Abstract: A rechargeable electrochemical cell comprising a negative electrode and a positive electrode is described. The positive electrode comprises a product having as overall formula Lip(NixMnyCozMmAlnAa)O2±b, wherein M signifies one or more elements from the group Mg, Ti, Cr, V and Fe, wherein A signifies one or more elements from the group F, C, Cl, S, Zr, Ba, Y, Ca, B, Sn, Sb, Na and Zn, and wherein 0.9<(x+y+z+m+n+a)<1.1, b<0.02, 0.9<p<1.110, 0.30<x<0.95, (y+z)?0.09, 0?m?0.05, 0?a?0.05, and 0?n?0.15. The negative electrode comprises composite particles, wherein the composite particles comprise silicon-based domains in a matrix material. The individual silicon-based domains are either free silicon-based domains that are not or not completely embedded in the matrix or are fully embedded silicon-based domains that are completely surrounded by the matrix material.

Abstract: A submicron sized Si based powder having an average primary particle size between 20 nm and 200 nm, wherein the powder has a surface layer comprising SiOx, with 0<x<2, the surface layer having an average thickness between 0.5 nm and 10 nm, and wherein the powder has a total oxygen content equal or less than 3% by weight at room temperature. The method for making the powder comprises a step where a Si precursor is vaporized in a gas stream at high temperature, after which the gas stream is quenched to obtain Si particles, and the Si particles are quenched at low temperature in an oxygen containing gas.