Transparent and Flexible Mn_(1-x-y)(Ce_xLa_y)O_(2-δ) Ultrathin-Film Device for Highly-Stable Pseudocapacitance Application

摘要

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(CexLay)O2-delta ultrathin films with controllable thicknesses (5-627 nm) and transmittance (approximate to 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(CexLay) O2-delta 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(CexLay)O2-delta crystallites. Furthermore, the Mn1-x-y(CexLay)O2-delta thin-film device exhibits excellent capacitance retention of approximate to 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(CexLay)O2-delta structure. The energy and power densities of the transparent flexible Mn1-x-y(CexLay) O2-delta full-cell pseudocapacitor device, is measured to be 0.088 mu Wh cm(-2) and 843 mu W cm(-2), respectively. These values show insignificant changes under vigorous twisting and bending to 45-180 degrees confirming these value-added materials are intriguing alternatives for size-sensitive energy storage devices.