METHOD OF PRODUCING PROTECTIVE SURFACE LAYERS FOR CATHODE MATERIALS FOR LITHIUM-ION CELLS

The subject of the invention is a method of producing protective surface layers for cathode materials intended for lithium-ion cells, comprising using an Nb source, a Li source, water and a cathode material for coating, which method comprises: (a) preparing a suspension by successively dispersing ethylene glycol with CHNNbO•HO, then adding water, LiOH •HO to the suspension obtained , and then a cathode material with the general chemical formula LiNiMnCoO, where x, a, b, c are numerical values and 0 < x, a, b, c < 1; wherein the individual components during dispersion in step (a) are added at time intervals of at least 5 minutes, and the process is carried out at a temperature in the range from room temperature to 80°C; wherein the water is added in a time interval before adding LiOH•HO and after adding CHNNbO •HO; (b) drying the suspension obtained in step (a) in a vacuum and then at a temperature in the range of 80 - 100°C for a period of at least 12 h, thereby obtaining a powder, and then carrying out, (c) annealing the powder obtained in step (c), in an air atmosphere at a temperature in the range of 300 - 600°C for at least 1 h, thereby obtaining a cathode material coated with a protective surface layer comprising Nb in an amount of at most 4% on the surface. The invention further includes a cathode material coated with a protective surface layer comprising Nb, which is obtained by the method according to the invention, and the use of such a material for producing a positive electrode of a lithium-ion cell comprising a cathode material coated with a protective surface layer comprising Nb, conductive carbon and a binder material.