The history of the battery
A battery can be defined as a system that directly converts the chemical energy of electrode materials into electrical energy through an electrochemical reaction. The earliest description of the battery appeared in an article published by Volta in the Journal of the Royal Society of London in 1800. Volta was a professor at the University of Pavia in Italy. In 1786, Galvani of Italy discovered that touching the thigh of a frog with a metal object would cause its muscles to twitch. He claimed that “animal electricity” is generated in frogs and transmitted through muscles. Volt doubted the credibility of “animal electricity” and confirmed that the animal’s body fluid acts as an electrolyte between two different metals. Volt invented the Volt stack in 1800 (see Figure a). In this device, a cloth soaked in an alkaline solution is used to separate two metal stacks, and then a wire is connected to both ends to generate an electric current. This is The original form of the battery as we know it today.
In 1932, a clay pot more than two thousand years ago was discovered at a site in Baghdad (see Figure b), which is considered to be the earliest battery specimen. The pot is 15cm high and includes a copper pillar fixed with a copper rod and an iron rod. The rod has been corroded by acid. Although some scholars believe that the handicraft is a primitive battery, it is impossible to verify whether it has such a purpose.
Batteries can be divided into primary batteries and secondary batteries (or rechargeable batteries). The primary battery is discarded after being used once, and the secondary (rechargeable) battery can be recharged and used many times. Since the invention of the volt stack, mankind has developed and commercialized various batteries.
The earliest widely used primary battery was the Leclanché (or zinc-manganese) battery, which was invented in 1865 by a French engineer named Leclanché. It includes a zinc negative electrode, a manganese dioxide (MnO2) positive electrode, and an acidic electrolyte composed of ammonium chloride NH4CI) and zinc chloride (ZnCL2). The battery has an electromotive force of 1.5 V and has a wide range of applications. Later, the acidic electrolyte in the Leclanché battery was replaced by the KOH alkaline electrolyte and evolved into an alkaline battery, which has the same voltage as the Leclanché battery, but the capacity and discharge capacity have been improved. Later, new types of primary batteries appeared, such as zinc-air batteries (1.4 V) and silver oxide batteries (1.5 V). The performance of primary batteries was significantly improved in the 1970s when 3V lithium was used as the negative electrode of lithium metal. The primary battery has been commercialized.
The oldest rechargeable battery is a lead-acid battery invented in 1859 by the French physicist Planté. Lead-acid batteries use lead dioxide as the positive electrode, lead as the negative electrode, and sulfuric acid as the electrolyte. The electromotive force of a single battery is 2V, and it is commonly used as an energy storage battery for motor vehicles. NiCd (1.2 V) batteries became popular in 1984 and replaced primary batteries in small electrical appliances. However, due to the harmful effects of cadmium on the environment, NiCd batteries are not widely used today.
In the early 1990s, compared to NiCd batteries, NiMH (1.2 V) batteries were favored due to environmental protection and better performance. The 3V lithium rechargeable battery that followed closely has rapidly occupied the market of portable devices, including mobile phones, notebook computers, and video cameras, due to its significantly improved energy density, compact structure, and light weight.
The development of battery technology
After the Volta stack was invented in 1800, two important milestones appeared in the development history of battery technology for more than 200 years. One is the development of a primary battery to a secondary (rechargeable) battery, and the other is an increase in the operating voltage to 3V. Lithium rechargeable batteries use lithium ions as the main charge carrier, and can still maintain an average discharge voltage of up to 3.7 V under the premise of light weight. Lithium rechargeable batteries have the highest energy density among all practical batteries, leading the innovation of battery technology.
Reviewing the changes in energy density with the development of rechargeable battery technology, it can be found that the mass specific energy of lead-acid batteries is about 30 Wh/kg, the volume energy density is about 100 Wh/L, and the energy density of lithium-ion batteries is 10% per year. The growth rate has been improved. At present, the mass specific energy of cylindrical lithium rechargeable batteries is about 200 Wh/kg, and the volume energy density is about 600.Wh/L (as shown in the figure below). The mass specific energy of lithium-ion batteries is 5 times that of lead-acid batteries and NiMH batteries, respectively. And 3 times
As a kind of rechargeable battery, NiMH battery has limited operating voltage and energy density, but it is very popular in the application field of hybrid electric vehicle (HEV) because of its excellent stability. In recent years, the emergence of plug-in hybrid electric vehicles (PHEV) and electric vehicles (EV) has attracted more attention to lithium rechargeable batteries. Compared with NiMH batteries, lithium rechargeable batteries have higher energy output. Rechargeable batteries used in electric vehicles must be able to charge quickly, be light in weight, and have excellent performance. Therefore, future technological developments around lithium rechargeable batteries may have considerable competitiveness.