Enhanced thermoelectric properties of binary CoSb3 by embedding FeCl3-intercalated graphene nanosheets

Filling the icosahedral lattice holes of the cage-compound CoSb 3 with alkali, alkaline-earth and rare-earth metal atoms can endow CoSb 3 with the transport characteristic of "phonon-glass-electron-crystal". However, the filler atoms greatly increase the cost in raw material as well as fabrication complexity. In this work, we embedded FeCl 3 -intercalated graphene nanolayers into polycrystalline CoSb 3 by a solution-dispersion method combined with spark plasma sintering technology. The graphene nanosheets were mainly distributed in grain boundaries. Due to the increased carrier concentration and mobility, the electrical conductivity was improved. Meanwhile, due to the enhanced interfacial phonon scattering, the lattice thermal conductivity was effectively suppressed. The thermoelectric figure of merit of the nanocomposite reached 0.6 at a mass content of 0.2 % FeCl 3 -intercalated graphene nanolayers, outperforming all reported values of binary CoSb 3 based nanocomposites, and even comparable to that of commercially used filled p-type Fe 3 CoSb 12 . This work provides a promising strategy for low-cost fabrication of p-type skutterudites.