Understanding Batteries-Concepts for Teaching By Harry T. Roman

Batteries and Electrochemistry Battery operation is governed by the laws of electrochemistry

Types of Batteries Two basic types of batteries: Primary batteries can be used only once and then are totally discharged and discarded. Secondary batteries are capable of being re-charged; their chemical reactions can be reversed- examples…cell phones, car batteries.

Typical Primary Batteries

Typical Secondary Battery

How Batteries/Cells Work There are three main components of a battery: two terminals made of different chemicals (typically metals), the anode and the cathode; and the electrolyte, which separates these terminals. The electrolyte is a chemical medium that allows the flow of electrical charge between the cathode and anode. When a device is connected to a battery — a light bulb or an electric circuit — chemical reactions occur on the electrodes that create a flow of electrical energy to the device.  

Dry Cell Cross Section Dry cell batteries are easy to make, modular, and have excellent quality assurance characteristics. They are easily distributed and sold everywhere in large numbers.

What are Batteries/Cells Like? Think of a hydroelectric dam: The dam height represents battery/cell voltage. The amount of water behind the dam is the capacity or total energy available. How much water comes out at a time [the battery draw] is the power expended. The more draw, the more rapidly the water is depleted. Bigger batteries of equal voltage have more total energy available.

Early Battery History 1800: The Voltaic Pile, Alessandro Volta, the first true battery of zinc and copper plates separated by brine soaked cloth.  1820: The Daniel Cell Battery  1838: The Porous Pot Cell  1859: Lead Acid Battery  1866: The Leclanché Cell, a Carbon-Zinc battery –the first dry cell battery [like ours today!]

Early Battery History Cont’d 1899: The Nickel-Cadmium Battery 1899: Waldmar Jungner invented the first nickel-cadmium rechargeable battery. 1901: The Edison Battery-- nickel-iron batteries originally intended for electric vehicle use; but later used in many industry applications. The rechargeable alkaline storage battery was invented by Thomas Alva Edison. 1912: Lithium and Lithium-Ion Batteries

Multiple Cell Batteries 12-Volt Car Batteries-are made of six 2.0 volt cells 9-Volt Batteries – are made of six 1.5 volt cells

Car Batteries Car batteries can still be largely wet cell designs-although many are gel-type cells now. Large banks of storage batteries can still be wet cell affairs, It all depends on costs and design characteristics.

Edison’s Batteries Thomas Edison invented and widely sold his rugged nickel-iron storage battery—which was a wet cell battery. Today, companies are still making that kind of battery

Tesla Solar Battery Pack

Large Scale Battery Back-up

Wet Cell Batteries Before dry cells, batteries were made of single cells built in series [and later parallel] to provide power and capacity for use in many applications.

Cu-Zn Test Cell Performance Electrolyte Volts Saltwater .92 TIDE detergent .88 Downy fabric softener .89 Windex .41 Bleach .77 Soda .98 Gatorade .98

Play Doh Electrolyte Metal Electrodes Volts Cu-Fe .24 Cu-Zn .78 Carbon-Zn [pencil lead] .70 Ni-Fe [Edison battery] .26 Cu-Al .57 Cu-Tin .31 Fe-Tin .14 Fe-Al .61 Tin-Al .38

Play Doh Electrolyte Cont’d Metal Electrolyte Volts Tin-Zn .50 Ni-Al .63 Ni-Tin .34 Ni-Cu .08 Carbon-Tin .68 Carbon-Al .84 Carbon-Fe .50

Play Doh Single Cell [Cu-Zn]

Play Doh --2 cells in series

Play Doh--3 cells in series

Play Doh -- 4 cells in series