NOVELTY - The lithium-based battery fiber (300) comprises a metallized fiber (200) comprising a fibrous substrate, an initiation-adhesion layer disposed over the fibrous substrate and a first metallic layer (208) disposed on the initiation-adhesion layer, an electrolyte layer (302) disposed over the first metallic layer, a cathode layer (304) disposed on the electrolyte layer, a second metallic layer (306) disposed on the cathode layer, an anode layer disposed on the first metallic layer, a protective coating layer (308) disposed on the second metallic layer, and a nanofilament layer.    USE - Used as a lithium-based battery fiber.    ADVANTAGE - The lithium-based battery fiber can be economically manufactured with lightweight, less power consumption and enhanced strength, and improves the charge storage capabilities of the electrochemical energy storage device.    DETAILED DESCRIPTION - The lithium-based battery fiber (300) comprises a metallized fiber (200) comprising a fibrous substrate, an initiation-adhesion layer disposed over the fibrous substrate and a first metallic layer (208) disposed on the initiation-adhesion layer, an electrolyte layer (302) disposed over the first metallic layer, a cathode layer (304) disposed on the electrolyte layer, a second metallic layer (306) disposed on the cathode layer, an anode layer disposed on the first metallic layer, a protective coating layer (308) disposed on the second metallic layer, and a nanofilament layer including graphitic nanofilaments. The anode layer is formed using a wet deposition process. The nanofilament layer is formed on a surface of the fibrous substrate. The initiation-adhesion layer is formed over the nanofilament layer. INDEPENDENT CLAIMS are included for:    (1) a method of forming a battery fiber; and    (2) an apparatus for forming a metallized fiber.    DESCRIPTION OF DRAWING(S) - The diagram shows a cross-sectional view of a battery fiber.    Metallized fiber (200)    First metallic layer (208)    Battery fiber (300)    Electrolyte layer (302)    Cathode layer (304)    Second metallic layer (306)    Protective coating layer. (308)