4,000-cycle lifetime means that batterie can still maintain ≥80% of the initial capacity after 4,000 charge/discharge cycles under specific conditions (e.g., 80% DOD discharge and 25℃ temperature) (IEC 61427 standard). Use take home energy storage for illustration. If one cycle is repeated every day (a 5kW photovoltaic system provides 20kWh of electricity per day and battery capacity is 10kWh), 4,000 cycles correspond to a service life of approximately 10.9 years (4,000/365), 6.8 times longer than that for lead-acid batteries (500 cycles/1.4 years). The total cost throughout the whole life cycle is reduced by 72% (on the basis of initial cost of lithium batteries at 6,000 vs.) Lead-acid (2000×7 replacement calculation).
The capacity degradation curve shows that the mean rate of capacity retention of LiFePO4 batterie was 95% (standard deviation ±1.2%) at 1000 cycles, and dropped to 82±2% at 4000 cycles. The actual test data of Tesla Powerwall shows that in the state of 2C daily charge and discharge (the charge and discharge rate is completed within 2 hours), after 4,000 cycles, the energy decreases to 79% of the nominal capacity, and the rate of growth of internal resistance is 0.03mΩ per cycle (0.08mΩ for ternary batteries). If used for peak shaving in the electric power system (with 10 shallow charge and discharge cycles on average per day and a discharge depth of 30%), the cycle life is extended to 15,000 cycles, which is equivalent to 25 years of operation (EPRI Power Research Institute model).
In the economic aspect, the LCOE of battery with 4,000 cycles in PV storage systems is 0.08/kWh (initial cost 500/kWh, operation and maintenance cost 0.005/kWh/year), which is 33% less than that of natural gas power generation (0.12/kWh). Byd’s experience shows that its 280Ah battery cells, used in commercial and industrial energy storage (at a system level of 1MWh), have a residual value rate of 40% after 4,000 cycles (which can be reused in a tiered application for low-speed electric vehicles), and the payback period of the investment has been cut from 8 years to 5.5 years.
The environmental effects are staggering. A 4,000 cycles battery will reduce carbon dioxide emissions by 180 tons throughout its entire lifetime (compared to coal power station, it could reduce emissions by 0.5kg per kWh), whereas its metal use of resources is 75% lower compared to low-cycle versions (e.g., 1,000 cycles) (use of lithium reduced from 8g/kWh to 2g/kWh). The EU Batteries Directive 2027 mandates that the minimum power battery cycle life be 5,000 times, encouraging industry technological upgrading.
Practical application limitations are: high-temperature (>45℃) conditions will reduce the cycle life by 50% (Arrhenius model, doubling of the aging rate for each 10℃ increase), while low-temperature charging and discharging at -20℃ will make the growth rate of lithium dendrites rise by three times (JESD22-A104 standard test). The 2023 Australian Household Storage Fire Survey suggests that forced air cooling systems can prolong batterie cycle life from the nominal 4,000 times to 4,800 times (temperature difference control ±3℃ vs. ±8℃).
In the vehicle application, the CATL EV’s Battery IE (NCM 811) was maintained at a 78% capacity retention after 4,000 fast charging cycles (1C discharging/1C charging), meeting the 8 years / 500,000 kilometers taxi operating requirement (with an average daily range of 300 kilometers). For energy storage battery (e.g., CATL EnerC), under the working condition of 0.5C, the capacity retention rate after 4,000 cycles is 85%. In photovoltaic power stations, it can reduce the abandoned light rate from 15% to 5% (NREL simulation data).