Research On The Performance Of Novel Two-dimensional Material Electrodes And Their Supercapacitors

The problem of depletion of fossil energy in nature is a common and urgent problem in the world,and the development of high-performance electrochemical devices and electrode materials is a key solution to this problem.Black Phosphorus（BP）and carbides,nitrides and carbonitrides of transition metals（MXenes）as two-dimensional materials can be ideal electrode materials for electrochemical devices due to their unique properties,but the application of two-dimensional materials in electrochemical devices still needs to be further explored.Therefore,in this thesis,the preparation of various electrode materials as well as the performance tests were carried out based on the synthesis of black phosphorus as well as MXene by compounding with different conducting polymers and analyzing their conducting mechanisms.The Ti₃C₂T_xflexible self-supporting films,MXene-CNT/PANI ternary composites and BP-PEDOT flexible films prepared based on 2D materials have unique and outstanding electrochemical properties,which provide a feasible approach to develop new 2D electrode composites.The details of this thesis are as follows:（1）The precursor MAX phase of Ti₃C₂T_x was etched with acid to obtain high-quality two-dimensional Ti₃C₂T_x materials,and Ti₃C₂T_x self-oriented thin film electrodes with super-large layer spacing were prepared by natural deposition method,which showed excellent cycling stability and high rate performance in relevant tests.283.7 F/g at a scan rate of 2 m V/s,and the calculated specific capacitance is still 63.2 F/g at a scan rate of 100m V/s;the maximum specific capacitance is 190 F/g at a charge/discharge current density of 1 A/g,and the specific capacitance is still 60 F/g even at a charge/discharge current density of 10 A/g.After 1000 cycles,the specific capacitance retention rate remained 108.6%,and after 10,000 cycles,it still maintains 96.3%capacity retention（57.8 F/g）.（2）MXene-CNT/PANI ternary electrode materials were prepared by in situ polymerization and their electrochemical properties were investigated,and it was demonstrated by various structural characterization methods that the polyaniline in the prepared materials was well compounded with two-dimensional Ti₃C₂T_x nanosheets and carbon nanotubes and constructed a special excellent conductive network,which accelerated the electron ion transport and provided more active.At the same time,the insertion of CNT/PANI materials between the two-dimensional Ti₃C₂T_x nanosheets also inhibits the self-stacking of Ti₃C₂T_xnanosheets,increases their layer spacing,and enhances their electrochemical properties.During the timing potential test,the discharge specific capacitance was 8175 F/g,6942 F/g,5890 F/g,and 3770 F/g at the current densities of 0.5 A/g,1 A/g,2 A/g,and 3 A/g,respectively,which proved to have good rate performance.（3）The anisotropy of black phosphorus was studied by various characterization methods,and the three characteristic peaks of the Raman spectrum were found to change periodically with the angle of the incident light,so that the orientation of the black phosphorus crystal could be determined.The black phosphorene was prepared using electrochemical method,and BP-PEDOT flexible electrode film was prepared by composite,and the material was found to have good conductive structure by characterization means.The obtained flexible electrode film still shows good electrochemical performance at higher currents,with a maximum specific capacitance of 2108.3 F/g at 0.5 A/g and still 545 F/g at 5 A/g.After 3000 charge/discharge cycles,the capacity ratio of the electrode is still up to 62.78 m Ah/g and the coulomb efficiency is maintained at 98.4%.It shows that the special structure and synergistic effects of the material make it have good recycling properties and high application potential.