Research On Using Nano-particle Suspension To Slow Down The Self-discharge Of Supercapacitors

The super capacitor（SC）based on the electric double layer mechanism has an ultra-long service life and a high degree of reliability,and has become an important energy storage device for periodic energy storage.However,the energy loss due to the rapid self-discharge（SDC）process is still a major challenge for supercapacitors.Current research shows that the self-discharge mechanisms of supercapacitors include Faraday charge transfer,diffusion-controlled Faraday process,and leakage current.Different electrode materials and electrolyte SC systems may encounter different SDC mechanisms.This paper proposes the use of high dielectric material barium titanate（BaTiO₃）nanoparticles as an electrorheological material dispersed in the ionic liquid1-ethyl-3 methyl-imidazole tetrafluoroborate（EMIMBF₄）as an electrolyte to slow down the self-discharge of supercapacitors.Electrorheological materials are a new type of functional materials and have wide application prospects.Regarding electrorheological materials,most electrorheological fluids are suspensions made by dispersing solid particles in non-polar liquids.The solid particulate materials in electrorheological fluids are called electrorheological materials.Solid particulate materials（electrorheological materials）in electrorheological fluids are generally organic semiconductor materials,inorganic non-metallic materials and polymer semiconductor materials.Solid particulate materials（electrorheological materials）in electrorheological fluids are generally organic semiconductor materials,inorganic non-metallic materials and polymer semiconductor materials.The important components of electrorheological fluid are the dispersed phase and dispersion medium.As the dispersed phase,it should be a solid particulate material with electrorheological activity（electrorheological material）,and as the dispersion medium,it should be insulating oil or other non-conductive liquid.Under the action of an external electric field,the shear strength of the electrorheological fluid becomes larger with the increase of the electric field strength,which can achieve a rapid,continuous and reversible transition between liquid and solid,and low energy consumption.Barium titanate is a substance with high dielectric constant,which can be used as the dispersed phase of the electrorheological fluid.Under electric field,it can change the rheological properties of the fluid and increase the viscosity of the liquid.Based on the above considerations,we synthesized barium titanate nanoparticles by hydrothermal method and dispersed them in the supercapacitor electrolyte,aiming to slow down the SDC of CSs caused by diffusion and redistribution of the charged ion group adsorbed on the electrode surface-based on its electrorheological effect.Carbonized sponge as an non-toxic and inexpensive material was employed as the electrode material for this experiment.Electric double layer capacitors（EDLCs）with electrolyte containing barium titanate（BaTiO₃@Urea）nanoparticles were assembled.For electrolyte based on 11-nm BaTiO₃ nanoparticles.The voltage charged of SCs dropped from 2.0 to 1.5V in 995s.While for 17-nm nanoparticles,a volume fraction of 3%dropped from 2.0V to 1.5V for 1209.12s.The addition of barium titanate（BaTiO₃）nanoparticles as an electrorheological material can better slow down the self-discharge of supercapacitor.