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Lattice oxygen redox offers an unexplored way to access superior electrochemical properties of transition metal oxides (TMOs) for rechargeable batteries. However, the reaction is often accompanied by unfavourable structural transformations and persistent electrochemical degradation, thereby precluding the practical application of this strategy. Here we explore the close interplay between the local structural change and oxygen electrochemistry during short- and long-term battery operation for layered TMOs. The substantially distinct evolution of the oxygen-redox activity and reversibility are demonstrated to stem from the different cation-migration mechanisms during the dynamic de/intercalation process. We show that the π stabilization on the oxygen oxidation initially aids in the reversibility of the oxygen redox and is predominant in the absence of cation migrations; however, the π-interacting oxygen is gradually replaced by σ-interacting oxygen that triggers the formation of O-O dimers and structural destabilization as cycling progresses. More importantly, it is revealed that the distinct cation-migration paths available in the layered TMOs govern the conversion kinetics from π to σ interactions. These findings constitute a step forward in unravelling the correlation between the local structural evolution and the reversibility of oxygen electrochemistry and provide guidance for further development of oxygen-redox layered electrode materials.

All-solid-state batteries are a potential game changer in the energy storage market; however, their practical employment has been hampered by premature short circuits caused by the lithium dendritic growth through the solid electrolyte. Here, we demonstrate that a rational layer-by-layer strategy using a lithiophilic and electron-blocking multilayer can substantially enhance the performance/stability of the system by effectively blocking the electron leakage and maintaining low electronic conductivity even at high temperature (60°C) or under high electric field (3 V) while sustaining low interfacial resistance (13.4 ohm cm 2 ). It subsequently results in a homogeneous lithium plating/stripping, thereby aiding in achieving one of the highest critical current densities (~3.1 mA cm −2 ) at 60°C in a symmetric cell. A full cell paired with a commercial-level cathode exhibits exceptionally long durability (>3000 cycles) and coulombic efficiency (99.96%) at a high current density (2 C; ~1.0 mA cm −2 ), which records the highest performance among all-solid-state lithium metal batteries reported to date.

Calcium-ion batteries (CIBs) are under investigation as next-generation energy storage devices due to their theoretically high operating potentials and lower costs tied to the high natural abundanc...

Despite the high energy density of lithium-rich layered-oxide electrodes, their real-world implementation in batteries is hindered by the substantial voltage decay on cycling. This voltage decay is widely accepted to mainly originate from progressive structural rearrangements involving irreversible transition-metal migration. As prevention of this spontaneous cation migration has proven difficult, a paradigm shift toward management of its reversibility is needed. Herein, we demonstrate that the reversibility of the cation migration of lithium-rich nickel manganese oxides can be remarkably improved by altering the oxygen stacking sequences in the layered structure and thereby dramatically reducing the voltage decay. The preeminent intra-cycle reversibility of the cation migration is experimentally visualized, and first-principles calculations reveal that an O2-type structure restricts the movements of transition metals within the Li layer, which effectively streamlines the returning migration path of the transition metals. Furthermore, we propose that the enhanced reversibility mitigates the asymmetry of the anionic redox in conventional lithium-rich electrodes, promoting the high-potential anionic reduction, thereby reducing the subsequent voltage hysteresis. Our findings demonstrate that regulating the reversibility of the cation migration is a practical strategy to reduce voltage decay and hysteresis in lithium-rich layered materials.

Increasing demands for performance beyond the limit of current lithium ion batteries for higher energy densities have rejuvenated research using lithium metal as an anode. However, commercial implementation has still been hampered due to safety issues. Herein, we introduce a lithium rechargeable battery system with an auxiliary electrode that can detect the potential signs of an internal short-circuit and simultaneously prevent cell failure by inhibiting further dendritic growth of lithium metal. Based on this working principle, we provide guidelines for an auxiliary electrode design and demonstrate that it can act as both a safety sensor and a lithium scavenger. Finally, we show that our in-house designed cell, using a flexible and self-standing auxiliary electrode, can effectively alert the danger of a short circuit in real-time without additional dendrite growth. We expect that this finding will open up unexplored opportunities utilizing various auxiliary electrode chemistries for safe rechargeable lithium metal batteries.

