How Many Times Is The Life Cycle Of NMC Battery

- Jun 11, 2020-

What is a NMC battery?


In nature, lithium is a light metal with a small atomic mass. Its atomic weight is 6.94g/mol and ρ=0.53g/cm3. Lithium has a lively chemical nature, and it is easy to lose electrons and be oxidized to Li+, so the standard electrode potential is negative, -3.045V, and the electrochemical equivalent is small, 0.26g/Ah. These characteristics of lithium determine that it is a very high Specific energy materials. 

The NMC battery refers to a lithium secondary battery using three transition metal oxides of nickel, cobalt and manganese as the positive electrode material. It fully combines the good cycle performance of lithium cobaltate, the high specific capacity of lithium nickelate and the high safety and low cost of lithium manganate. It uses molecular level mixing, doping, coating and surface modification methods to synthesize nickel. Co-manganese and other multi-element synergistic composite lithium intercalation oxide. It is a lithium ion rechargeable battery that has been widely researched and applied.


Life of NMC battery


The so-called lithium battery life means that after the battery is used for a period of time, the capacity declines to 70% of the nominal capacity (the battery capacity at room temperature 25°C, standard atmospheric pressure, and discharged at 0.2C), which can be regarded as the end of life. In the industry, the cycle life is generally calculated by the number of full-discharge cycles of a lithium battery. In the process of use, an irreversible electrochemical reaction will occur inside the lithium battery, resulting in a decrease in capacity, such as the decomposition of the electrolyte, the deactivation of the active material, and the collapse of the positive and negative electrode structures leading to a reduction in the number of lithium ion insertion and extraction, etc. . The experiment indicates that a higher rate of discharge will cause a faster capacity decay. If the discharge current is lower, the battery voltage will be close to the equilibrium voltage and more energy can be released.


The theoretical life of the NMC battery is about 800 cycles, which is medium in the commercial rechargeable lithium battery. Lithium iron phosphate is about 2,000 times, while lithium titanate is said to reach 10,000 cycles. At present, mainstream battery manufacturers promise more than 500 times in their ternary cell specifications (charge and discharge under standard conditions), but after the cell is assembled into a battery pack, due to consistency issues, mainly the voltage and internal The resistance cannot be exactly the same, its cycle life is about 400 times. The manufacturer recommends a SOC usage window of 10% to 90%. It is not recommended to perform deep charging and discharging, otherwise it will cause irreversible damage to the battery's positive and negative electrode structures. If it is calculated by shallow charging and shallow discharge, the cycle life will be at least 1000 times. In addition, if the lithium battery is often discharged under high rate and high temperature environment, the battery life will be greatly reduced to less than 200 times.


The number of life cycles of lithium batteries is determined according to battery quality and battery materials:

1. The cycle number of NMC material is about 800 times.

2. The cycle number of LFP battery is about 2500 times.

3. The cycle times of genuine batteries and defective batteries are different. Genuine batteries are designed and produced according to the cycle times in the battery manufacturer's specifications, and the defective battery cycles may sometimes be less than 50 times.


Life of NMC battery


The so-called lithium battery life means that after the battery has been used for a period of time, the capacity declines to 70% of the nominal capacity (the battery capacity at room temperature 25°C, standard atmospheric pressure, and discharged at 0.2C), which can be regarded as the end of life. In the industry, the cycle life is generally calculated by the number of full-discharge cycles of a lithium battery. In the process of use, an irreversible electrochemical reaction will occur inside the lithium battery, resulting in a decrease in capacity, such as the decomposition of the electrolyte, the deactivation of the active material, and the collapse of the positive and negative electrode structures leading to a reduction in the number of lithium ion insertion and extraction, etc. . The experiment indicates that a higher rate of discharge will cause a faster capacity decay. If the discharge current is lower, the battery voltage will be close to the equilibrium voltage and more energy can be released.

The theoretical life of the NMC battery is about 800 cycles, which is medium in the commercial rechargeable lithium battery. Lithium iron phosphate is about 2,000 times, while lithium titanate is said to reach 10,000 cycles. At present, mainstream battery manufacturers promise more than 500 times in their ternary cell specifications (charge and discharge under standard conditions), but after the cell is assembled into a battery pack, due to consistency issues, mainly the voltage and internal The resistance cannot be exactly the same, its cycle life is about 400 times. The manufacturer recommends a SOC usage window of 10% to 90%. It is not recommended to perform deep charging and discharging, otherwise it will cause irreversible damage to the battery's positive and negative electrode structures. If it is calculated by shallow charging and shallow discharge, the cycle life will be at least 1000 times. In addition, if the lithium battery is often discharged under high rate and high temperature environment, the battery life will be greatly reduced to less than 200 times.