Each bulk water simulation contains 234 water molecules, 1 CO 2- 3 anion and 2 Na + cations in a fully periodic ∼ 18 × 18 × 18 Å liquid region, consistent with a dilute 2.6 mM solution. Electrode simulations, instead contained 468 water molecules in a ∼ 18×18×36 Å liquid region (periodic in x and y), with two atomistic electrodes consisting of 3 layers of Au atoms in an FCC structure with a lattice constant of a Au = 4.07 Å truncated to reveal the (100) surface. The electrode interfaces were taken parallel to the xy plane with normal vectors in the ±z directions. The electrode simulations are large enough to include a bulk-like region between the interfacial regions with a Debye length of ∼ 8 Å. The electrodes were treated as ideal conductors as implemented in the LAMMPS ELECTRODE package. All nonhydrogen electrolyte atoms were modeled with Drude oscillator polarizable forcefield 50,51 using the LAMMPS DRUDE package to provide an accurate treatment of the forces on the highly polarizable carbonate anion. Symmetrized Drude force fields were used to improve numerical stability with a Drude mass of m D = 0.8 g/mol. The system was propagated using a dual Nosé-Hoover thermostat 50,57 using Nosé-Hoover chains at 300 K for the atoms and 1 K for the fictitious Drude sites with a relaxation time of 0.01 fs -1 and a timestep of 1 fs. The water was treated using the swm4-ndp model, and the ions used a polarizable force field previously used to study the air-water interface. The water molecules and carbonate anion were propagated as rigid bodies using the symplectic rigid-body integrator of Kamberaj et al, freezing all internal coordinates at their equilibrium values.