"The more a lithium battery is discharged, the greater the battery's wear and tear will be," said Tom Hartley, an electrical engineering professor at Eyron University who helps NASA research on extending battery life. "The more fully a battery is charged, the greater the battery's wear and tear will be." It is best for lithium batteries to be in an intermediate state of charge; otherwise, their lifespan will be longer."

Firstly, both excessively high and low battery levels have an adverse effect on the lifespan of lithium batteries, while the number of charge and discharge cycles is secondary. In fact, the number of rechargeable times marked on most sold electrical appliances or batteries is based on a benchmark test of 80% discharge. Experiments show that for the lithium batteries of some laptops, if the battery voltage is frequently raised by 0.1 volts above the standard voltage, that is, from 4.1 volts to 4.2 volts, the battery life will be halved. If it is increased by another 0.1 volts, the life will be reduced to one-third of the original. A long-term state of low or no battery power will cause the resistance to the movement of electrons inside the battery to increase increasingly, thus resulting in a reduction in battery capacity. NASA has set the battery power consumption of its Hubble Space Telescope at 10% of the total capacity to ensure that the battery can be charged and discharged 100,000 times without the need for renewal.

Secondly, temperature also has a significant impact on the lifespan of lithium batteries (this point can be ignored for mobile phones and other small electronic devices). Environments below freezing point may cause lithium batteries to burn out the moment electronic products are turned on, while overheated environments will reduce the battery's capacity. Therefore, if a laptop is used with an external power source for a long time without removing the battery, the battery will be constantly exposed to the high heat emitted by the laptop. More importantly, if the battery remains at 100% charge for a long time, it will soon become unusable.

From the above, we can summarize the following points to note for ensuring the capacity and lifespan of lithium batteries:

At present, most electronic products use lithium batteries. Since the advent of lithium-ion batteries in 1990, their performance has developed rapidly and they have been widely applied in society. As a result, lithium battery manufacturers have also achieved large-scale development. There is no need to fully charge the lithium battery to 100%, and it is even more important not to drain the battery completely. When conditions permit, try to keep the battery's charge around half full, and the smaller the amplitude of charging and discharging, the better.
The factory design of the General Motors Chevy Volt electric vehicle is to force the battery power to be maintained at 20% to 80%, and the built-in batteries of Apple laptops (including some other laptops and electronic products) may also use this method to increase the number of charge-discharge cycles of the battery.

Do not operate lithium batteries (especially those for laptops) for a long time when the device is powered by an external power source. Even if your laptop has good heat dissipation, keeping it at 100% battery for a long time is equivalent to killing the lithium battery.

1. If you have been using an external power supply to power your laptop for a long time or the battery level has exceeded 80%, remove the battery of your laptop immediately. There is no need to fully charge the battery during normal charging; charging it to around 80% is sufficient. Adjust the power options of the operating system, set the battery alert to above 20%, and keep the battery level below 20% during normal times. Charge it before it drops to 20%.

2. For small electronic devices such as mobile phones, once fully charged, the power cord (including the USB port with charging function) should be disconnected immediately. Keeping it connected all the time can damage the battery. It should be charged frequently. Charge it whenever you remember, but you don't have to fully charge the battery.

3. Whether it's a laptop or a mobile phone, etc., never let the battery run out.

4. If you are going on a trip, fully charge the battery. But please remember to charge your appliances whenever conditions permit. For the sake of battery life, never wait until the battery is completely drained.