TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Cell: Alternatively, electrochemical cell, comprises a first electrode compartment containing a first electrode; and a second electrode compartment containing a second electrode, where the first electrode comprises a first semi-solid comprising a cathode active material comprising at least one of a lithium transition metal phospho-olivine and a sodium manganese oxide, and/or the second electrode comprises a second semi-solid comprising an anode active material comprising a lithium titanate spinel; and the electrochemical cell is configured such that, during operation, none of at least one of the first and second semi-solids is transported out of the first or second electrode compartment, or, less than about 20 wt of at least one of the first and second semi-solids is transported out of the first or second electrode compartment. Electrochemical cell, comprises a first electrode compartment containing a first electrode; and a second electrode compartment containing a second electrode comprising a redox active ion-storing liquid, where the electrochemical cell is configured such that, during operation, none of the redox active ion-storing liquid is transported out of the second electrode compartment, or, less than about 20 wt. of the redox active ion-storing liquid is transported out of the second electrode compartment, and the first electrode comprises a first electrochemically active fluid and/or the electrochemical cell comprises a rechargeable battery. Electrochemical cell, comprises a first electrode compartment containing a first electrode; and a second electrode compartment containing a second electrode comprising a semi-solid electrochemically active fluid comprising an anode active material, where: the semi-solid electrochemically active fluid contains a carbon capable of exhibiting capacitive or pseudocapacitive charge storage, and the electrochemical cell is configured such that, during operation, none of the semi-solid electrochemically active fluid is transported out of the second electrode compartment, or, less than about 20 wt. of the semi-solid electrochemically active fluid is transported out of the second electrode compartment. Electrochemical cell comprises a first electrode compartment containing a first electrode; and a second electrode compartment containing a second electrode comprising an aqueous semi-solid electrochemically active fluid; where the electrochemical cell is configured such that, during operation, none of the aqueous semi-solid electrochemically active fluid is transported out of the second electrode compartment, or, less than about 20 wt. of the aqueous semi-solid electrochemically active fluid is transported out of the first or second electrode compartment. Electrochemical cell, comprises a first electrode compartment containing a first electrode; and a second electrode compartment containing a second electrode comprising a semi-solid comprising electronically conductive nanoscale particles; where the electrochemical cell is configured such that, during operation, none of the semi-solid is transported out of the second electrode compartment, or, less than about 20 wt. of the semi-solid is transported out of the second electrode compartment. Electrochemical cell, comprises a first electrode compartment containing a first electrode; and a second electrode compartment containing a second electrode, the second electrode comprising a semi-solid comprising at least one of fullerenes, carbon nanotubes, graphene, metals, metal sulfides, metal carbides, metal borides, metal nitrides, and metal oxides; where the electrochemical cell is configured such that, during operation, none of the semi-solid is transported out of the second electrode compartment, or, less than about 20 wt. of the semi-solid is transported out of the second electrode compartment. Electrochemical cell, comprises a first electrode compartment containing a first electrode; and a second electrode compartment containing a second electrode, the second electrode comprising a semi-solid or redox active ion-storing liquid, where: the electrochemical cell is configured such that, during operation, none of the second electrode is transported out of the second electrode compartment, or, less than about 20 wt. of the second electrode is transported out of the second electrode compartment, and during operation, the second electrode is circulated within the second electrode compartment. The electrochemical cell is configured such that, during operation, none of the first and second electrochemically active fluids are transported out of the first and second electrode compartments, or, less than about 20 wt. of the first and second electrochemically active fluids are transported out of the first or second electrode compartments. The electronic conductivity of the first and/or second electrochemically active fluid is at least about 10-6 S/cm. The first electrode compartment is configured such that the first electrochemically active fluid can be flowed into the first compartment, and the second electrode compartment is configured such that the second electrochemically active fluid can be flowed into the second compartment. First and/or second electrochemically active fluid comprises a semi- solid. First and/or second electrochemically active fluid contains lithium (Li+), sodium (Na+), magnesium (Mg2+), aluminum (Al3+), calcium (Ca2+), hydrogen (H+), and/or hydroxide ion (OH-). The first and/or second electrochemically active fluid contains Li+ and an ion storage compound comprising a metal fluoride. The metal fluoride comprises copper fluoride (CuF2), iron fluoride (FeF2, FeF3), bismuth fluoride (BiF3), cobalt fluoride (CoF2), and/or nickel fluoride (NiF2). Preferably: (a) first and/or second electrochemically active fluid contains Li+ and an ion storage compound comprising cobalt oxide (CoO, Co3O4), nickel oxide (NiO), copper oxide (CuO), and/or manganese oxide (MnO); (b) first and/or second electrochemically active fluid contains Li+ and an intercalation compound selected from compounds with formula Li1-x-zM1-zPO4, where M comprises at least one first row transition metal