Disclosed are open-framework solids that possess superior ion-transport properties pertinent to the electrochemical performance of next-generation electrode materials for battery devices. Disclosed compounds including compositions and architectures relevant to electrical energy storage device applications have been developed through integrated solid-state and soft (solution) chemistry studies. The solids can adopt a general formula of AxMy(XO4)z, where A=mono- or divalent electropositive cations (e.g., Li+), M—trivalent transition metal cations (e.g., Fe3+, Mn3+), and X═Si, P, As, or V. Also disclosed are oxo analogs of these materials having the general formulae AaMbOc(PO4)d (a≧b), and more specifically, AnMnO3x(PO4)n-2x, where A=mono- or divalent electropositive cations (e.g., Li+), M is either Fe or Mn, and x is between 0 and n/2.