硫、氮共掺杂三维石墨烯的全固态超级电容器

S,N co-doped three-dimensional graphene for all-solid-state supercapacitors

石墨烯以其超高导电性和超大比表面的独特优势常被应用于对称超级电容器的电极材料,然而二维石墨烯纳米片层间的范德华力容易导致片层堆叠。并且水溶液作为电解质组装的超级电容器在充电过程中可能发生水分解反应导致充电电压受限从而极大地降低它的能量密度。基于此,本研究采用水热法制备了硫、氮共掺杂的三维石墨烯气凝胶电极材料,研究了石墨烯材料的微观形貌、表面化学性质及水热反应时间对材料电化学性能的影响。结果表明:S,N-rGO-2具有发达的孔结构和高含量的杂原子。在5mV/s的扫描速率下比电容高达358.5F/g,使用固态电解质组装的全固态超级电容器充电电压可以达到1.8V,在1A/g的电流密度下比电容高达118.3F/g,能量密度达到14.9Wh/kg,并且10000次充/放电后的比电容保留率和库仑效率均接近100%。S,N-rGO-2表现出优异的双电层电容性能,可作为有潜力的超级电容器电极材料。

Graphene is often used as electrode material for symmetric supercapacitors due to its unique advantages of ultra-high conductivity and large specific surface area.However,the Van Der Waals forces between two-dimensional graphene nanosheets easily lead to sheet stacking.Moreover,the supercapacitor assembled with aqueous solution as the electrolyte may undergo a water splitting reaction during the charging process,resulting in a limited charging voltage,which greatly reduces its energy density.Based on this,in this study,sulfur and nitrogen co-doped three-dimensional graphene aerogel electrode materials were prepared by hydrothermal method.The effects of the microscopic morphology,surface chemical properties and hydrothermal reaction time of graphene materials on the electrochemical properties of the materials were investigated.The results showed that S,N-rGO-2 provided with a well-developed pore structure and high contents of heteroatom elements.The specific capacitance was as high as 358.5F/g at a scan rate of 5mV/s,the charging voltage of the all-solid-state supercapacitor assembled with solid electrolyte can reach 1.8V,the specific capacitance was as high as 118.3F/g at a current density of 1A/g and the energy density reached 14.9Wh/kg.The specific capacitance retention rate and Coulombic efficiency were both close to 100%after 10000 charges/discharges.S,N-rGO-2 exhibited excellent electric double-layer capacitance and can be used as the potential supercapacitor electrode material.