Abstract

To obtain symmetric supercapacitors (SCs) with high energy density, it is critical to fabricate an electrode with wide potential window and excellent capacitive performance. Herein, by using the strong double hydrolysis reaction between anions and cations, the FeOOH nanosheets on the surface of activated carbon cloth (FeOOH@AC) are prepared through a simple hydrothermal process. The FeOOH@AC electrode exhibits maximum capacitance of 4,090 mF·cm⁻² at wider potential window -1–0 V and 3,250 mF·cm⁻² at 0–1 V versus SCE in 2 M LiNO₃ electrolyte. With two pieces of FeOOH@AC electrodes the obtained symmetric SC can operate at the voltage window of 2 V. This FeOOH symmetric SC shows high energy density of 13.261 mWh·cm⁻³ at a power density of 14.824 mW·cm⁻³ and maintains 4.175 mWh·cm⁻³ at a maximum power density of 118.564 mW·cm⁻³, as well as excellent charge storage capacity and cyclic stability. Li ion adsorption and diffusion mechanism on the (200) facets of FeOOH are explained by the density functional theory (DFT) calculations. The simple synthesis process and excellent capacitance performance of the FeOOH@AC composite make it a very promising candidate for high performance symmetric SC electrodes.

中文翻译：

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低结晶FeOOH纳米片上的低Li离子扩散势垒和高性能储能

摘要

为了获得具有高能量密度的对称超级电容器（SC），制造具有宽电位窗和出色电容性能的电极至关重要。在此，通过利用阴离子和阳离子之间的强力双重水解反应，通过简单的水热法制备了活性炭布（FeOOH @ AC）表面的FeOOH纳米片。与在2 M LiNO ₃电解质中的SCE相比，FeOOH @ AC电极在较宽的电位窗口-1–0 V时显示最大电容为4,090 mF·cm ^-2，在0–1 V时显示为3,250 mF·cm ^-2。使用两片FeOOH @ AC电极，可获得的对称SC可以在2 V的电压窗口下工作。此FeOOH对称SC的能量密度为13.261 mWh·cm ^-3。在14.824毫瓦的功率密度·厘米^-3，并保持4.175 mWh的·厘米^-3，在118.564毫瓦的最大功率密度·厘米^-3，以及优良的电荷储存容量和循环稳定性。通过密度泛函理论（DFT）计算解释了FeOOH在（200）面上的锂离子吸附和扩散机理。FeOOH @ AC复合材料的简单合成工艺和出色的电容性能使其成为高性能对称SC电极的非常有希望的候选者。