A composition for use in an electrochemical redox reaction is described. The composition may comprise a material represented by a general formula MyXO4 or AxMyXO4, where each of A (where present), M, and X independently represents at least one element, O represents oxygen, and each of x (where present) and y represent a number, and an oxide of at least one of various elements, wherein the material and the oxide are cocrystailine, and/or wherein a volume of a crystalline structural unit of the composition may be different than a volume of a crystalline structural unit of the material alone. An electrode comprising such a composition is also described, as is an electrochemical cell comprising such an electrode. A process of preparing a composition for use in an electrochemical redox reaction is also described.