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We evaluated the structural change of the cathode material Li2MnO3 that was deposited as an epitaxial film with an (001) orientation in an all-solid-state battery. We developed an in situ surface X-ray diffraction (XRD) technique, where X-rays are incident at a very low grazing angle of 0.1°. An X-ray with wavelength of 0.82518 A penetrated an ∼2 μm-thick amorphous Li3PO4 solid-state electrolyte and ∼1 μm-thick metal Li anode on the Li2MnO3 cathode. Experiments revealed a structural change to a high-capacity (activated) phase that proceeded gradually and continuously with cycling. The activated phase barely showed any capacity fading. First-principles calculations suggested that the activated phase has O1 stacking, which is attained by first delithiating to an intermediate phase with O3 stacking and tetrahedral Li. This intermediate phase has a low Li migration barrier path in the [001] direction, but further delithiation causes an energetically favorable and irreversible transition to the O1 phase. We propose a mechanism of structural change with cycling: charging to a high voltage at a sufficiently low Li concentration typically induces irreversible transition to a phase detrimental to cycling that could, but not necessarily, be accompanied by the dissolution of Mn and/or the release of O into the electrolyte, while a gradual irreversible transition to an activated phase happens at a similar Li concentration under a lower voltage.

We evaluated the structural change of the cathode material Li

Interfacial phenomena of oxide cathode/sulfide electrolytes are crucial for the improvement of energy density and cycle stability of all-solid-state batteries. Thin-film batteries provide a simple reaction field for mechanistic studies. We fabricated a model film battery consisted of LiCoO2 cathode, LiNbO3 buffer layer, amorphous Li3PS4 electrolyte, and Li metal anode by physical vapor deposition. Structural changes at the cathode-side interface were investigated by in situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) using Ar etching. The LiCoO2 lattice showed a reversible change under high voltage operation with the upper cutoff voltage of 4.5 V. A cathode electrolyte interphase (CEI) layer was formed at the interface by decomposition of LiNbO3 and Li3PS4. The ionic and electronic conductivities of the CEI layer could be crucial to improve the reaction resistance and the cycle stability of the oxide cathode/sulfide electrolyte interface.

We combined the deuterium labeling and neutron reflectivity techniques to determine the fine structure of the electric double layer structure in an imidazolium ionic liquid (IL). For this, a simple and large scale deuteration method for imidazolium ILs was developed, where the deuteration level can be systematically controlled.

Lithium-rich layered rocksalt oxides are promising cathode materials for lithium-ion batteries, owing to their high charge–discharge capacities of over 250 mA h g–1. However, their poor rate capability remains to be addressed. Here, we investigate the effects of surface modification by amorphous Li3PO4 on the structures and electrochemical reactions in the surface region of an epitaxial Li2RuO3(010) film electrode fabricated by pulsed laser deposition. Structural characterization using surface X-ray diffraction (XRD), hard X-ray photoemission spectroscopy, and neutron reflectometry shows that surface modification by 3 nm thick Li3PO4 resulted in the partial substitution of P for Li in the surface region of Li2RuO3. The modified (010) surface exhibits better rate capability at 20 C (41% of the discharge capacity at 0.3 C) compared to the unmodified surface (5% of that at 0.3 C). In situ surface XRD confirmed that highly reversible structural changes occurred at the modified surface during lithium (de)inter...

The potential in each state of charge (SOC) during charging of Li1.2Ni0.13Mn0.54Co0.13O2 is higher than that during discharging. In other words, the potential hysteresis occurs between charging and discharging. Furthermore, the potential in each SOC changes according to the charge-discharge operating conditions, indicating that the charge-discharge reaction mechanism is also affected. To clarify the effect of charge-discharge operating conditions on the electrochemical reaction, Li1.2Ni0.13Mn0.54Co0.13O2 was charged and discharged under various charge-discharge operating ranges, and open-circuit potential (OCP), crystal structure, and oxidation states of the transition metals were evaluated by electrochemical measurement, X-ray diffraction (XRD), and X-ray absorption fine structure (XAFS). These results indicate that OCP, lattice parameters, and oxidation states of the transition metals of Li1.2Ni0.13Mn0.54Co0.13O2 in each SOC are not constant. The XRD results indicate that two phases, namely, LiNi0.33Mn0.33Co0.33O2-like and Li2MnO3-like, exist in Li1.2Ni0.13Mn0.54Co0.13O2. For the LiNi0.33Mn0.33Co0.33O2-like phase, the relationship between OCP, lattice parameters, and oxidation states of the transition metals in each SOC is not affected by the charge-discharge operating conditions, indicating that extraction and insertion of lithium ions for the LiNi0.33Mn0.33Co0.33O2-like phase progresses at almost the same potential. Although the extraction and insertion of lithium ions for the Li2MnO3-like phase progresses at almost the same potential in the low-SOC region, the OCP and lattice parameter in each SOC in the high-SOC region are not constant. Therefore, the extraction of lithium ions from the Li2MnO3-like phase in the high-SOC region causes the potential hysteresis of Li1.2Ni0.13Mn0.54Co0.13O2.

