Mechanically Induced Nanoscale Architecture Endows a Titanium Carbide MXene Electrode with Integrated High Areal and Volumetric Capacitance

Abstract

Complete utilization of electrochemically active materials while maintaining the high areal/volumetric packing density is a goal to be achieved in miniaturized supercapacitor devices, which therefore display both high volumetric and areal energy density. Although critical, it is usually challenging to achieve this goal by optimizing the electrode architecture. Dense packing of active materials maximizes the volumetric capacitance but also results in sluggish diffusion of the electrolyte. Structurization of the electrode by forming large pores creates a pathway for electrolyte penetration but reduces the volumetric energy density. Here, densified electrodes with hierarchical porous architecture at the nanoscale are reported, which provide an alternative solution. Worm‐like expanded titanium carbide MXene powders are produced in highly viscous reaction media and assembled by mechanical compression. The expanded morphology of the MXene powders translates into a buckling microstructure in the electrodes, resulting in 28.2 ± 4.1% porosity mainly in the form of nanosized pores. At the sub‐nanometer scale, the diffusion of electrolytes is enhanced in interlayer space of the bended lattice with pillared intercalants. These hierarchical structural features lead to both high areal and volumetric capacitance (11.4 F cm−2 coupled with 770 F cm−3) in hundred‐micrometers‐thick electrodes, which inspires the design of high‐performance electrochemical energy storage devices.

Two-Dimensional Effects of Ni-Based Metal–Organic Framework Materials on Electrochemical Actuators

“…This indicates that the material may be more conducive to ion diffusion. Based on the above analysis, the high electron transfer ability and ion diffusion rate of PEDOT:PSS/2D Ni-BDC are important reasons for the enhanced performance of the actuator. − …”

MXene-Based Ceramic Nanocomposites Enabled by Pressure-Assisted Sintering

“…The decrease in hardness likely arises from the presence of stacked MXene layers located at the grain boundaries. These grain boundaries are weaker since several layers of MXene can readily deform by bending, buckling, 87 and shearing. 60 Deformation can be facilitated by shearing of MXene layers which accommodates sliding and rotation of the alumina grains, resulting in softening of the nanocomposite material.…”

Hydroiodic‐Acid‐Initiated Dense yet Porous Ti3C2Tx MXene Monoliths toward Superhigh Areal Energy Storage

“…[19,20,28,29,33] h) The comparison of areal and volumetric capacitance between DMH-4 and other reported MXene-based electrodes with high thickness. [19,20,33,40,41] tension, like HI. The HI partially remained between the MXene nanosheets can preserve paths for ion transport.…”

“…f) Areal capacitance of DMH-4 and dense MXene films collected at scan rates ranging from 2 to 100 mV s −1 .g) The densities of DMH-4, filtrated MXene films,[19] and previously reported porous MXene assemblies [19,20,28,29,33]. h) The comparison of areal and volumetric capacitance between DMH-4 and other reported MXene-based electrodes with high thickness [19,20,33,40,41].…”