NOVELTY - A cathode (C1) comprises an electrochemically active material or combination of electrochemically active materials (M1) comprising: iron-fluorine-sulfur-oxygen compound (I); and/or a combination of iron metal, and lithium fluoride, lithium oxide, and/or lithium sulfide.    USE - As cathode for battery used in energy storage device (claimed) for electric vehicles, hybrid electric vehicles, consumer electronics, medical electronics, and grid storage and regulation.    ADVANTAGE - The cathode contains materials that participate in reactions that facilitate charge and discharge to produce electrical energy. The cathode contains a high capacity material that reversibly undergoes a redox reaction at a high rate over many cycles of charge and discharge. The high performance cathode materials maintain their good performance (e.g. high specific capacity, high energy density, high average discharge voltage, and low hysteresis) even when discharged at high rates. Their performance may not significantly degrade when the rate of discharge increases from 10 C to 100 C. The cathode materials maintain these properties over multiple cycles such as 10, 100 or 500 cycles.    DETAILED DESCRIPTION - A cathode (C1) comprises an electrochemically active material or combination of electrochemically active materials (M1) comprising: (i) a compound of the formula FeFaSbOc (I); and/or (ii) a combination of iron metal, and lithium fluoride, lithium oxide, and/or lithium sulfide, where the atomic ratio of the iron to fluorine, sulfur, and oxygen in (i) and (ii) is 1:a:b:c.    a=1-9;    b=0-3;    c=0-2.    INDEPENDENT CLAIMS are included for the following:    (1) an energy storage device comprising an anode, an electrolyte, and the cathode (C1); and    (2) preparing a cathode (C1) for a battery involving preparing an electrochemically active material or combination of electrochemically active materials (M1); and connecting the electrochemically active material to a current collector or a terminal for the battery.