READING PASSAGE The Power of Batteries Learn the fascinating history and science behind this groundbreaking electrical invention.

Batteries power so many things the copper in a process called The Dreaded in your everyday life that you reduction (you can remember this Dead Battery probably don’t think twice about as: Because electrons are negative, How annoying is them. Around 1800, an Italian they reduce positive charge). it when your cell physicist and chemist named phone battery dies? Alessandro Volta created a simple Oxidation reduction is an With any battery, battery called the voltaic pile, but exothermic reaction, meaning that eventually the before then there was no such energy is released as the reaction anode has no more thing as portable electricity. In occurs. Volta’s discovery meant that electrons to supply, his experiments, Volta found that potential chemical energy could and the battery will stacked disks of copper and zinc, be “stored” in a battery and used die or go flat.Some separated by cloth or paper soaked in the form of electrical energy batteries, like the in a salty solution, would produce whenever the time was right. one in your phone, a small amount of electrical energy The more voltaic cells that were are designed to (see diagram on next page). The stacked, the greater the voltage. be rechargeable. energy was the result of a chemical The same reaction known as oxidation MODERN INNOVATORS electrochemical reduction, or redox for short. The invention of the battery made processes that power supply portable, but the allowed the battery practical applications of the voltaic IN THE CHEMISTRY LAB to supply power If you connect the positive and cell were very limited. Enter the are reversed using negative terminals of a voltaic cell innovators who continued to an external power with a wire, the zinc begins to lose improve the battery by engineering supply (such as its electrons in a process called and experimenting with new plugging a cell oxidation. They then move toward materials, creating batteries that phone into its were more reliable, more powerful, charger). The easier to use, and longer-lasting. reverse flow of Notable advances in battery

Photo: Solar battery: Andreas Schlegel/fStop/Offset; various batteries: fmajor/iStock various batteries: Photo: Solar battery: Andreas Schlegel/fStop/Offset; electrons restores science include: the battery’s power- The Daniell Cell: the first practical giving abilities. source of portable power that provided a longer and more reliable current than Volta’s. Example application: telegraphy.

Lead-Acid Battery: the first battery that could be recharged. Example application: car battery.

continued Zinc-Carbon Battery: the first process, though, there will dry-cell battery. Unlike wet be setbacks along the way. cells, the zinc-carbon battery Batteries have their share of would not spill and did not have problems, including both safety to be kept upright. Example and environmental concerns. application: flashlight. A battery that has significant energy density, for instance, will Alkaline Battery: achieved cause a dangerous explosion better energy density (could if its cathode and anode store more energy per unit of accidentally come into contact. What’s a frog got to volume) than its predecessors. Over their history, batteries do with it? Do a quick Example application: television have been manufactured using online search to find out remote. heavy metals such as mercury how the very curious and lead along with other behavior of a dead frog Lithium-Ion Battery: significant components. They must be inspired Volta’s battery advancements in energy density recycled responsibly because experiments. and the ability to recharge more they pose a threat to humans than a thousand times. Example and the natural environment. application: cell phone. Are you the next innovator? Or what about a battery that In the future, you may be using How could you make a battery could recharge an infinite batteries that are paper-thin that is more environmentally number of times? Challenge and have the ability to recharge friendly? A battery that holds yourself to come up with the hundreds of thousands of a charge longer that is lighter, next great idea! times. As with any innovation smaller, safer, or stronger?

The Anatomy of a Battery A battery you bought at the store last week and the earliest versions of batteries have the same three components in common. Check out the diagram below: When a wire closes the circuit or connects the cathode and the anode, electrons: a) move into the wire from the anode, b) power a device, and c) continue on their way back to the cathode.

Cathode (+) Voltaic Pile — The positive terminal, The voltaic pile is made up of individual cells that where are stacked to increase the amount of voltage. positive ions are housed Positive Terminal The cathode in a Cathode + voltaic cell is made of Electrolyte — copper. A substance Electrolyte that allows A saltwater solution the flow functions as the of ions from — electrolyte. the cathode to the anode Anode — – Anode The anode is made — (-) The of zinc. negative terminal, where electrons This is one — are housed voltaic cell. Negative Terminal