Electrochemical characterization of biomass-derived anodes for potassium-ion batteries

As the global community confronts the pressing challenges of climate change, the urgency to transition to renewable energy sources becomes increasingly evident. A critical aspect of this transition involves coupling energy storage systems with renewable energy production, to address intermittency issues associated with it. However, the reliance on lithium-ion batteries (LIBs) poses significant challenges due to concerns regarding lithium scarcity, environmental impact, and escalating raw material costs. Potassium-ion batteries (KIBs) have emerged as a promising alternative to address these challenges. Potassium is abundant in nature, comprising approximately 2.6% of the Earth's crust, and its standard electrode potential (-2.93 V) is the closest to that of lithium, making KIBs an attractive option for sustainable energy storage solutions. However, the weight of the active material currently limits their application to stationary systems because it restricts energy density, while the large size of potassium ions critically hinders the development of this technology. In this optic, the quest for new anode materials becomes indispensable, and carbonaceous materials derived from biomass pyrolysis stand out as potential candidates, since they appear particularly suitable to enhance stability and performance in KIB applications. In fact, their amorphous and defect-dense structure confers unique properties upon these carbonaceous materials, including significant interlayer spacing and a pseudocapacitive charge storage behavior. Moreover, their eco-friendly and cost-effective production methods further enhance their appeal as sustainable materials for energy storage. The aim of this thesis work is to investigate the performance of various biomass-derived carbon materials as anodes for KIB applications in half-cell configuration. Following the selection of the most promising materials and the corresponding combinations of binder and electrolyte for cell assembly, the next phase involved a rigorous electrochemical and physical characterization. Techniques such as galvanostatic cycling and rate performance assessment, cyclic voltammetry at different scan rates, electrochemical impedance spectroscopy, Raman spectroscopy, X-ray diffraction, and scanning electron microscopy were employed. These analyses provided insights into critical aspects such as solid-electrolyte interphase (SEI) formation, charge storage mechanisms, and morphological structure. The selected materials, referred to as IND11 and RAIZ11, demonstrated remarkable cycling stability and reversible specific capacities at 0.05 A g-1 of 105.2 and 85.3 mAh g-1, with a capacity fading percentage of 11.2% and 6.7% after 500 cycles, respectively.