Two electrochemical reactions are possible in regard to Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 (0.5Li 2 MnO 3 −0.5LiNi 0.33 Mn 0.33 Co 0.33 O 2 ), viz, Li 2 MnO 3 -like and LiNi 0.33 Mn 0.33 Co 0.33 O 2 -like reactions. The open circuit potential (OCP) and changes in crystal structure during the charge-discharge process of Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 were investigated to clarify the mechanism responsible for the two reactions. Li 2 MnO 3 and LiNi 0.33 Mn 0.33 Co 0.33 O 2 were separately prepared for the investigation, and the OCPs and crystal structures in these cathodes were measured and then compared with those for Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 . The results obtained using X-ray diffraction (XRD) indicated that two phases existed in Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 . The changes in crystal structure of the two phases during the charge-discharge process were similar to those in Li 2 MnO 3 and LiNi 0.33 Mn 0.33 Co 0.33 O 2 . This indicated that two phases, viz, Li 2 MnO 3 -like and LiNi 0.33 Mn 0.33 Co 0.33 O 2 -like, existed in Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 . Li 2 MnO 3 -like, LiNi 0.33 Mn 0.33 Co 0.33 O 2 -like, and Li 2 MnO 3 -like phases were found to contribute mainly to electrochemical reactions in the low, middle, and high state of charge (SOC) ranges during the charge process from the results obtained using XRD and electrochemical measurements carried out on Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 . In contrast, the Li 2 MnO 3 -like and LiNi 0.33 Mn 0.33 Co 0.33 O 2 -like phases mainly contributed to electrochemical reactions in the low and high SOC ranges during the discharge process. Furthermore, the high polarization and potential decay during the charge-discharge cycling of Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 were mainly attributed to the Li 2 MnO 3 -like phase.

Deterioration mechanism of Li(Ni, Co, Mn)O 2 and Zr-O surface modified electrodes has been elucidated using epitaxial thin films synthesized by pulsed laser deposition. The electrodes comprise a mixture of layered rock-salt and spinel phases. The deterioration mechanism is analyzed using cyclic voltammetry, in situ X-ray diffraction measurements, and in situ neutron reflectometry. The spinel phase in the electrodes has low electrochemical activity and is not involved in Li insertion/extraction. The amount of Li participating in the charge-discharge reactions in the layered rock-salt phase increases with cycling, inducing a phase change at the electrode surface, lowering the reversibility. In contrast, in the Zr-O surface modified electrode, the spinel phase does not increase on charging/discharging. Thus, the Zr-O modification stabilizes the surface of layered rock-salt structure, thereby improving the cycling characteristics. Also, after the Zr-O modification, the Li concentration in the liquid electrolyte near the electrode/electrolyte interface increases during charging/discharging. The Zr-O surface modification not only stabilizes the electrode surface but also causes changes on the electrolyte side. Using the mixed model electrodes, we elucidate the mechanism of electrode deterioration and the origin of the improvement in cycling characteristics occurring on surface modification.

