Fiber electrode fabrication from spent graphite for Zn-ion batteries

The growth of the electric vehicle industry has been driven by increasing demand for sustainable transportation across various sectors. To fully transition to the era of electric vehicles, minimizing the usage of scarce and expensive metals in Li-ion batteries and developing effective battery recycling processes are two major challenges. Extensive research has focused on recycling cathodic parts of batteries, whereas comparatively little attention has been paid to anodes, primarily because graphite has a much lower value than the metals in cathodes, such as lithium, cobalt, and nickel. In this work, we established and proposed a sustainable alternative by recycling spent graphite from industrial lithium-ion battery recycling processes into fiber electrodes for Zn-ion batteries. The spent graphite was initially characterized and oxidized into graphene oxide (S_GO) before fabricating fibers via a facile and cost-effective wet-spinning technique. After chemical reduction, the reduced graphene oxide fibers were coated with MnO₂ and carbon black to obtain a fiber cathode. The fiber cathode is then assembled into a Zn-ion battery along with a Zn wire anode and xanthan gum gel electrolyte with 2 M ZnSO₄ and 0.2 M MnSO₄. The Zn-ion battery presented a maximum discharge capacity of ∼160 mAh g^-1 at 0.2C over 100 cycles.