What is the charging principle of lithium batteries?
2 Answers
The charging of lithium batteries is based on their structural characteristics. Below is relevant information about lithium batteries: 1. Discharging of lithium batteries: Due to the internal structure of lithium batteries, during discharge, not all lithium ions can move to the positive electrode. Some lithium ions must remain in the negative electrode to ensure smooth embedding channels for lithium ions during the next charge. Otherwise, the battery's lifespan will be shortened accordingly. To ensure that some lithium ions remain in the graphite layer after discharge, the discharge termination minimum voltage must be strictly limited, meaning lithium batteries cannot be over-discharged. The discharge termination voltage is typically 3.0V per cell and should not be lower than 2.5V per cell. The duration of battery discharge depends on the battery capacity and the discharge current. Battery discharge time (hours) = battery capacity / discharge current. The discharge current (mA) of a lithium battery should not exceed three times the battery capacity (e.g., for a 1000mAH battery, the discharge current should be strictly controlled within 3A). Otherwise, the battery may be damaged. 2. Protection circuit of lithium batteries: It consists of two field-effect transistors and a dedicated protection integrated block S--8232. The overcharge control transistor FET2 and the over-discharge control transistor FET1 are connected in series in the circuit. The protection IC monitors the battery voltage and controls it. When the battery voltage rises to 4.2V, the overcharge protection transistor FET1 cuts off, stopping the charge. To prevent false triggering, a delay capacitor is usually added to the external circuit. When the battery is in a discharged state and the voltage drops to 2.55V, the over-discharge control transistor FET1 cuts off, stopping power supply to the load. Overcurrent protection occurs when a large current flows through the load, controlling FET1 to cut off and stop discharging to the load, aiming to protect the battery and the field-effect transistors.
The working principle of lithium battery charging is quite fascinating. Let me explain it from an ordinary user's perspective. When you plug in the battery, the external power source converts electrical energy into chemical energy, driving lithium ions to detach from the cathode material, pass through an electrolyte layer, and migrate to the anode for storage. During discharge, the process reverses as ions flow back to the cathode, releasing energy. This mechanism is as intuitive as filling a water bucket. From my experience using smartphones and EVs, I've learned that fast charging isn't always better - excessive speed generates heat that may cause battery swelling or even fires. That's why I always use slow charging with OEM-certified chargers (avoiding knockoffs), combined with smart timers to stop at 80% capacity. This practice extends battery lifespan for several years. Regular temperature checks are crucial too - never charge in a sun-exposed car. This approach benefits both environmental protection and cost savings.
