Incorporating inorganic nanoparticles (NPs) into polymer matrices provides a promising solution for suppressing space charge effects that can lead to premature failure of electrical insulation used in high voltage direct current engineering. However, realizing homogeneous NP dispersion is a great challenge especially in high-molecular-weight polymers. Here, we address this issue in crosslinked polyethylene by grafting matrix-compatible polymer brushes onto spherical colloidal SiO 2 NPs (10-15 nm diameter) to obtain a uniform NP dispersion, thus achieving enhanced space charge suppression, improved DC breakdown strength, and restricted internal field distortion (10.6%) over a wide range of external DC fields from À30 kV/mm to À100 kV/mm at room temperature. The NP dispersion state is the key to ensuring an optimized distribution of deep trapping sites. A well-dispersed system provides sufficient charge trapping sites and shows better performance compared to ones with large aggregates. This surface ligand strategy is attractive for future nano-modification of many engineering insulating polymers. Published by AIP Publishing.
Developing advanced carbon nanomaterials with reasonable pore distribution and interconnection and matching the chargestorage capacities and electrode kinetics between the capacitive electrode and the battery-type electrode are two of the biggest challenges in lithium-ion capacitors (LICs). In this work, a sustainable strategy to fabricate N/S dual-doped hierarchical porous carbon nanofibers (N/S-CNF) is developed via electrospinning and thiourea treatment, and the N/S-CNF is employed as both the capacitor-type cathode and the battery-type anode for LICs. With rational design, N/S-CNF can not only offer a large specific surface area with a hierarchical pore structure but also be uniformly doped with heteroatoms, which is desirable for improving the electrochemical performance of both the cathode and the anode for LICs and alleviating the mismatch between the two electrodes. LICs assembled with the designed N/S-CNF electrodes can deliver a high energy density of 154 Wh kg −1 with a stable capacitance retention of 92% after 6000 cycles. Our work is expected to open up new avenues for developing heteroatom-doped porous carbon nanomaterials applied in other energy conversion and storage devices.
HEV-E2 fragment can be inserted into the plastid genome and the recombinant pE2 antigen derived is antigenic in mice. Hence, plastids may be a novel source for cost-effective production of HEV vaccines.
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