What is the charging principle of Lithium ion battery? How much is the charging current of Lithium ion battery?

Lithium ion battery works on the moving of Lithium ion between positive and negative electrode. During the charging process, Li+ is embedded and umembedded between the two electrodes: Li+ is umbedded from the positive electrode and embedded into the negative electrode through the elecrtolyte while charging, and the negative electrode is in a lithium-rich state. The opposite is true for electrical discharge.

1. Charging principle of lithium ion battery

Lithium-ion batteries work on the principle of charge and discharge.  When the battery is charged, lithium ions are generated on the positive side of the battery, and the resulting lithium ions travel through the electrolyte to the negative side.  

As a negative electrode, carbon has a layered structure with many micropores. Lithium ions arriving at the negative electrode will be embedded into the micropores of the carbon layer. The more lithium ions embedded, the higher the charging capacity.  

Similarly, when a battery is discharged (which is what we do with batteries), the lithium ions embedded in the negative carbon layer escape and travel back to the positive electrode.  The more lithium ions that return to the positive electrode, the higher the discharge capacity.  What we usually refer to as battery capacity is discharge capacity. 

Lithium-ion batteries generally require the charging process to be controlled in four stages: trickle charging (low-voltage precharging), constant current charging, constant voltage charging and charging termination.  

When the lithium-ion battery is directly connected to the power and charged without a charge management chip, the lithium-ion battery will suddenly enter a large current in the case of low power, which will cause damage to the lithium-ion battery. Because the current is large and the heat is fast, the battery life will be shortened.  

The basic requirements of lithium-ion battery charging are specific charging current and charging voltage, so as to ensure the battery charging safely.  Lithium-ion battery charging mode is voltage limit constant current, are controlled by IC chip. 

2. What is the charging current of lithium ion battery？

Lithium-ion batteries usually accept a maximum charge current of 1C or less, and laptop batteries have a maximum charge rate of 0.9C.  The so-called 1C charging rate refers to the capacity of 1 times the current to charge, charging time is 1 hour.  In fact, for long battery service life, you need to charge the battery for 10 to 4 hours at 0.1-0.3c.  

The national standard stipulates that the charging current of lithium ion battery is 02.C-1C, and the charging current of 100AH battery can be 20A-100A.  That is to say, for a battery with a capacity of 1500mAh, if it is charged at 0.2C, the charging current is 0.2×1500=300mA for 5 hours.  

Lithium iron phosphate batteries can generally use 1C or higher (15C) charge and discharge current, so it is more suitable for power lithium batteries.  

Generally, the charging current of lithium-ion batteries is set between 0.2C and 1C. The higher the current, the faster the charging, and the greater the heat of the battery.  Moreover, if the current is too large to charge, the capacity is not full enough, because the electrochemical reaction inside the battery takes time.