Sodyum-iyon pilleri için SnO2 nanolif anot malzemesinde porozitenin etkisinin incelenmesi

In recent years, rechargeable lithium-ion batteries became the solution for energy storage due to their high energy density and good cycle life. However, low abundance and high price of lithium are concerns for grid-scale energy storage systems. For these reasons, sodium-ion batteries have emerged as a promising alternative because of sodium's very high abundance, low price and similar electrochemical behaviour to lithium. However, most of the anode materials currently used for lithium-ion batteries cannot be used in sodium-ion batteries due to large ionic radius of sodium ions. Therefore, it is crucial to explore novel materials and designs for use as anodes in sodium-ion batteries. Generally, transition metal oxides have very high sodium storage capacities and most of them are environmentally friendly. Among different type of metal oxides, tin dioxide (SnO2) has gained great attention for its high sodium storage capacity, high availability and low toxicity. However, their huge volumetric expansion and shrinkage upon cycling and inevitable pulverization of the material inhibit their electrochemical performance. In this study, we focused on fabricating porously structured SnO2 nanofibers and nanotubes for their use as anodes in sodium-ion batteries. We introduced porosity to the structure so that material can expand into the pores upon cycling. Generally, creating nano-structures is beneficial for electrochemical performance of electrodes in rechargeable batteries. Also nanofibers and nanotubes stand out because of their additional mechanical stability when compared to nanoparticles. We used facile electrospinning to produce the samples. Different amounts of mineral oil were added to precursor solutions to get porous structure and also to observe nanotube formation. Porosity in the structure provided enough room for materail to expand upon sodiation without generating high mechanical strain. Hence, electrochemical performance was greatly improved. However, further increase in the porosity did not ameliorate the electrochemical performance more, meaning benefits of porosity is not infinite. On the other hand, nanotubes performed better than nanoparticles but fell short of nanofibers due to their very high surface area and thus high vulnerability to pulverization. Nevertheless, introducing porosity in the structure proved to be simple and cost-effective way to improve electrochemical performance of the anodes.