| Graphene with unique two-dimensional atomic-thick planar structure,high surface area,excellent mechanical and electrical properties,have been widely used as electrode materials that can overcome the shortcomings of traditional carbon materials.Based on the intrinsic properties of graphene,graphene assembled into three-dimensional macroscopic structures such as porous films and networks have good mechanical properties,excellent electrical conductivity and large specific surface area,which has become one of the materials that have attracted the attention of researchers.In this dissertation,heat treatment,laser treatment,and laser-induced oxidation were employed to regulate the graphene structure with high mechanical strength,good conductivity,and outstanding electrochemical properties for the application of flexible supercapacitors.The main contents of the paper are as follows:（1）Boron and Nitrogen co-doped holey graphene aerogels（BN-HGA）are fabricated using ammonia borane as a triple-functional precursor.The as-prepared BN-HGA possesses a high specific surface area(249m2 g-1)and rich B-N motifs with high surface polarity,which contributes to the rich and stable redox sites for the enhanced pseudo-capacitance.Moreover,the high hydrogen content in the ammonia borane cultures a reducing environment to preserve the integrity of the carbon matrix,which gives rise to the high electronic conductivity.In addition,the well-developed hierarchically porous structure facilitates the ion diffusion in the electrode.Thanks to these structural merits,the BN-HGA electrode furnishes good specific capacitance of 456 F g-1 at 1 A g-1 in three-electrode systems using sulfuric acid as the electrolyte.Meanwhile,the all-solid-state flexible supercapacitors based on the symmetric BN-HGA electrodes demonstrate high specific capacitance(345 m F cm-2 at 1 m A cm-2)and outstanding rate performance(80%retention at 20 m A cm-2).Furthermore,the flexible supercapacitor exhibits pleasant flexibility with marginal capacity loss as bent to arbitrary angles,which endows it a promising device for wearable energy storage.（2）Freezing-unfreezing cycles were adopted to prepare the PVA-H3PO4 gel film with strong toughness.Graphene oxide（GO）solution is sprayed on the surface of the gel film under a tensile state to form an ultrathin GO film.The film is treated by laser scanning at a wavelength of 450 nm under Ar/H2 mixed atmosphere.Raman spectroscopy confirms that laser treatments greatly improve the reduction and conductivity of the film and form a rich pore structure of graphene by controlling the laser intensity.Meanwhile,the laser not only does not impair the function of the gel electrolyte but also enhances the interface connection between the graphene and the gel layer.Using silver glue to connect the electrode to test the flexible,micro,and editable supercapacitor’s performances.The device with high volume-specific capacity and volume-specific power can achieve 3.0 F cm-3 under 8 m A cm-3.And we can increase the operating voltage and current of the device through series and parallel them.The devices in series can be integrated with a LED lamp for wearable devices.Moreover,the synthesized supercapacitors have good flexibility and stability and can form different shapes of supercapacitor applications by simple encapsulation and tailoring.（3）Based on the good flexibility and excellent electrical conductivity of commercial carbon fibers,the linear supercapacitors were obtained by using laser surface oxidation treatment to induce graphene structure on the surface of commercial carbon fiber in an ozone atmosphere.The volume（length）capacitance of the linear supercapacitor assembled by this method is 4.7 F cm-3(1.8 m F cm-1)at the current density of 87.0 m A cm-3(0.0667 m A cm-1).With the increase of the power density,the energy density is 0.15 m W·cm-3and the power density is 10.78 m Wh·cm-3.The energy density remains at 0.13 m W·cm-3 when the power density reaches 205.4 m Wh·cm-3.The device can still maintain good capacitive performance under the condition of bending or even knotting tests,indicating its good flexibility and can be applied to braided devices. |
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