TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Cell: In the redox fuel cell, b is from 0 to 2; c is from 10 to 18, preferably 12; and d is from 30 to 70, preferably 34-40. The polyoxometallate has the formula Xa(Z1W9V3O40), or X4(Z1W11V1O40).Z=B, P, S, As, Si, Ge, Al, Go, Mn or Se, preferably P, S, Si, Al or Go.Moreover, M is absent of molybdenum (Mo), or absent of any metals other than vanadium (V) and tungsten (W). The V centers in the polyoxometallate. The M consists of 1-3 different elements, or a combination of W, V and/or Mo. Also, M comprises: (a) at least two W atoms; (b) at least four W atoms; or (c) at least six W atoms, where M consists of W. The polyoxometallate comprises H6(AlW11V1O40) and/or K2H5(SiW9V3O40). The X comprises a hydrogen and optionally alkali metal and/or alkaline earth metal ions, or an alkali metal ion and a hydrogen ion. Also, X comprises one or more of hydrogen (H+), sodium (Na+), potassium (K+) or lithium (Li+). The catholyte solution comprises at least one ancillary redox species, where the ancillary redox species is selected from ligated transition metal complexes, triphenylamine type materials, additional polyoxometallate species, and combinations. The transition metals in the transition metal complexes are selected from manganese in oxidation states II-V, iron I-IV, copper I-III, cobalt I-III, nickel I-III, chromium (II-VII), titanium II-IV, tungsten IV-VI, vanadium II-V and molybdenum II-VI. The additional polyoxometallate compound is represented by the formula: Xa(ZbMcOd). The polyoxometallate is present at a concentration of between 5% and 15% the total amount of polyoxometallate. The additional polyoxometallate comprises H6-xNaxPMo9V3O40, where x=0-3; or H6-xNaxPMo65V4O40, where x=0-4. The triphenylamine type materials for use in combination with the polyoxometallates comprise formula (I).X=hydrogen and from functional groups comprising halogen, hydroxyl, amino, protonated amino, imino, nitro, cyano, acyl, acyloxy, sulfate, sulfonyl, sulfinyl, alkyamino, protonated alkylamino, quaternary alkylammonium, carboxy, carboxylic acid, ester, ether, amido, sulfonate, sulfonic acid, sulfonamide, phosphonic acid, phosphonate, phosphate, alkylsulfonyl, arylsulfonyl, alkoxycarbonyl, alkylsulfinyl, arylsulfinyl, alkylthio, arylthio, alkyl, alkoxy, oxyester, oxyamido, aryl, fused-aryl, arylamino, aryloxy, heterocycloalkyl;R1-8=hydrogen, halogen, hydroxyl, amino, protonated amino, imino, nitro, cyano, acyl, acyloxy, sulfate, sulfonyl, sulfinyl, alkyamino, protonated alkylamino, quaternary alkylammonium, carboxy, carboxylic acid, ester, ether, amido, sulfonate, sulfonic acid, sulfonamide, phosphonic acid, phosphonate, phosphate, alkylsulfonyl, arylsulfonyl, alkoxycarbonyl, alkylsulfinyl, arylsulfinyl, alkylthio, arylthio, alkyl, alkoxy, oxyester, oxyamido, aryl, fused-aryl, arylamino, aryloxy, heterocycloalkyl, heteroaryl, fused-heteroaryl, (2-5C)alkenyl, (2-5C)alkynyl, azido, phenylsulfonyloxy, amino acid or a combination;R1 and X and/or R5 and X=may together form an optionally substituted ring structure;R1 and R2 and/or R2 and R3 and/or R3 and R4 and/or R4 and R8 and/or R8 and R7 and/or R7 and R8 and/or R6 and R5=may together form an optionally substituted ring structure; and(L)=the optional presence of a linking bond or group between the two neighboring aromatic rings of the structure, and when present may form an optionally substituted ring structure with one or both of R4 and R8 and where at least one substituent group of the structure is a charge modifying substituent.The catholyte solution is substantially free from any ancillary redox species. The concentration of the polyoxometallate in the catholyte solution is between 0.01 M and 0.6 M, preferably 0.15 M and 0.4 M. EXAMPLE - No suitable example given.