Solid Electrolytes for Rechargeable Thin Film Lithium Batteries: A Review

Abstract

Batteries are major technological challenge in this new century as they are key method to make more efficient use of energy. Lithium batteries are characterized by high specific energy, high efficiency and long life. These unique properties have made lithium batteries the power sources of choice for the consumer electronics market with a production of the order of billions of units per year. Although today's Li-ion technology has conquered the portable electronic markets and is still improving. These batteries are also expected to find a prominent role as ideal electrochemical storage systems in renewable energy plants, as well as power systems for sustainable vehicles, such as hybrid and electric vehicles. Lithium batteries are important for energy storage in a wide variety of applications including consumer electronics, transportation and large-scale energy production. The performance of lithium batteries depends on the materials used. This review presents the state-of-the-art knowledge on crystalline, composite and amorphous inorganic solid lithium ion conductors, which are of interest as potential solid electrolytes in lithium batteries. Recent material developments of fast solid lithium ion conductors are reviewed. The discussion of crystalline Li ion conductors includes perovskite-type Lithium Lanthanum Titanates, NASICON-type, LiSICON- and Thio-LiSICON type Li ion conductors, as well as garnet-type Li ion conducting oxides. The part on composite Li ion conductors discusses materials containing oxides and mesoporous oxides. In the amorphous Li ion conductor part oxide and sulfide-phosphate based glasses are presented. As glassy solid electrolytes have large potential for a number of electrochemical applications, the most important among them being the solid state batteries. In order to successfully accomplish these applications it is necessary to have a background of the science and technology of glassy solid electrolytes. This presentation gives a brief account of the formation of glassy solid electrolytes, factors affecting ionic conductivity in these materials. Typical results have been discussed to get some insight into the glassy solid electrolytes. The status of lithium battery involving lithium conducting glasses and the challenges in its development have been highlighted. A lithium solid battery has features such as flexibility in shape of a cell design, leak proof of electrolyte, high safety, etc., but posses the challenge of how close its electrical performance can be made to that of a liquid electrolyte cell. Therefore, various efforts have so far been made to improve the ionic conductivity of the solids especially in consideration of its practical application to use at room temperature. The ionic conductivity of solid now reaches 1 x 10(-3) S cm(-1) at room temperature. Special emphasis is placed on the correlation between the composition, structure, and electrical transport properties of inorganic crystalline materials in terms of the required functional properties for practical applications. Fundamental advances in the solid state chemistry of ionic conducting solids are essential for clean energy supply. Several new directions are discussed in this context for solid electrolytes. This paper reviews the solid electrolytes in view of their electrochemical and physical properties for the applications in lithium batteries. This reviews the history and the present status of the research and development of solid electrolyte in the lithium battery, and presents an outlook of the future research and development activities. The paper also introduces the improvement of lithium polymer secondary batteries using solid polymer electrolyte (SPE) such as poly(ethylene oxide) (PEO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA) with the performance and the applications of its present commercial products. We have tried to focus on the study of these advanced solid inorganic and polymer electrolytes by evaluating their use in rechargeable lithium batteries. Important factors for the solid electrolyte such as effect of preparative parameters, characterization techniques, parameters for the battery performance, importance of ionic conductivity has been explained. This article is the story of the development of solid electrolyte and it describes how the difficulties were surmounted. This review focuses first on the present status of lithium battery technology, then on its near future development and finally it examines important new directions aimed at achieving quantum jumps in energy and power content.