Electrical Engineering, Ingram School of Engineering, Texas State University, San Marcos, Texas78666, United States.
Materials Science, Engineering & Commercialization Program, Texas State University, San Marcos, Texas78666, United States.
ACS Appl Mater Interfaces. 2023 Feb 15;15(6):8305-8318. doi: 10.1021/acsami.2c20202. Epub 2023 Feb 3.
Novel phase Q-carbon thin films exhibit some intriguing features and have been explored for various potential applications. Herein, we report the growth of different Q-carbon structures (i.e., filaments, clusters, and microdots) by varying the laser energy density from 0.5 to 1.0 J/cm during pulsed laser annealing of amorphous diamond-like carbon films with different sp-sp carbon compositions. These unique nano- and microstructures of Q-carbon demonstrate exceptionally stable electrochemical performance by cyclic voltammetry, galvanostatic charging-discharging, and electrochemical impedance spectroscopy for energy applications. The temperature-dependent magnetic studies (magnetization magnetic field and temperature) reveal the ferromagnetic nature of the Q-carbon microdots. The saturation magnetization and coercive field values decrease from 132 to 14 emu/cc and 155 to 92 Oe by increasing the temperature from 2 to 300 K, respectively. The electrochemical performances of Q-carbon filament, cluster, and microdot thin-film supercapacitors were investigated by two-electrode configurations, and the highest areal specific capacitance of ∼156 mF/cm was observed at a current density of 0.15 mA/cm in the Q-carbon microdot thin film. The Q-carbon microdot electrodes demonstrate an exceptional capacitance retention performance of ∼97.2% and Coulombic efficiency of ∼96.5% after 3000 cycles due to their expectational reversibility in the charging-discharging process. The kinetic feature of the ion diffusion associated with the charge storage property is also investigated, and small changes in equivalent series resistance of ∼9.5% and contact resistance of ∼9.1% confirm outstanding stability with active charge kinetics during the stability test. A high areal power density of ∼5.84 W/cm was obtained at an areal energy density of ∼0.058 W h/cm for the Q-carbon microdot structure. The theoretical quantum capacitance was obtained at ∼400 mF/cm by density functional theory calculation, which gives an idea about the overall capacitance value. The obtained areal specific capacitance, power density, and impressive long-term cyclic stability of Q-carbon thin-film microdot electrodes endorse substantial promise in high-performance supercapacitor applications.
新型相 Q 态碳薄膜具有一些有趣的特性，已被探索用于各种潜在的应用。在此，我们通过改变激光能量密度（0.5 至 1.0 J/cm），在不同 sp-sp 碳组成的非晶态类金刚石碳薄膜上进行脉冲激光退火，从而生长出不同的 Q 态碳结构（即纤维、团簇和微点）。这些独特的 Q 态碳纳米和微结构通过循环伏安法、恒流充放电和电化学阻抗谱对能量应用表现出异常稳定的电化学性能。温度依赖的磁研究（磁化强度-磁场和温度）表明 Q 态碳微点具有铁磁性质。随着温度从 2 到 300 K 的升高，饱和磁化强度和矫顽场值分别从 132 至 14 emu/cc 和 155 至 92 Oe 减小。通过两电极配置研究了 Q 态碳纤维、团簇和微点薄膜超级电容器的电化学性能，在 Q 态碳微点薄膜中，在电流密度为 0.15 mA/cm 时，观察到最高比面积比电容约为 156 mF/cm。Q 态碳微点电极在 3000 次循环后表现出约 97.2%的电容保持性能和约 96.5%的库仑效率，这归因于其在充放电过程中具有预期的可逆性。还研究了与电荷存储特性相关的离子扩散的动力学特征，约 9.5%的等效串联电阻和约 9.1%的接触电阻的微小变化在稳定性测试期间确认了出色的稳定性和活性电荷动力学。在 Q 态碳微点结构中，获得了约 5.84 W/cm 的高面功率密度和约 0.058 W h/cm 的面能量密度。通过密度泛函理论计算得到了约 400 mF/cm 的理论量子电容，这给出了整体电容值的概念。Q 态碳薄膜微点电极的获得的比面积比电容、功率密度和令人印象深刻的长期循环稳定性在高性能超级电容器应用中具有很大的应用前景。
