Supercapacitor Device Based On Elastic Graphene Aerogels For Sensitive Elastic-electrochemical Stress Sensor

Supercapacitors,also known as electrochemical capacitors(ECs),can serve as a new type of energy storage device by virtue of characteristics such as high energy density,a rapid charge-discharge rate and long cycle l ife in comparison with traditional secondary batteries and conventional dielectric capacitors.The preparation of high-performance electrode materials has been the research focus of supercapacitors.To effectively improve the performance,the development of compressible flexible supercapacitor via a facial and low-cost method is significant.Besides,a few studies make it possible for harvest electrical energy from mechanical work.Those researches provide us a new idea to associate the force with electrochemistry to expand the application field of surpercapacitor.Consequently,it is of great importance to explore the interaction between the force with electrochemistry under external stress.The specific research contents of this thesis are as follows:(1)A superelastic and active graphene aerogel with nitrogen and boron co-modification is developed by a simple naturally drying post-process.The resulting aerogel owns a robust three-dimensional architecture which exhibits highly repeatable compressibility even under 80%strain.In addition,the aerogel material offers a high specific capacitance of 336 F g-1 at 0.25 A g'1,the energy density of 13.99 Wh Kg-1 at the power density of 47.25 W Kg-1,and 90.74%specific capacitance retention even after 2000 cycles.Based on the symmetrical aerogel electrodes in a supercapacitor-type device structure,a facile novel self-powered stress sensor is developed preliminarily.(2)To explore the interaction between the force with electrochemistry under external stress in deep,a compressible all-solid-state graphene aerogels supercapacitor is synthesized using natural-drying method.The device exhibits with high energy density of 23.08 Wh Kg-1 at 240 W Kg-1.Taking advantage of the compressibility and excellent electrochemical performance of the graphene aerogel,a new type of stress sensor called elastic-electrochemical stress sensor is designed.The cell presents stable and sensitive current responses towards the applied stress by transforming mechanical energy to electrochemical energy.The high sensitive elastic-electrochemical stress sensor provides a new understanding on the mechanism of interaction between force and electrochemistry.(3)We further apply this elastic-electrochemical model to asymmetrically elastic electrochemical supercapacitor which is fabricated using CoMn2O4/rGO as positive electrode and ternary N,B,and S co-doped elastic graphene aerogel as negative electrode.The combination not only endows the device superior energy density of 53.33 Wh Kg-1 at a high density of 400.00 W Kg-1,but also offers a facile sensor application to feel external mechanical load with outstanding elasticity.Under the loading stress range from 0.1 to 10 N,the cell demonstrates sensitive current response towards the applied stress.It is observed that the elastic graphene aerogel offers important role by adjusting internal electric field,electric charge density and electrolyte contact in the device.(4)Among the supercapacitor materials,metal-organic frameworks represent a new kind of well-ordered porous materials with superior properties.In this work,a novel type of metal-organic frameworks derived porous hybrid octadecahedron oxides is reported.Owing to the peculiar polyhedral feature which exposes more active sites on their surfaces,the as-prepared hybrid octadecahedron oxides exhibit superior electrochemical storage performance with a capacitance of 948 F g-1 at a current density of 1.0 A g-1 and achieves a high energy density of 32.90 Wh Kg-1 at a power density of 250 W Kg-1.Our new-type octadecahedron cage structure offers a new opportunity for future MOF nanoarchitecture design.