Summary of patented technology for sodium ion batteries
[Abstract] This paper firstly carried out statistical analysis on the number of patent applications involving sodium ion batteries at home and abroad, and made statistical analysis on important applicants at home and abroad, and then proceeded from the technical branch of sodium ion battery cathode materials. The development status of patents at home and abroad has been elaborated.
[Keywords] sodium ion battery cathode material patent analysis
CLC number: TM912 Document code: A Article ID: 1009-914X(2016)18-0088-01
I. Introduction\u003cbr \u003e With the successful application of lithium-ion batteries on a global scale, the demand for lithium resources has increased greatly, and the reserves of lithium in the earth's crust are limited and unevenly distributed, which is applied to the development of smart grids and renewable energy. Long-life batteries for electrical energy storage can be an important bottleneck. Sodium is abundant in the earth's crust, accounting for 2.75%. It is the sixth abundant element and widely distributed. In addition, sodium has similar physical and chemical properties of lithium . Therefore, the development of sodium ion batteries for large-scale energy storage applications Technology has important strategic implications.
Second, domestic and foreign patent application summary
2.1 analysis of important applicants at home and abroad
Figure 1 shows the top 11 applicants for sodium ion batteries in the world, related to the number of patent applications, In the field, Japan has an absolute leading position, and its patent applications are large, and the top three are Japanese or American companies, indicating that Japan and the United States have strong industrialization strength in this field, and the development of sodium ion batteries is relatively high. Pay attention to it; although there are a large number of patent applications in China, among the top 11 applicants in China, all are university research institutes, indicating that domestic research on sodium-ion batteries is still in the growth stage, and has not yet gone from academic research to industry. Application.
From the distribution of global patent applications shown in Figure 2, patent applications involving cathode materials, anode materials, and electrolytes account for 47.7% of the total global applications, respectively. 39.5%, 8.9%, the global research on sodium-ion batteries focuses on the development of positive and negative materials. According to the technical distribution of the top four applicants in the world, the patent application of Sumitomo Co., Ltd. involves the positive and negative materials and electrolytes of sodium ion batteries, and the research and development focus is on the positive electrode materials; Toyota Auto Co., Ltd. It is entirely focused on the development of anode materials; the Chinese Academy of Sciences Physics has also studied the positive and negative materials and electrolytes of sodium ion batteries; among them, AQUI is the first company to commercialize sodium ion batteries. The focus is on the mutual matching of positive and negative materials, the selection of inexpensive electrolytes, the simple assembly and manufacturing process of the battery, and the compact design of the module structure. The purpose is to provide the market with low-cost modular sodium ions for grid storage. battery.
Third, sodium ion battery cathode material
3.1 oxide cathode material
Layered structure material NaxMO2+y is one of the earliest embedded compounds, M can represent one or more with different valence states Transition metal cation. The layered transition metal oxide is widely used in secondary battery electrode materials because of its reversible ion deintercalation ability. For example, layered LiCoO2, LiNiO2, and LiMnO2 are important cathode materials for lithium ion batteries. In the development of sodium ion battery cathode materials, people first focused on the sodium-based layered transition metal oxide. As early as 1985, the United States Corporation (ALLC) filed a patent application with US Patent No. 19850749325A to the US Patent Office, in which NaxCoO2 was used as a positive electrode material in sodium ion batteries; Xiangtan University submitted to China Patent Office in 2004. Patent application for sodium layered compound is NaxCoO2 or NaxMnO2, the application number is CN200410046836A; Sumitomo Chemical Co., Ltd. prepared a layered oxide of α-NaFeO2 type, specifically NaFe1-xMxO2 (wherein M is selected from trivalent metal) At least one element, and x satisfies 0 ≤ x \u003c 0.5), the composite oxide has a hexagonal crystal structure, and has an interplanar spacing corresponding to 5.36 by dividing the intensity of the XRD peak corresponding to the interplanar spacing of 2.20 The value of 2 or less obtained by the XRD peak intensity can prepare a battery which is free from a rapid decrease in discharge voltage as the discharge progresses (Publication No. JP2005317511 A).
3.2 Phosphate Cathode
In view of the polyanionic compounds, especially the transition metal phosphate LiMPO4 (M=Fe, Co, Ni, Mn, V, etc.), the great success in the field of lithium ion battery cathode materials, At present, researchers have turned their research hotspots into such compounds in order to find high-performance sodium ion battery cathode materials. Phosphate-based materials have a three-dimensional structure, as well as good stability and thermal stability. In addition, due to the induced effect of PO43-tetrahedron, the transition metal Mn+ in phosphate has a higher oxidation-reduction potential. Sumitomo Chemical Co., Ltd. (Publication No. CN101971393A) discloses an olivine-type phosphate, AaMbPO4(I), wherein A represents one or more elements selected from alkali metals, and M represents one or more elements selected from transition metals. , a is 0.5 to 1.5, and b is 0.5 to 1.5; a semiconductor energy research institute (Application No. JP2011082151A) discloses a method of forming a base layer on a support substrate, and forming a lithium iron phosphate layer or phosphoric acid on the base layer. a ferrite layer, and a lithium iron phosphate layer or a sodium iron phosphate layer by heat treatment, thereby using a single crystal lithium iron phosphate layer having an olivine structure or a single crystal iron phosphate having an olivine structure oriented in the \u003c010\u003e direction. The sodium layer is used as the positive electrode material. Since the sodium iron phosphate layer is a single crystal layer, sodium is unidirectionally arranged therein, so that sodium ions easily enter or leave the single crystal layer, thereby increasing the amount of ions leaving and entering the active material layer. Further increasing the capacity of the battery, on the other hand, the use of the single crystal active material can suppress the distortion of the grain boundary and prevent the crystal structure from being destroyed.
3.3 NASICON positive electrode material
NASICON (sodium superionic conductor) structural compound AxM2(PO4)3 (A = Li, Na, etc.; M is a transition metal element) has a three-dimensional open ion transport channel, generally with The high ion diffusion rate is a fast ion conductor material. NASICON structural materials have high ionic conductivity, and NASICON materials with variable valence transition metals can also be used as electrode materials. The volume deformation during charging and discharging is small, about 8.3%, which is a promising cathode material for sodium ion storage batteries. In 2004, Xiangtan University submitted a sodium-depleted layered compound or a phosphate compound with a sodium ion positive electrode material of Na3M2 (PO4) 3 , which is a patent application for Na3Fe2(PO4)3 or Na3Cr2(PO4)3 (application) No. CN02811313A); US Patent No. US20100899216A discloses that the positive electrode material is Na3M2(PO4)3, and M is selected from V, Mn, Fe, Co, Cu, Ni or Ti, further expanding the NASICON material family.
3.4 Other Materials
Fluorinated phosphates, Prussian blue sodium salts, etc. can be used as positive electrode materials for sodium ion batteries.
China's sodium ion battery has not been applied from academic research to industrial application. In the future development, domestic research and development of sodium ion battery should be strengthened, and cooperation between universities and enterprises should be encouraged. Accelerate China's technological innovation and protection in the field of sodium ion batteries.
 Pan Huilin, Hu Yongsheng, et al. Progress in electrode material structure of room temperature sodium ion storage battery[J]. Chinese Science: Chemistry, 2014.44(8): 1269-1279.