A study of the electrochemical performance of carbon materials from different types was carried out on true solid polymer-based poly(ethylene oxide) (PEO) with LiTFSI for application as the negative electrode in lithium ion solid-state batteries (LISSBs) at 60 degrees C. The reversible and irreversible capacity depend strongly on the crystallinity, the form of carbon and the impurities. A comparison of particle versus fiber was done when we investigated the charge/discharge characteristics with different current densities. The galvanostatic curves show high reversibility of the lithium-carbon in solid polymer electrolyte, The kinetics of electrochemical intercalation of lithium into carbon was studied by impedance spectroscopy especially for evaluating the diffusion coefficient in different origins of carbon. The degree of ionization of lithium was investigated by using solid-state Li-7 nuclear magnetic resonance spectroscopy when the electrode is fully intercalated or doped down to 0 V. The chemical shift of Li-7 NMR in lithium intercalation or doping in the carbons was classified in two ranges, 42 ppm and 9 ppm. Li-7 NMR suggests the carbon with a 42 ppm range is the best choice for LISSBs.