NOVELTY - An electrochemical composition comprises a cocrystalline material; and a cocrystalline oxide of element(s) from transition metal elements, zinc, cadmium, beryllium, magnesium, calcium, strontium, boron, aluminum, silicon, gallium, germanium, indium, tin, antimony, or bismuth.    USE - The composition is used in an electrochemical redox reaction (claimed). The composition may be useful in a variety of applications, environments and devices, e.g. an electrode (claimed) (e.g., a cathode) and an electrochemical cell (claimed) (e.g., a battery).    ADVANTAGE - The composition has good structural stability and electrochemical reversibility. The electrochemical cell comprising the electrode made of the composition may provide good charge/discharge capacity, good charge/discharge capacity retention, and/or good charge/discharge rate capability.    DETAILED DESCRIPTION - An electrochemical composition comprises a cocrystalline material represented by a general formula MyXO4, where the material is capable of being intercalated with ionic A to form AxMyXO4; and a cocrystalline oxide of element(s) from transition metal elements, zinc, cadmium, beryllium, magnesium, calcium, strontium, boron, aluminum, silicon, gallium, germanium, indium, tin, antimony, or bismuth. A volume of a crystalline structural unit of the composition is larger than a volume of a crystalline structural unit of the material alone.    M=element(s) from transition metal elements, Zn, Cd, Be, Mg, Ca, Sr, B, Al, Si, Ga, Ge, In, Sn, Sb, or Bi;    X=element(s) from P, As, Si or S;    A=element(s) from alkali metal elements, Be, Mg, Cd, B, or Al; and    x, y=0.8-1.2.    INDEPENDENT CLAIMS are included for:    (1) an electrode, comprising the electrochemical composition;    (2) an electrochemical cell, comprising the electrode; and    (3) a process of preparing the electrochemical composition, comprising combining a first material comprising the M, and a solution comprising a second material comprising the X, to produce a resulting solution, where the second material correspondingly comprises material(s) from phosphate, arsenate, silicate or sulfate; obtaining a particle mixture from the resulting solution; milling the particle mixture with an oxide of element(s) from transition metal elements, zinc, magnesium, aluminum or silicon, to produce a semicrystalline particle mixture; drying the semicrystalline particle mixture to provide a precursor; and calcining the precursor to produce a composition comprising the cocrystalline oxide and the cocrystalline material, where the composition is capable of being intercalated with the ionic A to form the AxMyXO 4.