Lattice oxygen redox activity offers an unexplored way to access the latent superior electrochemical property of transition metal oxides for rechargeable batteries. However, the redox reaction of the lattice oxygen is often accompanied by unfavorable structural transformations and the corresponding degradation of electrochemical performances, precluding its practical application. Herein, we explore the close interplay between the local structural change during the dynamic intercalation process and the solid-state oxygen electrochemistry in the short- or long-term battery operation for layered transition metal oxides. By employing two model systems of the layered Na0.6(Li0.2TixMn0.8−x)O2 with the oxygen redox capability, it is demonstrated that the substantially distinct evolutions in the oxygen redox activity and reversibility are caused by different cation migration mechanisms available in the system during the de/intercalation (i.e. out-of-plane and in-plane migrations of transition metals (TMs)). We show that the π stabilization upon the oxygen oxidation initially aids in the reversibility of the oxygen redox and is predominant in the absence of TM migrations, however, the π-interacting oxygens are gradually replaced by the σ-interacting oxygens that trigger the formation of O–O dimers and the structural destabilization over cycles. More importantly, it is revealed that the distinct TM migration paths available in the respective layered materials govern the conversion from π to σ interactions and its kinetics. It infers that regulating the dynamics of TMs in the layered materials can play a key role in delaying or inhibiting the deterioration of the oxygen redox reversibility. These findings constitute a step forward in unraveling the correlation between the local structural evolution and the reversibility of solid-state oxygen electrochemistry, and provide a guidance for developing oxygen-redox layered electrode materials.

The rampant generation of lithium hydroxide and carbonate impurities, commonly known as residual lithium, is a practical obstacle to the mass-scale synthesis and handling of high-nickel (>90 %) layered oxides and their use as high-energy-density cathodes for lithium-ion batteries. Herein, we suggest a simple in situ method to control the residual lithium chemistry of a high-nickel lithium layered oxide, Li(Ni0.91 Co0.06 Mn0.03 )O2 (NCM9163), with minimal side effects. Based on thermodynamic considerations of the preferred reactions, we systematically designed a synthesis process that preemptively converts residual Li2 O (the origin of LiOH and Li2 CO3 ) into a more stable compound by injecting reactive SO2 gas. The preformed lithium sulfate thin film significantly suppresses the generation of LiOH and Li2 CO3 during both synthesis and storage, thereby mitigating slurry gelation and gas evolution and improving the cycle stability.

The thermodynamic instability of the LiCoO2 layered structure at >0.5Li extraction has been considered an obstacle for the reversible utilization of its near theoretical capacity at high cutoff voltage (>4.6 V vs Li/Li+) in lithium-ion batteries. Many previous studies have focused on resolving this issue by surface modification of LiCoO2, which has proven to be effective in suppressing phase transformation. To determine the extent to which surface protection of LiCoO2 is effective despite its thermodynamic instability and presumably incomplete reversibility involving the O1 phase, here we verify the intrinsic reversibility of bulk LiCoO2 with extended lithium extraction by ruling out the effect of a surface. Specifically, first, we show that, contrary to conventional belief, electrochemical cycling of LiCoO2 at a cutoff voltage of 4.8 V (vs Li/Li+) results in better cycle stability and lower polarizations than those at 4.6 V. We demonstrate, using an exhaustive suite of characterization tools, that the ra...

RFBs, which use soluble redox species dissolved in electrolytes, show great promise for large-scale energy storage systems (ESSs) because of their scalability, cost-effectiveness, and design flexibility that can decouple power and energy for diverse purposes; however, their low energy density has limited their widespread application. Most conventional ways to increase the energy density to date have relied on either exploiting high-concentration electrolytes that contain large amounts of redox materials per volume or developing redox materials with higher solubility. Although this approach of exploiting high-concentration electrolytes is simple and effective, it results in unfavorable trade-offs, including increased electrolyte viscosity and high cell resistance, and often leads to the precipitation of salts, which causes the failure of the system. Furthermore, non-aqueous RFBs can be more vulnerable to these trade-offs because of the intrinsically lower ionic conductivity of non-aqueous electrolytes compared with that of their aqueous counterparts, which typically results in inferior power capability of the system. Here, we demonstrate that the use of multi-electron molecules as redox materials can offer an alternative route to overcome these issues and achieve high-energy-density RFBs. Unlike doubling the electrolyte concentration, for instance, which would easily result in the solubility limit being exceeded or significant reduction of the kinetics, the utilization of the double-redox activity from a single-redox material would approximately double the energy density without negatively affecting the electrolyte properties. Nevertheless, the use of a second-electron redox reaction in most redox-active materials in RFBs has often been shown to be irreversible or to promote severe degradation because of the poor chemical stability of the redox materials at highly oxidized states in the solution. In this study, we demonstrate, for the first time, an all organic flow system using a multi-electron redox-active organic material with the superior chemical stability, which is a phenazine derivative. In addition, an analysis of the electrochemical kinetic properties of redox couple on both diffusion- and charge transfer-controlled kinetic is conducted through rotating disk electrode test; The redox couple displays outstanding kinetic characteristics. Moreover, the redox couple presents the highest theoretical and practical energy density among reported redox couples for both aqueous and non-aqueous RFB at the same concentration. The redox mechanism and the chemical stability of redox couple are investigated through raman spectroscopy and density functional theory calculations. These findings on this multi-electron redox material provide a potential new pathway for the design of high-energy-density RFBs and practically feasible ESSs.

