An LED bulb includes a base, a shell connected to the base, one or more LEDs, a thermally conductive liquid, and a flexible diaphragm. The one or more LEDs are disposed within the shell. The thermally conductive liquid is held within the shell. The flexible diaphragm is in fluidic connection to the thermally conductive liquid, and is configured to deflect from a first position to a second position to compensate for expansion of the thermally conductive liquid.