Graphene fiber manufactured by joule heating and method of manufacturing the same

A method of manufacturing a graphene fiber, the method comprising:

• preparing a source solution including graphene oxide;
• supplying the source solution from a spinneret into a coagulation solution to form a graphene oxide fiber;
• reducing the graphene oxide fiber to form a primary graphene fiber;
• and
• Joule-heating the primary graphene fiber to form a secondary graphene fiber,
• wherein the primary graphene fiber is Joule-heated such that amorphous carbon in the primary graphene fiber is crystallized,
• wherein, as a supply rate of the source solution supplied from the spinneret into the coagulation solution increases, a degree of orientation of a graphene sheet in the primary graphene fiber is high, a resistance of the primary graphene fiber is low, so that a value of a current applied to the primary graphene fiber for Joule-heating the primary graphene fiber increases in the Joule-heating of the primary graphene fiber to form the secondary graphene fiber.