What is the cycle life of 18650 lithium batteries?

The current 3.7V 18650 lithium-ion battery generally has a cycle life of about 500-1000 times, while the 3.2V 18650 has a cycle life of over 2000 times. Of course, the prerequisite is that qualified batteries produced by legitimate manufacturers are qualified. If they are defective or counterfeit batteries, their lifespan will be very short.
The lifespan of a 18650 lithium battery is generally 300-500 charging cycles. Assuming that the amount of electricity supplied by a complete discharge is Q, without considering the decrease in electricity after each charging cycle, a lithium battery can supply or supplement a total of 300Q-500Q of electricity during its lifespan. From this, we can understand that if you charge with 1/2 each time, you can charge 600-1000 times; If 1/3 is used each time to charge, it can be charged 900-1500 times. Similarly, if charged randomly, the number of times is uncertain.
In short, no matter how it is charged, the total amount of electricity replenished from 300Q to 500Q is constant. So, we can also understand it this way: the lifespan of lithium-ion batteries is related to the total charging capacity of the battery, and is not related to the number of charges. The impact of deep discharge and shallow discharge on the lifespan of lithium batteries is not significantly different.
The theoretical lifespan of ternary lithium-ion batteries is about 800 cycles, which is considered moderate in commercial rechargeable lithium-ion batteries. Lithium iron phosphate has about 2000 cycles, while lithium titanate is said to have up to 10000 cycles. At present, mainstream battery manufacturers promise to produce ternary battery cells more than 500 times in their specifications. However, after the battery cells are assembled into battery packs, due to consistency issues, the important thing is that the voltage and internal resistance cannot be exactly the same, and their cycle life is about 400 times.
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