Italian Alessandro Volta invents the first battery known as a Voltaic pile. The article describes the history of the battery, how the cell works, how the battery generates the energy. Moreover, you can read what chemical reactions in the battery generates energy.


Let’s look at the history of the battery. Batteries invention would be a trip back in time, a century or two. That time the only way of making movable energy was either steam power or clockwork. They are handy power supplies as small as a finger or as big as a trunk. It makes us a steady to supply electrical energy whenever and wherever we need it. Suddenly we get through billions of them, and still, they have a significant environmental impact. Despite this fact, we couldn’t live our modern lives without them.

So, what is the battery?

A battery is a chemical power pack that can produce a limited amount of electrical energy, invented by Alessandro Volta. Unlike ordinary electricity, which flows to your home through wires generated by a power plant, a battery converts chemicals packed inside it into electrical energy.

The basic idea of portable power is nothing new; people have always had ways of making energy on the move. Even prehistoric humans knew how to burn wood to make fire, which is another way of producing energy – heat. By the time of the Industrial Revolution (in the 18th and 19th centuries), we’d mastered the art of burning lumps of coal to make power, so fueling things like steam locomotives. But it can take an hour to gather enough wood to cook a meal. Moreover, a locomotive’s boiler typically takes several hours to get hot enough to make steam. By contrast, they give us instant, portable energy; turn the key in your electric car, and it leaps to life in seconds!

What are the main parts of a battery?

The basic power unit inside a battery is called a cell, and it consists of three main parts. There are two electrodes, and a chemical called an electrolyte in between them. For our convenience and safety, these things are inside a metal or plastic outer case. There are two more handy electrical terminals, marked with a plus and minus, on the outside connected to the electrodes that are inside. The difference between a battery and a cell is simply that a battery consists of two or more cells hooked up, so their power adds together.

When you connect a battery’s two electrodes into a circuit, the electrolyte starts buzzing with activity. Slowly, the chemicals inside it convert into other substances – Ions (atoms with electrons) from the materials in the electrodes. These electrodes take part in chemical reactions with the electrolyte. At the same time, electrons march from one terminal to the other through the outer circuit, powering connected device. This process continues until it completely discharges the electrolyte. At that point, the ions stop moving through the electrolyte, the electrons stop flowing through the circuit, and the battery is flat.

Why do they need two different materials?

It is important to note that the electrodes in a battery are always from two dissimilar materials. This material difference is the key to how and why a battery works. One of those materials give up electrons; the other material receives them. 

To understand this, we need to delve back through the history of electricity to 1792. That time Italian scientist Luigi Galvani found he could make electricity with a bit of help from a frog’s leg.

Famously, Galvani stuck a couple of different metals into the leg of a dead frog and produced electricity. He believed it was made by the frog releasing its “animal electricity.” In fact, like his countryman Alessandro Volta soon realized, the important thing was that Galvani had used two different metals. In effect, the frog’s body was working as the electrolyte of a battery made with two different metallic electrodes stuck into it. 

What was so special about the electrodes? Chemical elements differ in their ability to pull electrons toward them—or give them up to other parts that pull on them more. We call this tendency electronegativity. Stick two different metals into an electrolyte, then connect them through an outer circuit, and you get a tug-of-war going on between them. One of the metals wins out and pulls electrons from the other, through the outer circuit—and that flow of electrons from one metal to the other is how a battery powers the circuit. That’s how different materials in battery generates energy. Now, let’s a bit better to understand how the battery works.

How does a battery work?

Now, what’s going on inside and how battery generates the energy. The battery’s positive terminal is connected to a positive electrode that is mostly hidden inside the battery. This we call the cathode. The outer case and the bottom of the battery make up the negative terminal, or negative electrode, which is also called the anode.

At school, you may have learned that the cathode is the negative electrode and the anode the positive electrode? However, that applies only to things like electrolysis (passing electricity through a chemical to split it up). Batteries are like electrolysis going backward. To avoid confusion, I suggest it’s best not to use the terms anode and cathode at all. It’s better to say “positive terminal” and “negative terminal.” Then it’s always clear what you mean, whether you’re talking about batteries or electrolysis.

Chemical reactions

The chemical electrolyte separates the positive and negative electrodes. It can be in the form of liquid, but in a typical battery, it’s often as a dry powder.