Platinum group metal-free (PGM-free) catalysts based on transition metal-nitrogen-carbon nanomaterials have been studied by a combination of ex situ and in situ synchrotron X-ray spectroscopy techniques, high-resolution Transmission Electron Microscope (TEM), Mößbauer spectroscopy combined with electrochemical methods and Density Functional Theory (DFT) modeling/theoretical approaches. The main objective of this study was to correlate the HO2− generation with the chemical nature and surface availability of active sites in iron-nitrogen-carbon (Fe-N-C) catalysts derived by sacrificial support method (SSM). These nanomaterials present a carbonaceous matrix with nitrogen-doped sites and atomically dispersed and, in some cases, iron and nanoparticles embedded in the carbonaceous matrix. Fe-N-C oxygen reduction reaction electrocatalysts were synthesized by varying several synthetic parameters to obtain nanomaterials with different composition and morphology. Combining spectroscopy, microscopy and electrochemical reactivity allowed the building of structure-to-properties correlations which demonstrate the contributions of these moieties to the catalyst activity, and mechanistically assign the active sites to individual reaction steps. Associated with Fe-Nx motive and the presence of Fe metallic particles in the electrocatalysts showed the clear differences in the variation of composition, processing and treatment conditions of SSM. From the results of material characterization, catalytic activity and theoretical studies, Fe metallic particles (coated with carbon) are main contributors into the HO2− generation.

An epitaxial-film model electrode of LiCoO 2 (104) was fabricated on SrRuO 3 (100)/Nb:SrTiO 3 (100) using pulsed laser deposition. The 50 nm thick LiCoO 2 (104) film exhibited lithium (de-)intercalation activity with a first discharge capacity of 119 mAh g −1 between 3.0 and 4.4 V, followed by a gradual capacity fading with subsequent charge-discharge cycles. In contrast, a 3.2 nm thick Li 3 PO 4 -coated film exhibited a higher intercalation capacity of 148 mAh g −1 with superior cycle retention than the uncoated film. In situ surface X-ray diffraction measurements revealed a small lattice change at the coated surface during the (de-)intercalation processes compared to the uncoated surface. The surface modification of LiCoO 2 by the Li 3 PO 4 coating could lead to improvement of the structural stability at the surface region during lithium (de-)intercalation at high voltage.

The behavior of halide ions on the Au(111) electrode surface in two ionic liquids (ILs), 1-buthyl-1-methylpyrrolidiniun bis(trifluoromethylsulfonyl)amide ([BMP]TFSA) and 1-buthyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([BMIM]TFSA), was investigated by monitoring the structure of the electrode surface. The potential dependences of the X-ray diffraction intensity, which originate from the Au(111)-(1 × 1) structure and the surface normal structure, were measured simultaneously with cyclic voltammograms. We considered the effects of both ion concentration and ion species. The results revealed that halide ions are coadsorbed with IL molecules on the electrode surface and increase the mobility of surface atoms. By contrast, the Au(111) surface does not reconstruct to the (p × √3) structure, even in the IL containing 200 mM Br–. This suggests that the interaction between halide ions and surface Au atoms is weaker than that between IL molecules and surface Au atoms; that is, the surface properties ...

Carbon supported Ni, Ni0.87Zn0.13, and Co hydrazine electrooxidation catalysts were synthesized by an impregnation/freeze-drying procedure followed by thermal annealing for use as anode catalyst of direct hydrazine hydrate fuel cells (DHFCs). The cell performance of DHFCs changed significantly when different catalysts were used as anode. Ammonia generation from anode outlet at open circuit voltage (OCV) condition was higher for Co/C than for Ni-based catalysts. To better understand the cause of different performance and selectivity of each anode catalyst, extensive ex-situ and operando characterization was carried out. Operando XAFS measurement of Ni–K and Co–K edge shows the potential dependence of atomic structure of Ni/C, Ni0.87Zn0.13/C, and Co/C during hydrazine electrooxidation reaction.

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Two classes of new materials possessing ion conductivity have been developed: a lithium ion conductor and a hydride ion conductor. Conventional perovskite and ordered rock-salt structures were adopted as frameworks for lithium migration, and electrochemically stable elements such as Al, Ga, Ta, and Sc were used in the materials to facilitate their use as low-potential negative electrodes. New compositions of (Li0.25Sr0.625V(Li,Sr)0.125)(Ga0.25Ta0.75)O3, and Li0.9Sc0.9Zr0.1O2 were found to be novel oxide-based lithium ion conductors. Oxyhydrides with K2NiF4-type structures were synthesized via a high-pressure synthesis method and their use in pure hydride ion conduction was demonstrated. The La2–x–y Sr x+y LiH1–x+y O3–y oxyhydrides showed wide composition ranges of solid solution formation and the conductivity increased with anion vacancies or the introduction of interstitial hydride ions. The performance of an all-solid-state TiH2/o-La2LiHO3 (x = y = 0, o: orthorhombic)/Ti cell provided conclusive evidence of pure H– conduction.

