Graphene Electrode Quantum Capacitance

A supercapacitor built from graphene doesn't just store charge in the electrolyte's electric double layer — the two-dimensional carbon sheet itself has a finite capacity to accept charge, called quantum capacitance, because its Dirac-cone band structure gives it a density of states that vanishes at the charge-neutrality point. This simulator renders an instanced honeycomb graphene lattice with an animated electrolyte ion layer above it and a live Dirac-cone diagram, and computes the real physics: C_Q(V,T) from graphene's linear dispersion, combined in series with a tunable Helmholtz double-layer capacitance C_H, to show why the smaller of the two — often the quantum term near the neutrality point — sets the real limit on how much charge a graphene electrode can actually store.