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Lithium Battery" is a kind of battery which is made of lithium metal or lithium alloy as negative electrode material and uses non-aqueous electrolyte solution. Lithium metal batteries were first proposed and studied by GilbertN.Lewis in 1912. In the 1970s, M.S.Whittingham proposed and began to study lithium-ion batteries. Because of the very active chemical properties of lithium metal, the processing, preservation and use of lithium metal require very high environmental requirements. Therefore, lithium battery has not been used for a long time. With the development of science and technology, lithium battery has become the mainstream.
Lithium batteries can be divided into two categories: lithium metal batteries and lithium ion batteries. Lithium-ion batteries do not contain metallic lithium and are rechargeable. Lithium metal battery, the fifth generation of rechargeable battery, was born in 1996. Its safety, specific capacity, self-discharge rate and performance-price ratio are better than lithium-ion battery. Due to their own high-tech requirements, only a few companies in a few countries are now producing the lithium-metal battery.
Battery life
Lithium ion batteries can only be charged and discharged 500 times?
I believe the vast majority of consumers have heard that the life of lithium batteries is "500 times", 500 times of charge and discharge, more than this number, the battery will "die". In order to prolong the life of the battery, many friends charge each time when the battery is completely exhausted. Does this really extend the life of the battery? The answer is no. The life of a lithium battery is "500 times", which refers not to the number of charges, but to a charge-discharge cycle.
A charging cycle means that the process of charging all the battery from full to empty and then from empty to full is not the same as charging once. For example, a piece of lithium electricity uses only half of the electricity on the first day, and then fills it with electricity. If this is the case the next day, it will be charged in half and charged twice in all, which can only be counted as one charging cycle, not two. As a result, it may usually take several charges to complete a cycle. For each charging cycle, the battery capacity is reduced a little. However, this power reduction is very small, high-quality batteries after multiple cycles, will still retain 80% of the original capacity, many lithium-powered products will still be used as usual after two or three years. Of course, lithium life still needs to be replaced after the end of the life.
And the so-called 500 times, refers to the manufacturer in a constant discharge depth (such as 80%) to achieve about 625 rechargeable times, up to 500 charging cycles.
(80% ≤ 625 ≤ 500) (neglecting factors such as reduced capacity of lithium batteries)
However, due to the various effects of real life, especially the discharge depth is not constant, so "500 charging cycle" can only be used as a reference battery life.
It is correct to say that the life of lithium is related to the number of times of charging cycle, but not directly related to the number of charges.
Simply understand, for example, that a piece of lithium electricity uses only half of the electricity on the first day, and then fills it with electricity. If this is the case the next day, it will be charged in half and charged twice in all, which can only be counted as one charging cycle, not two. As a result, it may usually take several charges to complete a cycle. For each charging cycle, the amount of electricity is reduced a little. However, the reduction is very small. High-quality batteries will still retain 80% of their original electricity after multiple cycles. That is why many lithium-powered products will still be used as usual after two or three years. Of course, lithium life needs to be replaced at the end of the day.
The life life of lithium electricity is generally 300 × 500 charging cycles. Assuming that the amount of electricity provided by a complete discharge is Q, if the reduction of electricity after each charging cycle is not taken into account, lithium electricity can provide or supplement 300Q-500Q power in total during its life. From this, we know that if you use 1 / 2 at a time, you can charge 600-1000 times; if you use 1 / 3 at a time, you can charge 900 times. And so on, if you charge at random, the number of times is uncertain. In short, no matter how much is charged, the total amount of electricity added to the 300Q~500Q is constant. Therefore, we can also understand that the life of lithium battery is related to the total charge of the battery, but not to the number of charges. There is no significant difference between deep discharge and shallow discharge on lithium life.
In fact, shallow charging is more beneficial to lithium electricity, only when the power module of the product is on time for lithium electricity, there is a need for deep charging. Therefore, the use of lithium power supply products do not have to stick to the process, everything to facilitate first, charging at any time, do not have to worry about affecting life.If lithium electricity is used above the specified operating temperature, that is, more than 35 °C, the battery will continue to reduce its power supply, that is, the battery will not be supplied for as long as usual. If the device is charged at this temperature, the damage to the battery will be even greater. Even if the battery is stored in a hotter environment, it will inevitably cause corresponding damage to the quality of the battery. Therefore, it is a good way to prolong the life of lithium as much as possible to keep it at a beneficial operating temperature.
If lithium electricity is used in low temperature environment, that is, below 4 °C, it will also be found that the battery life is reduced, and the original lithium electricity of some mobile phones can not even be charged at low temperature. But don't worry too much, this is only a temporary condition, unlike the use of high temperature environment, once the temperature rises, the molecules in the battery are heated, immediately return to the previous electricity.
To maximize the efficiency of lithium-ion batteries, it needs to be used frequently to keep electrons in lithium batteries flowing all the time. If lithium electricity is not often used, please remember to complete a charging cycle for lithium electricity every month, and do electricity calibration once, that is, once deep discharge.
Interpretation of the provisions of the national standard:
a. This definition specifies that the test of cycle life is carried out in a deep and deep way.
b. According to this model, the cycle life of lithium battery is still more than 60% after ≥ 300 cycles.
However, the number of cycles obtained by different cycle systems is very different, for example, the above other conditions remain unchanged, only changing the constant voltage voltage of 4.2 V to the constant voltage voltage of 4.1 V to test the cycle life of the same type of battery, so that the battery is no longer a deep charging mode, and the number of cycle life can be increased by nearly 60%. Then if the cutoff voltage is increased to 3.9V for testing, the number of cycles should be increased several times.
This statement of cyclic charge and discharge is less than one life, we should note that the definition of lithium battery charging cycle: a charging cycle refers to the lithium battery from full to empty, and then from empty to full process. And that's not the same as charging once. In addition, when you talk about the number of cycles, you can't ignore the conditions of the cycle. It makes no sense to put aside the rules to talk about the number of cycles, because the number of cycles is a means of testing battery life, not an end!
Langrui Energy (Shenzhen) Co.,Ltd
