How Do Batteries Light Up My Life?
Batteries are a common and essential household object used to run cordless power tools, clocks, flashlights, cellphones, laptop computers and start automobile engines. Batteries have been around since discovery by Alessandro Volta in 1800 so I have blithefully accepted their function and been oblivious to their process of storing electrical energy.
High school chemistry teaches that batteries contain chemicals but my understanding of the mechanism of converting chemicals to electricity is challenged. What process or reaction drives electricity out of a battery? On a technical note it must be realized that an atom has electrons revolving around a nucleus. For instance a common element, the carbon atom, has six electrons revolving or spinning around the nucleus. Electricity is the flow of electrons so electrons must be driven off or pushed away from their atom to create a current of electricity. In solar power sunlight energy moves electrons. Wind, hydro and coal burning generated power turn magnets inside coiled wire to push electrons out to transmission lines. Movement of electrons out of a battery can seem less mysterious when recognizing that lightning is the flow of electrons created by wind turbulence traveling hundreds of yards from cloud to cloud or cloud to ground. A more familiar experience is shuffling across a rug in leather-soled shoes and then touching another person to create a spark or shock from static electricity. These examples prove electrons can be easily moved.
Chemists realize most metals such as iron, lead, zinc and lithium exist in nature combined with another element such as oxygen or sulphur. These metals want to give up or share electrons, so to speak and join with another element to become more stable. A common example is pure sodium, which is a metal, but when it comes in contact with chlorine (bleach) it gives up an electron to form sodium chloride, common table salt. Likewise, when my cast iron frying pan is allowed to accumulate moisture after washing it forms rust overnight. Iron, “feels” unstable and seeks to share or give up electrons to oxygen in the presence of moisture to form iron oxide or rust. The phenomenon of a metal giving up electrons is the basic principle used in a battery.
Batteries consist of two chemicals called the electrochemical couple. Usually, one chemical is a pure metal that “feels” unstable seeking to give up or share its electrons with a chemical neighbor or couple. These two chemicals are the battery terminals on a car battery and the positive and negative ends of a flashlight battery. To prevent electrons from just jumping to the other chemical couple inside the battery, the space between them is filled with an electrolyte which produces resistance and prevents flow. In the case of the car battery, the negative terminal is pure lead. It is electron rich. The other terminal is electron deficient and is called the positive terminal. When the ignition key is turned, electrons flow out of the battery through wires connected to the engine starter motor and return to the battery at the positive terminal, accepting the shed electrons completing a chemical reaction within the electrolyte. Some batteries such as the automobile lead-acid battery, power tool batteries and lithium ion hybrid car batteries can be recharged by forcing electricity, at a greater strength than the battery discharged, to reverse the chemical reaction at the two terminals. Recharging requires direct current produced by the automobile engine powering an alternator but household rechargeable batteries require a device to convert alternating current from an electrical outlet to direct current.
Touching both terminals of an automobile battery with 12 volts of charge, is usually insufficient to create an electrical shock to the body whereas touching plug prongs in an electrical outlet at home with 120 volts is enough to create an uncomfortable shock and potentially stop the heart.
Today, batteries are necessary. We should raise our hands claiming, “All hail to the free spirit electron,” eager to flee its atomic bond in a battery and in the process create a controlled surge of energy.