MXene interlayer space expansion: Alleviating coulomb attraction and steric resistance on multivalent charge carriers toward micro-supercapacitors with enhanced areal energy density

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Vol. 922; p. 116716
• Main Authors: Peng, Ruhai, Yu, Bin, Hu, Haibo
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2022; Elsevier Science Ltd
• Subjects: Arrays; Attraction; Circuits; Coulomb attraction; Current carriers; Diffusion barriers; Electric potential; Electrodes; Elongation; Energy; Expansion; Hydrogels; Interlayer space; Interlayers; Micro-supercapacitors; MXenes; Polyacrylamide; Power sources; Self-assembly; Steric resistance; Supercapacitors; Ti3C2Tx; Voltage; Voltage window; Voltage window; Micro-supercapacitors; Coulomb attraction; Interlayer space; Ti3C2Tx; Steric resistance
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2022.116716

Sluggish bivalent Mg2+ diffusion between MXene interlayers arising from narrow physical space and strong electrostatic attraction is significantly facilitated by interlayer expansion via the insertion of bacterial cellulose nanospacer, endowing the further fabricated symmetric Mg-ions aqueous micro-supercapacitors with enhanced areal energy density. [Display omitted] •Mg2+ diffusion between MXene interlayers is facilitated by interlayer expansion engineering.•An areal energy density up to 32 μWh cm-2 is realized on the fabricated symmetric Mg2+ micro-supercapacitor.•A stretchable SMI-MSC array with stable output voltage under elongation up to 200% is fabricated. Sluggish multivalent charge carriers diffusion between MXene interlayers arising from narrow physical space and strong electrostatic attraction has long been a challenge in promoting the areal energy densities of MXene-based aqueous micro-supercapacitors (MSCs). Herein, a simple interlayer space expansion strategy of MXene-based self-assembled film electrode is proposed to alleviate coulomb attraction and steric resistance on divalent Mg2+ transfer toward symmetric Mg-ions aqueous micro-supercapacitors (SMI-MSCs) with significantly enhanced areal energy density. The electrochemical tests prove that the enlarged interlayer space by introducing 1D bacterial cellulose (BC) nanospacer between Ti3C2Tx flakes can effectively reduce the diffusion barrier of Mg2+ within the obtained Ti3C2Tx/BC composite film electrode. Benefiting from the simultaneously repressed kinetics of hydrogen/oxygen evolution on the Ti3C2Tx/BC composite film electrode rooting in the employed neutral polyacrylamide/Mg(CF3SO3)2 hydrogel electrolyte, the as-fabricated SMI-MSCs acquire a high areal energy density of 32 μWh cm−2 and a cell voltage up to 1.2 V. Encouraged by the superior energy efficiency of single SMI-MSC unit, a stretchable SMI-MSC array has further been fabricated via integrating the SMI-MSCs on flexible circuit board with bridge-island architecture. The obtained SMI-MSC array can provide stable and adjustable output of voltage and energy under elongation up to 200%, revealing great application potential for wearable/flexible power source.