Whether solid electrolyte can completely solve the safety problem of battery



2019 is a very difficult year for new energy automobile industry chain enterprises. Many enterprises are struggling to survive in the pain of subsidization decline, capital reduction pressure and tight capital chain.            Due to the continuous poor overall sales situation, there is pressure on the capital turnover of some complete vehicle and power battery manufacturers in the new energy vehicle industry. Some enterprises, due to the failure of customers to pay the payment as agreed, have increased the provision for bad debts of their accounts receivable, which has a negative impact on their business performance.            In this context, on February 10, the Ministry of industry and information technology issued the decision on Amending the regulations on the administration of new energy vehicle manufacturing enterprises and product access (Draft for comments).            The draft mainly cancels the requirements of "design and development capability" in the original provisions, and adjusts this part to the requirements of "technical support capability", requiring enterprises to have the technical support capability corresponding to the new energy vehicle products they produce; they can also test the whole vehicle and self-made parts, and can evaluate and confirm the technical requirements related to the technical support capability.            From the perspective of technical support ability, the technical control ability of enterprises in the production process is mainly to ensure the production quality and consistency. The test ability is also to ensure that the products produced meet the technical requirements of automobile products.            The adjustment of this opinion draft means that new energy vehicle manufacturers can not have their own design and development capabilities, as long as the technical support capabilities required for production are guaranteed.            01            Power battery is the core component of new energy electric vehicle. The power battery industry is not immune to the depression of new energy vehicle industry. From this point of view, the requirements of the draft for new energy vehicle industry are also applicable to the power battery industry.            To grasp the market direction, conform to the development of the times, and innovate the core technology are the fundamental principles. Excellent technical quality is always the guarantee of enterprise development and the guidance of market.            Today, the battery technology is relatively mature, but it also meets the bottleneck. It is in urgent need of the birth of a new generation of technology, especially in the field of new energy.            Solid state battery is expected to become the next generation of power battery technology, the most appealing one. Because the technology maturity of all solid-state battery is relatively high, many lithium-ion battery enterprises at home and abroad have also taken all solid-state battery technology as an important next-generation technology reserve.            In addition, the solid-state battery is also a technology strongly supported by a group of international top scholars, such as John Bannister goodinaf, who won the Nobel Prize in chemistry in 2019. Whether subjective or objective, the development of solid-state batteries is an inevitable choice.            In the early development of solid-state battery technology, due to the relatively low conductivity of solid-state electrolyte materials, research and development focuses on improving the conductivity of solid-state electrolyte, so sulfide electrolyte and oxide solid-state electrolyte with high ionic conductivity have attracted widespread attention.            All solid state lithium-ion battery, which uses solid electrolyte instead of traditional organic liquid electrolyte, is expected to fundamentally solve the safety problem of battery, and is an ideal chemical power supply for electric vehicles and large-scale energy storage. The key points include the preparation of solid-state electrolyte with high room temperature conductivity and electrochemical stability, high-energy electrode materials suitable for all solid-state lithium-ion batteries, and the improvement of electrode / solid-state electrolyte interface compatibility.            02            Solid state lithium battery is developed on the basis of lithium battery. Compared with traditional lithium battery, liquid or gum is no longer used as the conduction material between the positive and negative poles, which greatly improves the vehicle safety and high temperature resistance. It has the advantages of high safety, high energy density, long cycle life and wide working temperature range, among which solid electrolyte is the core.            In terms of technical path, solid electrolyte can be divided into oxide electrolyte, sulfide electrolyte, organic polymer electrolyte, LiPON type electrolyte, etc.            According to the material structure, oxide solid electrolyte can be divided into crystalline and glassy (amorphous) types, among which crystalline electrolyte includes perovskite type, NASICON type, LISICON type and garnet type. The research focus of glassy oxide electrolyte is the LiPON type electrolyte used in thin-film battery.            The oxide crystal solid electrolyte has high chemical stability and can exist stably in the atmospheric environment, which is conducive to the large-scale production of all solid-state batteries. The research focus is to improve the room temperature ionic conductivity and its compatibility with the electrode. At present, the main methods to improve the conductivity are element substitution and heterovalent element doping, and the compatibility with the electrode is also an important problem restricting its application.            The most typical sulfide crystal solid electrolyte is thio LISICON. Professor Kanno of Tokyo University of technology first found that the chemical composition is li4-xge1-xpxs4 in li2s-ges2-p2s system. The ionic conductivity at room temperature is as high as 2.2x10-3s/cm (where x = 0.75), and the electronic conductivity is negligible. The general formula of thio LISICON is li4-xge1-xpxs4 (a = Ge, Si, etc., B = P, A1, Zn, etc.).            Sulfide glass solid electrolyte is usually composed of P2S5, sis2, b2s3 and other network formers and network modifier Li2S. The system mainly includes li2s-p2s5, Li2S-SiS2, li2s-b2s3. It has a wide range of composition, high room temperature ionic conductivity, high thermal stability, good safety performance, wide electrochemical stability window (more than 5V). It has outstanding advantages in high power and high and low temperature solid-state batteries, and is a potential solid-state battery electrolyte material.            The solid polymer electrolyte consists of polymer matrix (such as polyester, polymerase, polyamine, etc.) and lithium salt (such as LiCl