| The demand of energy sources is becoming more urgent as the depletion of traditional fossil fuels.Exploiting the highly efficient energy storage devices has fundamental importance.Supercapacitor,being its a series of outstanding performances,such as large power density,ultra-fast charge and discharge rate,long cycle life and high reliability,has being the next-generation energy storage system for potential applications in hybride electric vehicles,portable electronics,smart grids,and so on.However the low energy density still is an insurmountable bottleneck and blocks the road to realize the large-scacle promotion and application of supercapacitor.Noteworthily,electrochemical properties of supercapacitors is highiy determined by the adopted electrode materials.Intentionally heteroatom doping to obtain functionalized porous carbon with foreign elements,including boron,nitrogen,oxygen,sulfur,phosphorous,and others,is a feasible approach to lead to higher capacitance.Besides,considering the environmental concern and economic value,ideally such electrode materials should be derived from the renewable resources in a highly efficient way,and should be economical and eco-friendly.At present,agricultural waste,food residue,household waste and sludge can be seen everywhere,most of the disposal methods are landfill or incineration,which not only pollutes the environment but also wastes resources.The reallocation and utilization of waste resources can achieve the simultaneous development of environmental protection and public welfare.Nevertheless,the complex and instability ingredients of raw bimass materials also lead to the uncertainty of carbon material properties.It is urgent to develop the corresponding technology and equipment to achieve qualitative and directional biochar preparation.This paper aims to obtain porous carbon materials with high stability and big specific capacity through novel,simple and efficient interface reaction.The innovative research contents are as follows: 1.The preparation and electrochemical properties of Durian peels based N,O,P,S-tetra-heteroatom self-doped porous carbonWe developed a novel strategy that can provide an aerophilic interfacial reaction to produce tetra-heteroatom self-doped porous carbon from Durian peels in facile environment.The unique aerophilic reaction and conversion interface was automatically created due to the utilization of phosphoric acid system and the specific carbonization temperature.Combined with a following thermal treatment,N,O,S,P tetra-heteroatom self-doped porous carbon with the increased carbon edge sites could be produced.The N and S elements were originated from the biomass and the O and P elements were from the dissolved oxygen and the H3PO4 reaction medium,respectively.By using this unique preparation strategy,the obtained carbon-based materials possess large specific surface area of 1809.32 m2·g-1 and 1672.24m2·g-1.Besides,abundant oxygen-containing functional groups,which can enhance the electrical conductivity,stability and hydrophily of carbon electrode matrials,were formed on the surface of as-obtained carbon samples using this unique preparation stratagem.The electrochemical properties of electrode materials were performed using a CHI 660 E electrochemical workstation in a three-electrode cell in 6 M H2SO4 and 6 M KOH aqueous electrolyte at room temperature,where platinum sheet,Hg/Hg O electrode and tetra-heteroatom self-doped porous carbon were used as the counter,reference electrodes and working electrodes,respectively.The obtained biochar showed higher capacitance of 433.70 F·g-1 at 1 A·g-1 in H2SO4 electrolyte,and good cycling stability with 106.70% over 10000 cycles at 10 A·g-1.It also exhibited excellent rate performance that the capacitance remained 83.19% and 73.75% when increased the current density from 1 A·g-1 to 10 A·g-1 in the corresponding solution of 6M H2SO4 and 6M KOH,respectively.After being assembled into symmetric supercapacitor device and using 6M KOH aqueous solution as the electrolyte,the as-prepared biochar could deliver a specific capacitance of 158.20 F·g-1 at a current density of 1 A·g-1,with a high energy density of 21.97 Wh·kg-1 at a power density of 500 W·kg-1 within a voltage window of 1.0 V.2.The preparation and electrochemical properties of Chinese silvergrass based N,O,P-tri-heteroatom self-doped porous carbonIn order to achieve the qualitative and directional preparation of different materials,experiments were conducted to explore the use of the same aerophilic interfacial reaction and different biomass materials,so as to obtain the universality of this preparation method.Chinese silvergrass was used as the biomass raw material,and the aerophilic interfacial reaction was obtained by adjusting the solid-liquid ratio.The differences between carbon-based materials prepared by aerophilic interfacial reaction and hydrothermal closed system were analyzed.It is found that the carbon based materials with high specific capacity and good rate performance can still be obtained by using the gasophilic reaction interface.Using three-electrode system,the obtained carbon-based material through the aerophilic interfacial reaction has a specific capacity of 552.57 F·g-1 at the current density of 1 A·g-1 in 6M H2SO4 electrolyte.when increase the current density from 1 A·g-1 to 50 A·g-1,the capacitance retention rate is 84.15%.This work provides an effective and economic approach to obtain heteroatom self-doped and highly stable carbon-based electrode materials. |
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