Transparent and Flexible Mn1−x−y(CexLay)O2−δ Ultrathin‐Film Device for Highly‐Stable Pseudocapacitance Application. (31st May 2021)

• Record Type: Journal Article
• Authors: Maroufi, Samane; Khayyam Nekouei, Rasoul; S. Mofarah, Sajjad; O'Mullane, Anthony P.; Yao, Yin; Lim, Sean; Cazorla, Claudio; Sahajwalla, Veena
• Is Part Of: Advanced functional materials. Volume 31:Number 30(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-05-31
• Subjects: anionic intercalation -- flexible portable capacitor -- long‐term durability -- percolation impact -- transparent pseudocapacitor; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202100880
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Control over the fabrication of state‐of‐the‐art portable pseudocapacitors with the desired transparency, mechanical flexibility, capacitance, and durability is challenging, but if resolved will have fundamental implications. Here, defect‐rich Mn1− x − y (Ce x La y )O2−δ ultrathin films with controllable thicknesses (5–627 nm) and transmittance (≈29–100%) are fabricated via an electrochemical chronoamperometric deposition using a aqueous precursor derived from end‐of‐life nickel‐metal hydride batteries. Due to percolation impacts on the optoelectronic properties of ultrathin films, a representative Mn1− x − y (Ce x La y )O2−δ film with 86% transmittance exhibits an outstanding areal capacitance of 3.4 mF cm −2, mainly attributed to the intercalation/de‐intercalation of anionic O 2− through the atomic tunnels of the stratified Mn1− x − y (Ce x La y )O2−δ crystallites. Furthermore, the Mn1− x − y (Ce x La y )O2−δ thin‐film device exhibits excellent capacitance retention of ≈90% after 16 000 cycles. Such stability is associated with intervalence charge transfer occurring among interstitial Ce/La cations and Mn oxidation states within the Mn1− x − y (Ce x La y )O2−δ structure. The energy and power densities of the transparent flexible Mn1− x − y (Ce x La y )O2−δ full‐cell pseudocapacitor device, is measured to be 0.088 μWh cm −2 and 843 µW cm −2, respectively. These values show insignificant changes under vigorous twisting and bending to 45–180° confirming these value‐added materials are intriguing alternatives for size‐sensitive energy storage devices. Abstract : This study reports the synthesis of defect‐rich Mn1− x − y (Ce x La y )O2−δ ultrathin films with controllable thicknesses, transmittance, and outstanding areal capacitance. This performance originates from the intercalation/de‐intercalation of anionic O 2− charges and intervalence charge transfer among cations with multioxidation states. This is a simplified yet precise approach, and has the potential to lead to the large‐scale and cost‐effective fabrication of highly stable and flexible pseudocapacitors.