Preparation and optimization of hard carbon anode for aqueous metal-ion battery systems

This study focuses on preparation and optimization of hard carbon, as an anode material for more sustainable aqueous metal-ion battery systems. Various ratios of active material/conductive agent/binder have been utilized in water-based electrode preparation and characterized via different electrochemical methods. The anode performance was tested in several aqueous electrolytes, containing monovalent and divalent cations such as sodium, potassium, zinc, and magnesium, additionally, double ion systems, with sodium and zinc together, have been utilized, the electrochemical performance was mainly evaluated via cyclic voltammetry (CV), although, other methods including AC impedance spectroscopy (EIS) and open circuit potential test (OCPT) were also adopted. These experiments were conducted using both coin cell and glass cell configurations, additionally assessing the cell performance in the symmetric systems was also performed. To ensure comprehensive understanding of obtained results, Dunn's equation was used, as a method to determine whether the system exhibited capacitive or battery like behavior in different electrolytes. Further morphological and compositional analysis of the formulated anodes, as well as cycled electrodes were conducted using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX), as a tandem approach to identify the quality of electrodes, in terms of uniformity and homogeneity in both, morphology/structure, as well as the elemental distribution; and most importantly, to evaluate the modification, if any, after the cycling of the electrode. The results of this study are aimed to deepen the understanding of the interaction between hard carbon anodes and different aqueous electrolytes, providing valuable insights for the advancement of sustainable energy storage technology.