Graphite Fiber Electrode by Continuous Wet-Spinning

In this study, we propose a graphite fiber electrode with electrochemical stability and mechanical flexibility for a possible application as wearable batteries. Graphene oxide (GO)-supported graphite fiber electrodes with a uniform diameter of 50 μm and a length of over 50 m are fabricated by a continuous wet-spinning process. GO, which is a thin sheet with 30–50 μm diameter and exhibits a liquid crystal behavior in its dispersion, can enhance the fiber formability and alignment of the graphite during wet-spinning. Scanning electron microscopy visualizes that the graphite plates with approximately 3 μm diameter are firmly wrapped by the GO sheets. A chemical treatment using hydrazine vapor reduces GO in the fiber, which is confirmed by Raman spectroscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, and electrical conductivity measurement. As a result, we successfully fabricate the rGO/graphite fiber electrode with graphite content as high as 70%. A fiber cell is assembled using the rGO/graphite fiber electrode and lithium wire counter electrode. The fiber cell shows an initial capacity of 265 mA h g–1 and maintains excellent capacity retention during 100 cycles except for the capacity loss in the initial cycles.