Non-noble metal electrocatalysts not only are a solution to limited resources but also achieve higher efficiency for fuel cells, especially in alkaline media such as alkaline membrane fuel cells. Co-polypyrrole-based electrocatalysts provide high oxygen reduction reaction (ORR) reactivity, but the active sites and reaction mechanism have yet to be elucidated fully. In this study, ex situ and in situ synchrotron characterization and theoretical study have been combined to evaluate the ORR mechanism on two possible active sites consisting of Co coordinated with pyrrolic nitrogen and Co coordinated with pyridinic nitrogen.

The surface structure of a lithium-rich layered material and its relation to intercalation properties were investigated by synchrotron X-ray surface structural analyses using Li2RuO3 epitaxial-film model electrodes with different lattice planes of (010) and (001). Electrochemical charge–discharge measurements confirmed reversible lithium intercalation activity through both planes, corresponding to three-dimensional lithium diffusion within the Li2RuO3. The (001) plane exhibited higher discharge capacities compared to the (010) plane under high rate operation (over 5 C). Direct observations of surface structural changes by in situ surface X-ray diffraction (XRD) and surface X-ray absorption near edge structure (XANES) established that an irreversible phase change occurs at the (010) surface during the first (de)intercalation process, whereas reversible structural changes take place at the (001) surface. These experimental findings suggest that the surface reconstructed phase limits lithium intercalation between the electrode and the electrolyte, leading to the poor rate capability of the (010) film. Surface structural changes at the initial cycling therefore have a pronounced effect on the power characteristics and stability of lithium-rich layered materials during battery operation.

Sulfide based ionic conductors are attractive solid electrolytes for all solid-state batteries owing to their high ionic conductivity and high reliability. One of remaining issues is to stabilize the lithium (de)intercalation reaction at the cathode/sulfide electrolyte interface in high potential regions for the development of all solid state batteries with high energy density. Here we investigated the interfacial reactions between LiMO2 (M= Ni, Mn, Co) and amorphous Li3PS4 using a model film battery. LiMO2 cathode/LiNbO3 buffer layer/Li3PS4 films were fabricated by pulsed laser deposition, and Li metal anode was deposited by vapor deposition. The thin-film battery had a well defined interface suitable for elucidating electrochemical reactions. The relationship between electrochemical properties and crystal structural changes were discussed based on crystal structures determined by in situ X-ray diffraction (XRD) measurements conducted under high voltage operation.

The structure of the perfluorosulfonated ionomer (PFSI)/Pt(111) interface in a membrane electrode assembly (MEA)-like configuration of a polymer electrolyte membrane (PEM) fuel cell, that is, a vacuum evaporated Pt layer/PEM(Nafion membrane)/PFSI(adhesion Nafion layer)/Pt(111) single crystal, and its bias-induced change were investigated by surface X-ray scattering measurement at an atomic level. Crystal truncation rod measurement shows that PFSI adsorbed on the Pt(111)-(1 × 1) surface without bias. When the Pt(111) electrode was positively biased to form Pt oxide, the PFSI layer was detached from the Pt surface and oxygen atoms penetrated into the Pt lattice.

We have directly probed the Ba 5d states in the ferroelectric barium titanate BaTiO 3 using two bulk-sensitive spectroscopic probes, resonant x-ray emission spectroscopy (RXES) and x-ray absorption spectroscopy in the partial fluorescence mode (PFY-XAS) at the Ba-L 3 edge. The results are compared with those of the non-ferroelectric barium sulfate BaSO 4 . While the RXES spectra point to a localized character for the Ba 5d states in both compounds, the main peak of the PFY-XAS spectrum, corresponding to the dipolar transitions from 2p to 5d, is found to be significantly broader for BaTiO 3 than for BaSO 4 . On the basis of band structure calculations, this broadening is ascribed to strong hybridization between the unoccupied Ba 5d and O 2p states in the ferroelectric. This suggests that the hybridization between the conduction states of the Ba 2+ and O 2− ions, and not only Ti 4+ and O 2− , plays a central role in determining the electronic structure of BaTiO 3 , and is therefore likely to be indirectly correlated with the occurrence of ferroelectricity in this material.