All-solid-state batteries are considered as one of the attractive alternatives to conventional lithium-ion batteries, due to their intrinsic safe properties benefiting from the use of non-flammable solid electrolytes in ASSBs. However, one of the issues in employing the solid-state electrolyte is the sluggish ion transport kinetics arising from the chemical and physical instability of the interfaces among solid components including electrode material, electrolyte and additive agents. In this work, we investigate the stability of the interface between carbon conductive agents and Li10GeP2S12 in a composite cathode and its effect on the electrochemical performance of ASSBs. It is found that the inclusion of various carbon conductive agents in composite cathode leads to inferior kinetic performance of the cathode despite expectedly enhanced electrical conductivity of the composite. We observe that the poor kinetic performance is attributed to a large interfacial impedance which is gradually developed upon the inclusions of the various carbon conductive agents regardless of their physical differences. The analysis through X-ray Photoelectron Spectroscopy suggests that the carbon additives in the composite cathode stimulate the electrochemical decomposition of LGPS electrolyte degrading its surface during cycling, indicating the large interfacial resistance stems from the undesirable decomposition of the electrolyte at the interface.

Lithium-ion batteries are expected to serve as a key technology for large-scale energy storage systems (ESSs), which will help satisfy recent increasing demands for renewable energy utilization. Besides their promising electrochemical performance, the low self-discharge rate (

Layered crystal structures are some of the most intensively studied intercalation hosts for guest ion insertion. For Mg insertion, layered transition metal sulfides or selenides have been used for reversible Mg intercalation; however, far less intercalation hosts have been found for layered oxides most likely because of the strong interaction between Mg 2+ and the oxide host. Here, we demonstrate that layered Li x Ni 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), which is an important commercial electrode for Li-ion batteries but has been regarded as electrochemically inactive in rechargeable Mg batteries, can function as a reversible host for Mg 2+ if water opens up the layers and screens the electrostatic interaction between Mg 2+ and the host. Upon the formation of water-intercalated NCM523, the discharge capacity dramatically increases utilizing the multi-redox reaction of Ni 2+ /Ni 3+ /Ni 4+ , which exhibits an average voltage of ∼3.1 V ( vs. Mg/Mg 2+ ) in rechargeable Mg batteries with an energy density of 589 Wh kg −1 in the first discharge.

Increasing demands for advanced lithium batteries with higher energy density have resurrected the use of lithium metal as an anode, whose practical implementation has still been restricted, because of its intrinsic problems originating from the high reactivity of elemental lithium metal. Herein, we explore a facile strategy of doping gas phase into electrolyte to stabilize lithium metal and suppress the selective lithium growth through the formation of stable and homogeneous solid electrolyte interphase (SEI) layer. We find that the sulfur dioxide gas additive doped in electrolyte significantly improves both chemical and electrochemical stability of lithium metal electrodes. It is demonstrated that the cycle stability of the lithium cells can be remarkably prolonged, because of the compact and homogeneous SEI layers consisting of Li–S–O reduction products formed on the lithium metal surface. Simulations on the lithium metal growth process suggested the homogeneity of the protective layer induced by the ga...

