Research On Graphene Composite Material And Its Self-driven Sensing All-in-one Devices

The emergence of portable and wearable flexible power electronic devices has given people a new experience of our daily life.At the same time,the development of flexible electronics requires more and more miniature energy devices,which not only require energy storage devices to provide excellent electrochemical performance,but also require further miniaturization,flexibility,and multifunctionality of them to meet the needs the multifunctional integration of flexible electronics.Traditional energy storage devices such as lithium-ion batteries cannot be widely used in flexible electronics due to their large size and poor mechanical properties.The emergence of self-driven sensing all-in-one devices has become a key factor affecting the development of flexible electronic devices.The design concept of the self-driven sensing all-in-one devices is to develop its multi-functional applications on the basis of micro-energy devices.One of the key factors affecting the performance of each function of an all-in-one system is the materials.Graphene,as a high specific surface area,high theoretical specific capacity,natural layered structure and other advantages,has become the most representative material for micro energy devices.Due to its energy storage mechanism,the low energy density becomes a key factor hindering its practical application.This paper will focus on the theoretical basis of energy density,prepare high-performance graphene composite materials,and develop multi-functional applications for micro-energy devices equipped with composite materials,and then prepare self-driving sensing all-in-one devices.The specific research contents and achievements are as follows:1.A novel structure of sodium ion intercalated 3D porous graphene composite electrode material is proposed.A sodium-ion intercalated nanoflower-like 3D graphene/1T-2H Mo Se₂composite electrode material was constructed using a one-pot hydrothermal synthesis method based on graphene grown by CVD on a 3D porous nickel foam framework,with high specific capacitance of 1407.5 F g^-1 and which a symmetric all-solid-state supercapacitor was fabricated with a high-power density of 3024 W kg^-1.Through theoretical calculation and result analysis,the excellent electrochemical performance of the composite electrode material is mainly attributed to the following four points:（1）The 3D porous network enables graphene to provide a larger specific surface area,which in turn provides more active sites point.In addition,the porous structure provides more transport channels for electrolyte ions.（2）The composite electrode material has the dual advantages of electric double layer capacitance and pseudo-capacitance.In addition,the advantages of the two electrode materials form a complementary effect.（3）The nanoflower-like Mo Se₂ has a larger specific surface area and more active sites,which enhances the reaction between the material and the electrolyte.（4）The successful intercalation of Na⁺,on the one hand,expands the interlayer spacing between the layers of the composite electrode material and reduces the ion transport resistance inside the material.On the other hand,the insertion of Na⁺improves the inherent poor electrical conductivity of Mo Se₂ material and further enhances the electrochemical performance of the composite electrode material.2.Innovatively developed laser-enhanced induction technology to fabricate high-performance planar micro-supercapacitors in one step on flexible substrates.By infrared laser,the carbon-containing PI substrate was induced into 3D porous graphene,and the precursor Mn Cl₂ was oxidized to Mn O₂.Due to the photothermal effect,the substrate will generate various gases,such as CO,CO₂,H₂,etc.and the gas diffusion to the environment,during the induction process.which will affect the morphology of the induced composite electrode material,forming a hierarchical pore structure composed of macroporous,mesopores and micropores,which reduces the resistance of electrolyte ions to transport and diffusion inside the material,and is conducive to the binding of ions to the active sites of the material.On the other hand,the temperature at which the laser acts locally on the substrate surface is as high as 1000°C.At high temperature,the active material is activated by high temperature annealing,providing more abundant active sites.Micro-supercapacitors fabricated with 3D porous laser-enhanced induced graphene/Mn O₂ composite electrode material have a high-power density of 1800 m W cm^-2.Due to the flexible substrate and gel electrolyte,the device exhibits both good mechanical properties and stability.3.Based on flexible micro-supercapacitors,a self-driven pressure sensing device and a self-variable-voltage visible light information transmission integrated system are constructed.The self-driven pressure sensing system can realize both energy storage and pressure sensing functions.Due to the contact resistance of the porous electrode material,the response time of the system to the pressure information is only 54 ms,and the sensitivity up to 0.45 to tiny pressures such as pulse.Based on the fact that the self-driven pressure sensing integrated system can realize the transformation of the pressure signal to the electrical signal,we have constructed a elf-variable-voltage visible light information transmission integrated system,and proposed a new solution for the self-driven,low-power visible light communication.The system is interconnected with Ga N UV LEDs on the basis of self-driven pressure sensing,and the captured pressure information is converted into electrical information and transmitted outward through optical information.In the future,based on the characteristics and advantages of the two systems,there will be unlimited application space in the field of the Internet of Everything.