What are the differences between electric, lithium-ion, and pneumatic angle grinders? Do you know how to choose?

Electric angle grinders
These mainly use a single-phase 220V power supply as the power source. They have sufficient power, stable operation, and are widely used. However, since they are driven by an electric motor, they tend to overheat more easily.

Lithium-ion angle grinders
When using electric tools, the restriction of the power cord greatly affects the user experience, and the same is true for angle grinders. Lithium-ion angle grinders mainly use pre-stored lithium-ion batteries, which are convenient for operation in places with insufficient power supply and are less affected by the environment. However, the battery power is still limited, so they are more suitable for short-term grinding, with a short battery life. Moreover, they are relatively expensive. Often, lithium-ion angle grinders are more costly than the corded ones.

Pneumatic angle grinders
Pneumatic angle grinders are relatively lightweight. Their power comes from an air pump, so a matching air pump is required. The advantages are low heat generation, high safety, easy maintenance, small volume, light weight, and convenient portability.