What is the life span of lithium battery?

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 battery was first proposed and studied by Gilbertn.Lewis in 1912. In the 1970s, M.S. Willingham proposed and began to study lithium-ion batteries. Due to the chemical characteristics of lithium metal is very lively, so that lithium metal processing, preservation, use, environmental requirements are very high. 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 battery can be roughly divided into two categories: lithium metal battery and lithium ion battery. 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-to-price ratio are all better than lithium ion battery. Because of its own high technology requirements, only a handful of companies in a few countries now produce lithium-ion batteries.

Battery life

Lithium ion battery can only charge and discharge 500 times?

Believe that the vast majority of consumers have heard of, the life of the lithium battery is "500", 500 times more than the number of times, the battery will "die", many friends in order to be able to extend battery life, each time to charge when the battery run out completely, so really have a longer effect on battery life? The answer is no. Lithium battery life is "500 times", refers to the number of times, but a charge and discharge cycle.

A charging cycle means that all the battery's energy is used from full to empty, and then from empty to full, which is not the same as charging once. For example, a lithium battery USES half its energy on the first day, and then recharges it. If this is still the case the next day, you can use half of the charge, and the total two charges down, this can only count as one charging cycle, rather than two. As a result, it usually takes several charges to complete a cycle. The battery capacity decreases a little with each charging cycle. But the reduction is so small that high-quality batteries retain 80% of their original capacity after multiple cycles, and many lithium-ion products continue to be used two or three years later. Of course, lithium battery life will eventually need to be replaced.

The so-called 500 times, refers to the manufacturer in a constant discharge depth (such as 80%) to achieve 625 times or so of charging times, reached 500 charging cycles.

(80%*625=500) (lithium battery capacity reduction and other factors are ignored)

However, due to various influences in real life, especially the discharge depth during charging is not constant, so "500 charging cycles "can only be used as a reference battery life.

Correct statement: the life of lithium battery is related to the number of charging cycles, and the number of charging times is not directly related.

A simple way to think about it, for example, is that a lithium battery USES half its energy on the first day, and then recharges it. If this is still the case the next day, you can use half of the charge, and the total two charges down, this can only count as one charging cycle, rather than two. As a result, it usually takes several charges to complete a cycle. With each charge cycle completed, the amount of charge decreases a little bit. However, the reduction is very small, and high-quality batteries retain 80% of their original charge after many cycles, which is why many lithium-powered products are still used after two or three years. Of course, lithium battery life will eventually need to be replaced.

Lithium battery life is generally 300 ~ 500 charging cycles. Assuming that the amount of electricity provided by a complete discharge is Q, if the reduction of the amount of electricity after each charging cycle is not taken into account, the lithium battery can provide or supplement 300q-500q of electricity in its lifetime. So we know that if you charge 1/2 every time, you can charge 600 to 1,000 times; If you fill it one-third of the time, you can fill it 900 to 1,500 times. Similarly, if the charging is random, The Times are uncertain. So anyway, no matter how much you charge it, you're going to get 300Q to 500Q of electricity, which is constant. Therefore, we can also understand that the life of lithium battery is related to the total charge quantity of the battery, and has nothing to do with the number of charges. The effect of deep discharge and shallow discharge on the life of lithium is not different.

In fact, shallow discharge and shallow charge are more beneficial to lithium battery. Only when the power module of the product is calibrated for lithium battery can deep discharge and deep charge be necessary. Therefore, lithium electric power supply products do not have to adhere to the process, everything in order to facilitate the first, charging at any time, do not have to worry about the impact of life.

If the above specified operating temperature, namely above 35 ° C environment using lithium electricity, battery power will continue to reduce, the battery power supply time won't be long as usual. If you have to charge the device at this temperature, the damage to the battery will be even greater. Even if the battery is stored in a hot environment, it will inevitably cause damage to the quality of the battery. Therefore, it is a good way to prolong the life of lithium battery to keep the operating temperature at the appropriate profit as far as possible.

