3.6.1　Operating Principles of Fuel Cells

A fuel cell is a galvanic cell in which the chemical energy of fuel is converted directly into electrical energy by means of electrochemical processes.The fuel and oxidizing agent are continuously and separately supplied to the two electrodes of the cell，where they undergo a reaction.Electrolyte is necessary to conduct the ions from one electrode to the other as shown in Figure 3.5.Fuel is supplied to the anode or positive electrode，where electrons are released from the fuel under catalyst.The electrons，under the potential difference between these two electrodes，flow through the external circuit to the cathode electrode or negative electrode，where combining positive ions and oxygen，reaction products，or exhaust are produced.The chemical reaction in a fuel cell is similar to that in a chemical battery.

Figure 3.5　Basic operation of a fuel cell

New words and expressions（单词和短语）

1.New words（单词）

2.Expressions（短语）

Notes to the text（难点解析）

★1.In contrast to a chemical battery，a fuel cell generates electric energy rather than storing it and continues to do so as long as a fuel supply is maintained.与化学蓄电池形成对比，燃料电池产生电能而不储存电能，并且只要维持燃料供给，它就将继续运行。

★2.A fuel cell is a galvanic cell in which the chemical energy of fuel is converted directly into electrical energy by means of electrochemical processes.燃料电池是一种原电池，借助于电化学过程，其内部燃料的化学能直接转换为电能。

Exercises（练习）

◆1.Translate the following passages（expressions）into Chinese（英译汉）

（1）In recent decades，the application of fuel cells in vehicles has been the focus of increased attention.

（2）cathode electrode

（3）oxidizing agent

◆2.Translate the following passages（expressions）into English（汉译英）

（1）正极

（2）化学反应

Reading material（阅读材料）

A fuel cell is an electrochemical device that produces electricity by means of a chemical reaction，much like a battery.The major difference between batteries and fuel cells is that the latter can produce electricity as long as fuel is supplied，while batteries produce electricity from stored chemical energy and，hence，require frequent recharging.

The basic structure of a fuel cell（Figure 3.5）consists of an anode and a cathode，similar to a battery.The fuel supplied to the cell is hydrogen and oxygen.The concept of fuel cell is the opposite of electrolysis of water，where hydrogen and oxygen are combined to form electricity and water.The hydrogen fuel supplied to the fuel cell consists of two hydrogen atoms per molecule chemically bonded together in the form H2.This molecule includes two separate nuclei，each containing one proton，while sharing two electrons.The fuel cell breaks apart these hydrogen molecules to produce electricity.