Electroactive materials for metal-ion batteries

A particulate material consists of a plurality of composite particles comprising a porous particle framework having micropores and/or mesopores with a total pore volume as measured by gas adsorption between 0.4 to 2.2 cm3/g. A plurality of electroactive material domains and a plurality of modifier material domains are disposed within the pore volume of the porous particle framework, wherein at least a portion of the modifier material domains are located between adjacent electroactive material domains. The modifier material domains may comprise one or more of carbon, oxygen and nitrogen, and may be an oxide, nitride, oxynitride or carbide passivation layer formed on the surface of the electroactive material domains, a passivation layer comprising a carbon-containing organic moiety covalently bonded to the electroactive material domains, or a pyrolytic carbon material. Alternatively, the modifier material may comprise a conductive metal or metal alloy, or an electroactive material comprising a boron or phosphorus dopant. The porous particle framework is preferably conductive carbon and the electroactive material may be selected from silicon, tin, germanium, aluminium, and mixtures and alloys thereof, and most preferably comprises silicon. A method of preparing the composite particles, and their use as electrode materials in metal-ion batteries, are also described.