Lithium-ion batteries are a type of battery that uses lithium metal or lithium alloys as the negative electrode material and employs a non-aqueous electrolyte solution. Due to the highly reactive chemical properties of lithium metal, its processing, storage, and application require stringent environmental conditions. With the advancement of science and technology, lithium-ion batteries have become the mainstream technology.
Precautions for using lithium-ion batteries
1. Avoid using the battery in harsh conditions, such as high temperature, high humidity, or prolonged exposure to direct sunlight in summer. Also, avoid throwing the battery into fire.
2. When removing the battery, ensure that the electrical appliance is powered off; the operating temperature should be maintained between -20 and 50°C.
3. Avoid storing batteries in electrical appliances that are not in use for extended periods of time.
How to use lithium-ion batteries
1. How to charge a new battery
It's important to note that lithium batteries enter a dormant state after being stored for a period of time, at which point their capacity is lower than normal, and their usage time is shortened. However, lithium batteries are easily activated; just 3-5 normal charge-discharge cycles are sufficient to activate the battery and restore its normal capacity. Due to the inherent characteristics of lithium batteries, they have virtually no memory effect. Therefore, no special methods or equipment are required to activate a new lithium battery in a user's mobile phone.
Regarding the "activation" of lithium batteries, many people believe that charging time must exceed 12 hours, repeated three times, to activate the battery. This claim of "charging for more than 12 hours for the first three times" is clearly a continuation of the practice with nickel batteries (such as nickel-cadmium and nickel-metal hydride). Therefore, this claim is fundamentally a misconception. Lithium batteries and nickel batteries have very different charging and discharging characteristics, and I can assure you that all the serious, official technical documents I have consulted emphasize that overcharging and over-discharging can cause significant damage to lithium batteries, especially liquid lithium-ion batteries. Therefore, it is best to charge according to the standard time and method, and especially avoid excessively long charging times exceeding 12 hours (just until the charger indicates a full charge).
Furthermore, lithium batteries and chargers automatically stop charging once the battery is fully charged; there is no "trickle" charging for 10+ hours as claimed by nickel-cadmium chargers. In other words, leaving your lithium battery on the charger after it's fully charged is pointless. And since no one can guarantee that the battery's charge/discharge protection circuitry will never change or that its quality will be flawless, your battery will be constantly teetering on the edge of danger. This is another reason why we oppose prolonged charging.
In addition, another aspect that cannot be ignored is that lithium batteries are also not suitable for over-discharge, as over-discharge is also very detrimental to lithium batteries.
2. When should charging begin during normal use?
It's common to see the claim that because the number of charge-discharge cycles is limited, phone batteries should be completely drained before recharging. However, the lifespan of lithium batteries is unrelated to this. Below is an example of an experimental table regarding lithium-ion battery charge-discharge cycles, with data on cycle life listed below:
Cycle life (50% DOD) > 1000 cycles
Cycle life (100% DOD) > 500 cycles
DOD stands for Depth of Discharge. As the table shows, the number of rechargeable cycles is related to the depth of discharge; the cycle life at 10% DOD is much longer than at 100% DOD. However, if we consider the relative total capacity of actual charging: 10% * 1000 = 100, 100% * 200 = 200, the latter's complete charge-discharge is still better. But the previous comment needs some correction: Under normal circumstances, you should recharge according to the principle of using up the remaining battery power before recharging. However, if you anticipate that your battery won't last the entire day the next day, you should start charging it promptly. Of course, if you're willing to carry a charger to the office, that's another matter.
The principle of fully discharging the battery before recharging doesn't mean going to extremes. A widely circulated saying, similar to prolonged charging, is "try to use up the battery completely." This practice is actually only used with nickel-cadmium batteries to avoid the memory effect, but unfortunately, it also applies to lithium-ion batteries. There have been cases where people continued using their phones after receiving low battery warnings, until the phones automatically shut down. In this example, the phones became unresponsive to charging and turning on, requiring repair. This was because the battery voltage was too low due to over-discharge, making it unable to charge or power on properly.
Do not overcharge or completely drain your mobile phone's lithium-ion battery. Charging before the battery is fully discharged will not damage it. Charging for 2-3 hours or less is ideal; it doesn't necessarily have to be fully charged. However, every 3-4 months, you should fully charge and fully discharge the lithium battery 1-2 times (normal charging time).
Lithium batteries that are not used for a long time should be stored in a cool, dry place, ideally at half charge (70-80% of full charge; for example, if your phone shows 4 bars when fully charged, then 3 bars is sufficient). Storing them fully charged is dangerous and can damage the battery, while storing them without charge will destroy the battery. Check the battery every 3-6 months to see if it needs to be recharged.
Lithium-ion batteries can be classified into liquid lithium-ion batteries and polymer lithium-ion batteries based on their electrolyte. The electrolyte in polymer lithium-ion batteries is a gel that does not flow, so there is no leakage problem, making them safer.
