Dry Cell (Primary Cell)

The Dry Cell is a Primary Cell

The cells from which electric energy is derived by irreversible chemical action are called primary cells. The primary cell is capable of providing an EMF when its constituent’s two electrodes and a suitable electrolyte are assembled together. The three main primary cells namely are the Daniel cell, the Leclanche cell, and the dry cell. None of these cells can be recharged electrically.

A zinc–carbon battery is a type of dry cell battery that delivers a potential of 1.5 volts. Although carbon is an important element of the battery's construction, it takes no part in the electrochemical reaction. The cell could more properly be called a "zinc–manganese" cell. The zinc can is the anode and the source of high potential electrons at a higher potential than the other terminal and hence it is marked negative. The manganese dioxide and carbon black paste is the cathode and the inert carbon rod is a non-corrodible conductor that makes the positive pole, which is at lower potential than the anode, hence it is marked with a positive sign. General purpose batteries may use ammonium chloride and/or zinc chloride as the electrolyte.

Zinc–carbon batteries were the first commercial dry batteries, developed from the technology of the wet Leclanché cell  and made flashlights and other portable devices possible, because the battery can function in any orientation. They are still useful in low drain or intermittent use devices such as remote controls, flashlights, clocks or transistor radios. Zinc–carbon dry cells are single-use primary cells, since they are not intended to be recharged.

Dry Cell (Primary Cell)

Syed Shiyaz Mirza Wednesday, 8 June 2016

Battery terms

Battery terms 

Acid: Any substance that donates protons

Alkali metals: Extremely reactive group of element in Group 1 of the periodic table.

Ampere: The Standard International base unit of current intensity. 1 Ampere flows through one Ohm of resistance, when a potential of one volt is applied. I=E/R.

Ampere-Hour: The quantity of electricity that passes through a circuit in one hour, when the rate of flow is one ampere.

Anion: A negatively charged non-metallic ion.

Anode: The electrode in an electrochemical/galvanic cell that experiences oxidation, or gives up electrons..

Battery Capacity: The total number of Ampere-hours that can be derived from a fully loaded battery, under a specified set of conditions. The current supplying capability of a battery in ampere-hours.

Cation: A positively charged metallic ion.

Cathode: The electrode in an electrochemical/galvanic cell, at which a reduction reaction occurs, or the electrode that receives electrons from an external circuit.

Charge Retention: The fraction of full capacity available from a battery under a specified set of conditions, after the battery has been stored for a given amount of time.

Charge: A quantity of electricity associated with a space, particle, or body.

Charging Efficiency: The ratio of output of a secondary battery to the input required to restore it to its original state, under a specified set of conditions.

Charge Retention: The holding of an electric charge by a cell or battery when no current is being drawn from it.

Coulomb: All electric charge exists in discrete quantities that are integral multiples of electronic charge or 1.6022 x 10^-19 Coulombs.

Coulombic Efficiency: The ratio of the output of charge by a battery to the input of charge. Coulombic efficiency is determined by the internal resistance of a cell.

Coulombic Output: The electrical energy or charge delivered by a battery when in use.

Current: The movement of charge carriers, such as electrons, holes, or ions. Expressed in amperes.

Current Drain: The withdrawal of current from a cell or battery.

Discharge: The conversion of the chemical energy stored within a cell to electrical energy, and the subsequent withdrawal this electrical energy into a load.

Discharge Profile: A graphic indicating the discharge characteristics of a battery system, as a function of time.

Discharge Rate: An expression of the speed with which a battery is being discharged, at a specific point in time.

Dry Cell: A cell with an immobilized electrolyte.

Electrochemical Reaction: A reaction whereby the chemical energy contained within cell components is converted to electrical energy, or conversely a reaction brought around by the supply of electrical energy, which gets converted to chemical energy. If only the first case is applicable, the cell is called an electrolysis cell. If only the second scenario applies, the cell is termed a galvanic cell.

Electrolyte: A solution through which an electric current may be carried through the motion of ions.

Electron: The elemental particle of an atom having a negative charge.

Energy: The capacity for doing work. Common forms of energy include electric energy, chemical energy, potential energy, heat energy, magnetic energy, mechanical energy, kinetic energy, etc. In the context of this exercise energy may be viewed as the work performed by electric power.

Energy Density: The ratio of the energy available from a battery, to its cell mass. Expressed in Joules per gram.

Hybrid Battery: Electrochemical cell in which one of the two active reagents is in the gas phase and maybe supplied from an external source.

