Electric Cells
Electric cells are devices that convert chemical energy into electrical energy. They consist of two electrodes (anode and cathode) and an electrolyte. When the electrodes are connected by a conductor, a chemical reaction occurs, generating a flow of electrons and creating an electric current. Electric cells are used in batteries to power various electronic devices.
6 Key excerpts on "Electric Cells"
- Dale Crane, Dennis Wilt(Authors)
- 2017(Publication Date)
- Aviation Supplies & Academics, Inc.(Publisher)
...6 Chemical Energy Into Electricity electrochemical cell. A device in which a chemical reaction produces electrical energy. One of the more important devices used to produce electricity is the battery, or more accurately, the electrochemical cell. All of nature is composed of atoms, which consist of a nucleus containing positive protons and neutral neutrons. Spinning around this nucleus in shells, or rings, are negatively charged particles of electricity, called electrons. When atoms of some of the chemical elements react with atoms of other elements, electrons are released from one element, and they are attracted to the other. The force of attraction for these electrons is an electrical pressure called voltage. Simple Chemical Cell The way chemical energy is changed into electrical energy may be seen by studying the simple electrochemical cell in Figure 6-1. Figure 6-1. In a simple electrochemical cell, the zinc reacts with chlorine ions from the hydrochloric acid to form zinc chloride. This reaction causes the zinc to release electrons, which travel through the external circuit to the copper, where they attract and neutralize hydrogen ions from the hydrochloric acid. Two atoms of hydrogen make one molecule of hydrogen gas, which forms as bubbles on the copper. A strip of zinc and a strip of copper placed in a solution of hydrochloric acid and water form an electrochemical cell. The electrolyte (the acid and the water) contains positive hydrogen ions and negative chlorine ions. Zinc is an active chemical element, and it reacts, or combines, with the chlorine to form zinc chloride. When negative chlorine ions from the electrolyte combine with the zinc, the zinc becomes negative; the ions have given it an excess of electrons. If a conductor joins the zinc and the copper, the excess electrons will leave the zinc and travel through the conductor to the copper, where they attract positive hydrogen ions from the electrolyte...
- Jung-Ki Park, Jung-Ki Park(Authors)
- 2012(Publication Date)
- Wiley-VCH(Publisher)
...Chapter 2 The Basic of Battery Chemistry Electrochemistry is the study of electron transfer caused by redox reactions at the interface of an electron conductor, such as a metal or a semiconductor, and an ionic conductor, such as an electrolyte. Technologies based on electrochemistry include batteries, semiconductors, etching, electrolysis, and plating. In this book, electrochemistry refers to the conversion of chemical energy into electric energy in various systems such as primary batteries, secondary batteries, and fuel cells. In particular, this chapter describes the electrochemical aspects of secondary batteries. 2.1 Components of Batteries 2.1.1 Electrochemical Cells and Batteries An electrochemical cell is the smallest unit of a device that converts chemical energy to electric energy, or vice versa. In general, a battery has multiple electrochemical cells, but it may be used to refer to a single cell. An electrochemical cell consists of two different electrodes and an electrolyte. The two electrodes of different electric potential create a potential difference when immersed in the electrolyte. This potential difference is also known as electromotive force. Electric potential, denoted by V, is the potential energy of a unit charge within an electric field, and electromotive force drives current in an electric circuit. Redox reactions occur at each electrode due to this force and the generated electrons pass through the external circuit...
eBook - ePub- Adrian Waygood(Author)
- 2018(Publication Date)
- Routledge(Publisher)
...Unfortunately, the cost of the power cord would be around $200-million! Well, thanks to electrochemical cells, we can use many of our electrical tools, small appliances, multimedia equipment and other gadgets without having to keep them permanently plugged into our wall sockets! Although, of course, we will still require the wall socket to regularly re-energise those cells. After electromagnetism, electrochemical action provides us with our second most important source of electrical energy. As well as powering our mobile phones and other electrical gadgets, cells and batteries are used to start our cars, propel submarines, provide emergency lighting, and a whole raft of other applications too numerous to mention. In this chapter, we are going to learn about the basic behaviour of an electrochemical cell, and examine a selection of these cells and batteries together with their application in electrical engineering. Also, in this chapter, to avoid any confusion, we will consistently describe current in external circuits in terms of electron flow, not conventional flow. The use of conventional flow in this context will be unnecessarily confusing! As we learnt in the chapter on potential and potential difference, an electrochemical cell uses a chemical reaction to release the energy necessary to separate charges, thus creating a pot ential difference across its terminals. This potential difference is then responsible for causing a drift of electric charges (free electrons) around the external circuit. These charges, of course, already exist in the conductors of the external circuit, and are not ‘injected into it’ by the cell! So what an electrochemical cell does not do, is to ‘store electric charges’ which it then ‘pumps around’ its external circuit. It is, therefore, techically incorrect to say that a cell ‘stores charge’, or that a cell ‘discharges’, or that a secondary cell can be ‘recharged’...
