A lithium-ion battery is a battery that stores and releases charge through the repeated migration of lithium ions between positive and negative electrodes. It is a battery technology with high energy density, large capacity and long life, and is widely used in contemporary electronic equipment and transportation.
Lithium-ion batteries use the migration of lithium ions between positive and negative electrodes to store and release charge. During charging, lithium ions are released from the positive electrode material (such as lithium manganate) and migrate to the negative electrode material (such as graphite) through the electrolyte (usually an organic solution). During discharge, lithium ions migrate from the negative electrode to the positive electrode, conducting current through the electrolyte, thereby releasing energy.
Lithium-ion batteries have a series of advantages over traditional nickel-cadmium and nickel-metal hydride batteries. First, they have higher energy density, meaning they store more energy per unit volume or mass, which means lithium-ion batteries can provide longer use times and greater power output. In addition, lithium-ion batteries have a low self-discharge rate and can retain a charge for a longer period of time, even if they are not used for an extended period of time. Lithium-ion batteries also have a relatively long life, capable of hundreds of charge and discharge cycles and have no “memory effect.”
Regarding the “memory effect”, this concept originated from nickel-cadmium batteries. During the charge and discharge cycle of nickel-cadmium batteries, the positive and negative electrode materials will undergo gradual structural changes, resulting in local loss of electrode active agents. If subjected to frequent incomplete charge and discharge cycles, the battery will gradually “remember” the ability to release and store only part of the energy, thus reducing the range of available charge. However, lithium-ion batteries are not affected by this effect.
The reason lithium-ion batteries don’t have a memory effect is that they use different electrode materials. The negative electrode usually uses carbon materials (such as graphite), while the positive electrode uses oxides (such as lithium manganate, lithium cobalt oxide, lithium iron phosphate, etc.). During the charging and discharging process of lithium-ion batteries, the movement of lithium ions between these materials is based on their electrochemical reactions rather than structural changes. Therefore, lithium-ion batteries do not cause problems with electrode material deactivation, nor do they suffer from memory effects.
Of course, there are also some problems with lithium-ion batteries. The first is safety. Due to the high-energy-density chemical reactions inside lithium-ion batteries, safety accidents such as overheating and explosion are prone to occur if they are improperly designed or used. Secondly, the cost of lithium-ion batteries is relatively high, mainly because the raw materials required are expensive and the production equipment is complex. In addition, the performance of lithium-ion batteries will also decrease in high and low temperature environments.
Nonetheless, the advantages of lithium-ion batteries far outweigh the disadvantages, making them one of the most commonly used battery technologies in contemporary electronic devices and transportation. With the continuous advancement of technology, people are also conducting in-depth research on lithium-ion batteries, aiming to improve their energy density, reduce costs, enhance safety, etc., so as to better meet the needs of modern society for electric energy.
