Preparation And Electrochemical Properties Of Graphite Fluoride/Conductive Polymer Composites

Lithium batteries have been widely used in the civil and military fields due tominiature, light-weight and large capacities. Electrochemical reaction of lithiumbatteries is mainly controlled by the system composed of cathode. anode andelectrolyte materials. This system also determines the theoretical voltage, specificenergy and specific capacity. The discharge voltage, energy density and power densityof lithium primary batteries highly depends on electrochemical properties of thecathode materials. Therefore, the research of cathode materials is important toimprove electrochemical performance of lithium primary batteries.Conducting polythiophene (PTh) has been synthesized by the chemicalpolymerization, and the effect of the temperature and reaction time of polymerizationon chemical structure and electrochemical performance on PTh has been investigated.The result shows that polymerizationoccurred at the α and α positionof the thiophenemonomer at low temperature. When the polymerization temperature is0℃(PTh0),PTh is layer-packed, forming the microscopic network morphology. Meanwhile, theelectrical conductivity of PTh reaches8.4times higher than that polymerized at55℃.Results of constant current charge and discharge and alternating-current impedanceshow that PTh0has a high discharge voltage platform, lower internal resistance, andgood cycle stability.The low conductivity of graphite fluoride (CFx) cathode material is one of mainreason for low rate capability of lithium primary batteries. Therefore, the integrationof highly conductive PTh into CFx can improve the electrochemical performance ofbatteries. CFx/PTh composite has been prepared as cathode electrode material oflithium primary batteries through in-situ chemical polymerization. The influence ofthe different proportions of CFx and PTh on the electrochemical performance hasbeen studied. CFx/PTh composite shows core-shell microstructure, and PTh (shell)encapsulated on surface of CFx (kernel) forms a uniform organic polymer layer. Theconductivity of CFx/PTh composite increases7orders of magnitude compared to CFx,which improves the rate capability of lithium primary batteries. The results ofelectrochemical test show that CFx/PTh composite has good rate capability, highenergy density and power density.