The volumetric energy density of the 21700 battery is much higher than that of the 18650 battery cell. Although the 21700 battery is better than the 18650 battery in terms of battery life and cost, it has defects in terms of battery cycle life.

Compared with the 18650 battery, the 21700 battery increases the physical size of the cylindrical cell. Although this will increase the energy volume, it will also reduce the cycle life and rate of the cell. If the size continues to increase, the safety and adaptability of the battery cell will be reduced, which will invisibly increase the potential safety hazards and design difficulties of new energy vehicles. According to estimates, for every 10% increase in capacity, the cycle life will be reduced by approximately 20%; charge and discharge rate Reduce by 30-40%, while the battery cell will heat up by about 20%. The increase in battery temperature and the shortened cycle life are fatal flaws for electric vehicles.
In theory, compared with 18650 battery, 21700 battery has shorter lifespan, longer charging time of the same capacity, and lower safety. The use of 21700 battery will greatly help the weight, battery life, and cost of electric vehicles.