Lithium-ion battery charging principle
The generally accepted fundamental principle of lithium-ion batteries is the so-called rocking chair theory. The charging and discharging of lithium-ion batteries does not involve the transfer of electrons through traditional methods, but rather through the movement of lithium ions in and out of the crystal structure of layered materials, resulting in energy changes. Under normal charging and discharging conditions, the movement of lithium ions generally only causes changes in the interlayer spacing and does not damage the crystal structure. Therefore, from the perspective of charging and discharging, lithium-ion batteries are ideal reversible batteries. During charging and discharging, lithium ions move back and forth between the positive and negative electrodes, much like a rocking chair, hence the nickname "rocking chair battery."
The advantages of lithium-ion batteries that we often talk about are in comparison to traditional nickel-cadmium (Ni/Cd) and nickel-metal hydride (Ni/MH) batteries. They have advantages such as high operating voltage, high specific energy, long cycle life, low self-discharge rate, and no memory effect.
The discharge current should not be too high, as excessive current will cause the battery to overheat, potentially resulting in permanent damage.
Over-discharge is absolutely prohibited. Lithium-ion batteries are most vulnerable to over-discharge. If the discharge voltage drops below 2.7V, the battery may become unusable.
routine maintenance of lithium-ion batteries
Lithium-ion batteries have very low self-discharge and can generally be stored for up to 3 years. Storing them under refrigeration will further improve their performance. Keeping lithium-ion batteries in a low-temperature environment is a good method. Lithium-ion batteries can be stored for more than six months at 20°C because of their low self-discharge rate and the fact that most of their capacity can be recovered. However, the self-discharge phenomenon inherent in lithium-ion batteries means that if the battery voltage is stored below 3.6V for an extended period, it can lead to over-discharge, damaging the internal structure of the battery and reducing its lifespan.
Therefore, lithium-ion batteries intended for long-term storage should be recharged every 3-6 months, ideally to a voltage of 3.8-3.9V (the optimal storage voltage for lithium-ion batteries is around 3.85V). They should not be fully charged. Lithium-ion batteries have a wide operating temperature range; they can still be used outdoors in northern winters, although their capacity will be significantly reduced. However, the capacity can recover once the battery returns to room temperature, as the temperature significantly affects their performance.
