the current collector. Recently, progresses have been made in thick electrode architecture design by incorporating external magnetic fields and carbon templates for fast charge transfer kinetics, but the complicated producing processes and fragile electrode mechanical properties limit their ability for practical applications. [10][11][12][13][14][15] Fiber like carbon materials with large aspect ratio, such as carbon nanotubes (CNT), can significantly improve electrode mechanical strength and energy density due to its excellent electron conductivity and good compatibility to form continuous network with lower electrical percolation threshold. [16][17][18][19] Nonetheless, CNT is still constrained to complicated syntheses by expensive or low throughput methods which limits their application in bunch commercial products.Cellulose nanofiber (CNF) as an emerging biomass binder shows great potential in field of flexible and freestanding electrode fabrication due to its 1D nanostructure, excellent electrochemical stability, and robust mechanical property. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] However, conventional CNFbased electrodes are characterized by low energy density owing to inadequate conductivity arising from the poor compatibility between CNF and conductive agents. Here, we report a conductive nanofiber network with decoupled electron and ion transfer pathways based on neutral carbon black (CB) nanoparticles and negatively charged CNF for high-loading thick electrode (up to 60 mg cm −2 ). This unique conductive CNF is achieved by a spontaneous electrostatic self-assembly technology as shown in Figure 1a. Microsize cellulose pulp was pretreated by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidization, which selectively oxidized the C6-hydroxyl group to a carboxyl group, leading to a strong negatively charged surface of the cellulose fibers. Negatively charged CNF was then obtained by disintegrating the microsized cellulose fiber down to the nanoscale by a probe sonication process for 1 h (Figures S1-S5, Supporting Information). Such negatively charged CNF can firmly absorb neutral CB nanoparticles by electrostatic attraction, forming a conformal conductive nanofiber. The conductive CNF can further assemble into an interconnected 3D network and tightly wrap the active electrode materials such as lithium iron phosphate (LFP) during the freeze-drying process (Figure 1b).Thick electrodes are appealing for high energy density devices but succumb to sluggish charge transfer kinetics and poor mechanical stability. Nanomaterials with large aspect ratio, such as carbon nanotubes, can help improve the charge transfer and strength of thick electrodes but represent a costly solution which hinders their utility outside of "lab scale production." Here, a conductive nanofiber network with decoupled electron and ion transfer pathways by the conformal electrostatic assembly of neutral carbon black particles on negatively charged cellulose nanofibers is reported. After integrating with ...

Carbon nanotube (CNT) forests were grown directly on a silicon substrate using a Fe/Al/Mo stacking layer which functioned as both the catalyst material and subsequently a conductive current collecting layer in pseudocapacitor applications. A vacuum-assisted, in situ electrodeposition process has been used to achieve the three-dimensional functionalization of CNT forests with inserted nickel nanoparticles as pseudocapacitor electrodes. Experimental results have shown the measured specific capacitance of 1.26 F/cm(3), which is 5.7 times higher than pure CNT forest samples, and the oxidized nickel nanoparticle/CNT supercapacitor retained 94.2% of its initial capacitance after 10,000 cyclic voltammetry tests.

The layer stacking order has profound effects on the physical properties of two-dimensional van der Waals heterostructures. For example, graphene multilayers can have distinct electronic band structures and exhibit completely different behaviors depending on the stacking order. Fascinating physical phenomena, such as correlated insulators, superconductors, and ferromagnetism, can also emerge with a periodic variation of the layer stacking order, which is known as the moiré superlattice in van der Waals materials. In this work, we realize the global phase transition between different graphene layer stacking orders and elucidate its microscopic origin. We experimentally determine the energy difference between different stacking orders with the accuracy of μeV/atom. We reveal that both the carrier doping and the electric field can drive the layer-stacking phase transition through different mechanisms: carrier doping can change the energy difference because of a non-negligible work function difference between different stacking orders; the electric field, on the other hand, induces a band-gap opening in ABC-stacked graphene and hence changes the energy difference. Our findings provide a fundamental understanding of the electrically driven stacking-order phase transition in few-layer graphene and demonstrate a reversible and noninvasive method to globally control the stacking order.

The cost effective synthesis and patterning of carbon nanomaterials is a challenge in electronic and energy storage devices. Here we report a one-step, scalable approach for producing and patterning porous graphene films with three-dimensional networks from commercial polymer films using a CO 2 infrared laser. The sp 3 -carbon atoms are photothermally converted to sp 2 -carbon atoms by pulsed laser irradiation. The resulting laserinduced graphene (LIG) exhibits high electrical conductivity. The LIG can be readily patterned to interdigitated electrodes for in-plane microsupercapacitors with specific capacitances of 44 mF cm À 2 and power densities of B9 mWcm À 2 . Theoretical calculations partially suggest that enhanced capacitance may result from LIG's unusual ultra-polycrystalline lattice of pentagon-heptagon structures. Combined with the advantage of one-step processing of LIG in air from commercial polymer sheets, which would allow the employment of a roll-to-roll manufacturing process, this technique provides a rapid route to polymer-written electronic and energy storage devices.

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