This technology is a method for producing silicon nanomaterials by mixing graphene oxide with silica-containing colloids, such as colloidal silica or exfoliated clay, to create a powder, followed by heat treatment with alkaline earth metals like magnesium to simultaneously reduce the silica and graphene oxide. This results in a composite where silicon and graphene are hybridized in a sheet-like structure.
While silicon has garnered attention as a high-capacity anode material for lithium secondary batteries, it suffers from significant volume expansion and contraction—up to approximately 400%—during charge and discharge cycles, which breaks contact between particles. This leads to reduced electrical conductivity and rapid capacity degradation.
This technology uses a magnesiothermic reaction to simultaneously produce silicon and graphene by adding alkaline earth metal cations to a graphene oxide-containing colloid, followed by restacking or freeze-drying to form a powder, and heat-treating it at 300–1,000°C in an inert or reducing atmosphere. Subsequent acid etching removes byproducts to yield high-purity nano-silicon, while the graphene buffers volume changes and maintains conductive pathways. Applicable to silicon-graphite hybrid anodes for EVs, high-capacity mobile device batteries, and mass production of silicon anode additives, this process enables the creation of volume-expansion-resistant silicon-graphene anodes using inexpensive silica raw materials and relatively low-temperature reduction.
WO2015-091968A1