Internal Resistance: The opposition or resistance to the flow of an electric current, within a cell.

Ion: A particle in solution that carries a positive or negative charge.

Ionic Conduction: In the context of this tutorial ionic conduction is the transfer of electric charge via ions contained within an electrolytic solution.

Leclanche Battery System: The Leclanche or zinc-carbon dry cell battery has existed for over 100 years and has been the most widely used of all dry cell batteries because of a combination of low cost, ready availability, and relatively strond performance.

Load: A term used to indicate the current drain on a battery when power is delivered to external devices or circuit elements..

Memory Effect:  A phenomenon in which a cell, operated in successive cycles to the same, but less than full depth of discharge, temporarily experiences a depression of its discharge voltage and subsequent loss of the remainder of its capacity at normal voltage levels. 

Nominal Voltage: The characteristic operating voltage or rated voltage of a battery.

Ohm: The basic unit of resistance, reactance, or impedance.

Operating Voltage: See Working Voltage

Oxidation: The loss of electrons by a chemical species.

Parallel: A term used to describe the inter-connection of cell or batteries in which all like terminals are connected together.

Polarization: The change of the potential of a cell or electrode via the passage of electric current.

Potential: The electrical pressure causes charge carriers to move through a substance or circuit.

Power: The rate of transmitting current or charge. Expressed in Watts.

Power Density: The ratio of power available from a cell to its cell mass.

Rated Capacity: The number of ampere-hours a battery can deliver under specific (rate of discharge, end voltage, temperature) conditions.

Recharge: The conversion of the electric energy provided by an external source into chemical energy, within a cell or battery.

Reduction: The gain of electrons by a chemical species.

Resistance: The opposition to current flow; expressed in Ohms.

Separator: An ion permeable, electronically non-conductive material, which prevents electronic contact between electrodes of opposite polarity, within the same cell.

Series: The inter-connection of cells or batteries whereby, the positive terminal of the first is connected to the negative terminal of the second, and so on. (Check this)

SLI Battery:  A battery designed to start internal combustion engines and power the electrical systems in automobiles when the engine is not running.

Specific Energy: The ratio of the energy output of a battery to its weight.

Solution: A uniform mixture of chemicals. In solution it is impossible to distinguish separate solute and solvent particles.

Standby Battery: A battery designed for emergency use in the vent of main power failure

State of Charge Indicator: A device indicating the condition of the battery in terms of remaining available capacity.

Turnaround Efficiency: The ratio of average voltage during discharge to average voltage during recharge under specified conditions of charge and discharge.

Volt: The basic unit expressing a difference of potential.

Voltage: Electromotive force or difference of potential. E=IR, where I is current and R is resistance.

Voltage Delay: The time delay required for a battery to deliver the required voltage after being placed under load.

Volumetric Energy: The ratio of available energy to cell volume. Expressed in Joules per cubic centimeter.

Working Voltage: The typical range of voltages of a battery during discharge.

