Working principle of lithium-ion batteries
Lithium-ion batteries use carbon materials as the negative electrode and lithium-containing compounds as the positive electrode. They contain no metallic lithium, only lithium ions. A lithium-ion battery is a general term for batteries that use lithium-ion intercalation compounds as the positive electrode material. The charging and discharging process of a lithium-ion battery is the process of lithium-ion insertion and extraction. During this process, an equivalent number of electrons are simultaneously inserted and extracted. During charging and discharging, lithium ions shuttle back and forth between the positive and negative electrodes, a process figuratively called a rocking chair battery.
Lithium-ion batteries have high energy density and high average output voltage. They have low self-discharge, below 10% per month. They have no memory effect. They have a wide operating temperature range of -20℃ to 60℃. They exhibit excellent cycle performance, can be charged and discharged quickly with a charging efficiency of up to 100%, and have high output power. They have a long lifespan. They are environmentally friendly and are known as green batteries.
Correct charging method for lithium-ion batteries
● Shallow discharge and shallow charge are more beneficial for lithium batteries. Deep discharge and deep charge are only necessary when the product's power module is calibrating the lithium battery. Therefore, products powered by lithium batteries do not need to be bound by the process; convenience should be the priority. Charge them whenever you want without worrying about affecting their lifespan.
● Avoid charging at excessively high temperatures. If lithium batteries are used in environments exceeding the specified operating temperature (above 35°C), the battery capacity will continuously decrease, meaning the battery's power supply time will not be as long as usual. Charging the device at such temperatures will cause even greater damage to the lithium-ion battery.
●Prevent charging at excessively low temperatures. If lithium batteries are used in low-temperature environments, i.e., below 4C, the battery life will also be reduced. Some original lithium-ion batteries in mobile phones may not even be able to charge in low-temperature environments.
● The safe operating voltage range for lithium batteries is 2.8~4.2V. Below or above this voltage range, the lithium ions in the battery become very unstable, potentially causing accidents. Therefore, a dedicated charger is required to ensure that lithium-ion batteries operate within this safe range.
● The charger charges the lithium-ion battery with a constant current. As the battery voltage increases, the charger simultaneously increases the charging voltage to speed up the charging process.
●After the lithium-ion battery is fully charged, try to avoid leaving it on the charger for more than 10 hours. If the phone will not be used for a long time, the polymer lithium-ion battery should be separated.
Lithium-ion battery charging is divided into two stages.
1. Constant current charging: The current is constant, while the lithium-ion battery voltage gradually increases during the charging process. According to the specifications, it is generally charged at a current of 0.2C (C is a way of expressing the battery's nominal capacity relative to the current; 0.2C is 200mA). When the battery voltage approaches the full charge voltage of 4.2V, the constant current charging is switched to constant voltage charging. This process takes approximately five hours.
2. Constant voltage charging: The voltage is constant, while the current gradually decreases as the cell saturation level increases. According to the specification, charging is considered to terminate when the current decreases to 0.01C (10mA). The total charging time, including this process and the constant current charging time, should not exceed eight hours.
