The significance of the band structure for lithiated carbons has been widely recognized, but the band structure is so far not available either theoretically or experimentally for carbons without well-defined structures such as those used in lithium ion batteries. We demonstrate that electron spin resonance can be used to deduce the density of electronic states at the Fermi level, D(E-F), in the course of electrochemical intercalation or deintercalation and to calculate the contribution of band model mechanism to the practical lithiated carbons.