Correct lithium battery usage rules

In digital devices, batteries play an important role in both technical and price considerations. Today, the market is selling digital devices, and the battery used has basically completed the transition from a nickel battery to a lithium battery. Perhaps because some Walkman batteries have just completed a revolution from nickel battery to lithium battery, people do not have a uniform understanding of lithium battery. In many cases, incorrect statements and practices are quite popular. Therefore, it is necessary to know a little about lithium battery and the correct use of lithium battery.
　
I. lithium battery types:
Currently, the secondary batteries used in the market mainly include Ni-Mh and Li-ion. Lithium-ion batteries are already in mass production, including liquid lithium-ion battery (LIB) and Polymer lithium-ion battery (LIP. Therefore, in many cases, Li-ion must be a lithium-ion battery. But it may not be a liquid lithium-ion battery, or a polymer lithium-ion battery.
Lithium-ion battery is an improved product of lithium battery. A lithium battery has been available for a long time, But lithium is highly active (remember its position in the periodic table of elements ?) The metal, which is not safe to use, often burns and bursts during charging, and then has an improved lithium-ion battery, the addition of components that can inhibit active lithium elements (such as cobalt and manganese) makes lithium battery safe, efficient, and convenient, and the old lithium battery is basically eliminated. As for how to distinguish them, it can be identified from the battery mark, lithium battery is Li, lithium ion battery is Li-ion. Now, the so-called "lithium batteries" used in laptops and mobile phones are actually lithium-ion batteries.
The basic structure of modern battery includes three elements: positive electrode, negative electrode and electrolyte. As a type of battery, lithium-ion battery also has these three elements. Generally, lithium-ion technology uses liquid or inorganic colloidal electrolyte. Therefore, a solid shell is required to accommodate combustible active ingredients, which increases the weight and cost of the battery, it also limits the size and shape flexibility. Generally, the minimum thickness of a liquid lithium-ion battery is 6mm, which is difficult to reduce.
The so-called Polymer lithium-ion battery is at least one or more of the three main structures using polymer materials as their main battery systems.
A new generation of Polymer lithium-ion battery has a high degree of polymer, so the shape can be thin (the shortest 0.5mm), any area and any shape, it greatly improves the flexibility of the battery design, and can meet product requirements to form a battery with any shape and capacity. At the same time, the unit energy of Polymer lithium-ion batteries is 50% higher than that of ordinary lithium-ion batteries, its capacity, charging and discharging characteristics, safety, operating temperature range, cycle life and environmental performance are greatly improved compared with lithium-ion battery.
At present, the liquid lithium-ion (LIB) battery sold on the market is very dangerous in the case of over-charging, which may easily cause the relief valve to break down and thus cause fire, therefore, protection IC lines must be installed to prevent excessive battery. In terms of Polymer lithium-ion battery, this type of battery has better charge and discharge resistance compared with liquid lithium-ion battery. Therefore, the requirements for external protection of IC lines can be relaxed. In addition, in terms of charging, polymer lithium-ion battery can be charged by using IC Fixed Current, compared with the cccv (constant currert-constant voltage) charging method used by lithium-ion battery, it can shorten the waiting time.
　
On the other hand, although the lithium-ion battery has many advantages, it also has defects, such as high price and low charge/discharge frequency. The lithium battery charge and discharge frequency is only 800-, and the number of improved products is only. However, Ni-MH batteries can charge more than 700 times, and some high-quality products can charge and discharge up to 1200 times. In this way, Ni-MH batteries have a longer life than lithium batteries. In addition, the price of Ni-MH batteries is much lower than that of lithium batteries. Strictly speaking, lithium battery also has a memory effect, but its memory effect is very low, which is negligible.
From this point of view, there is no perfect battery.
　
Ii. Use of lithium-ion battery
This part is the focus of this Article. We will discuss it in three points.
1. How to charge a new battery
When using a lithium battery, it should be noted that the battery enters sleep state after being placed for a period of time, the capacity is lower than the normal value, and the use time is shortened. However, the lithium battery can be easily activated, and the battery can be activated after 3-5 normal charging and discharging cycles to restore the normal capacity. Because of its own characteristics, the lithium battery has almost no memory effect. Therefore, the user's new lithium battery does not need special methods and devices during the activation process. Not only in theory, but in my own practice, the "natural activation" method of charging with the standard method was the best from the very beginning.
