Preparation And Properties Of Supercapacitor Based On SnO₂ Nanocomposites

Recently,supercapacitors?SCs?,as a new type of green energy storage device,have received much attention due to their fast charging,high power density,favorable reversibility and extraordinary cyclicity.However,challenges remained especially in improving energy density and reducing the cost.The type of electrode material is the key factor to determine the property of SCs.SnO₂ as one of promising electrode materials has been attracted more attention due to its rich resources,low cost,and environment friendly.Applications of SnO₂electrodes are limited as a result of poor conductivity and volume change,leading to disappointing specific capacity and cycle life.Hence,a perspective of complicated materials of carbonaceous and metallic oxides is put forward,which can exhibit high and stable performance through synergetic function.In this paper,we have prepared a series of composites based on low-dimensional SnO₂ with different morphologies and reduced graphene oxide.The electrochemical properties are studied.Detailed research is summarized as follows:1.The ultrafine SnO₂ nanorods/rGO composites are synthesized through a hydrothermal reaction.Influences of reactant concentrations,additive,and reaction temperature on as-prepared composites with different morphologies and sizes have been investigated.Electrochemical properties are measured in 1 M Na₂SO₄ electrolyte using a three-electrode system.The results reveal that the composites exhibit higher specific capacitance and longer cycling life than the sample based on SnO₂.A maximum capacity of 184.6 F/g at a current density of 100 mA/g is obtained,showing outstanding capacity retention of 98%after 6000cycles with the help of the combination of rGO and SnO₂ nanorods.2.The SnO₂ QDs/rGO composite with relatively high ductility has been synthesized by hydrothermal reaction.It was used as an electrode in a three-electrode system after adhering to nickel foam to avoid fussy preparation by adding carbon black and binder.The electrochemical properties of the composite are measured in 1 M Na₂SO₄ electrolyte and the results show that the prepared composites have a capacity of 253.3 F/g at a current density of100 mA/g.Moreover,the composites present an available capacity retention of 95.9%after6000 cycles through the measurement of cyclic voltammetry.3.Attempt of adding of MnO₂ into the SnO₂ nanorods/rGO composites was carried out by hydrothermal reactions.EDS and XRD measurement show no MnO₂ or other manganese oxides was generated.The crystallinity of nanorods is improved and particles are increasing along with the further reduction of rGO.Characterization of electrochemical performance indicated that a much higher capacity of 262.2 F/g than ultrafine SnO₂ nanorods/rGO composites at a current density of 100 m A/g in 1 M Na₂SO₄ electrolyte was obtained.