Today in Science and Technology History | March 20, 1800 Scientist Volta invented the first battery in human history

One of the qualities of a great scientist is his sensitivity to abnormal phenomena and his persistence in discovering them. In 1786, Italian biologist Galvani accidentally touched the exposed nerve on the leg of a dissected frog with a surgical scalpel. Surprisingly, the frog's leg immediately began to twitch violently. Later, his friend, Italian physicist Volta, was inspired by Galvani's frog leg experiment and invented the first battery in human history - the voltaic pile.

On March 20, 1800, Volta sent a manuscript describing his invention to the Royal Society of London. The Voltaic pile was superior to the "Leyden jar" in that the metal wires at both ends of the pile could be connected to obtain a continuous current. It was the prototype of the modern battery that we use widely today. With the invention of the Voltaic pile, people were able to obtain a relatively stable current for the first time, which provided conditions for further exploration and brought electrical research into the modern stage of quantitative research.

Galvani discovered bioelectricity

One day in 1786, Galvani was dissecting a frog carefully. He was fully focused and meticulous. He first used the scalpel in his hand to accurately cut the frog's abdominal muscles, and then carefully found the frog's lower limb nerves for research. When he was dissecting another frog, there was a generator working nearby, and the scalpel accidentally touched the generator. When he dissected the frog's nerves again, a phenomenon he had never seen before occurred: the frog's leg muscles twitched noticeably.

This phenomenon aroused Galvani's great interest. He initially thought that the frog, which was still alive and kicking just now, was not completely dead. Later, he finally discovered the inevitable connection between the generator, the scalpel and the twitching of the frog's nerves. He decided to test whether the electricity in the air would also cause the frog's legs to have the same reaction. Galvani connected one end of the frog's leg nerve to an insulated metal rod with a wire, placed the metal rod on the roof, and grounded the other end of the frog's leg nerve. He found that during thunderstorms, the frog's leg would twitch from time to time.

Next, Galvani conducted another experiment. When he placed a brass hook with a frog's leg nerve on an iron rod, the frog's muscles began to twitch, and this phenomenon occurred even on sunny days. Finally, he used two different metals to touch the muscles and nerves of a dead frog respectively, and then connected the two metals, and the muscles also twitched and trembled.

These phenomena should have made Galvani realize that the frog's twitching came from external electric current. However, Galvani, who had always been keen on studying bioelectric phenomena, believed that the frog's bioelectricity formed a circuit with the outside world. Galvani therefore inferred that electrical energy came from living muscles. The two metals of different properties just formed a circuit between the frog's nerves and muscles, and he called this electricity "bioelectricity."

◆Volta invented the first battery in human history

In 1799, after Volta turned 45, influenced by Galvani, he decided to continue his research on "bioelectricity".

Volta placed a metal zinc ring on a copper ring, pressed it with a piece of paper or wool ring soaked in salt water, and then placed another zinc ring and a copper ring on top. He repeated this process until 10, 20, or 30 rings were stacked into a column, which generated an obvious electric current. This is what later generations called the Voltaic pile.

The higher the columns are stacked, the stronger the current will be. It turns out that Volta created an amazing theory of potential difference through experiments: when different metals come into contact, opposite charges will appear on the surface, that is, there is voltage. He also found such a sequence: aluminum, zinc, tin, cadmium, antimony, bismuth, mercury, iron, copper, silver, gold, platinum, palladium. When any metal in this sequence comes into contact with the metal behind it, the front will always be positively charged and the back will be negatively charged. This is the world's first electrical element table. As long as there is a potential difference, an electric potential difference, that is, voltage, there will be current. In this way, people's understanding of electricity suddenly jumped out of the field of static electricity. It is no longer the electricity on the friction of fur, the electricity in the thunderstorm, the electricity in the Leyden jar, and not just the electricity in the animals, but the "flowing electricity" that can be controlled.

On March 20, 1800, Volta officially announced that electric charges flow in wires like water, from high voltage to low voltage, generating current, which is the potential difference. To this end, he wrote a paper entitled "On the Electricity Excited by the Contact of Dissimilar Metallic Materials" and sent it to the Royal Society of London. Unfortunately, it was deliberately shelved by Nicholson, a secretary in charge of paper work at the Royal Society at the time. Later, Volta published it under his own name, which finally made Nicholson's plagiarism condemned by the academic community.

On November 20 of that year, French Emperor Napoleon summoned Volta to Paris to watch the battery experiment in person. Excited, Napoleon ordered French scholars to set up a special committee on the spot to conduct large-scale related experiments, and awarded Volta a bonus of 6,000 francs and a medal, and also issued a commemorative gold coin with Volta's image as the main body.

◆The scientific community’s path to battery research and development

The invention of the voltaic pile triggered the scientific community's journey towards battery research and development.

The Voltaic pile can be regarded as the first battery of mankind. In 1836, British scientist Daniel improved the "Voltaic pile": using dilute sulfuric acid as the electrolyte, solving the battery polarization problem, and creating the first zinc-copper battery that can maintain a balanced current. Because this battery can be recharged and used repeatedly, it is called a "storage battery."

In 1887, the British Helleson invented the earliest dry cell battery. Its electrolyte was in a paste form, would not spill, and was easy to carry, so it was widely used.

In 1890, Edison invented the rechargeable iron-nickel dry battery, which brought the invention of batteries to a new stage.

With the development of science and technology, dry batteries have developed into a large family, and there are more than 100 types so far, such as zinc-manganese dry batteries, alkaline zinc-manganese dry batteries, magnesium-manganese dry batteries, zinc-air batteries, zinc-mercury oxide batteries, zinc-silver oxide batteries, lithium-manganese batteries, etc. These dry batteries are actually improved versions of the voltaic pile: ammonium chloride paste replaces the original salt water, graphite rods replace the original copper plates as the positive electrode, and the outer shell still uses zinc skin as the negative electrode of the battery.

Until Volta's later years, he kept saying: "Without Galvani's frog experiment, there would never be Voltaic current. When people use Voltaic current, they should first think of Galvani. It was his frog experiment that opened the door to my intelligence like lightning."