Differential Capacity Quantification of Non Reversible Plated Metallic Lithium Microstructures
Differential capacity sweeps at C/20 isolate non reversible plated lithium by separating reversible stripping peaks from active lithium inventory loss.
Graphite Deintercalation
Meaning
Extraction of lithium ions from the galleries between graphene layers in a carbon-based negative electrode happens during cell discharge. This graphite deintercalation restores the carbon host to its original state while releasing electrons to the external circuit. The process represents the reverse of the charging action.
Structural Response
Host materials undergo measurable volume contraction when the guest ions exit the host lattice. This graphite deintercalation causes the individual graphene planes to slide closer together, decreasing the electrode thickness. Repeated contraction can induce microcracks within the active material particles if the rate of ion removal is too high.
Electrode Dynamics
Activation energy required for the extraction process determines the voltage plateau characteristics under workload. As graphite deintercalation proceeds, the stage structure of the intercalation compound shifts from stage one to dilute stage four. This transition alters the chemical potential of the electrode and governs the open circuit potential of the battery.
Scientists analyze these phase boundaries using differential voltage curves to verify that the active graphite is fully utilized during deep discharge cycles.
Rate Limitation
Mass transport of lithium within the solid carbon matrix governs the maximum current density available during high power demand. Low temperatures restrict graphite deintercalation by reducing the solid-state diffusion coefficient of lithium ions. Consequently, the battery exhibits a lower operating voltage at sub-zero temperatures.