Views: 288 Author: Site Editor Publish Time: 2023-04-10 Origin: Site
A "lithium-ion battery" is a type of battery that uses lithium metal or lithium alloy as the negative electrode material and a non-aqueous electrolyte solution. The lithium metal battery was first proposed and studied by Gilbert N. Lewis in 1912. In the 1970s, M.S. Whittingham proposed and began research on lithium-ion batteries. Due to the highly reactive nature of lithium metal, processing, storage, and use of lithium metal require strict environmental requirements. Therefore, lithium batteries were not widely used for a long time. With the development of science and technology, lithium-ion batteries have now become mainstream.
Most consumers have heard that the lifespan of a lithium-ion battery is "500 cycles," meaning that after 500 charge-discharge cycles, the battery will no longer function properly. Many people try to extend the life of their batteries by waiting until they are fully depleted before recharging them, but this does not actually help prolong the lifespan of the battery. The lifespan of a lithium-ion battery refers to one charge-discharge cycle rather than just the number of times it has been charged.
One charging cycle refers to the process of using up all the battery's power from full to empty and then recharging it from empty to full, which is not equivalent to a single charge. For example, if a lithium-ion battery is only half used on the first day and then fully charged, and the same thing happens on the second day, i.e. it is charged after being half used, this counts as one charging cycle instead of two. Therefore, it may take several charging cycles to complete one cycle. Each completed charging cycle will slightly reduce the battery capacity. However, this reduction is very small, and high-quality batteries can still retain 80% of their original capacity after many cycles. Many lithium-ion powered products can still function normally after two or three years of use. Of course, lithium-ion batteries still need to be replaced when their lifespan ends.
The term "500 times" refers to the approximately 625 recharge cycles achieved by manufacturers at a constant discharge depth (such as 80%), which equals 500 charging cycles (80% * 625 = 500) (ignoring factors such as decreased battery capacity). The correct statement is that lithium-ion battery life is related to the number of completed charging cycles rather than directly related to the number of charges.
Therefore, due to various real-life factors, especially the fact that discharge depth during charging is not constant, "500 charging cycles" can only serve as a reference for battery life expectancy.