| abstract |
The invention provides methods for providing composite particles with a carbon coating and the resulting core-shell particulate material. The core-shell composite particles made by the method comprise (a) a core comprising a porous carbon framework with micropores and/or mesopores with a total pore volume of at least 0.4 cm3/g and a PD50 pore diameter of no more than 10 nm, and a plurality of electroactive material (e.g. Si) domains disposed within the micropores and/or mesopores of the porous carbon framework, and (b) an outer shell comprising a pyrolytic conductive carbon material at least partially surrounding the core. The outer shell is provided by subjecting the core material and a pyrolytic carbon precursor, e.g. a hydrocarbon vapour or solution, to a heat treatment, wherein the heat treatment is carried out at a temperature of no more than 700°C. This relatively low pyrolysis temperature prevents excessive damage to the underlying core. When a vapour is used, a transition metal catalyst or nickel carbonyl may be present. The PD50 pore diameter may be no more than 5 nm. The particles are preferably used in an electrode composition, especially for use in an anode for a metal-ion battery. |