Preparation Of Graphene Aerogel Composites And The Research Of Its Performance

Supercapacitors,a new kind of pulsed power supply,have features such as fast charge and discharge rates,long cycle life,and high power density.At present,the performance of supercapacitors is improving significantly,and it is widely used in rail transit,portable instrumentation equipment,and defense military.The supercapacitor is mainly composed of a current collector,a separator,an electrode material,and an electrolyte.Among them,the key factor affecting the performance of the supercapacitor device is the electrode material.Therefore,high-performance active materials are prepared by designing their morphology and structure.In this paper,graphite oxide?GO?was prepared by modified Hummers method,and it was then combined with MnO₂ and NiCo₂O₄ using hydrothermal method to obtain graphene aerogel?GA?composite materials.Its morphology,phase and electrochemical performance were tested and analyzed,the main research contents and results are as follows:1.The MnO₂ microsphere/graphene aerogel composites?MnO₂/GA?was prepared by hydrothermal in-situ self-assembly method.The phase,morphology and composition of the material were analyzed,and the electrochemical properties of the material were studied.The results showed that the MnO₂ microspheres were embedded in the graphene sheets,the MnO₂/GA composites exhibited a specific capacitance of 175 F g^-1 at the current density of 0.5 A g^-1,and the capacity retention rate was 73.5%after 1000 cycles and showed good cycle performance.2.The NiCo₂O₄ nanowires/graphene aerogel composites?NCO-NS/GA?were prepared by a simple hydrothermal method.Their phase,morphology,composition and electrochemical properties were characterized and analyzed.The results showed that the NiCo₂O₄ nanowires?NCO-NS?were grown in situ on a three-dimensional porous structure of GA,the NCO-NS/GA composites demonstrated a high specific capacitance of 720 F g^-1 at a current density of 1A g^-1,the material also had a retention rate of 84%of its initial capacitance after 1000 cycles.An asymmetric supercapacitors were assembled using NCO-NS/GA as positive electrode and activated carbon?AC?as negative electrode.When the power density was 658 W kg^-1,the highest energy density was 25.41 Wh kg^-1,indicating a good application prospect.3?The NiCo₂O₄ microspheres/graphene aerogel composites?NCO-MS/GA?were were successfully prepared by hydrothermal electrostatic self-assembly method.The structure and properties of the materials were tested.The results showed that the NiCo₂O₄ microspheres were distributed on the crimped graphene sheets.The specific capacitance of the composite was 715 F g^-1 at a current density of 1 A g^-1.The specific capacitance could retain about 79.0%of its initial capacitance after 1000 cycles.The asymmetric supercapacitor with NCO-MS/GA as the positive electrode and the activated carbon?AC?as the negative electrode was assembled.When the power density was 750 W kg^-1,the highest energy density was 23.13Wh kg^-1,showing some practical application value.