Temperature Effect And Its Regulation Of Carbon Nanotube Fiber-based Solid-state Supercapacitor

The rapid development of modern technology and people’s pursuit of convenient and intelligent lifestyle promote the continuous progress of flexible wearable electronic products.At the same time,the energy storage devices that complement electronic products have been explored more widely.Among them,the fiber-based supercapacitor,with the advantages of light weight,small size,high flexibility and braidability,has a great potential in the development of wearable electronic devices in the future,which has aroused the interest of a large number of domestic and foreign researchers.However,the temperature effect that cannot be ignored challenges the adaptability of flexible supercapacitors at different operating temperatures.This paper mainly discusses the influence of a certain temperature range on the electrochemical performance of carbon nanotube fiber-based supercapacitor.In order to solve the temperature-dependance of performance,the feasibility and effect of phase change thermal management were further investigated by using the phase change microcapsule.The work in this paper broadens the application of phase change microcapsules in the field of electronic energy storage and provided a reference for the temperature regulation/thermal management of flexible energy storage devices.The specific research contents are as follows:（1）Carbon nanotube fiber/carbon nanotubes/polyaniline（CNF/CNTs/PANI）composite electrode materials with 3D porous structure were prepared by electrochemical deposition.Then,a symmetrical all-solid-state supercapacitor was assembled with flexible polydimethylsiloxane（PDMS）film as substrate and polyvinyl alcohol-phosphoric acid（PVA-H₃PO₄）as electrolyte.The electrochemical properties of supercapacitors with ambient temperature range of-5～55℃were studied.The experimental results show that the fiber-based all-solid-state supercapacitor has obvious temperature dependence.The rising temperature can reduce the internal resistance and increase the capacitance of the supercapacitor.However,when the temperature is 55℃,the structure of electrode will be damaged,resulting in a decrease in capacitance,and the aging speed of the supercapacitor will be accelerated with the increased temperature.（2）A kind of inorganic phase change microcapsules（m PCMs）with n-tetrachlorane as the core material and silica as the shell material was prepared by means of interfacial condensation.The m PCMs with different mass fractions were combined with the flexible PDMS substrate phase.According to the change of the mechanical properties and heat storage properties of the composite with the ratio,the composite material with microcapsule content of 25%was selected as the substrate of the supercapacitor.A symmetrical solid supercapacitor was assembled into with the CNF/CNTs/PANI electrode material,the PVA-H₃PO₄ electrolyte and25%m PCMs-PDMS substrate.The results show that the temperature dependence of supercapacitors based on phase change composite substrate decreases under the same operating temperature range.In addition,under repeated cooling and heating at-5℃and 55℃,it is found that the electrochemical performance of the supercapacitor is closer and closer to that at25℃due to the temperature regulation of the phase change composite substrate.