Probing the In Situ Pseudocapacitive Charge Storage in Ti₃C₂ MXene Thin Films with X-ray Reflectivity

Journal Article · Tue Aug 31 00:00:00 EDT 2021 · ACS Applied Materials and Interfaces

DOI:https://doi.org/10.1021/acsami.1c10959· OSTI ID:1839940

Sobyra, Thomas B.  ^[1]; Mathis, Tyler S.  ^[2]; Gogotsi, Yury  ^[2]; Fenter, Paul  ^[1]

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1. Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Sciences and Engineering Division
2. Drexel Univ., Philadelphia, PA (United States)

MXenes are a large family of two-dimensional materials that are attractive for energy storage due to their high-rate charging capabilities as well as for electrochemical actuators, water purification, and many other technologies. Ion intercalation during electrochemically driven charge and discharge processes is the fundamental process associated with MXene functionality, which we have characterized here using in situ and operando X-ray reflectivity (XRR). Experiments performed at the Advanced Photon Source at Argonne National Laboratory monitored the changes in the structure of a Ti₃C₂ MXene film on a platinum current collector as a function of static applied potential between 0.3 and –0.7 V vs Ag/AgCl in an aqueous 0.1 M Li₂SO₄ electrolyte. Negative potential sweeps lead to a contraction of 1.2 Å in the interlayer spacing and a loss of electron density between the layers, likely due to Li⁺ ion insertion and water removal. The change in lattice spacing includes a continuous variation vs potential as well as an additional discrete contraction that occurs near –0.35 V that has the characteristics of a first-order transition. The continuous change in the MXene interlayer spacing is associated with the capacitive charge, while the discrete change in structure correlated to the weak feature in the cyclic voltammogram at –0.35 V can be interpreted as either a pseudocapacitive charging process or a potential-dependent change in capacity.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1839940
• Journal Information: ACS Applied Materials and Interfaces, Vol. 13, Issue 36; ISSN 1944-8244
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
MXenes
X-ray reflectivity
interlayer
intercalation
in situ
synchrotron