Modern society is closely linked to electricity. To obtain electrical energy, humans utilize various energy forms, including fossil fuels, hydropower, wind power, solar energy, chemical energy, and nuclear energy, converting this energy into electrical energy for use. Among these, devices that can directly convert the energy produced by chemical reactions into electrical energy are called chemical power sources (commonly referred to as batteries).
The development of chemical power sources can be traced back to the 18th century. In 1786, Italian biologist Garvani first observed the contraction of frog leg muscles during a frog dissection experiment and named it bioelectricity. Subsequently, in 1800, another Italian scientist, Volta, based on Garvani's research, proposed a new theory: he believed that the twitching of frog legs was caused by the current generated by the contact of different metals. Based on this hypothesis, Volta stacked zinc and copper sheets alternately and separated them with leather soaked in salt water, thus creating the world's first true chemical power source, the famous Voltaic pile, as shown in Figure 1-3. In 1836, British inventor Daniel improved Volta's design and developed the more practical Daniell battery. Since then, battery technology has entered a period of rapid development, with a series of new batteries such as lead-acid batteries, zinc-manganese batteries, and cadmium-nickel batteries emerging one after another. Since the beginning of the 20th century, with advancements in technology, various advanced battery products have been developed, including zinc-silver batteries, iron-nickel batteries, nickel-metal hydride batteries, lithium metal batteries, lithium-ion batteries, and fuel cells. These innovations are now widely used in various fields of modern society.
Currently, there are many types of batteries on the market, and their classification methods differ. Based on the type of electrolyte used, they can be divided into several categories: those using acidic aqueous solutions as electrolytes are called acidic batteries; those using alkaline aqueous solutions are called alkaline batteries; those using neutral aqueous solutions are called neutral batteries; and batteries that utilize organic electrolyte solutions are called organic electrolyte solution batteries. In addition, there are solid-state electrolyte batteries designed based on solid electrolytes; and batteries using molten salts as electrolytes are called molten salt electrolyte batteries.
More commonly, batteries are classified based on their operating characteristics and energy storage mechanisms, typically falling into four main categories：
Primary batteries
(1) Primary batteries, also known as galvanic cells, refer to a type of battery that cannot be restored to its initial state after discharge by recharging. This means that such batteries can only be used once. The reason primary batteries are non-rechargeable is that their internal chemical reactions are inherently irreversible, or even if theoretically reversible, achieving a reversible reaction under practical conditions is extremely difficult. Zinc-manganese batteries and lithium manganese dioxide batteries are two common examples of primary batteries.
Secondary batteries
(2) Secondary batteries, also known as storage batteries, are batteries that can restore their internal active materials to their pre-discharge state through recharging after discharge, thus enabling cyclic use. These batteries are widely used in daily life and industrial production. Representative secondary batteries include lead-acid batteries, nickel-metal hydride batteries, and lithium-ion batteries.
Storage batteries
(3) Storage batteries, also known as activated batteries, are characterized by the electrolyte and electrode active materials remaining separated during storage, or the electrolyte being in an inactive state. They only begin to operate when needed, after being activated by injecting electrolyte or other means. Because the positive and negative electrode active materials do not spontaneously discharge during storage, these batteries are ideal for long-term preservation. Zinc-silver batteries and magnesium-copper chloride batteries are two common types of storage batteries.
Fuel cells
(4) Fuel cells, also known as continuous batteries, have inactive electrode materials that serve as platforms for electrochemical reactions. The active materials required for the positive and negative electrodes are stored externally and continuously supplied to the battery during operation, thus providing continuous power. Fuel cells mainly include proton exchange membrane fuel cells and alkaline fuel cells.
Compared to other types of energy, chemical power sources are renowned for their high energy conversion efficiency, ease of operation, high safety, ease of miniaturization, and environmental friendliness. These characteristics make batteries indispensable in daily life and industrial production. The development of energy storage batteries is inseparable from overall social progress and technological innovation; simultaneously, the development of battery technology also promotes further exploration and development in the production and scientific fields.
Therefore, the field of energy storage batteries still has broad development prospects for a long time to come.