Single-step electrodeposition of CNT/GO–Zn composites for enhanced stability in AFLBs

Abstract

Although anode-free Li batteries (AFLBs) have the potential to provide high energy density, their practical use is hindered by challenges related to low coulombic efficiency, acceptable life cycle, and significant volume changes. Herein, zinc–carbon composites were electroplated on a Cu current collector. Both 1D (carbon nanotubes) and 2D (graphene oxide) nanostructured carbon particles were used as electroactive and stabilizing fillers to produce carbon nanotubes/Zn (CNT–Zn) and graphene oxide/Zn (GO–Zn) electrodes respectively. Lower concentrations of 0.01 g L⁻¹ Graphene Oxide (GO) and Carbon Nanotubes (CNTs) in the precursor plating solution produced composite coatings that effectively mitigated local current density fluctuations, enhancing conductivity and the mechanical strength of the coating layer. In contrast, a 0.05 g L⁻¹ concentration showed random CNT or GO aggregates. The Zn-composite electrodes demonstrated reduced plating resistance and volume expansion in half cells. Notably, the 0.01GO–Zn@Cu electrode exhibited a low nucleation overpotential. Additionally, there was an approximately 100% increase in cyclability, with an average Coulombic Efficiency (CE) above 95% for both 0.01GO–Zn@Cu and 0.01CNT–Zn@Cu cells compared to bare Cu and Zn@Cu. Full cells showed the same trend, significantly improving capacity retention and CE for composite-coated cells. GO exhibited superior electrochemical performance compared to CNTs by providing a more stable surface.