An energy storage device includes a cathodic material in an activated state; and an anodic material in an activated state; wherein: the cathodic material is a viologen covalently attached to, or confined within, a first polymer matrix, the first polymer matrix is configured to prevent or minimize substantial diffusion of the cathodic material in the activated state; and the anodic material is a phenazine, a phenothiazine, a triphenodithiazine, a carbazole, a indolocarbazole, a biscarbazole, or a ferrocene covalently attached to, or confined within, a second polymer matrix, the second polymer matrix is configured to prevent or minimize substantial diffusion of the anodic material in the activated state.