The main advantage of conical springs lies in their ability to compress themselves, thereby reducing the space required when compressed.
These springs require a larger available diameter at their base, but since all the coils interlock with one another, the space required along their compression axis is extremely small.
Another advantage of conical springs is the non-linearity of their forces. During compression, the large coils compress first. The greater the compression, the smaller the coils that are compressed (the stiffer ones), which increases the compressive forces. This therefore contributes to excellent shock absorption.
These conical springs are therefore widely used in small devices (batteries, push buttons, etc.)