With the driving range of new energy vehicles becoming increasingly limited, improving range has impacted the entire market. In the battery industry, ternary lithium batteries have rapidly captured the 3C and automotive markets due to their numerous advantages, gradually replacing traditional lead-acid batteries. Compared to traditional batteries, ternary lithium batteries offer advantages such as long lifespan, energy efficiency, environmental friendliness, low maintenance costs, complete charge/discharge, and light weight. Some promotional materials claim that ternary lithium batteries have a long lifespan, but is this truly the case? How many cycles does it actually have? Let's uncover the truth.
What is a ternary lithium battery?
In nature, lithium is the lightest metal with the smallest atomic mass. Lithium is chemically reactive, readily losing electrons to be oxidized to Li+. Its standard electrode potential is -3.045V, and its electrochemical equivalent is 0.26 g/Ah. These characteristics determine that lithium is a material with very high specific energy. Ternary lithium batteries are lithium-ion rechargeable batteries that use nickel, cobalt, and manganese transition metal oxides as cathode materials. They fully combine the excellent cycle performance of lithium cobalt oxide, the high specific capacity of lithium nickel oxide, and the high safety and low cost of lithium manganese oxide. By utilizing molecular-level mixing, doping, coating, and surface modification methods to synthesize composite lithium-intercalated oxides with synergistic effects of nickel, cobalt, and manganese, they are currently a widely researched and applied type of lithium-ion rechargeable battery.
The theoretical lifespan is only moderate.
The lifespan of a ternary lithium battery is calculated based on the percentage of capacity decay after a certain period of use, ending when the capacity lifespan reaches zero. The industry standard is to calculate the cycle life of a ternary lithium battery as one full charge followed by one discharge cycle. During use, irreversible chemical reactions within the lithium battery can cause a decrease in capacity, such as improper use or use at extremely high or low temperatures. These reactions include electrolyte decomposition, deactivation of active materials, and the collapse of the positive and negative electrode structures, leading to a reduction in the number of lithium ions inserted and extracted. Experiments show that higher discharge rates result in faster capacity decay; conversely, lower discharge currents allow the battery voltage to approach the equilibrium voltage, releasing more energy.
The theoretical lifespan of a ternary lithium battery is 1200 complete charge-discharge cycles, also known as a full cycle life. Based on usage frequency, a complete charge-discharge cycle every three days results in 120 complete charge-discharge cycles per year, giving a ternary lithium battery a lifespan of up to ten years. Even with wear and tear or a reduction in the number of charge-discharge days during use, it can still last up to eight years. Note that this refers to capacity lifespan; after eight years, the capacity of a ternary lithium battery will still be more than 60% of its original capacity, which is the basis of its standard.
The theoretical lifespan of ternary lithium batteries is moderate among commercially available rechargeable lithium batteries. Lithium iron phosphate batteries have a lifespan of approximately 2000 cycles, while lithium titanate batteries are said to reach 10,000 cycles. Currently, mainstream battery manufacturers promise more than 500 cycles (standard charge/discharge conditions) in their ternary cell specifications. However, after cells are assembled into battery packs, due to consistency issues—primarily voltage and internal resistance—their cycle life is approximately 400 cycles. Manufacturers recommend a SOC (State of Charge) window of 10% to 90% and discourage deep charge/discharge, as this can cause irreversible damage to the battery's positive and negative electrode structures. If calculated using shallow charge/discharge, the cycle life is at least 1000 cycles. Furthermore, if lithium batteries are frequently discharged at high rates and high temperatures, their lifespan will drastically decrease to less than 200 cycles.
