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Title: The critical role of point defects in improving the specific capacitance of δ-MnO 2 nanosheets

Abstract

3D porous nanostructures built from 2D δ-MnO 2 nanosheets are an environmentally friendly and industrially scalable class of supercapacitor electrode material. While both the electrochemistry and defects of this material have been studied, the role of defects in improving the energy storage density of these materials has not been addressed. In this work, δ-MnO 2 nanosheet assemblies with 150 m 2 g -1 specific surface area are prepared by exfoliation of crystalline K xMnO 2 and subsequent reassembly. Equilibration at different pH introduces intentional Mn vacancies into the nanosheets, increasing pseudocapacitance to over 300 F g -1, reducing charge transfer resistance as low as 3 Ω, and providing a 50% improvement in cycling stability. X-ray absorption spectroscopy and high-energy X-ray scattering demonstrate a correlation between the defect content and the improved electrochemical performance. The results show that Mn vacancies provide ion intercalation sites which concurrently improve specific capacitance, charge transfer resistance and cycling stability.

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE; National Science Foundation (NSF)
OSTI Identifier:
1346204
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature Communications; Journal Volume: 8; Journal Issue: 02, 2017
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE

Citation Formats

Gao, Peng, Metz, Peter, Hey, Trevyn, Gong, Yuxuan, Liu, Dawei, Edwards, Doreen D., Howe, Jane Y., Huang, Rong, and Misture, Scott T. The critical role of point defects in improving the specific capacitance of δ-MnO2 nanosheets. United States: N. p., 2017. Web. doi:10.1038/ncomms14559.
Gao, Peng, Metz, Peter, Hey, Trevyn, Gong, Yuxuan, Liu, Dawei, Edwards, Doreen D., Howe, Jane Y., Huang, Rong, & Misture, Scott T. The critical role of point defects in improving the specific capacitance of δ-MnO2 nanosheets. United States. doi:10.1038/ncomms14559.
Gao, Peng, Metz, Peter, Hey, Trevyn, Gong, Yuxuan, Liu, Dawei, Edwards, Doreen D., Howe, Jane Y., Huang, Rong, and Misture, Scott T. Thu . "The critical role of point defects in improving the specific capacitance of δ-MnO2 nanosheets". United States. doi:10.1038/ncomms14559.
@article{osti_1346204,
title = {The critical role of point defects in improving the specific capacitance of δ-MnO2 nanosheets},
author = {Gao, Peng and Metz, Peter and Hey, Trevyn and Gong, Yuxuan and Liu, Dawei and Edwards, Doreen D. and Howe, Jane Y. and Huang, Rong and Misture, Scott T.},
abstractNote = {3D porous nanostructures built from 2D δ-MnO2 nanosheets are an environmentally friendly and industrially scalable class of supercapacitor electrode material. While both the electrochemistry and defects of this material have been studied, the role of defects in improving the energy storage density of these materials has not been addressed. In this work, δ-MnO2 nanosheet assemblies with 150 m2 g-1 specific surface area are prepared by exfoliation of crystalline KxMnO2 and subsequent reassembly. Equilibration at different pH introduces intentional Mn vacancies into the nanosheets, increasing pseudocapacitance to over 300 F g-1, reducing charge transfer resistance as low as 3 Ω, and providing a 50% improvement in cycling stability. X-ray absorption spectroscopy and high-energy X-ray scattering demonstrate a correlation between the defect content and the improved electrochemical performance. The results show that Mn vacancies provide ion intercalation sites which concurrently improve specific capacitance, charge transfer resistance and cycling stability.},
doi = {10.1038/ncomms14559},
journal = {Nature Communications},
number = 02, 2017,
volume = 8,
place = {United States},
year = {Thu Feb 23 00:00:00 EST 2017},
month = {Thu Feb 23 00:00:00 EST 2017}
}
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