Preparation Of Expanded Graphite/Copper Nanoparticles-based Composites For Versatile Energy Storage

The environmental pollution and energy depletion caused by traditional energy have affected the development of human society.The result of efficient green energy and energy storage technology is the key to solve the above problems.Porous carbon-based materials play an irreplaceable role in the field of energy storage due to their unique physical and chemical properties,including low cost,anti-toxicity,stability,large specific surface area,excellent thermal and electrical properties and good encapsulation ability.Therefore,the development of energy storage materials with excellent thermal and electrochemical properties is one of the current research hotspots.In this paper,the three-dimensional network structure of expanded graphite/copper was constructed by the in-situ reduction method.The corresponding phase change materials and electrode materials were prepared.The main research contents are as follows:Firstly,graphite nanosheets（GNPs）and copper nanoparticles（Cu）composite porous materials were prepared using copper nitrate and expanded graphite as raw materials.High thermal conductivity EG/Cu/PW phase change composites（PCCs）were prepared using GNPs and Cu as functional matrix and paraffin wax as organic solid-liquid variable material.In PCCs,paraffin as PCM,copper nanoparticles,expanded graphite（EG）and interconnected seepage network make PCCS have high thermal conductivity.Under the load of 10-40 wt%EG,the sample’s thermal conductivity can be adjusted in the range of 4.11-34.26 W m^-1 k^-1.The highest thermal conductivity is 34.26 W m^-1 k^-1,which is about 170 times higher than pure paraffin(0.2W m^-1 k^-1),and there is almost no liquid paraffin leakage during phase transition.The composite has stable phase transformation behavior after 100 thermal cycle tests.Three-dimensional porous EG/Cu/Zn composites were prepared by electrodeposition of zinc on expanded graphite/copper nanoparticles（EG/Cu）sheets.The porous structure is conducive to the diffusion and transport of ions.At the same time,the large specific surface area of the expanded graphite also makes the electrode material contact with the electrolyte more fully,which is more conducive to guide the deposition of zinc and avoid dendrite growth.The prepared EG/Cu/Zn anode material has a reasonable rate and cycle performance as the anode material of asymmetric zinc ion battery.As a flexible electrode for mixed zinc ion capacitor,it has high specific capacitance and magnification performance and can be used as a power supply for 31cm² backlight plate.