Battery Terms , VHSE , VHSE EET

Battery terms

Syed Shiyaz Mirza

Voltage & Capcity of Major Battery Systems

Theoretical Voltage & Capcity of Major Battery Systems Primary Anode Cathode Reaction Mechanism Voltage% Energy% Density^ Leclanche                 Zn            MnO2       Zn + 2MnO2 à ZnO + Mn2O3    1.6 358 165 Magnesium  Mg MnO2 Mg + 2MnO2 + H2O à Mn2O3 + Mg(OH)2 2.8 759 195 Alkaline MnO2 Zn MnO2 Zn + 2MnO2 à ZnO + Mn2O3 1.5 358 400 Mercury Zn HgO Zn + HgO à ZnO + Hg 1.34 255 470 Mercad Cd HgO Cd + HgO + H2O à Cd(OH)2 + Hg 0.91 148 230 Silver Oxide Zn Ag2O  Zn + Ag2O + H2O à Zn(OH)2 + 2Ag 1.6 288 525 Zinc/O2 Zn O2 Zn + 0.5O2 à ZnO 1.65 1085 1300 Zinc/Air Zn Air Zn + 0.5O2 à ZnO 1.65 1353 1300 Li/SOCl2 Li SOCl2 4Li + 2SOCl2 à 4LiCl + S + SO2     3.65 1471 1100 Li/SO2 Li SO2 2Li + 2SO2 à Li2S2O4    3.1 1175 415 LiMnO2 Li MnO2 Li + MnIVO2 àMnIVO2(Li+) 3.5 1001 535 Li/FeS2 Li FeS2 4Li + FeS2 àLi2S + Fe  1.8 1307 500 Li/(CF)n Li (CF)n  nLi + (CF)n à nLiF + nC    3.1 2189 635 Li/I2(3)  Li I2(P2VP) Li + 0.5I2 à LiI  2.8 560 900 Secondary Anode Cathode Reaction Mechanism Voltage% Energy% Density^ Lead-Acid Pb  PbO2 Pb + PbO2 + 2H2SO4 à 2PbSO4 + 2 H2O 2.1 252 70 Edison Fe NiO2 Fe + 2NiOOH + 2H2O à 2Ni(OH)2 + Fe(OH)2  1.4 314 355 Nickel-Cadmium Cd NiO2  Cd + 2NiOOH + 2H2O à  2Ni(OH)2 + Cd(OH)2 1.35 244 100 Nickel-Zinc Zn NiO2 Zn + 2NiOOH + 2H2O à 2Ni(OH)2 + Zn(OH)2 1.73 372 120 Nickel-Hydrogen H2 NiO2 H2 + 2NiOOH à 2Ni(OH)2 1.5 434 60 Nickel Metal Hydride MH NiO2  MH + NiOOH à M + Ni(OH)2 1.35 240 240 Silver-Zinc Zn AgO Zn + AgO + H2O à Zn(OH)2 + Ag 1.85 524 180 Silver-Cadmium Cd AgO Cd + AgO + H2O à Cd(OH)2 + Ag 1.4 318 120 Zinc/Chlorine Zn Cl2 Zn + Cl2 à ZnCl2 2.12 835 - Zinc/Bromine Zn Br2 Zn + Br2 à Zn Br2 1.85 572 60 Lithium Ion LixC6 Li(i-x)CoO2 LixC6 + Li(i-x)CoO2 à LiCoO2 +C6 4.1 410 400 Lithium/MnO2 Li MnO2 Li + MnIVO2 à MnIVO2(Li+) 3.5 1001 265 Lithium/FeS2 Li(Al) FeS2 2Li(Al) + FeS2 à Li2FeS2 + 2Al  1.73 493 350 Lithium/FeSv Li(Al) FeS 2Li(Al) + FeS à Li2S + Fe + 2Al 1.33 459 220 Sodium/Sulfer Na S 2Na + 3S à Na2S3 2.1 792 345 Sodium/NiCl2 Na NiCl2 2Na + NiCl2 à 2NaCl + Ni 2058 787 190 Reserve Anode Cathode Reaction Mechanism Voltage% Energy% Density^ Cuprous Chloride Mg CuCl Mg + Cu2Cl2 à MgCl2 + 2Cu 1.6 386 80 Zinc/AgO Zn AgO Zn + AgO + H20 à Zn (OH)2 + Hg 1.81 512 75 Thermal  Li FeS2 Various 2.1-1.6 1307 100 Fuel Cells Anode Cathode Reaction Mechanism Voltage% Energy% Density^ H2O2 H2 O2 H2 + 0.5O2 à H2O 1.23 3660 - H2/Air H2 Air H2 + 0.5O2 à H2O 1.23 32702 - Methanol/O2 CH3OH O2 CH3OH + 1.5O2 à CO2 + 2H2O 1.24 2480 - Methanol/Air CH3OH Air CH3OH + 1.5O2 à CO2 + 2H2O 1.24 6225 - % - Theoretical Values ^ - Practical Value Source: The Handbook of Batteries (3rd Edition) by David Linden & Thomas Reddy

VHSE , VHSE EET , Voltage & Capcity of Major Battery Systems

Voltage & Capcity of Major Battery Systems

Syed Shiyaz Mirza

Cell- Classification

Classification of Cells or Batteries

Electrochemical batteries are classified into 4 broad categories.

1. A primary cell or battery is one that cannot easily be recharged after one use, and are discarded following discharge. Most primary cells utilize electrolytes that are contained within absorbent material or a separator (i.e. no free or liquid electrolyte), and are thus termed dry cells.

2.A secondary cell or battery is one that can be electrically recharged after use to their original pre-discharge condition, by passing current through the circuit in the opposite direction to the current during discharge. The following graphic evidences the recharging process.

Secondary batteries fall into two sub-categories depending on their intended applications.

• Cells that are utilized as energy storage devices, delivering energy on demand. Such cells are typically connected to primary power sources so as to be fully charged on demand. Examples of these type of secondary cells include emergency no-fail and standby power sources, aircraft systems and stationary energy storage systems for load-leveling.

