TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation (Claimed): Preparation of (I) comprises: (a) preparing a mixture containing at least one lithium-, a manganese-, iron-, metal (M2+)- and phosphate ion (PO43-)-precursor compound, in an aqueous solution to obtain a suspension; (b) dispersing or milling the mixture and/or the suspension; and (c) reacting the suspension under hydrothermal condition to obtain (I). Preferred Process: In the step (a) or (c), further carbon containing components are added. In the step (c), the obtained (I) is mixed with the carbon containing components. The process comprises performing a drying step at less than 100 degrees C and/or a calcining step at greater than 200 degrees C. The step (c) is carried out at 100-200 degrees C and a steam pressure of 1-40 bar. Preferred Components: (I) additionally contain carbon, which is evenly distributed in the entire (I). The carbon of the each particle of the mixed (I) is covered. The amount of carbon in (I) is less than or equal to 4 wt.%. The cathode further contains lithium-metal-oxygen-compounds comprising lithium cobalt dioxide (LiCoO2) and lithium nickel oxide (LiNiO2), lithium iron phosphate (LiFePO4), lithium manganese phosphate (LiMnPO4) and/or lithium manganese iron phosphate (LiMnFePO4). The cathode is free of conductive additives. Preferred Definitions:    M = Zn or Ca;    y = greater then 0 to less than 0.15; and    x = greater than 0 to less than 0.35.    SPECIFIC COMPOUNDS - 4 Compounds (I) are disclosed i.e. lithium-manganese-metal phosphate compound of formula (LiMn(0.56)Fe(0.33)Zn(0.10)PO4) (Ia), (LiMn(0.56)Fe(0.33)Mg(0.10)PO4) (Ib), (LiMn(0.80)Fe(0.10)Zn(0.10)PO4) (Ic) and (LiMn(0.85)Fe(0.10)Zn(0.05)PO4) (Id).    EXAMPLE - Lithium hydroxide monohydrate (105.5 g) was dissolved in distilled water (0.91 g) to obtain a basic solution. Ferrous sulfate heptahydrate (77.43 g), manganese sulfate monohydrate (79.88 g) and zinc sulfate heptahydrate (24.27 g) were dissolved in distilled water and 80% phosphoric acid (103.38 g) was slowly added under stirring. Then distilled water (0.4 l) was added to obtain an acid solution. Then the acid solution and the basic solution were subsequently added in an autoclave and intensively mixed to obtain precursor mixture or suspension. The precursor mixture or suspension was heated at 100-120 degrees C, and further heated at 130 degrees C for 2 hours. Then the mixture was cooled to 30 degrees C for 3 hours to obtain lithium-manganese-metal phosphate compound (Ia).