Back in the good old days when I graduated from my first course in radio and TV repair, battery technology was in its infancy with only a half dozen different technologies being used but today there are dozen to choose from. So which battery is best for your project? Primary cell batteries? Secondary cell batteries? Where do we begin in our exploration of modern battery technology?
Alessandro Volta, an Italian physicist, invented the first battery, the Voltaic Pile, in 1800. The Voltaic Pile, consisting of a stack of Zinc and Copper discs separated by pieces of cardboard soaked in a brine solution. The Voltaic Pile was not only the first successful battery it was the first wet cell battery with the brine acting as the electrolyte just as the diluted Sulphuric acid does in today’s lead-acid automobile storage battery. Gaston Plante, a French inventor, invented the first practical lead-acid storage battery in 1859. The lead-acid storage battery was the first secondary cell battery, the first rechargeable battery. Carl Gassner invented the first “dry” cell battery in 1881. To call the Gassner battery, a primary cell battery, a dry cell battery was really a misnomer because the electrolyte paste that separated the carbon anode or positive electrode from the zinc cathode or negative electrode was a very moist paste. If this paste became dry, the cell would cease to generate electricity. The primary cell was not recharbable so once the chemicals in the electrolyte paste were depleted the battery had to be replaced. From that humble beginning, battery technology started advancing in geometric proportions.
Therefore, okay, now we know that all batteries are composed of either primary cells or secondary cells. Remember, only secondary cells can be recharged. All cells, whether primary or secondary consists of four basic component parts, an anode, a cathode, a cardboard liner, and an electrolyte. The chemical electrolyte reacts with the anode and cathode to generate a potential difference or voltage between them. Let us look inside the common “D” cell used in most flashlights. If you decide to follow along with me and cut open a “D” cell be advised that it can be messy and the electrolyte, even though it’s not as caustic as Sulphuric Acid, it can irritate sensitive skin.
If we make our cut vertically slightly to one side of the center terminal, you will see the anode, the cathode, and the electrolyte. The anode, the porous carbon rod situated in the center of the cell, is the positive electrode. The zinc can is the cells cathode or negative electrode. The electrolyte paste situated between the cathode and anode is a compound consisting of ammonium chloride (NH4Cl) and manganese dioxide (MnO2). I’m not going to get into the chemical reactions here but suffice it to say that that these two chemical react with the zinc and carbon electrode in such a way that the chemical energy is converted into electrical energy. The Alkaline battery, the Silver battery, the Nichol-cadmium battery, the mercury cell battery, etc. all employ different chemical electrolytes, different materials for their anodes and cathodes, but the principles are the same.
An important thing to remember when working with different battery technologies is to never mix them together. Never under any circumstances mix primary cells with secondary cells. The same caution applies when recharging secondary cells, don’t mix battery technologies and make sure that the charger that you are using is designed for the type of batteries that you are recharging. Never attempt to recharge a primary cell because they were not designed to be recharged. Recharging generates gas inside a battery and primary cells were not designed to handle this gas. Primary cells can explode during an attempt at recharging sending metal fragment in every direction like shrapnel from an exploding bomb or hand grenade. Many people will tell you that they have charged cells that weren’t designated rechargeable, but don’t follow their example. I have seen batteries explode and it’s not pleasant.
AntoinCesar Becquerel, a French physicist, discovered the photovoltaic effect, which eventually led to the invention of the solar cell, in 1839. After another fifty years or so passed, Charles Fritts invented the first solar cell using a semiconductor junction. The photovoltaic effect converts light energy into electrical energy. The original solar cells were constructed of Selenium or copper-oxide and were very inefficient converting approximately 1 percent of the light energy impinging upon them into electrical energy. The efficiency of solar cells rose to a whopping 6-percent in 1941 when Russel Ohl invented the silicon solar cell. By the late 80s, solar cell efficiency had risen to 20-percent. Today, concentrator solar cells have an efficiency of 37-percent.
Fuel cells are another technology that converts chemical energy into electrical energy with water and heat being by products of that conversion. I’m about to publish an article covering this technology as an alternative energy source so I’m not going to cover it in this article.
