Exploring possibility of using shungite as universal carbonaceous anode material for lithium, sodium, and potassium-ion batteries

The presented study strives to further the knowledge of materials for battery technologies based on the first alkali metal ions: lithium, sodium, and potassium. The primary aim of the discussed research was to assess the possibility of creating a universal anode material for those three battery chemistries and investigate the insertion process of different ions in that material. The proposed active material is shungite, a naturally occurring carbon-rich mineral whose turbostratic structure was demonstrated by TEM microscopy. The lithium and potassium-based batteries achieved a similar initial capacity of ∼160 mAh g⁻¹ and were able to retain 147 and 133 mAh g⁻¹ after 50 cycles, respectively. The discharge capacity of sodium battery was only 55 mAh g⁻¹ but the capacity retention and cycle stability were satisfactory, which indicates that the low value is related to the mixed mechanism of sodium ion insertion/adsorption in the macroporous material instead of the degradation of the sodiated material over time. It was revealed that the purification process assisted with an ultrasound treatment develops the specific surface area of shungite and removes sulfur-based impurities. Such treatment significantly lowers the total cell impedance and enhances the battery cycling stability.