HYBRID CARBON MATERIALS FOR SODIUM-ION BATTERY ANODES

There is a demand for new affordable and inexpensive batteries, such as those based on sodium, but sodium-ion battery (NIB) technology is still in its early stages of development. The development of high-performance anodes and a full understanding of sodium storage mechanisms are the main issues that need to be solved. Lithium (LIB) and sodium ion batteries (NIB) have similar components and a similar electrochemical principle of operation. Graphite, the most common anode material used in commercial LIBs, exhibits poor electrochemical performance when used in NIBs. For NIBs, non-graphitic carbon is widely used as an anode material, since sodium ions can intercalate into pseudographitic domains and be reversibly adsorbed on surface edges, defects, and nanosized pores. In the present work, hybrid carbon materials based on the non-graphitizable phenol-formaldehyde resin with graphite-containing additives such as colloidal graphite (CG) and graphene modified with phenol-formaldehyde groups (GMF) were prepared and investigated as anodes for sodium-ion batteries. On the basis of the FF11 precursor, two series of experiments were carried out on the synthesis of 3 anode materials with the addition of 0.2; 1 and 5 wt. % graphite additives of the carbon mass in the resin. The fabricated materials were studied by transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. As a result of electrochemical measurements, it was established that the presence of CG additives in the FF11 anode material does not lead to a significant change in the shape of the charge-discharge curve and discharge capacity, however, it significantly improves the material cyclability: the Coulombic efficiency of the charge-discharge cycle in this case reaches 99.8-99.9% at 250 mAh/g discharge capacity. On the opposite, the introduction of GMF additives into the anode material leads to a significant increase in capacity, which reaches 293 mAh/g at an additive content of 5%, while the Coulombic efficiency remains at the level of 96.5-98.5%. It is shown that all investigated anode materials are characterized by high cyclic stability.