煤焦油衍生模板碳孔隙重整及高体积电容性能

Pore structure reformation of tar-derived templated carbons with highvolumetric capacitive properties

各类储能器件中,超级电容器因其功率密度高、充放电速度超快、循环寿命长等优点,是电化学储能技术的重要发展方向。其中,多孔碳电极是超级电容的核心材料。然而,传统多孔碳电极材料重点关注高孔隙率和高比面积的实现,从而导致疏松的碳骨架结构,使材料密度降低,进一步限制了超级电容器的体积性能。因此,具有合理孔隙结构和致密骨架的碳电极材料是提升双电层电容器体积性能的关键。以低成本煤焦油为碳源,对基于相转变过程制备的不同模板材料进行包覆后碳化,获得具有致密多孔结构的碳纳米片PCS。该材料中优化的分级孔结构降低了多余的中/大孔占比,使其具有高堆积密度(0.64 g/cm^(3)),可同时实现优异的质量和体积比电容性能。在水系双电层电容器中,制备的PCS电极在低质量负载2 mg/cm^(2)时可以获得277 F/cm^(3)的高体积比电容;在高质量负载8 mg/cm^(2)时,体积比电容仍保持244 F/cm^(3),且最大体积能量密度和功率密度分别为8.46 Wh/L和10.9 kW/L。此外,双电层对称电容器也表现出优异的循环稳定性(超过4万次循环),证明了PCS在双电层电容器高密度储能方面的应用潜力。

Among all kinds of energy storage devices,supercapacitors have attracted wide attention because of outstanding characteristics such as high power density,ultra-fast charge and discharge speed,and long cycle life.Porous carbon materials are widely used in electrical doubl layer capacitor(EDLC)electrode materials because of their adjustable multi-scale structure,high specific surface area and abundant pore structure.However,the high porosity results in loose carbon skeleton structures,which reduces the material density and further limits the volumetric performance of the double-layer capacitor.Therefore,the key to enhance the volumetric performance of double-layer capacitors lies in carbon electrode materials with a rational pore structure and a dense skeleton.In this study,low-cost coal tar was utilized as the carbon source,and a template method was used to carbonize the different template materials prepared by the phase transformation process after coated by tar,resulting in carbon nanosheets(PCS)with dense porous structure.The optimized hierarchical pore structure in the material reduced the proportion of surplus meso-/macropores,resulting in a high packing density of 0.64 g/cm^(3) and enabling both excellent gravimetric and volumetric capacitance properties.With an aqueous EDLC as demonstration,the fabricated PCS electrode can achieve a high-level volumetric capacitance of 277 F/cm^(3) at a low mass loading of 2 mg/cm^(2) and 243 F/cm^(3) at a high mass loading of 8 mg/cm^(2),with maximum volumetric energy density and power density reaching 8.46 Wh/L and 10.9 kW/L,respectively.In addition,double-layer symmetric capacitors also exhibited excellent cyclic stability,demonstrating the potential of PCS in high-density energy storage in double-layer capacitors.