The present invention relates to an electrochemical device, more particularly to an electrochemical device including a first electrode, a second electrode spaced apart from the first electrode and an electrolyte filled between the first electrode and the second electrode, wherein the electrolyte comprises a salt form of a carbon quantum dot anion and a metal cation having an average diameter in the range of 2 to 12 nanometers (nm) and a surface potential of −20 mV or less, the present invention provides an electrochemical device dramatically improving reliability, performance and durability by adopting an carbon quantum dot ion compound electrolyte having selective ion conductivity with a specific cation and suppressing side reactions caused by electrolyte as well as applicable in liquid, gel or solid phase.