In situ electrochemical X-ray absorption fine structure (XAFS) measurements were performed at the Pt L3 and Ce L3 edges of the Pt–CeOx/C catalyst, which was prepared by a combined process of precipitation and coimpregnation methods, as well as at the Pt L3 edge of the conventional Pt/C catalyst in oxygen-saturated H2SO4 solution to clarify the role of CeOx in the reduction of the overpotential for the oxygen reduction reaction (ORR) at the Pt–CeOx nanocomposite compared with the conventional Pt/C catalyst. XAFS measurements clearly show that the enhancement of ORR activity is attributed to the inhibition of Pt oxide formation by the CeOx layer, of which Ce3+ was oxidized to Ce4+ instead of Pt at the Pt oxide formation potential.

Ag/AgCl reaction at the Ag bilayer, which was underpotentially prepared on a Au(111) surface, was investigated using electrochemical quartz crystal microbalance (EQCM), scanning tunneling microscopy (STM), surface X-ray scattering (SXS), and electrochemical techniques. When the potential was scanned positively from -200 mV, the Cl^[-] ion was adsorbed on the Au(111) electrode surface around 0 mV, and then the phase transition of the adsorbed Cl^[-] ion layer from random orientation to (√3 x √3) structure took place at around +130 mV. The Ag bilayer and Cl^[-] ions were oxidatively reacted to form the AgCl monolayer with (√13 x √13)R13.9° structure around +200 mV, accompanied with the formation of AgCl monocrystalline clusters on the AgCl monolayer surface. The structure of the AgCl monolayer on the Au(111) surface was changed from (√13 x √13)R13.9° structure to (4 x 4) structure around +500 mV. When the potential was scanned back negatively, the AgCl monolayer was electrochemically reduced, and a Ag monolayer, not a bilayer, was formed on the Au(111) surface. In the subsequent potential cycles, the structural change between the Ag monolayer and the AgCl monolayer was reversibly observed. All oxidative structural changes were much slower than the reductive ones.

Lithium-rich layered rock-salt type Li2MnO3 is one of the most attractive cathode materials for lithium batteries because it achieved the high discharge capacities of 250−300 mAh g-1 after activation during the first cycling [1]. However, the structural deterioration in the following cycles at the cathode/liquid electrolyte interface leads to severe capacity fading. We reported that the Li2MnO3 films on solid system exhibit a high capacity of 250 mAh g–1 and better cycle stability, although liquid system showed severe capacity degradation [2]. To elucidate the activation process and high capacity phase contributing to high cycle stability, crystal structure changes at activation process were analyzed using the different initial structure of Li2MnO3. The initial structure was controlled by stacking solid electrolyte using two types of synthesis methods. The Li2MnO3 electrode films were synthesized on SrRuO3/SrTiO3(111) substrates by pulsed laser deposition (PLD). Amorphous Li3PO4 as the solid electrolyte was synthesized by PLD and magnetron sputtering. Lithium metal was used as the negative electrode, respectively. The crystal structure changes at activation process were analyzed by in situ X-ray diffraction (XRD) measurements. The Li2MnO3 structure had layered rock-salt type structure after stacking Li3PO4 by using PLD. On the other hand, in case of stacking by using magnetron sputtering, the Li2MnO3 changed disordered structure with the transition metal (TM) layer disordering of lithium and manganese ions in the honeycomb lattice. For the Li2MnO3 with layered rock-salt type structure, the discharge capacity increased continuously in the following cycles with persisting plateau region for several cycles. On the other hand, the Li2MnO3 with disordered structure showed about 300 mAh g–1 at the first cycle. The XRD intensity ratio of I 020/I 001 was zero after activation at both of initial structures [3]. Since the 020 peak arises from a superlattice structure by a honeycomb-type ordered arrangement of Li and Mn atoms in the TM layer, atomic arrangements in the TM layer transformed to a disordered state. This high capacity phase could contribute to its high capacity and cycle stability. Acknowledgment: This work was supported by the Research and Development Initiative for Scientific Innovation of New Generation Batteries 2 (RISING2) of the New Energy and Industrial Technology Development Organization (NEDO). References: [1] M. Sathiya et al., Nat. Mater., 2013, 12, 827-835.[2] K. Hikima et al., The 57th battery symposium in Japan, 2016, 2G22. [3] K. Hikima et al., The 58th battery symposium in Japan, 2017, 2C22.