Here, we introduce Na3V(PO3)3N as a novel 4V-class and zero-strain cathode material for Na-ion batteries. Structural analysis based on a combination of neutron and X-ray diffraction (XRD) reveals that the Na3V(PO3)3N crystal contains three-dimensional channels that are suitable for facile Na diffusion. The Na (de)intercalation is observed to occur at ∼4 V vs Na/Na+ in the Na cell via the V3+/V4+ redox reaction with ∼67% retention of the initial capacity after over 3000 cycles. The remarkable cycle stability is attributed to the near-zero volume change (∼0.24%) and unique centrosymmetric distortion that occurs during a cycle despite the large ionic size of Na ions for (de)intercalation, as demonstrated by ex situ XRD analysis and first-principles calculations. We also demonstrate that the Na3V(PO3)3N electrode can display outstanding power capability with ∼84% of the theoretical capacity retained at 10C, even though the particle sizes are on the micrometer scale (>5 μm), which is attributed to its intrinsi...

Summary Redox-active organic materials (ROMs) have recently attracted significant attention for redox flow batteries (RFBs) to achieve green and cost-efficient energy storage. In particular, multi-redox ROMs have shown great promise, and further tailoring of these ROMs would yield RFB technologies with the highest possible energy density. Here, we present a phenazine-based catholyte material, 5,10-bis(2-methoxyethyl)-5,10-dihydrophenazine (BMEPZ), that undergoes two single-electron redox reactions at high redox potentials (−0.29 and 0.50 V versus Fc/Fc+) with enhanced solubility (0.5 M in acetonitrile), remarkable chemical stability, and fast kinetics. Moreover, an all-organic flow battery exhibits cell voltages of 1.2 and 2.0 V when coupled with 9-fluorenone (FL) as an anolyte. It shows capacity retention of 99.94% per cycle over 200 cycles and 99.3% per cycle with 0.1 M and 0.4 M BMEPZ catholyte, respectively. Notably, the BMEPZ/FL couple results in the highest energy density (∼17 Wh L−1) among the non-aqueous all-organic RFBs reported to date.

Recent discovery of high-concentration electrolyte systems has opened a new avenue toward the high-voltage, safe, and low-cost aqueous rechargeable batteries. However, the need for generally high-cost organic solutes in the high-concentration electrolyte has become another major obstacle. Herein, we revisited all the commonly used low-cost solutes for high-concentration system and discovered that the use of NaClO4 solute effectively results in a wide electrochemical stability window by suppressing water decomposition and induces stable solid-electrolyte interphase (SEI) layer formation without involving the reduction of salt anions. The SEI layer, composed of Na2CO3 and Na O compounds including NaOH, guarantees the excellent electrochemical storage stability of the full-cell composed of Na4Fe3(PO4)2(P2O7) cathode and NaTi2(PO4)3 anode for the extended period of time. This new class of electrolyte systems provides remarkable cycle stability and a coulombic efficiency of ∼99% at 1C for over 200 cycles, which outperforms the state-of-the-art super-concentrated systems based on NaCF3SO3.

The production of rechargeable batteries is rapidly expanding, and there are going to be new challenges in the near future about how the potential environmental impact caused by the disposal of the large volume of the used batteries can be minimized. Herein, a novel strategy is proposed to address these concerns by applying biodegradable device technology. An eco-friendly and biodegradable sodium-ion secondary battery (SIB) is developed through extensive material screening followed by the synthesis of biodegradable electrodes and their seamless assembly with an unconventional biodegradable separator, electrolyte, and package. Each battery component decomposes in nature into non-toxic compounds or elements via hydrolysis and/or fungal degradation, with all of the biodegradation products naturally abundant and eco-friendly. Detailed biodegradation mechanisms and toxicity influence of each component on living organisms are determined. In addition, this new SIB delivers performance comparable to that of conventional non-degradable SIBs. The strategy and findings suggest a novel eco-friendly biodegradable paradigm for large-scale rechargeable battery systems.

The thermodynamic instability of the LiCoO

All-solid-state batteries are considered as one of the attractive alternatives to conventional lithium-ion batteries, due to their intrinsic safe properties benefiting from the use of non-flammable solid electrolytes in ASSBs. However, one of the issues in employing the solid-state electrolyte is the sluggish ion transport kinetics arising from the chemical and physical instability of the interfaces among solid components including electrode material, electrolyte and additive agents. In this work, we investigate the stability of the interface between carbon conductive agents and Li

We report a tree-like nanoporous tungsten trioxide (WO3) photoanode that largely improves the photoelectrochemical water oxidation performance. These novel WO3 photoanodes were prepared using a pulsed laser deposition method and their porosity was controlled by adjusting the oxygen partial pressure during the deposition process. The tree-like nanoporous WO3 photoanode has a nanoporous structure with a partially preferred alignment of the individual WO3 nanocrystals, which greatly improves the charge transport efficiency. Under simulated solar light illumination, the aforementioned features resulted in ∼9 times higher photocurrent density (1.8 mA cm−2 at 1.23 V vs. RHE) than a dense WO3 photoanode. An incident photon-to-current conversion efficiency of over 70% was also obtained at wavelengths of 350–400 nm.

