Research On The Application Of Wood Derived Carbon Composite Electrode In Micro-Supercapacitors

The rapid development of micro-electronic devices and micro-modular design has greatly increased the urgent demand for micro-electrochemical energy storage devices.Among them,high energy density 3D micro supercapacitors（3D MSCs）have received widespread attention as important micro energy storage modules in portable electronic devices.However,the low energy density,complex construction strategies,and low assembly accuracy of 3D MSCs restrict their practical applications.To address the above issues,this paper uses a three-dimensional wood-derived carbon conductive skeleton structure as a support and modifies a series of wood-derived carbon based self-supporting composite materials with high specific capacity electrode materials（CNTs,Mn O₂,Zn）.Using laser shaping technology,different types of mortise and tenon supported micro supercapacitors with high energy density are constructed.The main research work is as follows:Firstly,constructed micro-electrode with tenon structure based on laser micro-nano processing technology,and constructed high-capacity wood-derived carbon-based micro-supercapacitor by means of the hole frame positioning and assembly.In this work,alkyl-etched and high-temperature annealing processes were used to obtain Pinus sylvestris derived carbon.Nitrogen doped carbon nanotube arrays（N-CNT-WDC）were grown in situ on wood derived carbon surface and inner tube wall by vacuum impregnation and chemical vapor deposition techniques（CVD）.Tumbleweed shaped three-dimensional interconnected carbon nanotube network inside and wood-derived carbon pore provides abundant ion transport and electron conduction paths,which is conducive to the improvement of the performance of micro-supercapacitors.In order to further increase the specific surface area of the interdigital electrode,the alkali etching activation treatment of N-CNT-WDC is conducive to the formation of micropores and mesoporous pores on N-CNT-WDC,and promotes the full infiltration of electrolyte.N-CNT-WDC three-dimensional micro-supercapacitor packaged with Li Cl/PVA gel electrolyte presents excellent specific capacitance of 94 F cm^-3and excellent capacitance retention.The high volume energy density up to 12 m W h cm^-3 under the high current density.After 10000 cycles,the capacity retention rate is more than 85%,which have good cycle stability and long life.Secondly,broadening the potential window is an effective way to increase the energy density of 3D MSCs.Therefore,in this work,Mn O₂ clusters as were modified active substances by simple electrochemical deposition technology（ECD）on the three-dimensional skeleton structure of wood-derived carbon,which combined with N-CNT-WDC interdigital microelectrodes.An asymmetric micro-supercapacitor（AMSC）with wide potential window is constructed.By means of mortise and tenon positioning,the precise assembly of asymmetric electrode and the editable integration of micro supercapacitor are realized.AMSC has excellent specific capacitance of 108 F cm^-3,volume energy density of up to 38 m W h cm^-3 at the high current density.After 10000charging and discharging process capacitance retention rate is close to 90%.Three devices in series can be achieved output voltage of 4.8 V.It is better than most reported3D carbon based asymmetric supercapacitors.Thirdly,in order to further broaden the potential window and improve the energy density,this work constructed wood-derived carbon micro zinc ion hybrid capacitor（ZMSC）.By modifying N-CNTs and Zn at the positive and negative of ZMSC by ECD and CVD,respectively.3D ZMSC has an excellent specific capacitance of 423 F cm^-3,with a power density of up to 900 m W cm^-3 at a volume energy density of 91.13 m W h cm^-3,and capacity retention rate of 92%after 10,000 charge-discharge cycles at a current density of 4000 m A cm^-3.