The Research On Performance Of Prussian Blue Analog-based Electrode Materials For Thermal Battery

The development of clean energy is one of the effective ways to solve the energy crisis.Clean energy includes solar thermal,biological entities,thermal energy,wind energy and so on.Among these energy,increasing attentions are attached to the utilization and conversion of thermal energy.Thermal battery is a novel device combining heat-to-electricity conversion and energy storage,which is based on the dependence of electrode potential on temperature to construct thermodynamic cycle for direct heat-to-electricity conversion.By varing the temperature,the system is discharged at lower temperature with higher voltage than charged,thus thermal energy aborbed at higher temperature is converted to electricity at lower temperature.Thermal battery provides a new direction for the utilization of thermal energy.The Prussian blue-based analog electrode material and carbon-based composite applied on thermal battery are studies as follows:(1)Cobalt hexacyanoferrate(CoHCF)is preprared by direct precipitation method and its microstructure is analyzed.The electrochemical properties at room temperature and temperature coefficiency,heat-to-electricity conversion performance at changed temperature of CoHCF electrode are investigated.CoHCF electrode material has temperature coefficient is-0.6958 mV K-1.When the cell is tested at 45 ?C and 15 ?C,the specific charge capacity Qch,specific discharge capacity Qdis,CE,average charge voltage and average discharge voltage are 17.1171 mAh g-1,16.8720 mAh g-1,98.57%,622.0 mV and 629.9 mV,respectively.(2)A novel catalyst precursor ferrous tartrate(C4H4O6Fe)is obtained by one-step chemical synthesis.The influence of decomposition temperature on the morphology of the decomposing products is studied.Helical carbon nanotubes(HCNTs)are synthesized by chemical vapor deposition method using C4H4O6 Fe as catalyst precursor.The influence of growth temperature on carbon products’ morphology is investigated.Beside,the post treatment on HCNTs affects its properties.When temperature is higher than 600 ?C,the decomposing product of C4H4O6 Fe is porous Fe microparticle.The optimal growth temperature of HCNTs is 550 ?C in the experiment.(3)Cobalt hexacyanoferrate/helical carbon nanotubes(CoHCF/HCNTs)composite is synthesized by coprecipitation method and its microstructure is characterized.The electrochemical properties at room temperature and temperature coefficiency,heat-to-electricity conversion performance at changed temperature of CoHCF/HCNTs composite are analyzed.Compared to CoHCF as electrode alone,the composite exhibits better electrochemical and heat-to-electricity converson performance.CoHCF/HCNTs electrode material has temperature coefficient is-0.8903 mV K-1.When the cell is tested at 45 ?C and 15 ?C,the specific charge capacity Qch,specific discharge capacity Qdis,CE,average charge voltage and average discharge voltage are 20.2 mAh g-1,19.5 mAh g-1,96.53%,589.2 mV and 605.3 mV,respectively.