The lifespan of a lithium battery refers to the period after which its capacity decreases to 70% of its nominal capacity (at room temperature of 25°C, standard atmospheric pressure, and discharged at 0.2C). The industry generally calculates cycle life based on the number of full charge-discharge cycles.
The theoretical lifespan of ternary lithium batteries is approximately 800 cycles, which is moderate among commercially available rechargeable lithium batteries. Lithium iron phosphate batteries have a lifespan of around 2000 cycles, while lithium titanate batteries are said to reach 10,000 cycles. Currently, mainstream battery manufacturers promise more than 500 cycles (under standard charge and 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. Furthermore, if lithium batteries are frequently discharged at high rates and high temperatures, their lifespan will drastically decrease to less than 200 cycles.
The key to improving energy density lies in the cathode material, which determines the main performance of lithium-ion batteries. Among them, ternary materials refer to cathode materials composed of nickel, cobalt, and manganese or nickel, cobalt, and aluminum, namely lithium nickel cobalt manganese oxide (hereinafter referred to as "NCM") or lithium nickel cobalt aluminum oxide (hereinafter referred to as "NCA").
Depending on the content of nickel, cobalt, and manganese in the ternary materials, NCM materials can be further divided into NCM523, NCM622, NCM811, etc. NCM523 refers to ternary materials with a chemical composition of Li(Ni0.5Co0.2Mn0.3)O2. NCA, on the other hand, uses aluminum instead of manganese. The technological advantage of ternary materials lies in combining the advantages of LiCoO2, LiNiO2, LiMnO2, or LiAlO2, allowing Ni, Co, Mn, or Al to exert a synergistic effect. Ni mainly plays a role in increasing energy density; Co mainly plays a role in stabilizing the layered structure of the ternary material, improving electronic conductivity and cycle performance; Mn mainly plays a role in reducing cost and improving the structural stability and safety of the material. Different element ratios can yield different electrode characteristics.
