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A solar-powered integrated supercapacitor (SPIS) with an inverted organic solar cell (iOSC) as the energy conversion unit and a supercapacitor (SC) as the energy-storage unit is a workable combinat...

Laser-induced graphene (LIG) typically exhibits a mesostructure with a small specific surface area, which is detrimental to the electrochemical performance of micro-supercapacitors (MSCs). Herein, ...

The electrical conductivity and mechanical strength of fibers constructed from single-walled carbon nanotubes (CNTs) are usually limited by the weak interactions between individual CNTs. In this work, we report a significant enhancement of both of these properties through chemical cross-linking of individual CNTs. The CNT fibers are made by wet-spinning a CNT solution that contains 1,3,5-tris(2'-bromophenyl)benzene (2TBB) molecules as the cross-linking agent, and the cross-linking is subsequently driven by Joule heating. Cross-linking with 2TBB increases the conductivity of the CNT fibers by a factor of ∼100 and increases the tensile strength on average by 47%; in contrast, the tensile strength of CNT fibers fabricated without 2TBB decreases after the same Joule heating process. Symmetrical supercapacitors made from the 2TBB-treated CNT fibers exhibit a remarkably high volumetric energy density of ∼4.5 mWh cm

This work reports the thinnest and smallest hollow N-doped carbon boxes among recently reported hollow N-doped carbon materials. Hollow and N-rich microporous organic networks (H-NMONs) were prepared by the azide–alkyne Huisgen cycloaddition of tetra(4-ethynylphenyl)methane and 1,4-diazidobenzene on the surface of Cu2O nanocubes and the successive acid etching of inner Cu2O. The Cu2O nanocubes played roles of templates and networking catalysts. The networking reaction generated N-rich triazole rings in the MON. Heat treatment of H-NMONs under argon resulted in the formation of hollow N-doped carbon boxes (H-NCBs). The diameter and shell thickness of H-NCBs were 130 and 12 nm, respectively. The H-NCBs showed superior electrochemical performance in H2SO4 electrolyte as energy storage materials for supercapacitors, compared with that in KOH electrolyte. Among the H-NCBs, H-NCB-900 which was obtained by the heat treatment of H-NMON at 900 °C showed the best performance with capacitances of 286 and 251 F/g at ...

Li-iodine chemistry is of interest for electrochemical energy storage because it has been shown to provide both high power and high energy density. However, Li-iodine batteries are typically formed using Li metal and elemental iodine, which presents safety and fabrication challenges (e.g., the high vapor pressure of iodine). These disadvantages could be circumvented by using LiI as a starting cathode. Here, we present fabrication of a reduced graphene oxide (rGO)/LiI composite cathode, enabling for the first time the use of LiI as the Li-ion battery cathode. LiI was coated on rGO by infiltration of an ethanolic solution of LiI into a compressed rGO aerogel followed by drying. The free-standing rGO/LiI electrodes show stable long-term cycling and good rate performance with high specific capacity (200 mAh g–1 at 0.5 C after 100 cycles) and small hysteresis (0.056 V at 1 C). Shuttling was suppressed significantly. We speculate the improved electrochemical performance is due to strong interactions between the...

Fiber electrodes provide interesting opportunities for energy storage by providing both mechanical flexibility and the opportunity to impart multifunctionality to fabrics. We show here carbon nanotube (CNT)-embedded agarose gel composite fiber electrodes, with a diameter of ∼120 μm, consisting of 60 wt % CNTs that can serve as the basis for flexible and wearable fiber microsupercapacitors (mSCs). Via an extrusion process, CNT bundles are induced to align in an agarose filament matrix. Due to the shear alignment of the CNT bundles, the dehydrated filaments have an electrical conductivity as high as 8.3 S cm–1. The composite fiber electrodes are mechanically stable, enabling formation of twisted two-ply fiber mSCs integrated with a solid electrolyte. The fiber mSC shows a high capacitance (∼1.2 F cm–3), good rate retention (∼90%) at discharge current densities ranging from 5.1 to 38 mA cm–3, long cycle life under repeated charging/discharging (10% fade after 10 000 cycles) and good performance after at leas...

