Construction Of Three-dimensional Carbon-based Materials And Their Supercapacitance Properties At High Mass Loading Level

The rapid growth of the global population and economy has created a shortage between renewable energy sources and environmental damage.Therefore,it is urgent to develop efficient,stable and environmentally friendly energy storage equipment.Supercapacitors（SCs）are becoming a rising star of energy storage equipment on the market due to their long cycle life and high power density.However,supercapacitors have the disadvantage of low energy density compared to batteries,and most of them cannot be practically applied.Therefore,increasing the energy density is an urgent problem to be solved by the current supercapacitors.However,most of the current electrode materials with high energy density are acquired under low mass loading,which cannot meet commercial application standards.This paper will be carried out from the following two tasks,the specific research content is as follows:（1）Houttuynia cordata（HC）is used to prepare hierarchical porous carbon materials and the pore ratio is adjusted by changing the mass ratio of HC to K₂C₂O₄ to prepare a series of HC-x;HC-2.5 has the best specific surface area(1498 m² g^-1).The gravimetric specific capacitance can reach up to 410 F g^-1.At the same time,HC-2.5was tested for cycle stability.After 10,000 cycles,the capacitance of material increased to 110%.（2）Two-dimensional MXene is an ideal electrode material for supercapacitors due to its excellent metal conductivity and adjustable surface functional groups.However,MXene is prone to self-stacking,which in turn affects material utilization.The three-dimensional MXene structure is currently an effective way to solve the problem of material stacking,but the rigidity of MXene makes its cycle life extremely short.In this work,we use GO as a gel and umbrella to prepare a three-dimensional MXene-r GO-Ru O₂ structure through the assembly method.By adjusting the concentration of Ru³⁺soaking solution,a series of MXene-r GO-Ru O₂-x were prepared.When the mass load is 12 mg cm^-2,the prepared MXene-r GO-Ru O₂-4 electrode has the gravimetric and volumetric capacitance of 599 F g^-1 and 1198 F cm^-3,respectively,and under 11000cycles,The capacitance value is still 95%reserved.The three-dimensional MXene-r GO-Ru O₂ structure has extremely stable ion transport channels.When the mass load of the MXene-r GO-Ru O₂ electrode increases to 48 mg cm^-2,the gravimetric capacitance and volumetric capacitance are 507 F g^-1 and 1014 F cm^-3,respectively.In addition,the electrode material also has excellent rate performance.MXene-r GO-Ru O₂is assembled into a symmetrical supercapacitor,the energy storage device has an extremely stable energy density.As the power density increases from 0.7 W cm^-3 to4.6 W cm^-3,the energy density is only 21.7 m Wh cm^-3 and decreases to 21.3 m Wh cm^-3,and the light bulb is continuously lit for several minutes in the lighting experiment.This work provides research ideas for the preparation of other mass-loading loading electrode materials.