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Creators/Authors contains: "Choi, Jae Won"

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  1. The present article introduces a strategy for controlling oxidation and reduction reactions within polymer electrolyte membrane (PEM) networks as a means of enhancing storage capacity through the complexation of dissociated lithium cations with multifunctional groups of the polymer network. Specifically, co-polymer networks based on polysulfide (PS) and polyoxide (PO) precursors, photo-cured in the presence of succinonitrile (SCN) and lithium bis(trifluoro methane sulfonyl imide) (LiTFSI) salt, exhibited ionic conductivity on the order of mid 10−4 S/cm at ambient temperature in the 30/35/35 (weight %) composition. Lithium titanate (LTO, Li4Ti5O12) electrode was chosen as an anode (i.e., a potential source of Li ions) against lithium iron phosphate (LFP, LiFePO4) cathode in conjunction with polysulfide-co-polyoxide dual polyelectrolyte networks to control viscosity for 3D printability on conformal surfaces of drone and aeronautic vehicles. It was found that the PS-co-PO dual network-based polymer electrolyte containing SCN plasticizer and LiTFSI salt exhibited extra storage capacity (i.e., specific capacity of 44 mAh/g) with the overall specific capacity of 170 mAh/g (i.e., for the combined LTO electrode and PEM) initially that stabilized at 153 mAh/g after 50th cycles with a reasonable capacity retention of over 90% and Coulombic efficiency of over 99%. Of particular interest is the observation of the improved electrochemical performance of the polysulfide-co-polyoxide electrolyte dual-network relative to that of the polyoxide electrolyte single-network. 
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  2. Abstract Iron rhodium (FeRh) undergoes a first‐order anti‐ferromagnetic to ferromagnetic phase transition above its Curie temperature. By measuring the anomalous Nernst effect (ANE) in (110)‐oriented FeRh films on Al2O3substrates, the ANE thermopower over a temperature range of 100–350 K is observed, with similar magnetic transport behaviors observed for in‐plane magnetization (IM) and out‐of‐plane magnetization (PM) configurations. The temperature‐dependent magnetization–magnetic field strength (M–H) curves revealed that the ANE voltage is proportional to the magnetization of the material, but additional features magnetic textures not shown in the M‐H curves remained intractable. In particular, a sign reversal occurred for the ANE thermopower signal near zero field in the mixed‐magnetic‐phase films at low temperatures, which is attributed to the diamagnetic properties of the Al2O3substrate. Finite element method simulations associated with the Heisenberg spin model and Landau–Lifshitz–Gilbert equation strongly supported the abnormal heat transport behavior from the Al2O3substrate during the experimentally observed magnetic phase transition for the IM and PM configurations. The results demonstrate that FeRh films on an Al2O3substrate exhibit unusual behavior compared to other ferromagnetic materials, indicating their potential for use in novel applications associated with practical spintronics device design, neuromorphic computing, and magnetic memory. 
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  3. The year 1975 can be claimed to be the year of inception for the research and development of solid polymer electrolytes (SPEs) for Lithium-Ion Batteries (LIB), when the ionic conductivity of polyethylene oxide–alkaline metal ion complex was found by Peter Wright from the University of Sheffield. However, SPE research has undergone a leapfrog development, with conductivity values improving from 1 × 10–7 S·cm−1 to 1 × 10– 1 S·cm−1. The seed of development of SPEs spurs from the need for introducing design freedom to battery structures as well as the need for leak-proof electrolytes, greater operational safety, higher energy density, and other considerations. While the benefits of SPEs are evident, poor interfacial contact is a major factor limiting their application. This review presents the history of SPEs and shows how the additive manufacturing (AM) could prove beneficial for the improvement of performance and the functional implementation of SPEs. While the article articulates a technical review of additively manufactured SPEs, it also provides a lab-to-market perspective that could aid in shaping the future of green technology in energy storage. It also aims to provide an overall picture about the evolution and diversity of research advances in the development of greener SPEs through AM technology. 
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  4. null (Ed.)