Study On Preparation Of Three-Dimensional Graphene-Based Energy Storage Materials By Self-Propagating Method

Graphene has great value in the field of electrochemical energy storage because of its excellent conductivity,flexibility and unique electrochemical performance.In this paper,a series of three-dimensional electrodes were prepared with different active materials by the self-propagating thermal reduction.These three-dimensional electrodes were assembled into corresponding electrochemical systems,the novel three-dimensional electrodes obtained better performance than common electrode which prepared by conventional shaping process.In the argon-protected glove box,the pure graphene oxide film was contacted with a 300? hot plate to initiate a self-propagating reaction,and a fluffy three-dimensional rGO electrode was obtained quickly and easily.Capacitance performance was measured in 3 mol L-1 H2SO4 electrolyte.The results show that the self-propagating three-dimensional graphene electrode has a specific capacitance of 170.8 F g-1 at 5 mV s-1 and 94.6 F g-1 at 1000 mV s-1.The rate performance is significantly better than graphene prepared by traditional thermal reduction.A three-dimensional AC/graphene composite electrode with graphene as a multifunctional conductive binder was prepared by self-propagation method,and its electrochemical capacitance performance in 3 mol L-1 H2SO4 solution was studied.Thermal reduction electrode(AC/rGO-HR)and traditional activated carbon electrode prepared with PTFE as binder(AC-PTFE)were compared.Due to the plugging effect of the PTFE binder,the specific capacity of the conventional AC-PTFE electrode at a sweep rate of 5 mV s-1 is only 152.6 F g-1,while the use of graphene as a conductive binder The specific capacities of AC/rGO-HR and AC/rGO-SP of each electrode were 197.8 F g-1 and 202.5 F g-1,respectively.When the scan rate reaches 100 mV s-1,the capacity retention rates of AC-PTFE,AC/rGO-HR and AC/rGO-SP electrodes are 90.7%,87.7%and 92.8%,respectively.This shows that the performance of the capacitor material not only needs to build an electronic conductive network inside the electrode,but also needs to consider the effect of ion transmission inside the electrode on the overall performance of the electrode.Graphene oxide has been added to the MXene solution,and the film was formed by vacuum-filtered and then self-propagating in an inert atmosphere.The gas released during the self-propagating reduction reaction of graphene oxide impacts the two-dimensional stacking structure of MXene.The open structure MXene/rGO composite films were tested in 3 mol L-1 H2SO4 solution as electrolyte.The results show that the addition of only 10%rGO can increase the capacity of the electrode from 283.8 F g-1 of pure MXene membrane to 354.3 F g-1 of MXene-rGO-10 composite membrane,and with the increase of rGO content,the rate performance is also significantly improved.The capacity retention rates of pure MXene film,MXene-rGO-10,MXene-rGO-20,and MXene-rGO-30 at 1000 mV s-1 are 27.7%,70.4%,78.8%and 84.0%,respectively.NiO is used as active material,graphene is used as the conductive binder,and a self-propagating method is used to construct a NiO-rGO composite film with a three-dimensional conductive network,which is used as a negative electrode of a lithium ion battery and an electrode prepared by direct thermal reduction.A comparison was made.The results show that the addition of rGO can effectively improve the cycling stability and rate performance of the material.At the same time,the NiO/rGO-HR electrode obtained by direct reduction is difficult to penetrate the electrolyte due to the wrapping of graphene,and the electrode capacity is difficult to exert.The NiO/rGO-SP electrode obtained by self-propagating reduction has a higher specific capacity due to its open sheet structure.