Research On The Performance Of Flexible Thermo-electrochemical Material And Device As Well As Its Application

As an emerging technology that converts thermal energy into electrical energy,thermoelectric technology has significant advantages such as zero emission and no noise.More importantly,as a sustainable energy source,it is expected to solve the problem of energy shortages and achieve carbon peaking and carbon neutrality.Conventional thermoelectric materials are mainly based on solid-state semiconductors or conductive polymers,but they suffer from the following problems:their Seebeck coefficients are low(usuallyμV·K^-1),the elements employed are rare and precious,their intrinsic stretchability and flexibility are limited.The new thermo-electrochemical cell is expected to address the above difficulties well.Compared with conventional thermoelectric technology,the seebeck coefficient of thermo-electrochemical cell is one order of magnitude higher and it owns excellent intrinsic flexibility.The overwhelming Seebeck coefficient can ensure a considerable output voltage under limited temperature difference conditions which would have great potential for wearable flexible energy devices.Because of the small temperature difference between the human body and ambient environment,devices with high Seebeck coefficient are capable of generating high voltage to directly power small wearable electronic devices and achieve self-powered.In this paper,[Fe（CN）₆]^3-/[Fe（CN）₆]^4-and I^-/I₃^-hydrogel-based thermoelectrochemical cells were synthesized and the effect of ion concentration on the thermoelectric output performance was investigated.Afterwards,a thermoelectric device based on the best performing thermoelectrochemical material was constructed.Ultimately,the device was utilized as a power source for lactic acid sensors to explore the feasibility of self-powered.The primary contents are made up of the following two parts:1.Synthesis and characterization of hydrogel-based thermoelectrochemical cell.After the successful preparation of PVA hydrogel,redox pair was introduced into the three-dimensional pores of the hydrogel by diffusion method.The thermoelectrochemical cell was endowed with high Seebeck cofficient of thermo-electrochemical cells as well as excellent flexibility of the hydrogel.Furthermore,the effect of different concentrations of redox ion on the thermoelectric output property of the material was analysed in detail.The results showed that the thermoelectrochemical cell prepared by PVA soaked in 200 m M K₃[Fe（CN）₆]/K₄[Fe（CN）₆]and 400m M KI/KI₃solutions possessed the better output performance on account of the better three-dimensional pore structure which is in favor of ionic mass transport and kinetic process.Based on the optimization of structural parameters,a flexible thermoelectric device with 3 p-n pairs were constructed.Subsequently,a thermoelectric device based on the three sets of material with the most outatanding performance was constructed and was tested to achieve a Seebeck coefficient of5.4 m V·K^-1and an output current of 1.73μA.2.Construction and performance study of a self-powered lactic acid sensing system.Firstly,taking advantage of conductive carbon cloth fiber as substrate,Pt nanoparticles were deposited on its surface by cathodic deposition method.Then,lactate oxidase and chitosan solution were coated on its surface after drying.Finally,the lactate sensor was successfully obtained.Afterwards,the mentioned thermoelectric decive was utilized as the excitation power of the lactate sensor to test its current response and anti-interference performance.The results suggested that the sensor generated different current responsive values to different concentrations of lactate solution,and the sensitivity up to 0.1μA/m M.While there is no obvious electrical response to other components in the sweat（0.02μA/m M）,indicating its excellent immunity to interference.In practical application,the system could be utilized as a non-invasive detection method to be attached to human skin and test the concentration of lactic acid in sweat according to the measured current value which can be regard as the basis for diagnosing the level of human health.