UNUSUAL CYCLING BEHAVIOR OF DISORDERED CARBONS IN LI/C CELLS

Much work has been done on the use of carbon as an anode material for secondary lithium cells. Here we report on lithium intercalation in very disordered carbons such as glassy carbon and carbon black. These carbons show novel features not seen in the intercalation of more ordered carbons such as graphite and petroleum coke. Extra capacity is seen when the disordered carbons are cycled above room temperature. This capacity does not depend upon the choice of electrolyte, but depends strongly on the lower voltage limit. When the cells are discharged to close to zero volts, extra capacity is observed around 0.9 V on charge. A simple thermal trapping model does not explain the observed behaviour.