In recent times, ionic liquids (IL) have been studied as a new solvent because of their unique features, in particular, tunability and designability. The electrochemical window, viscosity, conductivity, and hydrophobicity of ILs can be tuned by altering their molecular structures. One of the applications of ILs is an electrolyte solution for electrochemical devices. In the last two decades, many researchers have investigated the IL/electrode interfaces, where the electrochemical reactions exactly occur. It has been well known that both the electrode surface and the electrical double layer (EDL) structure affect the kinetics of electrochemical reactions. However, the IL/electrode interface, especially, the EDL structure has not been well understood. The EDL formed in ILs is assumed to have different structure from that formed in aqueous electrolytes due to IL's high ionic strength. In this study, the EDL structure formed in the deuterated 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([BMIM-d15]TFSA) was elucidated using neutron reflectivity (NR) technique. To analyze the EDL structure, it is important that the technique must not the disturb the EDL structure during measurements and the measurement should be carried out under the ideal electrochemical condition. The NR technique satisfies the both conditions. Further, neutron does not decompose organic compounds, including ILs. Therefore, the NR is suitable for the analysis of EDL structure. [BMIM-d15]TFSA was synthesized at the National Deuteration Facility (NDF), Australian Nuclear Science and Technology Organization (ANSTO). Before use, [BMIM-d15]TFSA was dehydrated at 80°C under vacuum for 24 h. Si(100) electrode was used as the working electrode. The working electrode was cleaned with acetone, ethanol, and Milli-Q. Pt wires were used as the reference and counter electrodes. The electrode potential was controlled by IviumStat. The specially designed electrochemical cell for NR measurements made from Kel-F was used and it was assembled in a glove box filled with Ar gas. NR measurements were carried out at BL-17 SHARAKU, Materials and Life Science Experimental Facility (MLF), Japan Proton Accelerator Research Complex (J-PARC). NR profiles were analyzed using Motofit. Firstly, an impedance measurement was carried out to elucidate the flat band potential of Si electrode in [BMIM]TFSA. The flat band potential was estimated at –0.88 V vs Pt. In NR measurements, NR profiles were taken at open circuit voltage (OCV), –1.1 V (negative than the flat band potential) and +0.5 V (positive than the flat band potential). The analysis reveal that at any electrode potential, where we measured in this study, the EDL consists of IL molecule layers and a bulk IL layer. At the electrode potential, E = –1.1 V, [BMIM]+ molecules adsorb on the electrode surface and a TFSA– molecules adsorb on the [BMIM]+ layer. On the other hand, at E = +0.5 V, the stacking order was opposite, i.e., the first and second layer consist of TFSA– and [BMIM]+ molecules, respectively. The electrode surface is negatively charged when the electrode potential is negative than the flat band potential and vice versa. Therefore, these results show that the EDL structure reflects the charge of electrode surface. The detail measurements and analysis are under way.

The interfacial structures of Ag bilayer prepared by underpotential deposition on Au(111) (Ag(2ML)/Au(111)) were determined by ex situ scanning tunneling microscopy and in situ surface X-ray scattering measurements before and after oxidative adsorption and after reductive desorption of a self-assembled monolayer (SAM) of hexanethiol (C6SH) in alkaline ethanol solution. While no structural change was observed after oxidative formation of C6SH SAM on the Ag(2ML)/Au(111) in an ethanol solution containing 20 mM KOH and 0.1 mM C6SH, some of the Ag atoms in the bilayer were stripped when the SAM was reductively desorbed.

Surface and bulk structural changes in LiNi0.8Co0.2O2 were observed during electrochemical reactions using synchrotron X-ray scattering and a restricted reaction plane of two-dimensional (2D) epitaxial-film electrodes. The bulk structural changes confirmed lithium diffusion through the (110) surface, which is perpendicular to the 2D edges of the layered structure. No (de)intercalation reaction was observed through the (003) surface in the voltage range of 3.0−5.0 V. However, intercalation proceeded below 3.0 V, which indicates unusual three-dimensional lithium diffusion in the 2D structure in the overlithiated state. Structural changes at the electrode surface were different from those in the bulk. Contact with the liquid electrolyte caused an abrupt deformation of the surface crystal lattice, followed by restructuring upon applying a cell voltage. These slow reconstruction processes were dependent on the crystal lattice orientations. The reaction mechanism of the intercalation electrodes for lithium batt...

