However, the way most people use lithium batteries still stays in the old wrong way of using Ni-MH-Ni-Cd batteries. In this paper, the correct use of the most widely used battery lithium battery is expounded in detail, and the number of people who have misunderstood it is sampled and counted, with emphasis on the correct methods of charging the lithium battery for mobile phones for the first three times.
Key words: introduction to the misunderstanding of over-discharge and over-charge of lithium battery without memory. Since the appearance of 1990, lithium-ion battery has developed rapidly because of its excellent performance and has been widely used in society. Lithium-ion batteries have rapidly occupied many fields with incomparable advantages over other batteries, such as well-known mobile phones, notebook computers, small cameras and so on. More and more countries have applied this kind of batteries to military purposes. The application shows that lithium ion battery is an ideal small green power supply.
Scientists often say that the advantages of lithium-ion batteries are for traditional nickel-cadmium batteries (ni/cd) and nickel-hydrogen batteries (ni/mh). It has the advantages of high working voltage, large specific energy, long cycle life, low self-discharge rate and no memory effect.
At present, the basic principle of lithium battery is the so-called "rocking chair theory". The charge and discharge of lithium batteries do not realize the transfer of electrons in the traditional way, but realize the energy change in childhood through the entry and exit of lithium ions in layered material crystals. Under normal charge and discharge conditions, the entry and exit of lithium ions will generally only cause the change of interlayer spacing, and will not cause the destruction of crystal structure. Therefore, from the charge and discharge reflection, lithium ion battery is an ideal reversible battery. When charging and discharging, lithium ion moves back and forth between the positive and negative poles of the battery, just like a rocking chair, so some people call lithium ion battery a rocking chair battery.
Misunderstanding of daily use of lithium batteries. For the "activation" of lithium batteries, there are many sayings: the charging time must exceed 12 hours, and it must be repeated three times before the battery can be activated. This statement that "the first three charges should last more than 12 hours" is obviously a continuation from the statement of nickel batteries (such as nickel cadmium and nickel hydrogen). So this statement can be said to have been misinformed from the beginning. After sampling survey, it can be seen that quite a few people have confused the charging methods of the two batteries.
The charging and discharging characteristics of lithium battery and nickel battery are quite different. All the serious and formal technical data I have consulted emphasize that overcharge and overdischarge will do great harm to lithium batteries, especially liquid lithium-ion batteries.
Therefore, it is best to charge in a standard time and manner, especially not more than 12 hours.
Usually, the charging method introduced in the mobile phone manual is the standard charging method suitable for this mobile phone.
In addition, the mobile phone or charger of lithium battery will automatically stop charging after the battery is fully charged, and there is no so-called "trickle charging" in which the nickel charger lasts 10 hour. in other words
If your lithium battery is fully charged, it is also charged in vain on the charger. None of us can guarantee that the characteristics of the battery charge and discharge protection circuit will never change and the quality will be foolproof.
So your battery will be in danger for a long time. This is another reason why children are opposed to long-term charging.
The experimental table of lithium ion battery charge and discharge cycle shows that the cycle life data are as follows:
Cycle life (10% DOD): 1000 times.
Cycle life (100% DOD): 200 times.
Where dod is the abbreviation of discharge depth. It can be seen from the table that the charging times are related to the depth of discharge, and the cycle life under 10% DOD is much longer than that under 100% DOD. of course
If converted into actual relative total capacity:10% *1000 =100, 100% * 200 = 200, the latter is better. However, the life of lithium batteries is mainly reflected in the charge-discharge cycle, which is an absolute concept. Last time, I used 30% electricity and was fully charged. Next time, I used 70% electricity and was fully charged. This is just a charging cycle. Therefore, we still use the slogan of the inventor of lithium battery "charging immediately means charging immediately".
Charging for a long time and completely discharging will lead to overcharge and overdischarge, which will cause permanent damage to the anode and cathode of lithium-ion batteries. From the molecular level, excessive discharge will lead to the release of too many lithium ions from negative carbon, which will lead to the collapse of its lamellar structure. Overcharging will force too many lithium ions into the negative carbon structure, some of which will never be released. This is why lithium-ion batteries are usually equipped with charge and discharge control circuits. Lithium-ion batteries are generally equipped with management chips and charging control chips. The management chip contains a series of registers, which are used to store the capacity, temperature, id, charging state and discharging time. These values will change gradually during use. The main function of "charging and discharging once a month" in the instruction manual should be to correct the improper values in these registers. So that the charging control and the nominal capacity of the battery conform to the actual situation of the battery. The power statistics chip can sample and calculate the power of the battery, that is, wh, by recording the discharge curve (voltage, current and time). The value that scientists read in the battery information. However, the discharge curve of lithium-ion battery will change after repeated use. If the chip has never had a chance to read a complete discharge curve again, the calculated power will be inaccurate. Therefore, scientists need deep charge and discharge to calibrate the battery.
The correct method of charging lithium battery for the first three times and matters needing attention in daily use.
During the first three times of charging, it is completely unnecessary to charge the battery for a very long time, such as 12 hour to activate the battery. The charging circuit is already protected, so it's no use plugging it in.
In the process of frequent use, complete discharge (power failure until black screen is used) should be avoided.
After being unused for a long time, or frequently charged and discharged for a period of time, the method is to charge once, and then the battery can be charged and discharged immediately, and it needs to be charged and discharged again for recalibration after being used for a long time.
If the battery is not used for a long time, it is recommended to charge it to 40% before placing it to protect the battery.
Finally, the life of lithium battery is mainly reflected in the charge and discharge cycle, which is an absolute concept. The last time it was fully charged with 30% electricity, the next time it was fully charged with 70% electricity, which happened to be a charging cycle.
Shi Siqi, Ouyang Chuying, Wang Zhaoxiang. Physical problems in lithium-ion batteries and their research progress [j]. Physics, 2004
Xiang (Liu) Hu Guorong (Hu) Xiaoyu
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