A
lithium transition metal oxide powder for use in a rechargeable battery is disclosed, where the surface of the primary particles of said
powder is coated with a first inner and a second outer layer, the second outer layer comprising a
fluorine-containing
polymer, and the first inner layer consisting of a
reaction product of the
fluorine-containing
polymer and the primary particle surface. An example of this
reaction product is LiF, where the
lithium originates from the primary particles surface. Also as an example, the
fluorine-containing
polymer is either one of PVDF, PVDF-HFP or PTFE. Examples of the
lithium transition metal oxide are either one of —LiCOdMeO2, wherein M is either one or both of Mg and Ti, with e<0.02 and d+e=1; —Li+aM′1−aO2±bM1kSm with −0.03≦a≦0.06, b<0.02, M′ being a
transition metal compound, consisting of at least 95% of either one or more elements of the group Ni, Mn, Co, Mg and Ti; M1 consisting of either one or more elements of the group Ca, Sr, Y, La, Ce and Zr, with 0≦k≦0.1 in wt %; and 0≦m≦0.6, m being expressed in mol %; and —LiaNixCOyM″O2+eAf, with 0.9<a′<1.1, 03.5≦x≦0.9, 0<y≦0.4, 0<z≦0.35, e<0.02, 0≦f≦0.05 and 0.9<(x+y+z+f)<1.1; M″ consisting of either one or more elements from the group Al, Mg, and Ti; A consisting 1000 of either one or both of S and C. For making the coated
powder, an example process comprises the steps of:—providing a bare lithium transition
metal oxide powder, mixing this powder with a fluorine-containing polymer, and heating the obtained powder-polymer mixture at a temperature between at least 50° C. and at most 140° C. above the
melting temperature of the fluorine-containing polymer.