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(0.64g/cm3),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2mg/cm2时可以获得277F/cm3的高体积比电容;在高质量负载8mg/cm2时,体积比电容仍保持244F/cm3,且最大体积能量密度和功率密度分别为8.46Wh/L和10.9kW/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 characteristicssuch 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 andabundant pore structure. However, the high porosity results in loose carbon skeleton structures, which reduces the material density andfurther 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 tarwas utilized as the carbon source, and a template method was used to carbonize the different template materials prepared by the phasetransformation process after coated by tar, resulting in carbon nanosheets (PCS) with dense porous structure. The optimized hierarchicalpore structure in the material reduced the proportion of surplus meso- / macropores, resulting in a high packing density of 0.64 g/ cm3 andenabling both excellent gravimetric and volumetric capacitance properties. With an aqueous EDLC as demonstration, the fabricated PCSelectrode can achieve a high-level volumetric capacitance of 277 F/ cm3 at a low mass loading of 2 mg/ cm2 and 243 F/ cm3 at a high massloading of 8 mg/ cm2, with maximum volumetric energy density and power density reaching 8.46 Wh/ L and 10.9 kW/ L, respectively. Inaddition, double-layer symmetric capacitors also exhibited excellent cyclic stability, demonstrating the potential of PCS in high-densityenergy storage in double-layer capacitors.

0 引言

1 试验

   1.1 模板的制备及PCR和PCS的制备

   1.2 材料结构表征

   1.3 电极的制备及电化学性能测试

2 结果与讨论

   2.1 材料制备及结构表征

   2.2 三电极体系的电化学性能

   2.3 对称双电层电容器的电化学性能

3 结论