What is a ternary lithium battery?
Ternary lithium batteries are lithium-ion rechargeable batteries that use nickel, cobalt, and manganese transition metal oxides as cathode materials. They 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. They utilize 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.
Ternary lithium battery lifespan
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 a 0.2C discharge rate). The industry generally calculates cycle life by the number of full charge-discharge cycles. During use, irreversible electrochemical reactions occur inside the lithium battery, leading to capacity reduction. These reactions include electrolyte decomposition, deactivation of active materials, and the collapse of the positive and negative electrode structures, resulting in a reduction in the number of lithium ions inserted and extracted. Experiments show that higher discharge rates lead to faster capacity decay; conversely, lower discharge currents allow the battery voltage to approach the equilibrium voltage, releasing more energy.
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 about 2,000 cycles, while lithium titanate batteries are said to reach 10,000 cycles. Currently, mainstream battery manufacturers promise more than 500 cycles (standard charge and discharge conditions) in their ternary cell specifications. However, after the cells are assembled into battery packs, due to consistency issues, mainly voltage and internal resistance, they cannot be completely identical, resulting in a cycle life of approximately 400 cycles.
The manufacturer recommends a SOC (State of Charge) window of 10% to 90%, and discourages deep charging and discharging, as this can cause irreversible damage to the battery's positive and negative electrode structures. If calculated using shallow charging and discharging, 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.
