Shelby Boyd^1*, Karthik Ganeshan^2*, Wan-Yu Tsai^3*, Tao Wu^4*, Saeed Saeed^1*, De-en Jiang^4*, Nina Balke^5*, Adri van Duin^2*, Veronica Augustyn^1*

1 Department of Materials Science and Engineering, North Carolina State University, Raleigh NC 27606, USA

2 Department of Mechanical Engineering, Pennsylvania State University, University Park PA 16803, USA

3 Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA

4 Department of Chemistry, University of California, Riverside, CA 92521, USA

5 Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA

* Corresponding authors emails: skboyd2@ncsu.edu, kug46@psu.edu, tsaiw@ornl.gov, wutaozky@outlook.com, smseed@ncsu.edu, djiang@ucr.edu, balken@ornl.gov, acv13@psu.edu, vaugust@ncsu.edu

DOI10.24435/materialscloud:kh-y2 [version v1]

Publication date: Jul 16, 2021

How to cite this record

Shelby Boyd, Karthik Ganeshan, Wan-Yu Tsai, Tao Wu, Saeed Saeed, De-en Jiang, Nina Balke, Adri van Duin, Veronica Augustyn, Effects of interlayer confinement and hydration on capacitive charge storage in birnessite, Materials Cloud Archive 2021.110 (2021), doi: 10.24435/materialscloud:kh-y2.

Description

Nanostructured birnessite (δ-MnO2) exhibits high specific capacitance and nearly ideal capacitive behavior in aqueous electrolytes, rendering it an important electrode material for low-cost, high power energy storage devices. The mechanism of electrochemical capacitance in birnessite has been described as both faradaic (involving redox) and non-faradaic (involving only electrostatic interactions). To clarify the capacitive mechanism, we characterized birnessite’s response to applied potential using ex situ X-ray diffraction, electrochemical quartz crystal microbalance, in situ Raman spectroscopy, and operando atomic force microscopy dilatometry to provide a holistic understanding of its structural, gravimetric, and mechanical response. These observations are supported by atomic-scale simulations using density functional theory for the cation-intercalated structure of birnessite and ReaxFF-based molecular dynamics, as well as ReaxFF-based grand canonical Monte Carlo simulations on the dynamics at the birnessite/water/electrolyte interface. We show that capacitive charge storage in birnessite is governed by interlayer cation intercalation. We conclude that the intercalation appears capacitive due to the presence of nanoconfined interlayer structural water, which mediates the interaction between the intercalated cation and the birnessite host and leads to minimal structural changes.

Materials Cloud sections using this data

Files

File name	Size	Description
README.txt MD5md5:1574ab992c45c725ad8845137102d9c9	2.3 KiB	readme
Experimental.zip MD5md5:1f8353cd214d9d3c4eb8433d2940b660	1.2 MiB	data files for electrochemistry, Raman, EQCM, XRD, and AFM
reaxff_raw.zip MD5md5:eacb3e69eeb169ae83f671ec53c54ec0	521.5 KiB	reaxff simulation input files and plots
MnO2-DFT-calculation.7z MD5md5:b1dcce33c8628e9531bf7aa05b66bee1	42.1 KiB	DFT data files

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Keywords

oxide energy storage electrochemistry