Lithium ion batteries appeared in the 90 s 

Areas of application: mobile phones, laptops, cameras, electric vehicle. 

Advantages: high open circuit voltage (monomer battery voltage up to 3.6 ~ 3.8 V), specific energy, long cycle life and pollution-free, no memory effect, small self-discharge. Faults: a charge and discharge protection, cost is very high, can't use large current discharge (organic electrolyte). 

The main types: liquid lithium ion battery and lithium ion battery.

Why is li-ion battery protection more critical?

The cathode of a lithium-ion battery is mainly carbon or graphite, which can store and release lithium ions. Once overcharging occurs, the lithium ions become lithium and the metal is deposited on the surface of carbon or graphite. Because lithium is so active, any impact or other cause can cause it to burn; The lithium ion battery electrolyte for flammable organic matter. Therefore, once the overcharge voltage occurs due to wrong charging, when the voltage is above 4.7v, the lithium-ion battery will overheat or even burn.

In order to prevent overdischarge from shortening battery life, the lithium ion battery needs overdischarge protection. 

Protect the lithium ion battery:

1, to prevent over charging voltage 

2, prevent discharge the allowable value of more than 

3, prevent over-current 

4, short circuit protection 

5, prevent the battery temperature 

6, prevent the battery internal pressure increases