The ability of manganese oxides to exhibit charge-storage behavior characteristic of either batteries or electrochemical capacitors (ECs) offers an intriguing opportunity to design electrode materials that innately deliver both high power and high capacity. We previously demonstrated that lamellar birnessite-type MnOx, when expressed in carbon nanofoam–based electrode architectures (MnOx@CNF), amplifies charge storage by pseudocapacitance in aqueous electrolytes (e.g., Na₂SO₄; Li₂SO₄). Herein, we extend the functionality of these established electrode materials by varying the ionic composition of the electrolyte in which they are cycled. For example, cycling MnOx/C nanofoam electrodes in aqueous 1 M ZnSO₄ yields battery-like voltammetric features reminiscent of those previously reported for “rechargeable Zn-ion batteries.” When cycling in mixed Na₂SO₄:ZnSO₄ electrolytes, we retain Zn²⁺ redox peaks, but now superimposed on a pseudocapacitive background arising from the presence of Na₂SO₄. The Zn²⁺ redox provides high capacity (up to 230 mAh g^–1 normalized to MnOx) at low rates (<5 mV s^–1), while pseudocapacitance mechanisms take over at high rates to mitigate the effects of slow kinetics for Zn²⁺ insertion. Fundamental electrochemical properties are established using a three-electrode half-cell configuration. We apply peak-current kinetic analyses (for CV data) and AC impedance to deconvolve the complex mechanisms that give rise to battery-like and pseudocapacitive charge-storage features. On the basis of three-electrode studies, we down-select electrolyte compositions for testing MnOx@CNF, paired against Zn metal, in two-electrode Swagelok cells that are subjected to galvanostatic cycling at challenging C-rates (1C–20C).