eBook - ePub- Yves Brunet, Yves Brunet(Authors)
- 2013(Publication Date)
- Wiley-ISTE(Publisher)
...Chapter 6 Fuel Cells: Principles and Function 1 6.1. What is a cell or battery? A fuel cell is a system that produces electricity and heat using a chemical energy source: the fuel. Cells, batteries, and accumulators are all very precise electrochemical entities, but they are considered to be more or less equivalent or have vague boundaries. The cell is an electrochemical device invented by Alessandro Volta in 1800 to produce electricity using a stack of electrodes and compartments (cells formed by the electrodes), which contains chemical reagents and which has now become commonly available in cylindrical or disk form. These containers enclose an initially fixed quantity of chemical reagents and can, therefore, only produce a limited quantity of electricity, up to the point where the chemical energy is exhausted. Only if this process, known as discharge of the cell, is reversible, by recharging the cell (which is done by injecting electrical energy by connecting it to an electric power supply) can the system again have the same capacity as it had initially. An electrochemical cell that is rechargeable is known as an accumulator. The term battery, which is borrowed from artillery, is used for both rechargeable and non-rechargeable systems. Theoretically, it refers to a set of cells that have been joined together, but it is also used for a single cell, which is why the different terms can seem to mean the same thing. Electrochemists distinguish between the systems with the help of a notion of order (which is unfortunately of little clarification): a “primary battery” is not rechargeable, whereas a “secondary battery” is rechargeable (accumulator). Note that in French, the word pile is reserved for primary batteries, and the word batterie is reserved for accumulators, whereas in English there is no such distinction...
eBook - ePub- Bill Mantovani(Author)
- 2019(Publication Date)
- In Easy Steps Limited(Publisher)
...Its unit is the ampere (A). Voltage (V) Electromotive force (emf) is what creates the flow of current in a circuit and is measured in volts. The potential difference (pd) is the voltage difference or voltage drop between any two points. Power (P) This is a measure of the rate at which energy is transferred. Power is measured in watts (W). Conductor A material with lots of charge-carrying free electrons, such as metal. Insulator A material where the electrons are firmly bound to the nucleus of its atoms so that they cannot move and hence conduct charge. Where an atom has more electrons than protons it is negatively charged, and positively charged if it has fewer electrons than protons. One ampere of current is calculated by: I = Q/t (t is the time in seconds and Q is the charge.) The effects of the flow of an electric current can be detected in many different ways – for example, as heat, light, magnetism, etc. Primary Cells Electrical energy can be produced by a number of means, including mechanical and chemical. A device that generates a charge when a chemical reaction takes place is called a cell. There are two main types: primary and secondary. First, we look at primary cells. The simplest primary or voltaic cell consists of the following: A positive electrode (anode) consisting of a copper plate A negative electrode (cathode) consisting of a zinc plate An electrolyte of dilute sulfuric acid The sulfuric acid is poured into a container, and the electrodes are placed into the electrolyte. If the two electrodes are then connected together outside of the cell, a current will flow from the copper electrode to the zinc electrode, and through the electrolyte back to the copper electrode. In this simple form, the voltaic cell only works properly for a short time. As it generates current, a layer of hydrogen bubbles starts to build up on the copper electrode, causing its output to become less and less. Also, the zinc electrode has to be totally pure...
eBook - ePubElectrical Engineering
Fundamentals
- Viktor Hacker, Christof Sumereder(Authors)
- 2020(Publication Date)
- De Gruyter Oldenbourg(Publisher)
...6 Electrochemistry 6.1 Basic electrochemical concepts With special regard to electrical engineering, this chapter covers the branch of electrochemistry that deals with the generation and storage of electric current. The electrochemical oxidation and reduction reactions take place at the phase boundaries of the electrode and the electrolyte. Galvanic cell Chemical energy is transformed into electrical energy, current is produced, and electrochemical reactions take place spontaneously (negative free enthalpy). Galvanic cells are categorised into three subgroups: Primary cells Secondary cells Fuel cells Electrolytic cell Electric energy is transformed into chemical energy. Two electrodes made of electron-conducting material, and the electrolytes with ion conductivity are conductively connected 62 to each other. At the two spatially separated electrodes electrochemical reactions take place. Half-cell A half-cell consists of one single electrode and an electrolyte into which the electrode is submerged (e.g. copper in a copper sulphate solution). If a (metal) electrode is submerged into a metal salt solution (same metal), the surface of the electrode becomes charged. With base metals (e.g. zinc) some metal atoms enter the solution and the released electrons stay on the surface of the electrode, which is now negatively charged. The positively charged metal ions remain bound to the negatively charged metal surface. Thereby an electrical double layer is formed where the negative and the positive charges balance each other out. When two half-cells are combined, a galvanic cell (connected through ionic conductor and electron conductor) is formed. Anode : Electrode where the oxidation processes take place...
