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The article presents a study that dealt with the influence of oxygen plasma treatment on surface properties of poly(p-phenylene benzobisox-azole) (PBO) fibers and interfacial properties of PBO fiber reinforced poly(phthalazinone ether sulfone ketone). The study used X-ray photoelectron spectroscopy, Atomic force microscopy, and scanning electron microscopy to analyze surface chemical composition, and surface morphologies. Dynamic contact angle analysis enabled characterization of surface energy.

One-dimensional tunnel and layer frame crystal structure materials are extremely attractive for energy storage in electrode materials. The energy storage properties of the electrode materials depend on their conductivity. Furthermore, the conductivity of electrode materials can be tailored through combination or doping with other materials, which transforms their properties from semiconductor to semimetallic or metallic and allow them to show unequaled performance for storage devices. In this work, heterostructures of manganese oxide (MnO) and modified sodium titanate (Na 2 Ti 6 O 13 ) (MnO@Na 2 Ti 6 O 13 ) nanowires are attained by the in situ thermal decomposition method. The heterojunction between MnO and Na 2 Ti 6 O 13 allows the semiconductor properties of pure Na 2 Ti 6 O 13 to show remarkable metallic behavior for improving the electrochemical performance. The capacitance of MnO@Na 2 Ti 6 O 13 heterojunction nanowires can reach 272.3 F g -1 , a power intensity of 250 W kg -1 at the energy density of 37.83 Wh kg -1 and retain 5000 W kg -1 at 6.67 Wh kg -1 as well. The energy storage mechanism of the MnO@Na 2 Ti 6 O 13 heterostructure is studied by density functional theory. All of the results show that the MnO@Na 2 Ti 6 O 13 heterostructure material has the potential to be an excellent supercapacitor material in the future.

Nanomaterials with tunnel structures are extremely attractive to be used for electrode materials in electrochemical energy storage devices. Tunnel-structured Ti-doped Na 4 Mn 9 O 18 nanoparticles (TNMO-NPs) were synthesized by a facile and high-production method of the solid-state reaction with a high-energy ball-milling process. As electrode materials in the supercapacitor cell, the as-synthesized TNMO-NPs exhibit a high specific capacity of 284.93 mA h g -1 (0.57 mA h cm -2 /1025.75 F g -1 ). A superior rate capability with a decay of 36% is achieved by increasing the scan rates from 2 to 25 mV s -1 . To further explore the storage mechanism of Ti-doped Na 4 Mn 9 O 18 materials, density functional theory (DFT) calculations were used to calculate the activation energy for the ion immigration in the electrode, and the results show that the minimum ion diffusion barrier energy is 0.272 eV, indicating that the sodium ions could insert into the system easily. Through the scan-rate-dependent cyclic voltammetry analysis, the capacity value indicates a mixed charge storage of capacitive behavior and Na + intercalation progress. A maximum energy density of 77.81 W h kg -1 at a power density of 125 W kg -1 is achieved, and a high energy density of 54.79 W h kg -1 is maintained even at an ultrahigh power density of 3750 W kg -1 . The TNMO-NP supercapacitors show excellent flexibility at various bent (0-180°) states. The capacitive performance of the TNMO-NPs makes them promising cathode materials for flexible supercapacitors with high specific capacities and high energy densities.

LiCoO 2 (LCO) usually can deliver high energy density but low power density in Li-ion batteries (LIBs). Whether LCO could be used as electrode material for high-performance supercapacitors is dependent on promoting its power density. Owing to Faradaic redox reactions taking place on its surfaces or inside crystals through ion intercalation/deintercalation from the surfaces, increasing the specific area of LCO is a key factor to promote its rate capability. Herein, we report a facile strategy to prepare LCO nano-flakes with high specific area exceeding that of currently used micro-scale particles in LIBs. LCO as a nano-flake structure is expected to have a high fraction of Li atom exposure, which benefits fast redox reactions taking place on the surfaces. An LCO-based electrode exhibits an excellent specific capacitance of 581.3 F g -1 at 0.5 A g -1 , high power density of 2262 W kg -1 at an energy density of 41.0 Wh kg -1 , and good cycling stability (83.9% capacitance retention at 6 A g -1 after 2000 cycles) in LiCl aqueous electrolyte. Faradaic redox behaviors have been analyzed, indicating an ideal diffusion-controlled process. Moreover, a full solid-state symmetric supercapacitor is assembled using LCO nano-flake-based electrodes, which presents good performance with light weight and flexibility. Impressively, three charged supercapacitors in series can light 100 green light emitting diodes for 14 min. LCO in nano-flake structure form with high power density could be an excellent material for superior supercapacitors.