The element that increases its electrical conductivity as temperature increases is carbon, specifically in its diamond form.

Here's why:

* Semiconductors: Diamond is a semiconductor, meaning its conductivity falls between that of a conductor and an insulator.

* Temperature Dependence: In semiconductors, the number of free charge carriers (electrons) increases with temperature. This is because thermal energy excites electrons from their bound state to the conduction band, where they can freely move and conduct electricity.

Important Note: While diamond's conductivity increases with temperature, it's still a very poor conductor compared to metals.

Let me know if you'd like more details about semiconductors or electrical conductivity!