Superconducting batteries were batteries that used room-temperature superconductors. These batteries were super-efficient.
(Note: The background section of this page uses most of the same words as Terra Futura's page on room-temperature superconductors to save time.)
The concept of absolute zero started in the 18th century with Guillame Amontons. He discovered a lower limit of temperature. This was later incorporated in the 19th century by Lord Kelvin into his new temperature scale as absolute zero. At the same time as Lord Kelvin, Michael Faraday discovered the concept of refrigeration. Faraday was able liquify almost every gas. Liquid oxygen, liquid nitrogen, liquid hydrogen, and liquid helium were the only gases he could not liquify. Liquid helium was the last of the permanent gases to be liquified by Dutch physicist Heike Kamerlingh Onnes in 1908. That is what won him the Nobel Prize, four years later. In 1911, Onnes was researching how materials conducted at low temperatures. Onnes discovered that at 4 K mercury lost all resistance to electricity. It was dubbed a superconductor. Superconductivity, along with a later of Onnes' called superfluidity, were best understood by quantum mechanics. It was thought that by the end of the 20th century, maglev trains and superconducting power lines would be commonplace. This prediction could not be further from the truth. The problem was that superconductors were supercold. Then, in 1986, two scientists discovered high-temperature superconductivity. The maximum that was ever achieved in the late 20th century was 138 K. Then, with the discovery of superconductors based on iron, the maximum went up in 2013. After World War III, room-temperature superconductors were discovered. The discovery of room-temperature superconductors brought forth a new era: The Age of Magnetism. Maglev technology became cheaper and was used in cars, buses, and trains. It was also used in power lines that never lost electricity. Many technologies were revolutionized by room-temperature superconductors. One notable example was batteries.
Tech Level: 12
With discovery of room-temperature superconductors in the 2050s, applications started getting put forward. Among the most notable was superconducting batteries. These batteries were super-efficient. No charge was lost for a while. This was the best battery for electric cars. Cell phones did not need to be recharged as much. It was a new age of electromagnetism where all electronics discharged slowly and recharged quickly. Everyone was happy.