If in low temperature environment, namely 4 ° C below used in li-ion battery, also found that the use of the battery time is reduced, some mobile phone original lithium electricity even in low temperature environment not to electricity. But don't worry too much, this is just a temporary situation, unlike the use of high temperature environment, once the temperature rises, the molecules in the battery are heated, immediately restore the previous power.

To get the most out of a lithium-ion battery, you need to use it regularly to keep the electrons flowing. If you do not often use lithium battery, please remember to complete a charging cycle for lithium battery every month, and do a power calibration, that is, deep discharge and deep charge once.

Normal call is "charge and discharge cycle", is not equal to "charge times", cycle refers to, the battery from full charge to use up, this is a cycle, if your battery from full charge state, used a tenth of the power, and then full again, this is a tenth of a cycle, so charge 10 times, just basically count as a cycle. Once again, from full charge, you use half of it and then you fill it up, and then you use half of it and then you fill it up again, and this is a cycle, and then you charge it up twice. So the cycle simply depends on "the cumulative amount of energy released from the battery," not on "the number of charges."

And this nominal charge and discharge cycle number doesn't mean you can't use up, but after doing so many cycles, the battery's ability to store electricity will drop to a point.

For example, for a lithium battery, the nominal charge and discharge cycle is "no less than 60% of the nominal capacity after 500 times".

After 500 cycles, the battery can only store 60% of the power of the new battery

Lithium battery has no fixed charge times limit, the regular manufacturers out of the battery can generally charge and discharge at least 500 times, and the capacity to maintain more than 80% of the initial capacity, a day a charge can be used for 2 years. Normally, a mobile phone battery will not last long after being charged 1000 times.

Mobile phone battery maintenance method:

1, each fully charged use, reduce the number of charges, improve the service life of the battery.

2, do not fully discharge the battery, usually less than 10% of the power needs to be charged.

3, use the original charger to charge, do not use universal charging.

4. Do not use your mobile phone during charging.

5, do not overcharge, the battery is full of stop charging.

Yes, according to the experimental results, the life of lithium battery decreases with the increase of charging times. Generally, the charging times of lithium battery are 2000-3000 times

Cycle is the use, we are using the battery, is concerned about the use of time, in order to measure the rechargeable battery can be used for how long such a performance, the definition of cycle number. Actual users use a variety of conditions, because different conditions of the test is not comparable, to have a comparison must standardize the definition of cycle life.

Lithium battery cycle life test conditions prescribed by the national standard and requirement: the environment temperature is 20 ℃ under the condition of + 5 ℃, 1 c to charge, when the voltage of the battery to charge limit voltage of 4.2 V, instead of constant voltage charging, until the charging current is equal to or less than 1/20 c, stop charging, shelved 0.5 h ~ 1 h, then in 1 c discharge current to termination voltage 2.75 V, after the discharge, suspended 0.5 h ~ 1 h, then the next recharge cycles, until two consecutive discharge time is less than 36 min, thinks life is terminated, cycle number must be greater than 300 times.

Interpretation of national standard provisions:

A. This definition stipulates that the cycle life test shall be conducted in A deep charge and discharge manner

B. The cycle life of lithium battery is stipulated. According to this mode, after more than 300 cycles, the capacity is still more than 60%

However, different cycles of the circulation system is very different, such as more than the other conditions unchanged, only change the constant-voltage voltage of 4.2 V to 4.1 V voltage for the same model of the constant pressure of the battery cycle life test, so the battery is not deep filling way, the final test number of cycle life can be improved by almost 60%. If the cut-off voltage is increased to 3.9v for testing, the number of cycles should be increased by several times.

This is about the cycle charge and discharge of a life is less than once, we should pay attention to the definition of the lithium battery charging cycle: a charging cycle refers to the lithium battery all the electricity from full to empty, then from empty to full process of charging. This is not the same as charging once. In addition, when we talk about cycle times, we should not ignore the condition of cycle times. It is meaningless to talk about cycle times without rules, because cycle times are a means to detect battery life, not an end!