Fiber electrode for lithium secondary battery, fabrication method therefor, and lithium secondary battery including fiber electrode

Abstract

Provided is a method for mass manufacturing, at low cost, of a fiber positive electrode for a lithium secondary battery, which has excellent charge/discharge cycle characteristics, and which is capable of charging/discharging with high current density, and a main active material of which is a lithium-doped transition metal oxide. The method includes the steps of: (a) forming a tubular coating of either a transition metal oxide or a transition metal hydroxide on a carbon fiber current collector; and (b) performing, in a lithium ion containing solution in a sealed system under presence of an oxidant or a reductant, heat treatment at 100 to 250° C. on the carbon fiber current collector, on which the tubular coating of either the transition metal oxide or the transition metal hydroxide is formed, to obtain a coating of a lithium-doped transition metal oxide on the carbon fiber current collector. Further provided are: a fiber negative electrode for a lithium secondary battery, which has high current density, high energy density, and excellent charge/discharge cycle characteristics, and which can be fabricated in a relatively easy manner; and a method for fabricating the fiber negative electrode. The fiber negative electrode for a lithium secondary battery includes: (c) a carbon fiber current collector; (d) an outer layer which is a tubular composite layer of a Sn oxide and MOformed on the carbon fiber current collector; and (e) an intermediate layer formed of a Sn alloy, which has a lithium occlusion capacity and which is present at an interface between the carbon fiber current collector and the outer layer. The method for fabricating the fiber negative electrode for a lithium secondary battery includes: forming a coating of one of Sn and a Sn alloy, and a coating of at least one kind of metal selected from the group consisting of Fe, Mo, Co, Ni, Cr, Cu, In, Sb, and Bi, on a carbon fiber current collector by an electroplating method; and then performing heat treatment on the carbon fiber current collector under a trace oxygen atmosphere at 350 to 650° C. Moreover, the lithium secondary battery includes: the fiber positive electrode and the fiber negative electrode fabricated in the above methods; and an electrolyte.