Abstract: The invention relates to a nickel mixed hydroxide with Ni as the main element and with a layer structure, comprising at least one element Ma from the group comprising Fe, Cr, Co, Ti, Zr and Cu which is present in two different oxidation states which differ by one electron in terms of the number of outer electrons; at least one element Mb from the group comprising B, Al, Ga, In and RE (rare earth metals) present in the trivalent oxidation state; optionally at least one element Mc from the group comprising Mg, Ca, Sr, Ba and Zn present in the divalent oxidation state; apart from the hydroxide, at least one additional anion from the group comprising halides, carbonate, sulfate, oxalate, acetate, borate and phosphate in a quantity sufficient to preserve the electroneutrality of the mixed hydroxide; and water of hydration in a quantity which stabilizes the relevant structure of the mixed hydroxide.