Many sayings about the "activation" problem of lithium battery are that the charging time must be over 12 hours, and the battery must be retried three times to activate the battery. This "charge for the first three times is charged for more than 12 hours" is obviously a continuation of the statement from the nickel battery (such as nickel-cadmium and nickel-Mh. Therefore, it can be said that it was a false positive at the beginning. The charging and discharging characteristics of lithium battery and nickel battery are very different, and can be clearly told to everyone, all the serious official technical materials I have read have emphasized that charge and discharge can cause great damage to lithium batteries, especially liquid lithium-ion batteries. Therefore, it is best to charge according to the standard time and standard method, especially do not charge over 12 hours. Generally, the charging method described in the product manual is the standard charging method suitable for the product.
In addition, the charger of the lithium battery will automatically stop charging after the battery is full, there is no nickel charger called for a 10-Hour "streaming" charge. That is to say, if your lithium battery is fully filled, it is also a white charger. No one of us can guarantee that the battery charging and discharging protection circuit features will never change and the quality will be safe, so your battery will be on the verge of danger for a long time. This is another reason for us to oppose long charging.
In addition, if you do not remove the charger after charging for a certain period of time, the system will not only stop charging, but also start discharge-charging cycle. The vendor may have its own purpose, but it is obviously unfavorable for the lifetime of battery and cell phone/charger. At the same time, long Charging takes a long time and often needs to be carried out at night. However, in the case of China's power grid, the voltage at night is high in many places, and the voltage fluctuates greatly. As we have already said before, lithium battery is very delicate. It is much inferior to the ability of nickel power to withstand fluctuations in charge and discharge, which brings additional risks.
In addition, the lithium battery is not suitable for overdischarge, And the overdischarge is also very unfavorable to the lithium battery. This raises the following question.
2. When should I start charging normally?
This is often seen in our forum. because the number of charge and discharge operations is limited, the battery power should be used up and recharged as much as possible. However, I found an experiment table on lithium-ion battery charging and discharging cycles. The following figure shows the cycle life data:
Cycle Life (10% DOD):> 1000 times
Cycle Life (100% DOD):> 200 times
DOD is the abbreviation of discharge depth. As can be seen from the table, the number of recharges is related to the discharge depth. The cycle life of 10% DOD is much longer than that of 100% DOD. Of course, if it is equivalent to the actual total charge capacity: 10% * 1000 = 100,100% * 200 = 200, it is better to fully charge and discharge the latter.
However, you need to charge your resources in advance to cope with the predicted upcoming busy use of digital devices, even if there is still a lot of power remaining in the battery, because you have not really lost the "1" charge cycle life, that is, "0. X times, and often this X is very small.
The principle of remaining battery power usage and re-charging does not require you to go to the extreme. A widely spread saying like long charging is that "it is best to use up battery power as much as possible and use automatic shutdown ". This is actually just a nickel battery method, the purpose is to avoid the memory effect, unfortunately it also spread on the lithium battery. There was a warning that the battery of the MD lithium battery was too low and the battery was still not charged. Results In this example, the battery did not respond in the subsequent charging and startup, and had to send the battery to customer service for repair. This is because the battery voltage is too low due to excessive discharge, so that it does not have normal charging and boot conditions.
3. correct practices for lithium batteries
To sum up, my most important tips for lithium battery charging and discharging problems in use are:
1. charge according to the standard time and procedures, even the first three times;
2. When the power usage is too low, you should start charging as soon as possible;
3. Lithium Battery activation does not require special methods. In normal use, lithium battery will be activated naturally. If you insist on using the "first three 12 hours long charge activation" method, it will not actually work.
Therefore, all the 12-hour ultra-long charging and the use of lithium batteries for automatic power-off are wrong. If you used to follow the incorrect statement, please correct it in time. It may not be too late.
Of course, the protection for lithium batteries is quite guaranteed when the charger's own protection and control circuit are of good quality. Therefore, the understanding of charging rules is the focus, and some concessions can be made in some cases. For example, if you find that you have to charge before going to bed at night, you can also charge before going to bed. The key to the problem is that you should know what the correct approach is and do not deliberately follow the wrong statement. The biggest characteristic of lithium battery is higher than energy. What is Bi power? The specific energy refers to the energy of a unit of weight or a unit of volume. The specific energy is expressed by Wh/kg or WH/L. Wh is the unit of energy, W is the tile, H is the hour, KG is the kg (weight unit), L is the litre (volume unit ). For example, if The rated voltage of the nickel-cadmium battery is 1.2 V and its capacity is 800 Mah, the energy of the battery is 0.96wh (12 V × 08ah ). The rated voltage of the same size of Lithium-manganese dioxide battery is 3 V, and its capacity is 1200 Mah, the energy is 3.6wh. If the two batteries have the same volume, the ratio of Lithium-manganese dioxide battery to energy is 3.75 times that of nickel-cadmium battery! Published in: http://www.360doc.com/content/10/0926/00/2487067_56409876.shtml