材料科学
纳米颗粒
化学工程
锰
插层(化学)
形态学(生物学)
兴奋剂
超级电容器
电化学
电极
纳米技术
物理化学
无机化学
冶金
光电子学
遗传学
生物
工程类
化学
作者
Shenggen Huang,Jian Sun,Jian Yan,Jiaqin Liu,Weijie Wang,Qingqing Qin,Wenping Mao,Wei Xu,Junfeng Wang
标识
DOI:10.1021/acsami.7b18762
摘要
In this work, Al-doped MnO2 (Al-MO) nanoparticles have been synthesized by a simple chemical method with the aim to enhance cycling stability. At room temperature and 50 °C, the specific capacitances of Al-MO are well-maintained after 10 000 cycles. Compared with pure MnO2 nanospheres (180.6 F g–1 at 1 A g–1), Al-MO also delivers an enhanced specific capacitance of 264.6 F g–1 at 1 A g–1. During the cycling test, Al-MO exhibited relatively stable structure initially and transformed to needlelike structures finally both at room temperature and high temperature. In order to reveal the morphology evolution process, in situ NMR under high magnetic field has been carried out to probe the dynamics of structural properties. The 23Na spectra and the SEM observation suggest that the morphology evolution may follow pulverization/reassembling process. The Na+ intercalation/deintercalation induced pulverization, leading to the formation of tiny MnO2 nanoparticles. After that, the pulverized tiny nanoparticles reassembled into new structures. In Al-MO electrodes, doping of Al3+ could slow down this structure evolution process, resulting in a better electrochemical stability. This work deepens the understanding on the structural changes in faradic reaction of pseudocapacitive materials. It is also important for the practical applications of MnO2-based supercapacitors.
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