"Gel Self-propagation" Method For The Mass Production Of Two-dimensional Carbon-based Materials For Supercapacitors

The development of supercapacitors is an important part of accelerating the process of global fossil fuel phase-out.Compared to traditional energy storage devices,supercapacitors are booming because of their ultra-high cycle life characteristics and absolute advantages in power density.Among the electrode materials of supercapacitors,carbon materials represented by graphene gradually occupy a dominant position in the field of supercapacitor electrode materials.However,the expensive manufacturing cost of graphene and its complicated preparation process make graphene unable to enter the production&application field extensively,thus deriving extensive research on graphene-like 2D carbon material as an inexpensive substitute for graphene.On the other hand,the carbon structure of a single structure and composition has a limited space for improvement.To this end,researchers are paying more attention to creating more space for the performance of materials through the construction of structures and the introduction of multi-dimensional components.Therefore,a synthetic strategy based on the structure and composition control of 2D carbon materials will reinvigorate the development of carbon materials in the field of supercapacitors.This paper is based on the macro-preparation strategy of "gel-self-propagation" method We achieved the mass production by rapidly heat-treating the gel precursor and utilizing the characteristics of self-propagating reaction to make the gel "blow" into large-sized 2D carbon nanosheets.In the subsequent work,we introduced nickel nitrate into the experimental system to realize the structural regulation of 2D carbon nanosheets by pore structure.We further introduced a carbon source in the heat treatment process,and in situ catalyzed the growth of 1D carbon nanotubes on the 2D carbon nanosheets,thereby realizing the composition control of the materials.It is worth noting that compared to other synthetic strategies,this strategy does not require multiple steps of experimental operation to achieve material preparation and subsequent optimization.In fact,we have realized the growth,structure and composition control of 2D carbon nanosheets by rationally utilizing the characteristics of the raw materials of the system and the advantages of the reaction conditions.Both the preparation of 2D porous carbon nanosheets(PNCNS)and the construction of 2D carbon-based heterostructures(PNCNS@CNTs)can be achieved only by a one-step heat treatment process.More importantly,just by changing the size of the heat treatment equipment cavity and increasing the amount of carbon source,the amplification of the production can be easily achieved.Compared with unoptimized 2D carbon nanosheets(NCNS),the surface area(SSA)of structurally controlled PNCNS increased from the initial 18 8 m~2/g to 94 8 m~2/g,and it also showed superiority.In electrochemical performance.The PNCUS@CNTs,which were subsequently component-controlled by constructing a heterostructure,exhibited a specific surface area of up to 375 8 m~2/g and exhibit a specific capacitance of 124 F/g at a current density of 1 A/g.In the subsequent investigation of the effect of heat treatment temperature,the symmetric supercapacitor assembled from the heterogeneous structural materials of the optimal condition group exhibited a device specific capacity of 40 F/g and maintained 88% of the initial capacity after 10,000 cycles,showing the huge application potential of the material system.In addition,in the extension work for this subject,we have studied the 2D carbon-based material as a conductive substrate with Ni O nanosheets and the composite material exhibits a maximum height specific capacity of 660 F/g at a current density of 1 A/g.and even at a high current density of 20 A/g a specific capacitance of 532 F/g can be also achieved,demonstrating its significant advantage as a substrate material.Finally,we extended the synthesis strategy to the gluconic acid system.The experimental results also showed the same structural characteristics and performance rules,and in this process,the environmentally friendly preparation of waste utilization was also realized.This low-cost,green and simple mass production process and the 2D carbon-based materials obtained through structural regulation and component control are expected to create more application value in the energy storage system.