This　paper　focuses　on　the　formulation,　fabrication　and　characterization　of　a　novel　composite　for　high-temperature　heat　energy　storage.　The　proposed　composite　is　a　shape-stable　phase　change　material　consisting　of　the　eutectic　chloride　(MgCl2-NaCl-KCl)　as　phase　change　material,　expanded　graphite　(EG)　for　heat　conduction　enhancement　and　shape　stability,　and　SiO2　nanoparticles　for　the　further　improvement　of　specific　heat　and　thermal　conductivity.　The　composite　was　prepared　following　a　three-step　procedure:　mechanical　dispersion,　tableting　and　sintering.　Concerning　the　material　characterization,　a　suite　of　techniques　were　used,　including　simultaneous　thermal　analysis　(STA)　and　laser　flash　analysis　(LFA).　The　consequences　demonstrate　that　using　EG　and　SiO2　nanoparticles　ensure　the　stability　and　preventing　the　leakage　of　the　eutectic　chloride.　A　thorough　comparison　with　the　pure　ternary　chloride　shows　that　the　composite　specific　heat　increased　up　to　1.36　times　in　solid-state　and　1.63　times　in　liquid-state,　and　the　thermal　conductivity　increased　by　23.2　and　9.2　times　in　the　solid　and　liquid　state,　respectively.　Upon　inspection　with　scanning　electron　microscopy,　a　high-density　nanostructure　was　observed　and　distributed　evenly　in　the　pores　of　EG,　which　appear　to　be　the　reason　for　the　enhancement　of　specific　heat　and　thermal　conductivity　of　the　material.　Finally,　the　nano-SiO2/MgCl2-NaCl-KCl/EG　composite　has　the　advantages　of　wide　working　temperature　range,　shape　stability,　high　specific　heat　and　thermal　conductivity,　which　has　a　promising　application　in　a　high-temperature　thermal　storage　system.　(c)　2021　Published　by　Elsevier　Ltd.