Research On Low Temperature Resistant Energy Storage Devices Based On Composite Photothermal Conversion Layer Of Carbonized Sponge

With the emergence and widespread use of more and more portable electronic devices,people’s demand for electrical energy is becoming more and more urgent.This high intensity demand for electrical energy has also greatly promoted the research and design of energy storage devices,which have gradually become an important key technology to support all kinds of portable electronic products in modern society,and their development prospect has also attracted much attention.As supercapacitors are widely used,their performance at low temperatures has become an issue of concern.The electrolyte of supercapacitors is prone to phase change and loss of activity at low temperatures,and their electrode capacitance decreases significantly at low temperatures,thus affecting their performance.Therefore,the low temperature environment becomes a shortcoming limiting the supercapacitor.In order to overcome this difficulty,different types of composite photothermal materials are designed in this paper,and the main research contents and results include:（1）A porous CMF sponge skeleton was prepared using a high temperature anaerobic environment and used as the overall structure of the photothermal composite.Silver nanowires Ag NWs were synthesised by an improved polyol procedure and the CMF was immersed in a homogeneous dispersion of Ag NWs to finally form a three-dimensional porous carbon-based framework.The addition of Ag NWs on the CMF surface was demonstrated to have a significant enhancement effect on the photothermal conversion by thermal simulation calculations.The experimental results showed that the supercapacitor specific capacitance was enhanced by 348.41%at-20°C and 669.35%at-50°C under low-temperature environment after light exposure.（2）Preparation of Black-Ti O₂@CMF composite photothermal material,the semiconductor can absorb energy after absorbing light,which enables its electrons to leap from the original valence band to the conduction band,and the heat released from the leap of electrons from the high energy level to the low energy level can be uniformly absorbed by the CMF carbon-based grid structure and transferred to the surface of the supercapacitor electrode,which can improve the energy storage capacity of the supercapacitor in low temperature environment.The thermodynamic calculations of the photothermal materials were carried out when the surface shapes were tapered,convex,concave,serrated and flat.（3）Based on the entry point of combining carbon-based photothermal materials with carbon-based skeletons,this chapter introduces multi-walled carbon nanotubes MWCNTs compounded with CMF to obtain carbon-based composite carbon-based photothermal materials MWCNTs@CMF by exploiting the high light-absorbing properties of MWCNTs.286.35%increase in specific capacitance of supercapacitor after illumination at-15°C,-20°C and-20°C was experimentally demonstrated.The specific capacitance of the supercapacitor was increased by 211.89%after illumination at-20°C and 201.67%after illumination at-50°C.Such excellent photothermal conversion materials are also applicable to other energy storage devices in low temperature environments.