Influence of the Ni Catalyst on the Properties of the Si-C Composite Material for LIB Anodes

The subject of this study was Si-C composites for lithium-ion battery (LIB) anodes obtained by carbonization of nanodispersed silicon with carbon monofluoride. To determine the possibility of increasing the degree of graphitization of nanodispersed carbon forming shells around the silicon particles at lower temperatures, nickel in the form of an alcoholic solution of Ni(NO3)2 was introduced as a catalyst into the pellets of the resulting composite. The XRD, Raman scattering and EDS methods were used to investigate changes both in the phase and elemental composition of materials resulting from the annealing of the Ni-containing Si-C composite over the temperature range of 500–1100 °C. It was found for the first time that nickel silicides that emerged during the annealing became catalysts and, at the same time, intermediate products, of cubic silicon carbide (β-SiC) synthesis, which reduced its temperature formation from ~1100 °C to ~800 °C. The same compounds had a catalytic effect on the carbon atom association, leading to an increase in the degree of its graphitization. The influence of changing the composition of the investigated material on the electrochemical characteristics of the obtained negative LIB electrodes was traced.