Preparation Of Bacterial Cellulose-based Thermogalvanic Cells And Their Applications In Extreme Environments

To solve the problem of energy crisis and environmental pollution,developing clean energy and improving energy utilization are effective ways to ensure the sustainable development of social.Heat energy,including waste heat,is ubiquitous in our production and life.If this part of energy can be used efficiently,this will effectively solve the crisis we faced.Thermoelectric power generation technology has attracted extensive attention due to its simple structure,no pollution and maintenance-free characteristics.With the development of the technology,a new type of thermoelectrochemical cell（thermogalvanic cell）has emerged,which has a large Seebeck value,and has the advantages of low cost and continuous output.It has a certain practical application prospect and has become one of the hot research directions.Water-based thermogalvanic cells encapsulated with quasi-solid thermogalvanic cells have attracted considerable attention because of their ability to improve the fluid leakage risk of water-based cells.However,the inherent problems of water evaporation and freezing at low temperature,as well as the poor mechanical properties after simple encapsulated,still seriously limit the applicable temperature range and long-term stability of the thermogalvanic cells,especially under harsh environmental conditions.In this paper,ultra-robust and flexible quasi-solid thermogalvanic cells was constructed by simple impregnation process using natural bio-based material bacterial cellulose as encapsulation material and mixed aqueous solution of Potassium ferricyanide/ferrocyanide as electrolyte.The prepared bacterial cellulose-based thermogalvanic cells（BC-TGCs）has excellent mechanical properties.The tensile strength,Young’s modulus and toughness are 3.4 MPa,10.77 MPa and 644.6 KJ m^-3 respectively,which are significantly higher than the existing quasi-solid thermogalvanic cells.Secondly,in order to improve the adaptability of the thermogalvanic cells in extreme environment,we introduced the strong hygroscopic salt lithium bromide into BC-TGCs,and evaluated the drying and freezing resistance of the optimized BC-TGCs through TG,DSC,weight changes and other tests.The thermoelectric performance of the optimized BC-TGCs was further evaluated,and its thermoelectric performance at different temperatures was analyzed by measuring Seebeck coefficient,electrical conductivity,cyclic voltammetry and output test.The results show that it can produce stable voltage under small temperature gradient in a wide operating range of-50°C to 50°C,and has considerable environmental tolerance,and can operate stably under harsh conditions for a long time.Finally,we successfully demonstrated the feasibility of the application of the optimized BC-TGCs in different scenarios.The results show that they can adapt to different temperatures and harsh environments,which greatly expands the application scenarios of thermogalvanic cells.This research will provide an effective solution for a portable,flexible and robust energy source for low-grade thermal energy harvesting.