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How long is the life of a lithium battery?

scanning:110 author: from: time:2019-08-06 classify:Company news
Lithium batteries have a service life of only two to three years. Lithium batteries are generally capable of charging and discharging 300-500 times. It is best to partially discharge the lithium battery instead of completely discharging it, and try to avoid frequent full discharges. Once the battery is off the production line, the clock begins to move. Lithium batteries last for only two to three years, whether you use them or not.

Lithium batteries have a service life of only two to three years.


Lithium batteries are generally capable of charging and discharging 300-500 times. It is best to partially discharge the lithium battery instead of completely discharging it, and try to avoid frequent full discharges. Once the battery is off the production line, the clock begins to move. Lithium batteries last for only two to three years, whether you use them or not.


A "lithium battery" is a type of battery using a lithium metal or a lithium alloy as a negative electrode material and using a nonaqueous electrolyte solution. Lithium metal batteries were first proposed and studied by Gilbert N. Lewis in 1912. In the 1970s, M.S. Whittingham proposed and began researching lithium-ion batteries. Due to the very active chemical properties of lithium metal, the processing, storage and use of lithium metal are very demanding on the environment. Therefore, lithium batteries have not been used for a long time. With the development of science and technology, lithium batteries have become the mainstream.


Lithium batteries can be roughly divided into two categories: lithium metal batteries and lithium ion batteries. Lithium-ion batteries do not contain metallic lithium and are rechargeable. The fifth-generation lithium-metal battery of rechargeable batteries was born in 1996, and its safety, specific capacity, self-discharge rate and performance price ratio are better than lithium-ion batteries. Due to its own high technical requirements, only a few companies in the country are producing such lithium metal batteries.


Use of lithium ion batteries


This part is the focus of this article, we will talk about it in three points.


1. How to charge a new battery


In the use of lithium batteries, it should be noted that after the battery is placed for a period of time, it enters a sleep state. At this time, the capacity is lower than the normal value, and the use time is also shortened. However, the lithium battery is easy to activate, as long as it is 3-5 times normal charging and discharging.


The battery cycle activates the battery and restores normal capacity. Due to the characteristics of the lithium battery itself, it is determined that it has almost no memory effect. Therefore, the new lithium battery in the user's mobile phone does not require special methods and equipment during the activation process. Not only in theory, but from my own practice, it is best to use a standard method of charging this "natural activation" method from the beginning.


For the "activation" problem of lithium batteries, many sayings are: charging time must be more than 12 hours, repeated three times in order to activate the battery. This statement that "the first three charges should be charged for more than 12 hours" is obviously a continuation of the nickel battery (such as nickel cadmium and nickel hydrogen). So this kind of statement can be said to be misinformation at the beginning. The charge and discharge characteristics of lithium batteries and nickel batteries are very different, and it is very clear to tell you that all the serious formal technical information I have reviewed emphasizes that overcharge and overdischarge will make lithium batteries, especially liquid lithium. Ion batteries cause great damage. Therefore, charging is preferably performed in accordance with standard time and standard methods, especially for ultra-long charging of more than 12 hours. Usually, the charging method described in the mobile phone manual is a standard charging method suitable for the mobile phone.


In addition, the lithium battery phone or charger will automatically stop charging when the battery is full, there is no so-called "turbulent" charging of the nickel battery charger for 10 hours. In other words, if your lithium battery is full, it will be white charger on the charger. And none of us can guarantee that the characteristics of the battery's charge and discharge protection circuit will never change and the quality will be foolproof, so your battery will be on the edge of danger for a long time. This is another reason why we oppose long charging.


In addition, on some mobile phones, after charging for more than a certain period of time, if you do not remove the charger, then the system will not stop charging, and will start the discharge-charge cycle. Perhaps the manufacturer of this approach has its own purpose, but it is clearly unfavorable for the life of the battery and the phone/charger. At the same time, long charging takes a long time and often needs to be carried out at night. In the case of China's power grid, the voltage at night is high in many places and fluctuates greatly. As mentioned above, the lithium battery is very delicate, it is much less resistant to fluctuations in charge and discharge than nickel, and this brings additional danger.


In addition, another aspect that cannot be ignored is that lithium batteries are also not suitable for over-discharge, and over-discharge is also disadvantageous for lithium batteries. This leads to the following problem.


2. When should I start charging during normal use?


This statement can often be seen in our forums, because the number of charge and discharge cycles is limited, so the battery of the mobile phone should be recharged as much as possible. But I found an experimental table on the charge and discharge cycle of lithium-ion batteries. The data on cycle life are listed below:


Cycle life (10% DOD): >1000 times


Cycle life (100% DOD): >200 times


Among them, DOD is the abbreviation of depth of discharge. As can be seen from the table, the number of chargeables is related to the depth of discharge, and the cycle life at 10% DOD is much longer than that of 100% DOD. Of course, if you convert to the relative total capacity of the actual charge: 10% * 1000 = 100, 100% * 200 = 200, the latter's full charge and discharge is still better, but the former netizen's statement to do some correction: in normal In this case, you should reserve the charge according to the principle that the remaining battery power is used up and recharge, but if your battery is not likely to stick to the whole day on the 2nd day, you should start charging in time. Of course, if you are willing to carry it back It’s a different matter to get the charger to the office.


And you need to charge to cope with the expected important events that will cause the communication to be busy, even if the battery still has a lot of power, then you only charge in advance, because you have not really lost "1" charge cycle life. That is, "0.x" times, and often this x will be small.


