Lithium battery containing cathode material and electrolyte additives for high voltage application

A lithium secondary cell having an operating voltage ≥4.35V, comprising

• a cathode comprising a powderous, doped LiCoO2 active material comprising a core and a surface layer, wherein the active material is doped by at least 0.5 mole % of one or more of Mn, Mg and Ti, and wherein
• when the active material is doped by Mg, the Mg:Co ratio in the surface layer versus the Mg:Co ratio in the core is >2, or
• when the active material is doped by Mn, the Mn:Co ratio in the surface layer versus the Mn:Co ratio in the core is >2, or
• when the active material is doped by Ti, the Ti:Co ratio in the surface layer versus the Ti:Co ratio in the core is >2;
• an anode comprising graphite, and
• an electrolyte comprising a carbonate-based solvent, a lithium salt and both a succinonitrile (SN) and a lithium bis(oxalato) borate (LiBOB) additive,
• wherein the core of the active material has a layered crystal structure and consists of the elements Li, a metal M and oxygen, wherein the metal M has the formula M=Co1-a″M′a″, with 0≤a″≤0.05, wherein M′ is Al or M′ is Al and one or more elements selected from the group consisting of Mg, Ti, Ga and B;
• and the surface layer comprises Li, Co, and inorganic N-based oxides or lithiated oxides, wherein N is one or more metals of the group consisting of Al, Mg, Ti, Ni, Mn, Fe, Cu, Ca, Ba, Y, Sn, Sb, Na, Zn, Zr and Si;
• and wherein in the active material the molar ratio Al:Co>0.004.