, the solid state battery product market will usher in opportunities of vigorous development in the next few years. Many technical problems need to be solved. "In order to solve the safety problem of electric vehicles, the current solid-state batteries have added a part of solid electrolyte. Most of them are the improvement of the existing lithium ion battery technology, belonging to semi-solid batteries." Liu Yanlong told the reporter that the all solid state lithium-ion battery is a solid electrode material and solid electrolyte material. The lithium-ion battery does not contain any liquid. "Solid state battery" is different from "all solid state battery", but there is still a long way to go. Liu Yanlong introduced that there are still technical problems in electrolyte conductivity, lithium metal plasticity, interface compatibility, etc. For example, in the contact with the electrode, the liquid electrolyte can contact the electrode to the maximum extent, while the solid electrolyte and the electrode are difficult to fully cooperate, and the conductivity is lower than the liquid electrolyte; In the process of frequent charging and discharging, the volume of various materials will expand and contract. How to ensure the stability of electrode structure needs further research. Considering the practical problems faced by all solid state batteries and the industry's urgent expectations for high safety and high energy density power lithium-ion batteries, semi-solid state batteries have become a practical choice at present. The battery structure design is gradually changing from reducing the use of liquid to all solid state liquid free battery. Liu Yanlong acknowledged that theoretically, all solid state battery is a development direction of power lithium-ion battery, but at present, no all solid state battery has been manufactured to test its competitiveness in the whole life cycle. "Whether the all solid state lithium ion battery can truly solve the intrinsic safety problem of lithium ion requires more extensive and in-depth research and data accumulation." He believes that all solid state batteries have a basis for industrialization only when their safety, energy density, cycle life and cost are close to or even better than existing lithium ion batteries. Liu Yanlong believes that it is very difficult to industrialize all solid state batteries in a short time, at least until 2030. "All solid state batteries must first be manufactured and applied to low current electronic products, and then gradually applied to high current and high-speed electric vehicles."

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