Hysteresis during Lithium Insertion in Hydrogen‐Containing Carbons

We studied lithium insertion in hydrogen‐containing carbons heated at temperatures near 700°C. High capacities with large hysteresis (lithium insertion into these carbons at nearly 0 V and removal at nearly 1 V) were shown to be proportional to the hydrogen content of the samples. It is believed that the lithium atoms may bind on hydrogen‐terminated edges of hexagonal carbon fragments, causing a change in the bond from sp 2 to sp 3 . We have carefully studied the electrochemical insertion of lithium in hydrogen‐containing carbons using a variety of charge‐discharge rates and cycling temperatures. These measurements allow the hysteresis to be quantified. A simple model, which treats the bonding change as an activated process, is used to model the hysteresis in the cells qualitatively.