NOVELTY - Electrode comprises a cubic ionic conductor compound having a framework (I) and a cation compound (II).    USE - The electrode is useful in an electrochemical cell (claimed) and electrochemical storage devices for vehicles, where the electrochemical cell includes a lithium-ion battery, a hybrid-ion battery, a sodium-ion battery, a semisolid flow cell batteries, hybrid electrochemical cells, supercapacitors, fuel cells and redox-flow batteries.    ADVANTAGE - The electrode exhibits high ionic conductivity, thermal stability, energy density and purity and improved reversible electrochemical cycling properties, and improves charge/discharge rate performance and reduces the power consumption of the battery.    DETAILED DESCRIPTION - Electrode comprises a cubic ionic conductor compound having a framework of formula ((MT3X10)(n-)) (I) and a cation compound of formula (AxMT3X10) (II), where a T3X10 trimer of a TX4 tetrahedra share one common X anion is organized around an octahedral MX6 site such that each MX6 octahedron is connected to three different T3X10 trimers by two bridging X anions connected to two different TX4 tetrahedra within the T3X10 trimer.    M = cation in octahedral coordination;    T = cation in tetrahedral coordination;    X = anion;    n = net charge of the framework of 0-16;    A = variable number of additional non-framework chemical species that can fit into an open space within the framework with a net charge of +n; and    x = less than 10.    INDEPENDENT CLAIMS are included for:    (1) a solid electrolyte comprising the cubic ionic conductor compound;    (2) a composition comprising a nitrophosphate compound of formula (A3-xLiyM(PO3)3N) (AA), (A3-xLiyM(z-w)(PO3)3N) (BB) or (A(M)2-xLiyA1M(z-w)(PO3)3N) (CC);    (3) an electrochemical cell comprising a cathode, an anode and an electrolyte solution, where the cathode comprises the electrode; and    (4) synthesizing substantially pure crystalline nitrophosphate comprising either mixing stoichiometric amounts of a metal oxide, a metaphosphate and urea, heating the mixture to 300-400 degrees C under flowing ammonia gas for 1-10 hours, heating the mixture to 700-800 degrees C for 10-30 hours under flowing ammonia, and collecting the substantially pure crystalline nitrophosphate, or mixing stoichiometric amounts of metal oxide, sodium acetate, and diammonium hydrogen phosphate, heating the mixture to 300-400 degrees C for 1-10 hours, and heating the mixture to 600 degrees C for 10-30 hours under flowing ammonia, or dissolving sodium metaphosphate into solution, ammonium metal, citric acid and urea in water to form solution, heating the solution at 60-90 degrees C for 1-10 hours, drying the resulting solution to obtain a dried gel, grinding or ball-milling the dried gel, heating the dried gel to 400 degrees C in air for 10-20 hours to obtain a resulting material, and heating the resulting material at 600-800 degrees C for 10-20 hours under flowing ammonia gas.    y = 0.