CFx/SiO2　composites　with　different　SiO2　sources　have　been　synthesized　as　cathode　materials　for　primary　lithium　batteries.　The　effect　of　modification　with　different　SiO2　sources　on　the　performance　of　CFx　has　been　investigated　with　FT-IR,　X-ray　diffraction　(XRD),　scanning　electron　microscopy　(SEM),　BET,　X-ray　photoelectron　spectroscopy　(XPS),　and　electrochemical　measurements　(galvanostatic　discharge,　EIS).　Based　on　the　FT-IR　and　XPS　analyses,　it　is　confirmed　that　semi-ionic　C-F　has　existed　in　SiO2　modified　CFx　and　the　F/C　has　decreased　which　may　be　caused　by　the　reaction　between　SiO2　and　CF2.　The　BET　illustrated　that　the　surface　area　of　SiO2　modified　CFx　was　extremely　larger　than　that　of　pristine　CFx.　Furthermore,　electrochemical　measurements　displayed　an　enhancement　in　the　discharge　capacity　and　plateau　of　the　CFx/SiO2　composites,　as　well　as　an　improvement　in　their　power　density　and　energy　density.　In　particular　the　CFx-mSiO(2)　exhibits　a　discharge　capacity　of　587　mA　h　g(-1),　with　a　plateau　of　2.28　V　at　a　current　density　of　5C,　accompanied　by　a　maximum　power　density　of　9689　W　kg(-1)　and　about　three　times　higher　energy　density　than　that　of　pristine　CFx.