This study comprehensively investigates three types of graphite materials as potential anodes for potassium-ion batteries. Natural graphite, artificial carbon-coated graphite, and mesocarbon microbeads (MCMB) are examined for their structural characteristics and electrochemical performances. Structural analyses, including HRTEM, XRD, Raman spectroscopy, and laser particle size measurements, reveal distinct features in each graphite type. XRD spectra confirm that all graphites are composed of pure carbon, with high crystallinity and varying crystal sizes. Raman spectroscopy indicates differences in disorder levels, with artificial carbon-coated graphite exhibiting the highest disorder, attributed to its outer carbon coating. Ex-situ Raman and HRTEM techniques on the electrodes reveal their distinct electrochemical behaviors. MCMB stands out with superior stability and capacity retention during prolonged cycling, attributed to its unique spherical particle structure facilitating potassium-ion diffusion. The study suggests that MCMB holds promise for potassium-ion full batteries. In addition, artificial carbon-coated graphite, despite challenges in hindering potassium-ion diffusion, may find applications in commercial potassium-ion battery anodes with suitable coatings. The research contributes valuable insights into potassiumion battery anode materials, offering a significant extension to the current understanding of graphite-based electrode performance.

MCMB (Mesocarbon microbeads) is a kind of anode material for lithium-ion secondary battery. MCMB charge/discharge cycle stability is one of the important criterion at lithium-ion battery operation. In this study, the cycling stability of a lithium-ion secondary battery has been examined. MCMB was made by the direct solvent extraction method. After the MCMB was carbonized and graphitized, the measurement of charge/discharge capacity and efficiency were carried out. In the result, discharge capacity of MCMB in the initial cycle was above 290.0 mAh/g. After the second cycle, efficiency of charge/discharge MCMB was about 98%. These results were similar to the commercial MCMB product.

MCMB (mesocarbon microbeads) has been synthesized from coal tar pitch, petroleum pitch and polymer compound generally. But yield of MCMB was low about 20~40 wt% and was not above 50 wt%. Neither MCMB was replaced with natural graphite because of economic performance, refining MCMB, and control of the particle size distribution. This study was performed to elevate yield of MCMB and to develop technique of particle size distribution. As the result, yield of MCMB that was synthesized from coal tar pitch increased more than 60 wt% about raw material and particle size of MCMB was restrained according to control of QI (quinoline insoluble) ingredient in raw pitch, heat treatment temperature and time.