tailieunhanh - Chapter 1: Electrochemical Energy Storage

Electrical energy plays an important role in our daily life. It can universally be applied and easily be converted into light, heat or mechanical energy. A general problem, however, is that electrical energy can hardly be stored. Capacitors allow its direct storage, but the quantities are small, compared to the demand of most applications. In general, the storage of electrical energy requires its conversion into another form of energy. In batteries the energy of chemical compounds acts as storage medium, and during discharge, a chemical process occurs that generates energy which can be drawn from the battery in form. | 1 Electrochemical Energy Storage D. BERNDT INTRODUCTION Electrical energy plays an important role in our daily life. It can universally be applied and easily be converted into light heat or mechanical energy. A general problem however is that electrical energy can hardly be stored. Capacitors allow its direct storage but the quantities are small compared to the demand of most applications. In general the storage of electrical energy requires its conversion into another form of energy. In batteries the energy of chemical compounds acts as storage medium and during discharge a chemical process occurs that generates energy which can be drawn from the battery in form of an electric current at a certain voltage. For a number of battery systems this process can be reversed and the battery recharged . the intake of electric energy can restore the chemical composition that contains higher energy and can closely reestablish the original structures within the battery. As a consequence two different battery systems exist Primary batteries that are designed to convert their chemical energy into electrical energy only once. Secondary batteries that are reversible energy converters and designed for repeated discharges and charges. They are genuine electrochemical storage systems. Copyright 2003 by Expert Verlag. All Rights Reserved. There is no clear border between them and some primary battery systems permit charging under certain conditions. Usually however their rechargeability is limited. The first part of this book Chapters 2 to 14 concerns batteries of larger capacities that are employed as standby batteries in stationary applications provide energy in vehicles like forklift trucks or stabilize an electrical network like the starter battery in motor cars. Rechargeable batteries usually are the choice in such applications since primary batteries would be too expensive for the required rather high capacity. The second part Chapters 15 to 19 regards batteries mainly in