A composite powder for use in the negative electrode of a battery and a battery comprising such a composite powder

A composite powder for use in a negative electrode of a battery, the composite powder comprising composite particles, which comprise a matrix material and silicon, wherein the composite particles have a volumetric particle size distribution having a d10 and a d90, wherein, over at least part of the size range from d10 to d90, the composite particles have a size-dependent silicon content, with a positive correlation between the particle size and the silicon content, wherein a fine fraction of the composite powder has an average particle size D1 and a silicon content S1 and a coarse fraction of the composite powder has an average particle size D2 and a silicon content S2, and a size dependence factor F is defined as F=(S2−S1)/(D2−D1), wherein the value of the size dependence factor F is at least 0.04 wt % silicon/μm, and wherein D1 is defined as the d50-value of the volumetric particle size distribution of the fine fraction as measured by laser diffraction and D2 is defined as the d50-value of the volumetric particle size distribution of the coarse fraction as measured by laser diffraction.