We present a form of hematite (α-Fe 2 O 3 ) nanostructured architecture suitable for photoelectrochemical water oxidation that is easily synthesized by a pulsed laser deposition (PLD) method. The architecture is a column-like porous nanostructure consisting of nanoparticles 30–50 nm in size with open channels of pores between the columns. This nanostructured film is generated by controlling the kinetic energy of the ablated species during the pulsed laser deposition process. In a comparison with the nanostructured film, hematite thin film was also synthesized by PLD. All of the developed films were successfully doped with 1.0 at% of titanium. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and UV–visible spectroscopy were used to characterize the films. To fabricate the photoelectrochemical (PEC) cell, Ti-doped hematite films were used as the working electrode, Ag/AgCl as the reference electrode, platinum wire as the counter electrode and an aqueous solution of 1 M NaOH as the electrolyte. The photovoltaic characteristics of all cells were investigated under AM 1.5G sunlight illumination of 100 mW/cm 2 . The photocurrent density was enhanced by approximately 220% using nanostructured film at 0.7 V versus Ag/AgCl compared to hematite thin film, and the highest photocurrent density of 2.1 mA/cm 2 at 0.7 V/Ag/AgCl was obtained from the 1.0 at% Ti-doped hematite nanostructured film. The enhanced photocurrent density is attributed to its effective charge collection due to its unique column-like architecture with a large surface area.

A great interest has emerged on metal–oxygen batteries with a hope for ultra-high-energy-density batteries [1]; of these, the intrinsic high energy efficiency and reversibility make sodium–oxygen batteries as one of the most promising post-lithium-ion batteries. In contrast to the lithium peroxide formation in lithium–oxygen batteries, the formation of sodium superoxide discharge product brings out unique electrochemical properties of sodium–oxygen batteries. Intense studies have revealed that the high capacity and low polarization of sodium–oxygen batteries are attributable to the solution phase formation and decomposition of sodium superoxide, which has substantial stability and solubility in ethereal electrolytes.[2-4] However, recent studies have raised out the issue on chemical instability that sodium superoxide undergoes parasitic reactions with the ethereal electrolytes in sodium–oxygen batteries.[4-8] We have previously demonstrated the mechanism that the dissolution of sodium superoxide into the electrolytes liberates reactive superoxide anion and triggers the parasitic reactions.[4] Other products formed as a result of parasitic reactions require higher polarization to be recharged and do not involve oxygen evolution during the charge process, which seriously deteriorates cell efficiency and reversibility during storage period of batteries. These phenomena should be closely linked with the storage properties or shelf-life of batteries. The detrimental effects of storage after discharge in sodium–oxygen batteries may be amplified when it comes to be applied for practical batteries in electric vehicles (EVs) since EVs sometimes cannot be immediately recharged depending on the consumers’ utilization patterns. Therefore, proper strategies to accomplishment long living sodium superoxide have to be addressed for maintaining high efficiency and reversibility of sodium–oxygen batteries. A rational tuning of the electrolyte possesses the key to control the chemical stability of discharge products and improve storage properties of the sodium–oxygen batteries. In this study, we explore a concentrated electrolyte to prevent the dissolution and parasitic reactions of sodium superoxide in sodium–oxygen batteries. Through a couple of solution characterization techniques, unique solvation structures of concentrated electrolytes are revealed with the elimination of free solvents. Time-resolved ex situ characterizations confirm that sodium superoxide stored in the concentrated electrolyte exhibits prolonged lifetime compared to that in normal electrolytes. We finally demonstrate that highly durable sodium superoxide in the concentrated electrolyte succeeds to preserve both high energy efficiency and oxygen reversibility of sodium–oxygen batteries despite the insertion of storage period after discharge. This is the first study to successfully improve the chemical stability and lifetime of sodium superoxide by simple tuning of electrolyte concentrations in sodium–oxygen batteries. This finding is complementary to the previous understanding on the solution chemistry of sodium–oxygen batteries, highlighting the importance for understanding the role of electrolytes on the sodium–oxygen chemistry. References [1] Chem. Soc. Rev. 2017, 46, 2873. [2] Nat. Chem. 2015, 7, 496. [3] J. Phys. Chem. C 2016, 120, 20068. [4] Nat. Commun. 2016, 7, 10670 [5] Chem. Commun. 2016, 52, 9691. [6] J. Phys. Chem. L 2017, 8, 4794. [7] ChemSusChem 2016, 9, 1795. [8] ACS Appl. Mater. Interfaces 2016, 8, 20120

