Research Of Electrolyte Optimization Of Liquid Thermocell

In recent years,people’s demand for green and clean energy is getting higher and higher,and researchers are actively exploring various new green energy development technologies.There is a lot of wasted heat energy in the surrounding environment of human life,such as factory waste heat,solar heat,geothermal heat,ocean heat,human body surface heat dissipation,etc.The waste heat energy in the environment has various forms and abundant reserves.It belongs to green energy and has attracted extensive attention from researchers in recent years.However,due to the low temperature and easy dissipation of heat energy,it is difficult to collect and transform the heat energy.Liquid thermocell（Thermocell）,as a new thermoelectric conversion technology,has obvious advantages in low temperature differential thermoelectric conversion.In this thesis,the technology of environmental low temperature heat energy collection is studied by liquid thermocells.In the study of liquid thermal batteries,Fe（CN）₆^4-/Fe（CN）₆^3-is the most common working hydrothermal solution in liquid thermal batteries,constituting redox system,due to the high thermoelectric conversion efficiency of Fe（CN）₆^3-and Fe（CN）₆^4-.First,we studied the effect of adding large guanidine cations on the thermoelectric conversion performance of liquid thermocells with Fe（CN）₆^4-/Fe（CN）₆^3-system as redox couple.The results show that after guanidine hydrochloride is added,thermistor crystals will form in the hydrothermal solution.Thermistor crystals are beneficial to improve the difference in ion concentration between hot and cold parts of the solution,and reduce the thermal conductivity at the same time.The thermoelectric conversion ability of liquid thermocells is obviously improved.Before guanidine hydrochloride was added,the open circuit voltage,short circuit current and Seebeck coefficient were 26.5 m V,1.1 m A and 0.44m V/K respectively.After guanidine hydrochloride was added,the open-circuit voltage reached 116.4 m V,the short-circuit current reached 6.8 m A,and the Seebeck coefficient reached 2.25 m V/K.Second,in order to further improve the performance of liquid thermal batteries,N,N-dimethylacetamide,neopentarglycol,1,3-butanediol,1,4-butanediol,1,6-hexadiol,methyl propylene glycol and dipropylene glycol were selected as additives based on the mixed system of Fe（CN）₆^4-/Fe（CN）₆^3-and guanidine hydrochloride.The performance of liquid thermocells is further optimized.The results showed that the addition of the above organic compounds did not destroy the thermal crystallization properties of guanidine hydrochloride,and the electrical properties of the liquid thermocells were significantly improved.Among them,neopentylene glycol has the most obvious effect on improving thermoelectric conversion performance.Under the temperature difference of 50 K,the open-circuit voltage of liquid thermocell with neopentylene glycol can be increased from 116.4 m V to 142.9 m V.Its short circuit current increased from 6.8 m A to 7.1 m A.Se increased from 2.26 m V/K to 2.97 m V/K.This work confirmed that the addition of organic compounds such as N,N-dimethylacetamide,neopentarglycol,1,3-butanediol,1,4-butanediol,1,6-hexadiol,methyl propylene glycol and dipropylene glycol in coordination with the thermal crystallization of guanidine hydrochloride further effectively improved the performance of liquid thermocells.