The principle that the remaining battery power is used up and refilled is not to go to extremes. One of the more widely spread sayings like long charging is that "try to use up the battery power of the mobile phone, it is best to use automatic shutdown." This practice is actually only a nickel battery, the purpose is to avoid memory effects, unfortunately it is also circulating on lithium batteries. Some people have used the example of automatic shutdown since they have been warning that the mobile phone battery is too low. As a result, the mobile phone in this example did not respond during the subsequent charging and booting, and had to be sent to the customer service for repair. This is actually caused by the battery being over-discharged and the voltage is too low, so that it does not have normal charging and power-on conditions.


3, the correct practice for lithium battery mobile phones


To sum up, my most important tips on the charging and discharging problems of lithium battery mobile phones in use are:


1. Charge according to standard time and procedures, even if it is the first three times;


2. When there is a low battery power prompt, you should start charging as soon as possible;


3. The activation of the lithium battery does not require a special method. The lithium battery will naturally activate during normal use of the mobile phone. If you insist on using the "first three 12-hour long charge activation" method that is circulated, it will not actually work.


Therefore, all the pursuit of 12 hours of ultra-long charging and the use of lithium battery mobile phones to automatically shut down are wrong. If you have done it in the wrong way, please correct it in time, maybe it is not too late.


Of course, in the case of good quality of the mobile phone and charger protection and control circuit, the protection of the lithium battery is quite guaranteed. So the understanding of the charging rules is the key point, and in some cases it is also possible to make some concessions. For example, if you find that the phone must be charged before you go to sleep at night, you can also start charging before going to bed. The point is that you should know what the right approach is and don't deliberately follow the wrong way.


For ease of reading, the subheadings are listed below:


1. Understanding memory effects


2. Does the battery need to be activated?


3. Do you have to charge for 12 hours in the first three times?


4. Is the rechargeable battery optimal?


5. Is it really the charging current, the faster the charging?


1. Understanding memory effects


The battery memory effect refers to the reversible failure of the battery, that is, the performance that can be restored after the battery fails. The memory effect is that the battery automatically maintains this specific tendency after being subjected to a specific duty cycle for a long time. This is first defined in a nickel-cadmium battery. Nickel-cadmium bag batteries have no memory effect, and sintered batteries have a memory effect. Now nickel metal hydrogen (commonly known as nickel-hydrogen) batteries are not bound by this memory effect definition.


Because of the improvement of the modern nickel-cadmium battery process, the above memory effect has been greatly reduced, and another phenomenon replaces this definition, which is the "lattice" of nickel-based batteries. Generally, nickel-cadmium batteries are subject to these two types. The combined effect of the effect, while the nickel-hydrogen battery is only affected by the "lattice" memory effect, and the impact is smaller than that of the nickel-cadmium battery.


In practical applications, the method of eliminating memory effects has strict specifications and an operational process. Improper operation can be counterproductive.


For nickel-cadmium batteries, the normal maintenance is regular deep discharge: an average of one month (or 30 cycles) for a deep discharge (discharge to 1.0V / per section, foreigners called exercise), the usual use is to use light batteries Or use the shutdown method to ease the formation of memory effect, but this is not exercise, because the instrument (such as mobile phone) will not use 1.0V / every section to shut down, you must have a special equipment or line to complete the work. Fortunately, many NiMH battery chargers have this feature.


For nickel-cadmium batteries that have not been exercised for a long time, due to the accumulation of memory effects, the capacity recovery cannot be performed with exercise. In this case, a deeper discharge (foreigner called recondition) is required, which is a battery with a small current for a long time. A process of discharging to 0.4V per section requires professional equipment.


For NiMH batteries, the frequency of exercise can be effectively relieved every three months. Because the cycle life of NiMH batteries is much lower than that of nickel-cadmium batteries, almost no recondition is used.


▲Recommendation 1: It is not necessary to discharge the battery before each charge, and it is harmful, because the battery life is unnecessarily shortened.


▲Recommendation 2: It is not advisable to use a resistor to connect the positive and negative terminals of the battery for discharge. The current cannot be controlled, it is easy to over-discharge to 0V, and even the battery polarity of the series battery pack is reversed.


2. Does the battery need to be activated?


The answer is that the battery needs to be activated, but this is not what the user has to do. I have visited the lithium ion battery manufacturer. The lithium ion battery has to go through the following process before leaving the factory:


Lithium-ion battery shell infusion of electrolyte --- sealing --- formation, is constant pressure charging, and then discharge, so that several cycles, so that the electrode fully wet the electrolyte, fully activated, to meet the capacity requirements, this is activated Process---Division, is to test the capacity of the battery to select different performance (capacity) of the battery to classify, classify the battery, perform capacity matching, etc. The lithium-ion battery that has come out is activated to the user. The nickel-cadmium batteries and nickel-hydrogen batteries that we all use are also activated after they are activated. Some of them require the battery to be in the open state after activation. After the activation, the battery is sealed. This process can only be completed by the battery manufacturer. It is.


There is a problem here, that is, the battery from the battery factory to the user's hand, this time is sometimes very long, short one month, long half year, this time, because the battery electrode material will be passivated, so the manufacturer recommends the first use The battery is preferably subjected to 3 to 5 full charge and discharge processes in order to eliminate the passivation of the electrode material to achieve maximum capacity.


In the three national standards for nickel-metal hydride, nickel-cadmium and lithium-ion batteries issued in 2001, the initial capacity test has clearly defined that the battery can be deep-filled for 5 times, and once it meets the requirements, the test Can stop. This is a good explanation of the phenomenon I said.


★ So it is ok to call it "second activation". The "new" battery that users use for the first time should try to perform several deep charge and discharge cycles.