Lithium-ion batteries are expected to serve as a key technology for large-scale energy storage systems (ESSs), which will help satisfy recent increasing demands for renewable energy utilization. Besides their promising electrochemical performance, the low self-discharge rate (

This paper describes a single ASIC chip that demodulates and decodes vestigial side band (VSB) digital TV signals. The VSB IC has been implemented for the receiver based on the ATSC digital TV standard. It features fast digital carrier recovery and robust channel equalization. The IC is fabricated with 0.35 /spl mu/m CMOS technology with 3 metal layers. It can be applied to both modes of signal reception -8 VSB for terrestrial broadcast and 16 VSB for cable transmission.

We present several filters for the Grand Alliance (GA) vestigial sideband (VSB) receiver. Especially, we design the digital filters for the digital frequency and phase lock loop (DFPLL), which can be easily integrated in a single VLSI chip, with limited bit length coefficients using canonic signed digit (CSD) code and evaluate the performance of the designed filters by comparing the frequency characteristics with the real coefficient filters. The CSD code conversion is a class of quantization in which the filter coefficients are quantized. A filter represented by a CSD code is called the CSD filter. The quantized coefficients which are restricted to the set of representable numbers by and digit CSD code with 2 nonzero digit (L=2, M=7) are considered. In spite of the simplified hardware (H/W) structure for implementation, it is shown that the CSD filters attain little difference compare to the case of real filters using real coefficients. When we select SEC STD60, the ASIC implementation of filters for the DFPLL using CSD filters requires about 30/spl sim/35 K gates.

We propose a new digital carrier recovery loop architecture for the Grand Alliance high definition television (HDTV) system. We have developed an application specific integrated circuit (ASIC) based on the new architecture. The developed ASIC has a gate count of 60 K with a gate array technology that features 0.5 /spl mu/m, 3.3 V and 2-metal-layer technology. The pull-in range of the proposed architecture is about /spl plusmn/250 kHz with 0 dB carrier-to-noise ratio (CNR).

A color liquid crystal display (LCD) panel typically used in consumer products is composed of R, G, and B subpixels. Due to the subpixel structure and color microfilters, a single LCD panel system (SLPS) using such a panel has a low resolution, low brightness, and a poor appearance of the individual color pixel elements. These problems are solved by having a three LCD panel system (TLPS) which is composed of three black/white (B/W) LCD panels. However, this system requires high cost and high hardware (H/W) complexity. We propose a new LCD system using B/W and color LCD panels called the hybrid LCD panel system (HLPS) to overcome the drawbacks of other types of LCD panel applications. Also, the associated color coding algorithm for maximizing the effect of the proposed system is developed. In spite of using the simplified H/W structure, little visual difference has been attained in comparison with the TLPS in the terms of the resolution and brightness, and the color fidelity is better than the SLPS. Among the three types of the LCD projector, the 7.34% light utilization efficiency of the HLPS is the highest. Also, the HLPS is compact and relatively inexpensive.

Grid-scale energy storage systems (ESSs) that can connect to sustainable energy resources have received great attention in an effort to satisfy ever-growing energy demands. Although recent advances in Li-ion battery (LIB) technology have increased the energy density to a level applicable to grid-scale ESSs, the high cost of Li and transition metals have led to a search for lower-cost battery system alternatives. Based on the abundance and accessibility of Na and its similar electrochemistry to the well-established LIB technology, Na-ion batteries (NIBs) have attracted significant attention as an ideal candidate for grid-scale ESSs. Since research on NIB chemistry resurged in 2010, various positive and negative electrode materials have been synthesized and evaluated for NIBs. Nonetheless, studies on NIB chemistry are still in their infancy compared with LIB technology, and further improvements are required in terms of energy, power density, and electrochemical stability for commercialization. Most recent progress on electrode materials for NIBs, including the discovery of new electrode materials and their Na storage mechanisms, is briefly reviewed. In addition, efforts to enhance the electrochemical properties of NIB electrode materials as well as the challenges and perspectives involving these materials are discussed.

