Agudosi Elochukwu Stephen, Abdullah Ezzat Chan, Numan Arshid, Mubarak Nabisab Mujawar, Aid Siti Rahmah, Benages-Vilau Raúl, Gómez-Romero Pedro, Khalid Mohammad, Omar Nurizan
Department of Chemical Process Engineering, Malaysia-Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia (UTM), Jalan Sultan Yahya Petra, 54100, Kuala Lumpur, Malaysia.
State Key Laboratory of ASIC and System, SIST, Fudan University, Shanghai, 200433, China.
Sci Rep. 2020 Jul 8;10(1):11214. doi: 10.1038/s41598-020-68067-2.
Electrochemical stability of energy storage devices is one of their major concerns. Polymeric binders are generally used to enhance the stability of the electrode, but the electrochemical performance of the device is compromised due to the poor conductivity of the binders. Herein, 3D binder-free electrode based on nickel oxide deposited on graphene (G-NiO) was fabricated by a simple two-step method. First, graphene was deposited on nickel foam via atmospheric pressure chemical vapour deposition followed by electrodeposition of NiO. The structural and morphological analyses of the fabricated G-NiO electrode were conducted through Raman spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDS). XRD and Raman results confirmed the successful growth of high-quality graphene on nickel foam. FESEM images revealed the sheet and urchin-like morphology of the graphene and NiO, respectively. The electrochemical performance of the fabricated electrode was evaluated through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) in aqueous solution at room temperature. The G-NiO binder-free electrode exhibited a specific capacity of ≈ 243 C g at 3 mV s in a three-electrode cell. A two-electrode configuration of G-NiO//activated charcoal was fabricated to form a hybrid device (supercapattery) that operated in a stable potential window of 1.4 V. The energy density and power density of the asymmetric device measured at a current density of 0.2 A g were estimated to be 47.3 W h kg and 140 W kg, respectively. Additionally, the fabricated supercapattery showed high cyclic stability with 98.7% retention of specific capacity after 5,000 cycles. Thus, the proposed fabrication technique is highly suitable for large scale production of highly stable and binder-free electrodes for electrochemical energy storage devices.
储能装置的电化学稳定性是其主要关注点之一。聚合物粘结剂通常用于增强电极的稳定性，但由于粘结剂的导电性较差，装置的电化学性能会受到影响。在此，通过一种简单的两步法制备了基于沉积在石墨烯上的氧化镍（G-NiO）的三维无粘结剂电极。首先，通过大气压化学气相沉积将石墨烯沉积在泡沫镍上，然后进行NiO的电沉积。通过拉曼光谱、X射线衍射（XRD）、场发射扫描电子显微镜（FESEM）和能量色散X射线光谱（EDS）对制备的G-NiO电极进行了结构和形貌分析。XRD和拉曼结果证实了高质量石墨烯在泡沫镍上的成功生长。FESEM图像分别揭示了石墨烯和NiO的片状和海胆状形貌。在室温下的水溶液中，通过循环伏安法（CV）、恒电流充放电（GCD）和电化学阻抗谱（EIS）对制备电极的电化学性能进行了评估。在三电极电池中，G-NiO无粘结剂电极在3 mV s时表现出约243 C g的比容量。制备了G-NiO//活性炭的两电极配置，以形成在1.4 V稳定电位窗口下运行的混合装置（超级电容器）。在电流密度为0.2 A g时测量的不对称装置的能量密度和功率密度分别估计为47.3 W h kg和140 W kg。此外，制备的超级电容器显示出高循环稳定性，在5000次循环后比容量保留率为98.7%。因此，所提出的制备技术非常适合大规模生产用于电化学储能装置的高度稳定的无粘结剂电极。
