tailieunhanh - Gel

Introduction: The rapid growth of the miniature electronic and computer-related industries has led to great demand for smaller and lighter batteries with improved safety, energy, and power characteristics. Lithium polymer batteries are expected to meet the above requirements and are thus considered as next-generation rechargeable batteries. The conventional lithium-ion batteries, which contain a large amount of liquid electrolyte, emit an appreciable amount of gas and this is attributed to the decomposition of a protective layer at the carbon surface. . | Gel AM Stephan Central Electrochemical Research Institute Karaikudi India S Thomas Mahatma Gandhi University Kottayam India 2009 Elsevier . All rights reserved. Introduction The rapid growth of the miniature electronic and computer-related industries has led to great demand for smaller and lighter batteries with improved safety energy and power characteristics. Lithium polymer batteries are expected to meet the above requirements and are thus considered as next-generation rechargeable batteries. The conventional lithium-ion batteries which contain a large amount of liquid electrolyte emit an appreciable amount of gas and this is attributed to the decomposition of a protective layer at the carbon surface. This phenomenon eventually leads the battery system to safety hazards. By virtue of their advantages such as high theoretical capacity improved safety lower material costs ease of fabrication into flexible geometries and the absence of electrolyte leakage lithium polymer batteries have placed an unprecedented demand for battery researchers. Polymer electrolyte can be defined as a membrane that possesses transport properties comparable with that of common liquid ionic solutions. In principle a polymer electrolyte battery can be formed by sandwiching the electrolyte between a lithium metal or a composite carbon anode and a composite cathode as depicted in Figure 1. Because of its rigid structure the electrolyte can also serve as a separator. The prerequisites for a polymer electrolyte to be used in any battery system are 1 high ionic conductivity at ambient and subambient temperatures 2 good mechanical strength 3 appreciable transference number 4 good thermal and electrochemical stabilities and 5 better compatibility with electrodes. Although the ionic conduction in polymer electrolyte was discovered by D. E. Fenton and coworkers in 1973 its technological importance was recognized only after a decade. Polymer electrolytes used in lithium batteries can be .