Current TV systems suffer from uncomfortable visual artifacts such as edge flicker, interline flicker and line crawling, due to the inherent nature of the interlaced scanning process. Besides, the increasing demands of large TV screens have turned the problem of reducing visible line structures in a TV screen into an important issue. To lessen the visual affects of those artifacts, a technique known as an interlaced to progressive conversion (IPC) technique has been widely studied in various shapes. In the paper, the authors propose a new algorithm for interlaced to progressive conversion, referred to as a directional correlation dependent interpolation filtering (DIF) algorithm, which is composed of a correlation-dependent linear interpolation for a signal in the low horizontal frequency band and a line doubling method for a signal lying in the high horizontal frequency band. The DIF algorithm splits the horizontal frequency band of a given input 2D signal into two adjoint signals and applies two isolated interpolation schemes for the respective bands. In the algorithm, the authors develop a directional correlation dependent, interpolation technique depending on the spatial correlations between the spatially symmetric samples in the observation sliding window centered at the sample to be estimated. Computer simulations and the hardware implementation of the proposed algorithm to evaluate its performance are rigorously evaluated. The authors design a chip for luminance/chrominance interpolation with peaking process (YCIP) which has been tested with a real sequence of LDP images. >

This paper describes a new ghost cancellation system built-in NTSC television based on the Korean ghost cancellation reference (KGCR) signal. The system has a highly integrated transversal filter, an unique circuit for control of the system and a high performance algorithm for calculating the filter coefficients. Laboratory and field test results confirm that the system is effective in canceling several combination of ghosts, which exist in real situations. >

The present study was undertaken to investigate the influence of resveratrol on vascular smooth muscle contractility and to determine the mechanism involved. Denuded aortic rings from male rats were used and isometric contractions were recorded and combined with molecular experiments. Resveratrol at a low concentration (0.03 mmol/l) relaxed directly and more markedly fluoride-induced vascular contraction than phorbol ester-induced contraction. Furthermore, resveratrol more markedly inhibited fluoride-induced increases in pMYPT1 levels than phorbol ester-induced increases. It also more markedly inhibited fluoride-induced increases in pMYPT1 levels than pERK1/2 levels, suggesting that the mechanism involved the inhibition of Rho-kinase activity and the subsequent phosphorylation of MYPT1. This study provides evidence regarding the mechanism underlying the relaxation effect of resveratrol on agonist-induced vascular contraction regardless of endothelial function.

We have developed a new TV system equipped with a digital filter which expands a given 4:3 image vertically at the rate of 2/3 to fit into a 16:9 wide monitor leading to a pleasing visual quality. The algorithm for enlarging an image vertically can be classified in two categories: deflection and digital signal processing. The digital signal processing scheme is employed to overcome the shortcomings introduced by the deflection scheme, and it maintains the resolution of the image with a good quality.

The well known methods for survivor path storage and decoding are the register-exchange method (REM) and the trace-back method (TBM). The REM is conceptually simple, but it is not appropriate for VLSI implementation because it requires large power consumption and large chip area. The TBM is the preferred method in the VLSI implementation of Viterbi decoders (VD) having large constraint length and high performance. However, the TBM requires last-in-first-out (LIFO) buffer and has to use multiple read operations for high speed operation. This multiple operation results in complex control logic. In this paper, we propose a new survivor memory management method called trace-delete method (TDM) and realize this algorithm in hardware (H/W) for VLSI implementation and we compare the TDM with the TBM in terms of latency, the number of memory elements, and the requirements of control logic. The main advantage of the proposed method can be found as short latency and less requirements on additional control logic. Especially, if we combine the TDM with block interleaving the implementation is even simpler than the TBM. The method is studied with particular relevance to HDTV.

In this paper, we propose a new survivor memory management method called the trace-delete method (TDM). Hardware (H/W) realization of the proposed algorithm for VLSI implementation is considered. Comparison of the TDM with the trace-back method (TBM) is also provided in terms of latency, the number of memory elements, and the requirements of control logic. The main advantages of the proposed method are short latency and less requirements on additional control logic. The performance is also evaluated when the method is applied to the Grand Alliance HDTV system.

We design a new transversal filter for ghost cancelling, which can be easily integrated in one chip, with a limited tap length using sparse canonical signed digit (CSD) code coefficients and evaluate the performance through simulation.