selected from the group consisting of Ti, V, Cr, Mn, Fe, Co and Ni, where x is from 0 to 1 and z can be positive or negative; (c) first and/or second electrochemically active fluid contains Li+ and an intercalation compound selected from compounds with formula (Li1-xZx)MPO4, where M is one or more of V, Cr, Mn, Fe, Co, and Ni, and Z is a non-alkali metal dopant such as one or more of Ti, Zr, Nb, Al, or Mg, and x ranges from 0.005 to 0.05; (d) first and/or second electrochemically active fluid contains Li+ and an intercalation compound selected from compounds with formula LiMPO4, where M is one or more of V, Cr, Mn, Fe, Co, and Ni, in which the compound is optionally doped at the Li, M or O-sites; (e) first and/or second electrochemically active fluid contains Li+ and an intercalation compound selected from Ax(M'1aM''a)y(XD4)z, Ax(M'1-aM''a)y (DXD4)z, and Ax (M'1-aM''a)y (X2D7)z, where x, plus y(l-a) times a formal valence or valences of M', plus ya times a formal valence or valence of M'', is equal to z times a formal valence of the XD4, X2D7, or DXD4 group; and A is at least one of an alkali metal and hydrogen, M' is a first-row transition metal, X is at least one of phosphorus, sulfur, arsenic, molybdenum, and tungsten, M'' any of a Group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB, and VIB metal, D is at least one of oxygen, nitrogen, carbon, or a halogen; (f) first and/or second electrochemically active fluid contains Li+ and an intercalation compound selected from (A1-aM''a)xM'y (XD4)z, (A1-aM''a)xM'y (DXD4)z and (A1-aM''a)xM'y (X2D7)z, where (1-a)x plus the quantity ax times the formal valence or valences of M'' plus y times the formal valence or valences of M' is equal to z times the formal valence of the XD4, X2D7 or DXD4 group, and A is at least one of an alkali metal and hydrogen, M' is a first-row transition metal, X is at least one of phosphorus, sulfur, arsenic, molybdenum, and tungsten, M'' any of a Group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB, and VIB metal, D is at least one of oxygen, nitrogen, carbon, or a halogen; (g) first and/or second electrochemically active fluid contains Li+ and an intercalation compound selected from ordered rocksalt compounds LiMO2, where M comprises at least one first-row transition metal but may include non-transition metals including but not limited to Al, Ca, Mg, or Zr; (h) first and/or second electrochemically active fluid comprises a solid comprising amorphous carbon, disordered carbon, graphitic carbon, or a metal-coated or metal-decorated carbon; (i) first and/or second electrochemically active fluid comprises a solid comprising a metal or metal alloy or metalloid or metalloid alloy or silicon; (j) first and/or second electrochemically active fluid comprises a solid comprising nanostructures including nanowires, nanorods, and nanotetrapods; (k) first and/or second electrochemically active fluid comprises a solid comprising an organic redox compound; or (l) first and/or second electrochemically active fluid comprises a solid selected from ordered rocksalt compounds LiMO2 including those having the alpha -NaFeO2 and orthorhombic-LiMnO2 structure type or their derivatives of different crystal symmetry, atomic ordering, or partial substitution for the metals or oxygen, where M comprises at least one first-row transition metal but may include non-transition metals including but not limited to Al, Ca, Mg, or Zr and the negative electrode comprises a flowable semisolid ion-storing redox composition comprising a solid selected from amorphous carbon, disordered carbon, graphitic carbon, or a metal-coated or metal-decorated carbon. The electrochemical cell comprises a positive electrode active material comprising a solid selected from Ax(M'1-aM''a)y(XD4)z, Ax(M'1-aM''a)y(DXD4)z, and Ax(M1-aM''a)y(X2D7)z, and where x, plus y(1-a) times a formal valence or valences of M', plus ya times a formal valence or valence of M'', is equal to z times a formal valence of the XD4, X2D7, or DXD4 group, and A is at least one of an alkali metal and hydrogen, M' is a first-row transition metal, X is at least one of phosphorus, sulfur, arsenic, molybdenum, and tungsten, M'' any of a Group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB, and VIB metal, D is at least one of oxygen, nitrogen, carbon, or a halogen and the negative electrode comprises a flowable semi-solid ion-storing redox composition comprising a solid selected from amorphous carbon, disordered carbon, graphitic carbon, or a metal-coated or metal-decorated carbon. Electrochemical cell comprises a positive electrode active material comprising a compound with a spinel structure. Electrochemical cell comprises a positive electrode active material comprising a compound selected from LiMn2O4 and its derivatives; layered- spinel nanocomposites in which the structure includes nanoscopic regions having ordered rocksalt and spinel ordering; olivines LiMPO4 and their derivatives, in which M comprises one or more of Mn, Fe, Co, or Ni, partially fluorinated compounds such as L1VPO4F, other polyanion compounds, and vanadium oxides VxOy including V2O5 and V6On. Electrochemical cell comprises a negative electrode active material comprising graphite, graphitic boron-carbon alloys, hard or disordered carbon, lithium titanate spinel, or a solid metal or metal alloy or metalloid or metalloid alloy that reacts with lithium to form intermetallic compounds, including the metals Sn, Bi, Zn, Ag, and Al, and the metalloids Si and Ge. The negative electrode active material comprises lithium titanate spinel. The ion-exchange medium comprises an ion-permeable membrane. First and/or second electrochemically active fluid has a steady-state shear viscosity of less than about 1.5x106 cP. The cathode active material comprises a sodium manganese oxide, where the sodium manganese oxide comprises Na4Mn9O18. Preferred Method: Assembling electrochemical cell comprises sealing the first electrochemically active fluid within the first electrode compartment, and sealing the second electrochemically active fluid within the second electrode compartment. At least one of the first and second electrode compartments has a fixed volume.