To promote the development of supercapacitors and their applications in modern electronics, it is crucial to explore novel supercapacitor electrode materials. As a representative member of the rising 2D MXenes,...

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Coarse-grained molecular dynamics simulations were performed to investigate the mobility of nanoparticles (NPs) embedded in end-linked polymer networks, considering both the entangled and unentangled cases. For the entangled case, where the network strand length N x is longer than the entanglement length N e , the strand dynamics exhibits a heavily entangled subdiffusive feature before being restricted within the fluctuation distance d fluct by the permanent cross-links. The dynamics of NPs with size d NP smaller than the entanglement tube length d T in such network follows the same behavior as that in entangled linear polymers, while for NPs with size comparable to d T , their motion is suppressed by the entanglements. The constraint release of the entanglements would allow the particles to pass through but is slightly restricted by the permanent network junctions. For the unentangled case, where N x / N e < 1, the network strands can move only locally with suppressed subdiffusive behavior due to the restrictions imposed by the adjacent network junctions. Consequently, the coupled NP dynamics is also reduced. In addition, when d NP is larger than the strand fluctuation distance d fluct , the NPs are trapped by the network cages and can diffuse at long times through hopping, which is partially masked by the NP thermal fluctuations, as reflected from the NP trajectories. Such hopping fashion of NP motion becomes more apparent with increasing the network confinement ratio before being permanently localized within the network. Increasing the NP− polymer attraction would further hamper the NP mobility. In general, this work provides some insights into understanding how the permanent cross-links affect the network dynamics and thereby the coupled NP mobility.

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MXenes have shown great potential for supercapacitor electrodes due to their unique characteristics, but simultaneously achieving high capacitance, rate capability, and cyclic stability along with good mechanical flexibility is exceptionally challenging. Here, highly enhanced capacitance, rate capability, and cyclic stability, as well as good mechanical flexibility for T 3 C 2 T x MXene-based supercapacitor electrodes are simultaneously obtained by engineering the electrode structure, modifying the surface chemistry, and optimizing the fabrication process via an optimized integration approach. This approach combines and more importantly optimizes three methods that all require a calcination process: carbonizing in situ grown polymer ("C polymer ") on the MXene, alkali treatment ("A"), and template sacrificing ("P"); and the optimized processes lead to more abundant active sites, faster ion accessibility, better chemical stability, and good mechanical flexibility. The obtained P-MXene/C polymer -A electrodes are binder-free and self-supporting and not only have good mechanical flexibility but also demonstrate much larger capacitances and better rate performance than the pristine MXene electrode. Specifically, the P-MXene/C PAQ -A electrode (PAQ: quinone-amine polymer) achieves a high capacitance of 532.9 F g −1 at 5 mV s −1 , together with superior rate performance and improved cyclic stability (97.1% capacitance retention after 40 000 cycles at 20 A g −1 ) compared with the pristine MXene (79.6% retention) and P-MXene-A (77.3% retention) electrodes. In addition, it is discovered that carbonizing in situ grown polymers can variously remove the −F group and the removal effect can be accumulated with that by the alkali treatment.