Ternary lithium-ion batteries are also known as ternary polymer lithium batteries. Ternary polymer lithium batteries refer to lithium batteries that use lithium nickel cobalt manganese oxide (Li(NiCoMn)O2) ternary cathode materials as cathode materials. Ternary composite cathode material precursor products are made from nickel salts, cobalt salts, and manganese salts. The ratio of nickel, cobalt, and manganese can be adjusted according to actual needs. Batteries with ternary materials as cathodes are safer than lithium cobalt oxide batteries.
I. Charging of Ternary Lithium-ion Batteries
The maximum charging termination voltage for a single lithium-ion battery is 4.2V. Overcharging is not allowed, otherwise the battery will be ruined due to excessive loss of lithium ions at the positive electrode. When charging lithium-ion batteries, a dedicated constant current and constant voltage charger should be used. First, charge at a constant current until the voltage across the lithium-ion battery reaches 4.2V, then switch to constant voltage charging mode. Charging should be stopped when the constant voltage charging current drops to 100mA.
The charging current (mA) can be 0.1 to 1.5 times the battery capacity. For example, for a 1350mAh lithium-ion battery, the charging current can be controlled between 135mA and 2025mA. A typical charging current can be selected at around 0.5 times the battery capacity, and the charging time is approximately 2 to 3 hours.
Discharge of ternary and tertiary lithium-ion batteries
Due to the internal structure of lithium-ion batteries, not all lithium ions can move to the positive electrode during discharge; a portion must remain at the negative electrode to ensure they can readily intercalate during the next charge. Otherwise, battery life will be shortened. To ensure that some lithium ions remain in the graphite layer after discharge, the minimum discharge termination voltage must be strictly limited; in other words, lithium-ion batteries cannot be over-discharged.
The discharge termination voltage of a single lithium-ion battery is typically 3.0V, and should not be lower than 2.5V. The discharge time depends on the battery capacity and the discharge current. Battery discharge time (hours) = battery capacity / discharge current. Furthermore, the discharge current (mA) of a lithium-ion battery should not exceed three times its capacity. For example, for a 1000mAh lithium-ion battery, the discharge current should be strictly controlled below 3A; otherwise, the battery will be damaged.
It's easy to see that during the charging and discharging process of a lithium-ion battery, lithium ions are in a state of motion, moving from the positive electrode to the negative electrode and back to the positive electrode. If we figuratively compare a lithium-ion battery to a rocking chair, with the two ends of the chair representing the battery's electrodes, the lithium ions are like excellent athletes running back and forth between the two ends. Therefore, experts have given lithium-ion batteries another endearing name: rocking chair batteries.
