Fe₂O₃ Nanoparticles Anchored on the Ti₃C₂T_x MXene Paper for Flexible Supercapacitors with Ultrahigh Volumetric Capacitance

Abstract

Ti3C2T x MXene, with high conductivity and flexibility, has drawn great attention in the wearable energy storage devices. However, the easy nanoflake-restacking phenomenon greatly restricts the achievable electrochemical performance of Ti3C2T x -based supercapacitors, in particular volumetric capacitance. Herein, we report a flexible hybrid paper consisting of Fe2O3 nanoparticles (NPs) anchored on Ti3C2T x (Fe2O3 NPs@MX) via electrostatic self-assembly and annealing treatments. The interlayer spacing of Ti3C2T x nanoflakes is effectively enlarged through the incorporation of Fe2O3 NPs, allowing more electrochemical active sites to store charge. Meanwhile, Ti3C2T x nanoflakes form a continuous metallic skeleton and inhibit the volume expansion of Fe2O3 NPs during the charging/discharging process, enhancing the cycling stability. The flexible, ultrathin (4.1 μm) Fe2O3 NPs@MX hybrid paper shows considerably improved electrochemical performances compared to those of pure Ti3C2T x and Fe2O3, including a wide potential window of 1 V, an ultrahigh volumetric capacitance of ∼2607 F cm–3 (584 F g–1), and excellent capacitance retention after 13,000 cycles. Besides, the as-assembled symmetric solid-state supercapacitor exhibits an energy density of 29.7 Wh L–1 and excellent mechanical flexibility. We believe that the present nanostructure design, decorating NPs within a two-dimensional metallic network, has general applicability and could be used to fabricate highly efficient composites for advanced energy storage devices.

A Multi‐Scale Structural Engineering Strategy for High‐Performance MXene Hydrogel Supercapacitor Electrode

“…Nevertheless, similar to other 2D materials, aggregation and self‐restacking of flexible MXene flakes are usually inevitable during the electrode fabrication due to strong van der Waals interactions and hydrogen bonds between adjacent nanosheets. To address the problem, intercalated agents like CTAB, [ 13 ] TAEA, [ 14 ] Fe 2 O 3 , [ 15 ] Be 2+ , [ 16 ] and conducting polymers [ 17 , 18 , 19 , 20 ] have been introduced to expand the interlayer spacing of MXene flakes to counteract the effect of the self‐stacking propensity. The expanded interlayer spacing facilitates ion accessibility at the microscopic scale because MXene is a pseudocapacitive intercalation material in acidic electrolyte, in which oxygen‐containing functional groups undergo protonation with the intercalated H + , accompanied by a transformation in the titanium oxidation state.…”

Amine-Assisted Delaminated 2D Ti3C2Tx MXenes for High Specific Capacitance in Neutral Aqueous Electrolytes

“…The C 1s spectra consist of three kinds of carbon species, i.e., C–O, C–C, and Ti–C in both samples (Figure S7). , Importantly, Figure c–f shows the XPS Ti 2p and O 1s spectra of Ti 3 C 2 T x -HF and Ti 3 C 2 T x -TMAOH, respectively, and their component peak fitting results. The Ti 2p spectra of both Ti 3 C 2 T x -TMAOH and Ti 3 C 2 T x -HF can be deconvolved into three doublets: C–Ti–O (464.6 and 458.7 eV), C–Ti–OH (462.6 and 456.8 eV), and Ti–C (461.4 and 455.6 eV).…”

Prospective advances in MXene inks: screen printable sediments for flexible micro-supercapacitor applications

“…Besides, the performance of screen-printed MSCs can be further improved by chemical modification and making the composite of MXenes before the formulation of printable inks. 100,101 However, the comparability of the MXene composites with screen printable ink rheology and substrates surface interactions is an important consideration. An additive-free MXene ink on the other hand helps in improving the areal capacitance, but the stability of bare MXenes under moist conditions is to be more focused on for MXene based MSCs with high reproducibility.…”