Wang Chenxiang, Sung Kimberly, Zhu Jason Zi Jie, Qu Sheng, Bao Jiawei, Chang Xueying, Katsuyama Yuto, Yang Zhiyin, Zhang Chonghao, Huang Ailun, Kroes Bradley C, El-Kady Maher F, Kaner Richard B
Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, California 90095, USA.
Department of Materials Science and Engineering and California NanoSystems Institute, University of California, Los Angeles, California 90095, USA.
Mater Horiz. 2024 Feb 6;11(3):688-699. doi: 10.1039/d3mh01032e.
The development of potent pseudocapacitive charge storage materials has emerged as an effective solution for closing the gap between high-energy density batteries and high-power density and long-lasting electrical double-layer capacitors. Sulfonyl compounds are ideal candidates owing to their rapid and reversible redox reactions. However, structural instability and low electrical conductivity hinder their practical application as electrode materials. This work addresses these challenges using a fast and clean laser process to interconnect sulfonated carbon nanodots into functionalized porous carbon frameworks. In this bottom-up approach, the resulting laser-converted three-dimensional (3D) turbostratic carbon foams serve as high-surface-area, conductive scaffolds for redox-active sulfonyl groups. This design enables efficient faradaic processes using pendant sulfonyl groups, leading to a high specific capacitance of 157.6 F g due to the fast reversible redox reactions of sulfonyl moieties. Even at 20 A g, the capacitance remained at 78.4% due to the uniform distribution of redox-active sites on the graphitic domains. Additionally, the 3D-tsSC300 electrode showed remarkable cycling stability of >15 000 cycles. The dominant capacitive processes and kinetics were analysed using extensive electrochemical characterizations. Furthermore, we successfully used 3D-tsSC300 in flexible solid-state supercapacitors, achieving a high specific capacitance of up to 17.4 mF cm and retaining 91.6% of the initial capacitance after 20 000 cycles of charge and discharge coupled with 90° bending tests. Additionally, an as-assembled flexible all-solid-state symmetric supercapacitor exhibits a high energy density of 12.6 mW h cm at a high power density of 766.2 W cm, both normalized by the volumes of the full device, which is comparable or better than state-of-the-art commercial pseudocapacitors and hybrid capacitors. The integrated supercapacitor provides a wide potential window of 2.0 V using a serial circuit, showing great promise for metal-free energy storage devices.
高效赝电容电荷存储材料的开发已成为缩小高能量密度电池与高功率密度及长寿命双电层电容器之间差距的有效解决方案。磺酰化合物因其快速且可逆的氧化还原反应而成为理想候选材料。然而，结构不稳定性和低电导率阻碍了它们作为电极材料的实际应用。这项工作通过一种快速且清洁的激光工艺将磺化碳纳米点互连形成功能化多孔碳框架，从而应对这些挑战。在这种自下而上的方法中，所得的激光转换三维（3D）乱层碳泡沫作为氧化还原活性磺酰基团的高表面积导电支架。这种设计利用悬垂磺酰基团实现了高效的法拉第过程，由于磺酰部分的快速可逆氧化还原反应，导致比电容高达157.6 F/g。即使在20 A/g的电流密度下，由于氧化还原活性位点在石墨域上的均匀分布，电容仍保持在78.4%。此外，3D-tsSC300电极显示出超过15000次循环的显著循环稳定性。使用广泛的电化学表征分析了主要的电容过程和动力学。此外，我们成功地将3D-tsSC300用于柔性固态超级电容器，实现了高达17.4 mF/cm²的高比电容，并在20000次充放电循环以及90°弯曲测试后保留了初始电容的91.6%。此外，组装好的柔性全固态对称超级电容器在766.2 W/cm³的高功率密度下表现出12.6 mW h/cm³的高能量密度，两者均按整个器件的体积进行归一化，这与现有商业赝电容器和混合电容器相当或更优。集成超级电容器使用串联电路提供2.0 V的宽电位窗口，对无金属储能装置显示出巨大潜力。