The reliability and durability of energy storage devices are as important as their essential characteristics (e.g., energy and power density) for stable power output and long lifespan and thus much more crucial under harsh conditions. However, energy storage under extreme conditions is still a big challenge because of unavoidable performance decays and the inevitable damage of components. Here, we report high-temperature operating, flexible supercapacitors (f-SCs) that can provide reliable power output and extreme durability under severe electrochemical, mechanical, and thermal conditions. The outstanding capacitive features (e.g., ∼40% enhancement of the rate capability and a maximum capacitances of 170 F g(-1) and 18.7 mF cm(-2) at 160 °C) are attributed to facilitated ion transport at elevated temperatures. Under high-temperature operation and/or a flexibility test in both static and dynamic modes at elevated temperatures100 °C, the f-SCs showed extreme long-term stability of 100000 cycles (93% of initial capacitance value) and mechanical durability after hundreds of bending cycles (at bend angles of 60-180°). Even at 120 °C, the versatile design of tandem serial and parallel f-SCs was demonstrated to provide both desirable energy and power requirements at high temperatures.

Sulfonated poly(arylene ether sulfone) membranes with cross-linked structures (C-SPAES) were simply prepared by simultaneously casting and heating the polymer solutions composed of sulfonated poly(arylene ether sulfone) with azidomethyl side groups (SPAES-N3), cross-linkers such as 1,4-diethynylbenzene and 4,4′-diazido-2,2′-stilbenedisulfonic acid disodium salt tetrahydrate, and a click reaction catalyst such as CuBr and N,N,N′,N″,N″-pentamethyldiethylenetriamine in N,N-dimethylacetamide, where SPAES-N3 were prepared by the substitution of sulfonated PAES (SPAES) through chloromethylation followed by azidation reaction. C-SPAES membranes obtained using the optimum amount of the cross-linkers showed much improved chemical and physical stabilities and mechanical strength compared with linear SPAES membrane. Since the cross-linked structures were formed by the cross-linker having sulfonic acid groups, C-SPAES membranes showed higher ion exchange capacity and proton conductivity than the linear SPAES membrane...

A series of organic/inorganic hybrid block and random copolymers were prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization using poly(ethylene glycol) methyl ether methacrylate (PEGMA) and 3-(3,5,7,9,11,13,15-heptaisobutylpentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane-1-yl)propyl methacrylate (MA-POSS) as monomers in order to study the effect of polymer morphology and POSS content on the properties of polymer electrolytes. Flexible and dimensionally stable free-standing films were made from the hybrid block and random copolymers mixed with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) when the contents of MA-POSS unit were larger than 31 and 16 mol %, respectively. The ionic conductivity of the solid-state block copolymer (PBP) electrolyte was found to be 1 order of magnitude higher than that of the random copolymer (PRP) electrolyte when they had similar MA-POSS content, although their glass transition temperature values of their ion-conducting segments were quite clos...

Here we report new H3PO4-doped cross-linked benzoxazine–benzimidazole copolymer membranes showing high proton conductivity and long-term durability for use in proton-exchange membrane fuel cells at elevated temperatures (>100 °C). The cross-linked copolymer membranes were prepared by mixing of poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole] (PBI) with 3-phenyl-3,4-dihydro-6-tert-butyl-2H-1,3-benzoxazine (pBUa) in N,N-dimethylacetamide, with subsequent stepwise heating to 220 °C, and even large-sized films (30 cm × 140 m) could be easily prepared. The membranes showed high proton conductivities of up to 0.12 S cm–1 at 150 °C under anhydrous conditions. Membrane–electrode assemblies (MEAs) employing the membranes showed operating voltages of 0.71 V at 0.2 A cm–2. Furthermore, the MEAs displayed long-term durability up to 1999 cycles, with much slower performance decay, −0.03 mV h–1, than those prepared using the PBI membrane in in situ accelerated lifetime mode (load cycling testing).