• Cells that are essentially utilized as primary cells, but are recharged after use rather than being discarded. Examples of these types of secondary cells primarily include portable consumer electronics and electric vehicles.

Primary vs. Secondary – A Comparison

The following table summarizes the pros and cons of primary and secondary batteries.

Primary

Secondary

Lower initial cost Higher life-cycle cost  Disposable. Disposable. Replacement readily available. Typically lighter and smaller; thus traditionally more suited for portable applications. Longer service per charge and good charge retention. Not ideally suited for heavy load/high discharge rateperformance. Not ideally suited for load-leveling, emergency backup,hybrid battery, and high cost military applications.  Traditionally limited to specific applications.

Higher initial cost. Lower life-cycle cost  if charging in convenient and inexpensive. Regular maintenance required. Periodic recharging required. Replacements while available, are not produced in the same numbers as primary batteries. May need to be pre-ordered. Traditionally less suited for portable applications, although recent advances in Lithium battery technology have lead to the development of smaller/lighter secondary batteries. Relative to primary battery systems, traditional secondary batteries (particularly aqueous secondary batteries) exhibit inferior charge retention. Superior high discharge rate performance at heavy loads Ideally suited for load-leveling, emergency backup, hybrid battery and high cost military applications The overall inherent versatility of secondary battery systems allows its use and continuing research for a large spectrum of applications.

A third battery category is commonly referred to as the reserve cell. What differentiates the reserve cell from primary and secondary cells in the fact that a key component of the cell is separated from the remaining components, until just prior to activation. The component most often isolated is the electrolyte. This battery structure is commonly observed in thermal batteries, whereby the electrolyte remains inactive in a solid state until the melting point of the electrolyte is reached, allowing for ionic conduction, thus activating the battery.  Reserve batteries effectively eliminate the possibility of self-discharge and minimize chemical deterioration. Most reserve batteries are used only once and then discarded. Reserve batteries are used in timing, temperature and pressure sensitive detonation devices in missiles, torpedoes, and other weapon systems.

Reserve cells are typically classified into the following 4 categories.

• Water activated batteries.
• Electrolyte activated batteries.
• Gas activated batteries.
• Heat activated batteries.

The fuel cell represents the fourth category of batteries. Fuel cells are similar to batteries except for the fact that that all active materials are not an integral part of the device (as in a battery). In fuel cells, active materials are fed into batteries from an outside source. The fuel cell differs from a battery in that it possesses the capability to produce electrical energy as long as active materials are fed to the electrodes, but stop operating in the absence of such materials. A well-known application of fuel cells has been in cryogenic fuels used in space vehicles. Use of fuel cell technology for terrestrial applications has been slow to develop, although recent advances have generated a revitalized interest in a variety of systems with applications such as utility power, load-leveling, on-site generators and electric vehicles.

Cell- Classification , VHSE EET

Cell- Classification

Syed Shiyaz Mirza

Cell- Introduction

Cell

Introduction

A battery is a device that converts chemical energy  into electric energy by means of an electrochemical reaction (Oxidation & Reduction). This type of reaction involves the transfer of electrons from one material to another via an electric circuit.While the term battery is often used the cell is the actual electrochemical unit used to generate or store electric energy.

In understanding the differences between a cell and a battery, one should think of a battery as one or more of these cells connected in series, or parallel, or both, depending on the desired output voltage and capacity.

Basic Components of Cells 

Cells are comprised of 3 essential components.

• The Anode is the negative or reducing electrode that releases electrons to the external circuit and oxidizes during and electrochemical reaction.
   
• The Cathode is the positive or oxidizing electrode that acquires electrons from the external circuit and is reduced during the electrochemical reaction.
   
• The Electrolyte is the medium that provides the ion transport mechanism between the cathode and anode of a cell. Electrolytes are often thought of as liquids, such as water or other solvents, with dissolved salts, acids, or alkalis that are required for ionic conduction. It should however be noted that many batteries including the conventional (AA/AAA/D) batteries contain solid electrolytes that act as ionic conductors at room temperature.

How it Works?

When in operation the electrochemical cell essentially discharges its chemical energy in favor of electric energy. If the cell is connected via an external circuit from the cathode to the anode, electrons flow from the oxidized anode and are received by the cathode, which is subsequently reduced. The electric circuit is completed by cations and anions, within the electrolyte, which flow to the cathode and anode, respectively.

Cell- Introduction

Cell- Introduction

Syed Shiyaz Mirza