Structure changes of LiNi 0.5 Mn 0.5 O 2 were detected at the electrode/electrolyte interface of lithium cell using synchrotron X-ray scattering and two-dimensional model electrodes. The electrodes were constructed by an epitaxial film of LiNi 0.5 Mn 0.5 O 2 synthesized by pulsed laser deposition (PLD) method. The orientation of the film depends on the substrate plane; the 2D layer of LiNi 0.5 Mn 0.5 O 2 is parallel to the SrTiO 3 (1 1 0) substrate ((1 1 0) LiNi 0.5 Mn 0.5 O 2 //(1 1 0) SrTiO 3 ), while the 2D layer is perpendicular to the SrTiO 3 (1 1 1) substrate ((0 0 3) LiNi 0.5 Mn 0.5 O 2 //(1 1 1) SrTiO 3 ). The in situ X-ray diffraction of LiNi 0.5 Mn 0.5 O 2 (0 0 3) confirmed three-dimensional lithium diffusion through the two-dimensional transition meal layers. The intercalation reaction of LiNi 0.5 Mn 0.5 O 2 will be discussed.

Potential-dependent surface structures of Au(111) and Au(100) single-crystal electrodes in a 50 mM H2SO4 solution were investigated at an atomic level using in situ surface X-ray scattering (SXS) techniques. It was confirmed that both the Au(111) and Au(100) surfaces were reconstructed with an attached submonolayer of an oxygen species, most probably water, at 0 V (vs Ag/AgCl). Results at +0.95 V supported a previously suggested model for both the Au(111) and the Au(100) electrodes that, based on infrared and scanning tunneling microscopy measurements, the surfaces were a (1 x 1) structure with the coadsorbed sulfate anion and hydronium cation (H3O+). At +1.05 V, where a small amount of an anodic current flowed, adsorption of a monolayer of oxygen species was observed on both surfaces. When the single-crystal gold electrodes were electrochemically oxidized at +1.40 V, the expansion of the gold surface by about one monolayer of Au atoms was observed, suggesting the penetration of oxygen into the surface gold layers (i.e., the formation of two layers of surface oxide). When the surface oxide was reduced at +0.65 V, the surface structure returned back to the structure observed at +0.95 V before the oxide formation (i.e., a (1 x 1) structure with coadsorbed sulfate anion and H3O+). When the potential was reduced to 0 V, the surfaces were reconstructed again but with slightly more random structures than those before the potential cycle.

The electrochemical behaviour of TiO2 under X-ray irradiation was studied. Under X-ray irradiation a current, a negative shift in the rest potential, and electrochemical oxidation and decomposition of [FeII(CN)6]4− were clearly observed. The incident photon-current conversion efficiency and energy conversion efficiency was 400–2000% and 0.2–2%, respectively, depending on sample conditions. These results show that the photoelectrochemical reactions were promoted by X-rays with a high incident photon-current conversion efficiency. The photocurrent and photopotential were observed above 4.965 keV, which corresponds to the Ti–K edge, indicating that electron-hole pairs are formed during the relaxation process of the excited Ti atoms.

A new experimental technique was developed for detecting structure changes at electrode/electrolyte interface of lithium cell using X-ray reflectometry and two-dimensional model electrodes with a restricted lattice-plane. The electrodes were constructed with an epitaxial film of LiCoO2 synthesized by pulsed laser deposition method. The orientation of the epitaxial film depends on the substrate plane; the 2D layer of LiCoO2 is parallel to the SrTiO3 (1 1 1) substrate ( ( 0 0 3 ) LiCo O 2 / / ( 1 1 1 ) SrTi O 3 ) , while the 2D layer is perpendicular to the SrTiO3 (1 1 0) substrate ( ( 1 1 0 ) LiCo O 2 / / ( 1 1 0 ) SrTi O 3 ) . The anisotropic properties were confirmed by electrochemical measurements. Ex situ X-ray reflectivity measurements indicated that the impurity layer existed on the as-grown LiCoO2 was dissolved and a new SEI layer with lower density was formed after soaking into the electrolyte. In situ X-ray reflectivity measurements indicated that the surface roughness of the intercalation (1 1 0) plane increased with applying voltages, while no significant changes in surface morphology were observed for the intercalation non-active (0 0 3) plane during the pristine stage of the charge–discharge process.