When you connect the battery to a lamp and switch on, it starts the chemical reaction. One of the reactions generates positive ions and electrons at the negative electrode. The positive ions flow into the electrolyte, while the electrons flow around the outside circuit to the positive electrode. During the circuit, make the lamp light up on the way. There’s a separate chemical reaction happening at the positive electrode, where incoming electrons recombine with ions taken out of the electrolyte, so completing the circuit.

The electrons and ions flow because of the chemical reactions happening inside the battery—the most usually two of them going on simultaneously. The exact reactions depend on the materials of the electrodes and electrolyte. Whatever chemical reactions take place, the general principle of electrons going around the outer circuit, and ions reacting with the electrolyte, applies to all batteries. As a battery generates power, the chemicals inside it gradually convert into different chemicals. Their ability to generate power dwindles, the battery’s voltage slowly falls, and the battery eventually runs flat. In other words, if the battery cannot produce positive ions, it has become depleted, it can’t produce electrons for the outer circuit either.

It turns out that, because of the chemistry of the electrolyte, electrons can’t flow through it in this simple way. So far as the electrons are concerned, the electrolyte is pretty much an insulator: a barrier they cannot cross. Their most natural path to the positive electrode is actually by flowing through the outer circuit.

Types of batteries

Batteries come in all different shapes, sizes, voltages, and capacities. Although they use all sorts of different chemical electrolytes and electrodes, there are only two main types: primary and secondary. 

  • Primary batteries are ordinary, disposable ones that can’t be recharged. 
  • Secondary batteries can be recharged, often even hundreds of times. You can recharge secondary batteries just by passing a current through them in the opposite direction to which it would normally flow. When you charge, for example, your cellphone, you are just running the chemical reactions inside it in reverse mode.

Measuring batteries

We already know how the battery work, now let’s understand how to measure them. When the battery dies in your flashlight, you go out and buy a replacement. Typically, you buy one the same size so that it will fit inside the case. But they are like boxes. As bigger boxes can hold more stuff, so the size of a cell is a measurement of how much electrical energy it can store. Why? Bigger batteries contain more chemical electrolyte and bigger electrodes so they can release more power. 

If you want a more precise idea of how much electrical energy a battery holds, you have to look on the side for a measurement:

  • in mAh(milliampere-hours) 
  • in Watt-hours(a measurement used on bigger batteries).

Voltage is the other important measurement marked on batteries. The higher the voltage, the more current a battery will produce when it’s connected into a given circuit, which is why this kind of voltage is sometimes also called an electromotive force(EMF). The power something like a lamp or electric motor produces (or consumes) is proportional to the voltage across it, so a higher voltage usually means more power. 

In other words, high-power gadgets tend to need higher voltages than low-power ones, which is, for example, cordless power drills with powerful electric motors. This kind of devices need higher-voltage batteries than simple flashlights which only have to power small light bulbs or LEDs).

Alessandro Volta

In full Conte Alessandro Giuseppe Antonio Anastasio Volta, (born February 18, 1745, Como, Lombardy [Italy]—died March 5, 1827, Como), Italian physicist whose invention of the electric battery provided the first source of continuous current.

Volta became a professor of physics at the Royal School of Como in 1774. In 1775 his interest in electricity led him to improve the electrophorus, a device used to generate static electricity. He discovered and isolated methane gas in 1776. Three years later he was appointed to the chair of physics at the University of Pavia.

In 1791 Volta’s friend Luigi Galvani announced that the contact of two different metals with the muscle of a frog resulted in the generation of an electric current. Galvani interpreted that as a new form of electricity found in living tissue, which he called “animal electricity.” Volta felt that the frog merely conducted a current that flowed between the two metals, which he called “metallic electricity.” He began experimenting in 1792 with metals alone. (He would detect the weak flow of electricity between disks of different metals by placing them on his tongue.) Volta found that animal tissue was not needed to produce a current. That provoked much controversy between the animal-electricity adherents and the metallic-electricity advocates, but, with his announcement of the first electric battery in 1800, victory was assured for Volta.

Key Tags: Alessandro Volta, electric pile, how battery generates the energy, how the battery works

Next: Now we know how inventor Alessandro Volta invents the first electric pile and let’s understand something more about the next stage of Smart Cities evolution: