"Lithium battery" is a kind of battery with lithium metal or lithium alloy as cathode material and non-aqueous electrolyte solution. In 1912, lithium metal battery was first proposed and studied by gilbertn.lewis. In the 1970s, m.s.whittingham proposed and began to study lithium-ion battery. Due to the very active chemical properties of lithium metal, the processing, preservation and use of lithium metal have very high requirements for the environment. Therefore, lithium battery has not been developed for a long time Application. 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 can be recharged. 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 its own high-tech requirements, only a few countries' companies are producing this lithium metal battery.

Battery life

Lithium ion battery can only be charged and discharged 500 times?

I believe most consumers have heard that the service life of lithium batteries is "500 times", and 500 times of charging and discharging. Beyond this number, the battery will "die". In order to prolong the service life of the battery, many friends charge it every time when the battery is completely discharged. Does this really prolong the service life of the battery? The answer is No. The service life of lithium battery is "500 times", which refers not to the number of times of charging, but to a cycle of charging and discharging.

A charging cycle means the process of all battery power from full to empty, and then from empty to full, which is not equivalent to charging once. For example, a lithium battery uses only half of its power on the first day, and then it is fully charged. If it is still the case the next day, that is, charge it half way, and charge it twice in total, this can only be counted as one charging cycle, not two. Therefore, it may take several times to complete a cycle. After each charging cycle, the battery capacity will be reduced a little. However, this reduction in power consumption is very small. After many cycles of charging, high-quality batteries will still retain 80% of their original capacity. Many lithium battery power supply products are still used as usual after twoorthree years. Of course, lithium batteries still need to be replaced at the end of their life.

The so-called 500 times means that the manufacturer has achieved about 625 chargeable times at a constant discharge depth (such as 80%), reaching 500 charging cycles.

(80%*625=500) (ignoring factors such as the reduction of lithium battery capacity)

Due to the various effects of 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: lithium battery life is related to the completion times of charging cycle, not directly related to the charging times.

A simple understanding, for example, is that a lithium battery uses only half of its power on the first day, and then it is fully charged. If it is still the case the next day, that is, charge it half way, and charge it twice in total, this can only be counted as one charging cycle, not two. Therefore, it may take several times to complete a cycle. Each time a charging cycle is completed, the power will be reduced a little. However, the reduction is very small. High quality batteries will still retain 80% of the original power after many cycles. This is why many lithium battery power supply products are still used as usual after twoorthree years. Of course, lithium batteries need to be replaced at the end of their life.

The service life of lithium battery is generally 300 ~ 500 charging cycles. Assuming that the power provided by a complete discharge is Q, if the reduction of power after each charging cycle is not considered, the lithium battery can provide or supplement 300q-500q power in total within its service life. From this, we know that if you charge with 1/2 each time, you can charge 600-1000 times; If you charge with 1/3 each time, you can charge 900 ~ 1500 times. And so on. If it is charged randomly, the number of times is variable. In short, no matter how charged, a total of 300q ~ 500q of power is added, which is constant. Therefore, we can also understand in this way: the service life of lithium battery is related to the total charging capacity of the battery, and has nothing to do with the charging times. There is little difference between deep discharge and deep charge and shallow discharge and shallow charge on the life of lithium battery.

In fact, shallow discharge and shallow charge are more beneficial to lithium batteries. Deep discharge and deep charge are necessary only when the power module of the product is calibrated for lithium batteries. Therefore, products powered by lithium batteries don't have to stick to the process. Everything comes first. They can be charged at any time without worrying about affecting their service life.

If lithium battery is used in an environment higher than the specified operating temperature, that is, above 35 ° C, the power of the battery will continue to decrease, that is, the power supply time of the battery will not be as long as usual. If you charge the device at such a temperature, the damage to the battery will be greater. Even if the battery is stored in a hot environment, it will inevitably cause corresponding damage to the quality of the battery. Therefore, it is a good way to prolong the service life of lithium battery to keep it at an appropriate operating temperature as far as possible.

If lithium batteries are used in low temperature environment, that is, below 4 ° C, the service time of batteries will also be reduced, and some original lithium batteries of mobile phones can't even be charged in low temperature environment. But don't worry too much. This is only a temporary situation, which is different from the use in high-temperature environment. Once the temperature rises and the molecules in the battery are heated, it will immediately return to the previous power level.

If you want to give full play to the maximum efficiency of lithium-ion batteries, you need to use them often to keep the electrons in the lithium battery in a flowing state. If you don't use lithium batteries often, please remember to complete a charging cycle for lithium batteries every month and do a power calibration, that is, deep discharge and deep charge.

The formal name is "charge and discharge cycle", which is not equal to "charge times". Cycle refers to the cycle from full charge to run out of battery. If your battery is in full charge state, it uses one tenth of the power, and then it is full again, which is one tenth of a cycle. If you charge it for 10 times, it is basically a cycle. Similarly, from full charge, half charge and then full charge, and then half charge and then full charge, this is also a cycle. At this time, you are charged twice. Therefore, the cycle only depends on "how much electricity is released from the battery", and has no direct relationship with "charging times".

Moreover, the nominal number of charge and discharge cycles does not mean that the battery cannot be used after it is used up, but after so many cycles, the battery's ability to store electricity will decline to a certain extent,

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

That is, after 500 cycles, the battery can only store 60% of the electricity when the new battery is used, which means that the performance has decreased to a certain extent

There is no fixed limit on the number of times to charge lithium batteries. Batteries from regular manufacturers can generally be charged and discharged at least 500 times, and the capacity remains at more than 80% of the initial capacity. One charge a day can be used for 2 years. Usually, if the mobile phone battery is charged 1000 times, the battery will be seriously not durable.

Maintenance method of mobile phone battery:

1. Fully charged each time, reduce the number of charges and improve the service life of the battery.

2. It is not necessary to discharge the battery completely. Usually, it needs to be charged when the power is less than 10%.

3. Use the original charger instead of universal charger.

4. Do not use your mobile phone during charging.

5. Don't overcharge. Stop charging after the battery is full.

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

Cycle is the use. We are using the battery, and we are concerned about the use time. In order to measure the performance of how long the rechargeable battery can be used, the definition of cycle times is stipulated. The actual use of users is ever-changing, because tests with different conditions are not comparable, and the definition of cycle life must be standardized for comparison.

The test conditions and requirements for the cycle life of lithium batteries specified in the national standard: under the ambient temperature of 20 ℃± 5 ℃, charge at 1C. When the voltage at the battery end reaches the charging limit voltage of 4.2V, change to constant voltage charging until the charging current is less than or equal to 1/20c, stop charging, lay aside for 0.5h ~ 1H, and then discharge at 1C current to the termination voltage of 2.75V. After discharge, lay aside for 0.5h~1h, and then carry out the next charging and discharging cycle, Until the time of two consecutive discharges is less than 36min, the service life is considered to be terminated, and the number of cycles must be greater than 300.

Interpretation of national standards:

A. This definition stipulates that the cycle life test is carried out in the way of deep charging and deep discharging

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

However, the cycle times obtained by different cycle systems are quite different. For example, the above other conditions remain the same. Only changing the constant voltage of 4.2V to the constant voltage of 4.1V to test the cycle life of the same type of battery. In this way, this battery is no longer a deep charging method, and the cycle life times can be increased by nearly 60%. If the cut-off voltage is increased to 3.9v for testing, the number of cycles should be increased several times.

As for the statement that one cycle of charge and discharge will lead to one less life, we should pay attention to the definition of the charging cycle of lithium battery: a charging cycle refers to the process of all the power of lithium battery from full to empty, and then from empty charge to full charge. This is not equivalent to charging once. In addition, when talking about the number of cycles, you can't ignore the conditions of cycles. It's meaningless to talk about the number of cycles without rules, because the number of cycles is a means to detect the battery life, not an end!