Activated carbons were prepared from carbonized phenolic resins by steam-activation. Three different novolak type phenol formaldehyde resins were synthesized under different formaldehyde (F) to phenol (P) molar ratios (F/P = 0.3, 0.5 and 0.8) and were used as the precursors for activated carbons. The activated carbons obtained from resins synthesized under typical F/P ratios were microporous, which is characteristic for activated carbons derived from phenolic resins. However, it was found that by decreasing the F/P ratio of the precursor resin to values lower than those usually adopted for commercial phenolic resin production, i.e., values lower than 0.5, activated carbons with developed mesopores could be obtained. Structural information of the precursor resins obtained from Raman spectroscopy indicated that although typical novolak resin structures could be found in all the resins, the resins synthesized at lower F/P ratios included larger amounts of phenol and lower molecular weight substances. This is thought to have led to a large difference in their thermoplastic natures. The existence of low molecular weight substances was also confirmed through thermogravimetric analysis of the resins during carbonization. CO2, C2H6, n-C4H10 and i-C4H10 adsorption isotherms of the prepared activated carbons were also measured at 298 K for the better understanding of micropore development within the samples. The obtained data suggested that micropore development was not so much influenced by the F/P ratio of the precursor resin.

Activated carbons were prepared from carbonized phenolic resins by steam-activation via a pre-treatment, that is mixing of raw materials with Ca(NO3)2·4H2O and acid-treatment after carbonization. This pre-treatment method has been reported as a method to produce mesoporous activated carbons. In the present work, three different novolak type phenol formaldehyde resins were synthesized under different molar ratio of formaldehyde (F) to phenol (P) (F/P = 0.3, 0.5, and 0.8) and were used as the precursors for activated carbons. It was confirmed that the pre-treatment method effectively enhances mesopores on activated carbons from synthesized phenolic resins prepared by F/P = 0.3 and 0.5, and their pore size distributions depended on the synthesizing conditions (F/P). Namely, it was found that by decreasing the F/P ratio of the precursor resin to the values lower than those usually adopted for commercial phenolic resin production, i.e., less than 0.5, activated carbons with developed mesopores could be obtained. The micropore developments of activated carbons were also influenced by F/P, and the influences were on the formation of pores larger than 0.40 nm. It was suggested that the thermoplastic nature of prepared resins (that can be changed by F/P) influence the porous properties of resultant activated carbons and the effect of the pre-treatments.

An in situ experimental technique was developed for detecting structure changes at the electrode/electrolyte interface of lithium cell using synchrotron X-ray reflectometry and two-dimensional model electrodes with a restricted lattice plane. The electrode was constructed with an epitaxial film of LiNi0.8Co0.2O2 synthesized by the pulsed laser deposition method. The orientation of the epitaxial film depends on the substrate plane; the 2D layer of LiNi0.8Co0.2O2 is parallel to the SrTiO3 (1 1 1) substrate ( ( 0 0 3 ) LiC o 0.2 N i 0.8 O 2 / / ( 1 1 1 ) SrTi O 3 ) , while the 2D layer is perpendicular to the SrTiO3 (1 1 0) substrate ( ( 1 1 0 ) LiC o 0.2 N i 0.8 O 2 / / ( 1 1 0 ) SrTi O 3 ) . These films provided an ideal reaction field suitable for detecting structure changes at the electrode/electrolyte interface during the electrochemical reaction. The X-ray reflectometry indicated a formation of a thin-film layer at the LiNi0.8Co0.2O2 (1 1 0)/electrolyte interface during the first charge–discharge cycle, while the LiNi0.8Co0.2O2 (0 0 3) surface showed an increase in the surface roughness without forming the surface thin-film layer. The reaction mechanism at the electrode/electrolyte interface is discussed based on our new experimental technique for lithium batteries.