Research progress on secondary batteries such as solid lithium air battery/solid lithium sulfur battery

[Introduction]

Zhou Haoshen and He Ping team of the School of Modern Engineering and Applied Science of Nanjing University were invited to present a study entitled “Rechargeable Solid-State Li-Air and Li-S Batteries: Materials, Co nstruction and Challenges” in the journal Energy Materials, Adv. Energy Mater. The progress article systematically analyzes, summarizes and forecasts the research hotspots in the field of secondary batteries such as solid-state lithium-air batteries and solid-state lithium-sulfur batteries.

[Graphic introduction]

Figure 1 Schematic diagram of solid lithium-sulfur battery and solid lithium air battery

(a) Schematic diagram of a solid lithium-sulfur battery;

(b) Schematic diagram of a solid lithium air battery.

Figure 2 Several crystal structure types

(a) Perovskite type (LLTO);

(b) NASICON type (LAGP);

(c) garnet type (LLZO);

(d) thio-LISICON type (LGPS).

【research content】

The energy crisis and environmental pollution issues have promoted the development and utilization of new energy sources. The storage and use of energy requires an efficient energy conversion system. Lithium-air batteries and lithium-sulfur batteries have received extensive attention due to their extremely high theoretical specific energy (3600 Whkg-1 for lithium-air batteries and 2600 Whkg-1 for lithium-sulfur batteries). However, the organic electrolytes currently used in most related studies may cause safety problems such as leakage, burning and explosion. In addition, the dendrite growth based on the metal lithium negative electrode may cause a safety hazard of the short circuit. To solve these problems, the researchers used an inorganic solid electrolyte instead of an organic liquid electrolyte to design a solid lithium air battery and a lithium sulfur battery as shown in FIG. Solid-state lithium air and lithium-sulfur batteries have outstanding safety advantages, avoiding the problem of flammability of organic electrolytes. The inorganic solid electrolyte has excellent mechanical strength and can effectively block lithium dendrite puncture. In addition, in the lithium-sulfur battery, the solid electrolyte can avoid the "shuttle effect", thereby improving the coulombic efficiency and cycle life performance of the lithium-sulfur battery. For lithium-air batteries, the solid electrolyte can effectively protect the metal-lithium anode from carbon dioxide and moisture, ensuring long-term use of the battery.

This article first introduces four solid electrolytes suitable for lithium ion conduction. As shown in Fig. 2, they are perovskite type, NASICON type, garnet type and thio-LISICON type. Then systematically analyze various electrolyte structures, transport properties, chemical and electrochemical properties, and summarize the different applications of different electrolytes in lithium air batteries and lithium sulfur batteries. Next, the paper introduces some important cathode materials for solid-state lithium air batteries and lithium-sulfur batteries, and summarizes the methods for improving the performance of electrode materials. The electrode reaction mechanism of two solid-state secondary batteries was analyzed from a microscopic point of view. Finally, this paper focuses on the problems of the electrode-electrolyte interface between solid-state lithium air batteries and lithium-sulfur batteries, and points out ways to improve the interface transport properties and stability.

Liu Yijie, a 15th-level Ph.D. student in the School of Modern Engineering and Applied Sciences, is the first author of the article, and Associate Professor He Ping and Professor Zhou Haoshen are the authors of the communication. Since 2012, the team has been the first to conduct solid-state lithium-air battery research in China, and for the first time realized the design and preparation of solid lithium-air battery and lithium-sulfur battery based on Li1+xAlyGe2-y(PO4)3. In addition, the team introduced inorganic-polymer composite electrolytes into lithium-air batteries, significantly improving the power characteristics and stability of lithium-air batteries. (Acs Energy Lett 2017, 2 (6), 1378-1384; Energ Environ Sci 2017, 10 (4), 860-884.) Relevant research has attracted widespread attention and recognition from domestic and foreign counterparts. Based on this research basis, The team continuously received funding from the National Key R&D Program and the Fund's key projects.