Topics

Here is a table of contents for the Electrochemical Species Band Diagram (ESBD) project.

As a main prerequisite, please read the intro page for the definition and motivation for species voltage ViV_i.

The ViV_i landscape:

Materials I - Dilute Charge Carriers:

Materials II - Electrostatics, Transport, and Complex Materials:

  • Basic electrostatics - Debye screening and the local charge neutrality approximation.
  • Capacitance - Dielectric and chemical capacitance; the capacitive divider.
  • Basic transport - Ohm's law, concentration polarization, and liquid junction potentials.
  • Saturation (application spotlight) - The common reason why current saturates in transistors and electrochemical processes.
  • Other conductors - Metals, fast ionic conductors, and mixed conductors.

Redox and electrode potentials:

  • Half-reactions - Electrons "in solution": redox and the Nernst equation in ViV_i land. Standard electrode potentials as floating levels Ve(Ox/Red)V^\circ_{\mathrm{e}^-}(\mathrm{Ox}/\mathrm{Red}).
  • Electrode potential - One electrode: visualizing EE, overpotential, and mixed potentials.
  • Reference electrodes & cells - Reference electrodes, full cells, liquid junction potentials, and the "absolute" vacuum reference.
  • Interface kinetics - The current–overpotential law: Butler–Volmer as the exponential interface element, Tafel, the diode connection, and Marcus–Gerischer.

Application highlights: (Planned, coming soon! Follow my twitter for updates.)

  • Redox-flow batteries: one redox couple per tank, exchanging H+\mathrm{H}^+ across a membrane.
  • Acid–base flow batteries: a bipolar-membrane stack whose interior runs entirely on ions; tanks in series as mutual chemical capacitors.
  • Solid oxide fuel cells: VO2V_{\mathrm{O}^{2-}} landscape.
  • Cell biology: The proton motive force as a VH+V_{\mathrm{H}^+} drop; the electron transport chain as a VeV_{\mathrm{e}^-} cascade.
  • Lead-Acid Batteries: A system where the electrolyte is a reactant.
  • Electroplating: A kinetic-driven process.
  • Corrosion: A mixed-potential, non-equilibrium system.

The rabbit holes -- appendices, advanced topics, notes:

Thermodynamics:

  • Understanding electrochemical potential - Why μˉi\bar\mu_i is the real, indivisible chemical potential — and why that makes ViV_i (and band diagrams) work.
  • Reaching any $V_i$ - Are ViV_i "real voltages"? How to access each one in practice.
  • Offsets galore - An interactive tour of every arbitrary convention in the framework — and which ones actually move anything.
  • Non-ideal solutions - Focussing on technical difficulties of single-ion activities.
  • Chemical capacitance matrices - Mutual chemical capacitance (thermodynamic) vs internal chemical capacitance (extrathermodynamic), as capacitance matrices.

Messy electrostatics:

  • $\phi$ under the microscope - Which ϕ\phi? The microscopic potential, its smoothed average, and the working convention: why ions answer to none of them.
  • Vacuum levels - The one honest potential: real, measurable, and ending at the surface.
  • Inhomogeneities and electrostatics - Per-species quasi-electric fields: what replaces "the electric field" inside materials. Plus the beyond-the-simple-case catalog.

Appendices: