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Lithium metal batteries (LMBs) are considered the most promising next-generation battery system because of their high energy density and safety. Significant research effort has been devoted to developing more stable and energy-dense LMBs than the state-of-the-art Li-ion batteries. However, the LMB performance remains unsatisfactory for commercialization, primarily owing to the inability of solid electrolytes to block Li dendrite propagation. Herein, we demonstrate highly stable LMB employing garnet-type oxide electrolyte by introducing a carbon-based interlayer with careful interface engineering. We theoretically and experimentally demonstrate that our design effectively regulated Li deposition away from the solid electrolyte, preventing dendrite penetration. We further demonstrated that the interface condition between the interlayer and solid electrolyte is critical and present an effective strategy to achieve an optimal interface. Overall, our garnet-type oxide-based LMB exhibited a high energy density of ~ 680 Wh/L for over 800 cycles at room temperature without using external pressure.

An all-solid-state battery with a lithium metal anode is a strong candidate for surpassing conventional lithium-ion battery capabilities. However, undesirable Li dendrite growth and low Coulombic efficiency impede their practical application. Here we report that a high-performance all-solid-state lithium metal battery with a sulfide electrolyte is enabled by a Ag–C composite anode with no excess Li. We show that the thin Ag–C layer can effectively regulate Li deposition, which leads to a genuinely long electrochemical cyclability. In our full-cell demonstrations, we employed a high-Ni layered oxide cathode with a high specific capacity (>210 mAh g−1) and high areal capacity (>6.8 mAh cm−2) and an argyrodite-type sulfide electrolyte. A warm isostatic pressing technique was also introduced to improve the contact between the electrode and the electrolyte. A prototype pouch cell (0.6 Ah) thus prepared exhibited a high energy density (>900 Wh l−1), stable Coulombic efficiency over 99.8% and long cycle life (1,000 times). Solid-state Li metal batteries represent one of the most promising rechargeable battery technologies. Here the authors report an exceptional high-performance prototype solid-state pouch cell made of a sulfide electrolyte, a high-Ni layered oxide cathode and, in particular, a silver–carbon composite anode with no excess Li.

The history of the secondary battery with Li metal anode, having a high theoretical specific capacity of 3860mAh/g and the most negative electrochemical potential among anode materials, is rather old, and the first portable phone equipped with a Li metal secondary battery was commercially released in 1988. But it soon faded out from the market because of the safety issue. Instead of the Li metal anode, various carboneous anodes (so-called lithium ion batteries) emerged and took over the market, and since then they have been used to power a wide range of portable devices and, in particular, a number of pure electric and plug-in hybrid vehicles. The capacity of a conventional carboneous anode, however, is approaching its theoretical limit, and the use of Li metal anode is regaining serious attention for secondary batteries. Currently there are two major difficulties in using Li metal anode: dendrite formation and low coulombic efficiency (CE). In a typical operating condition of a lithium-ion battery, Li metal easily grows dendritically on the substrate, leading to a poor coulombic efficiency and sometime a short circuit with penetrating through the separator and reaching to the cathode. Although several approaches have reduced Li dendrite formation, the phenomenon has not been avoided adequately so far. The low CE is induced by not only the dendritic growth of the Li metal, but also the subsequent destruction and rebuild of the SEI layer according to the cycle. The currently reported CE of the Li metal anode is ~99% at most, and it requires a large amount of Li reservoir, leading to the decrease of the energy density and the exhaustion of the electrolyte. To overcome these difficulties, we use Li anode in an all-solid-state battery (ASSB). Since no SEI forms on anode, high CE is anticipated. But it is known that the short circuit is not prevented even by using solid electrolyte (SE), because Li grows on the surface of the SE grains and propagates through the grain boundaries. In this study, we found that such short circuit phenomenon is largely inhibited by using a metal foil coated with carbon black (CB) as a substrate for the Li deposition. The CB electrochemically reacts with Li, but we set the capacity of the CB layer much smaller than that of the cathode, and hence a large part of the Li ions are to precipitate as Li metal on the anode during the charge, and works as a Li metal anode. We fabricated the ASSB in the following way. First we made a slurry of carbon black by mixing it with a PVdF binder in NMP, and coated it on a Ni foil. The SE layer was made from Argyrodite-type Li6PS5Cl powders spread over non-woven cloth, and the cathode sheet was made from the mixture of NCM, Argyrodite SE, conductive agent and PTFE binder. They are stacked and enclosed in a pouch cell to form an all-solid-state battery. The cycle test was performed at 0.1C for charge and at 0.1C (1st cycle) and 0.33C (later cycles) for discharge. The result is shown in fig. 1. The cell showed an excellent cycle performance with no short circuit over 150 cycles. The initial capacity was 166 mAh/g-NCM (~5mAh/cm2), and the averaged cycle retention was ~ 99.91%/cycle between 2nd and 150th cycle. We also fabricated an ASSB whose carbon layer on the anode is substituted with graphite and performed the same test, but it was terminated by a short circuit at the 2nd cycle. Figure 1

In this study, we have investigated the rate-limiting process of 4H-SiC solution growth using Si-Cr based melt, and have tried high-speed growth. It is revealed that the rate-limiting process of SiC growth under our experimental condition is interface kinetics, which can be controlled by such factors as temperature and supersaturation of carbon. By enhancing the interface kinetics, SiC crystal has been grown at a high rate of 2 mm/h. The FWHM values of X-ray rocking curves and threading dislocation density of the grown crystals are almost the same as those of seed crystal. Possibility of high-speed and high-quality growth of 4H-SiC has been indicated.

We report the results of the systematic investigation into correlations between energetics and hexagonal stacking configurations for carbon, silicon, SiC, BN, AlN, GaN, and InN polytypes with sp3-bonded networks. The atomistic geometry, energetics, and electronic structure for these compounds with up to the periodic stacking length of L = 8 have been carefully calculated based on the density functional theory within the generalized gradient approximation (GGA). Using the Axial Next-Nearest-Neighbor Ising model extracted from the GGA calculations, we have also studied the energetics for more than 6 million kinds of nonequivalent stacking polytypes with up to L = 30, whose configurations have been deduced by the efficient polytype generation algorithm [E. Estevez-Rams and J. Martinez-Mojicar, Acta Crystallogr., Sect. A: Found. Crystallogr. 64, 529 (2008)], and illustrated some trends of structural and energetic properties for these compounds.

We attempted the traveling solvent method (TSM) growth of SiC on 6H-SiC(0001) substrates using Si and Si-M (M=Ti, Cr and Dy) solvents at growth temperatures of 1500-1800°C. It was confirmed that 4H-SiC polytype was extremely stabilized in the highly carbon dissolved liquid phase. 4H-SiC growth on 6H-SiC, i.e. hetropolytype epitaxial growth, was observed only from Si-Dy solvent. The Dy content above 60at% was necessary to obtain 100% 4H-SiC polytype.

We performed liquid phase epitaxial growth of SiC layers on on-axis 4H-SiC substrates using Si solvent. It was found that the polytype controllability of the epilayer significantly depends on the growth process conditions. By optimizing them, polytype mixing in the epilayers can be completely suppressed. It is shown that the density of basal plane dislocations in the epilayers is much less than in the substrates due to on-axis growth. SIMS analysis showed that the concentrations of trace impurity elements (B,Al,Ti,V,Cr,Fe,Ni,P) in the epilayers are under lower detection limit. The only impurity is nitrogen resulting in an n-type layer. Carrier concentrations Nd-Na ranging from high 1016 to low 1017cm-3 are achievable.

LPE (liquid phase epitaxy) growth of low nitrogen unintentionally doped SiC epitaxial layer on on-axis 4H-SiC substrate using nitrogen getter Si based solution was investigated to realize basal plane dislocation (BPD) free epitaxial layer. A significant reduction in BPD was demonstrated.

We have successfully grown 3C-SiC(111) single crystals 10mm x 10mm in dimension on 6H-SiC(0001) substrate by the solution growth method using cold crucible technique. The growth rate of 60μm/hr was achieved. The use of Si-Ti-C ternary solution as well as the electromagnetic stirring are responsible for the relatively high growth rate in solution method. The threading dislocation density is low and the etch pit density amounts to 105-106 /cm2 at the lowest region. Polytype of the grown layer has changed from 3C to 6H with an increase in the dip depth of substrate. A mathematical model was applied to get better understanding of what happened in the crucible.

Top seeded solution growth of SiC on on-axis 6H-SiC was performed using Si solvent at growth temperature as high as 1645-1870°C. It was found that different polytypes of SiC layers were grown on 6H-SiC depending on gas species during growth. The growth under He atmosphere produced 6H-SiC homoepitaxial layers. On the other hand, the growth under N2-He atmosphere led to 3C-SiC epitaxial layers. It was obvious that the nitrogen dissolved in solvent strongly favoured the 3C-SiC polytype formation on 6H-SiC. We also conducted characterization of 3C-SiC layers grown on 6H-SiC (0001)Si by TEM, molten KOH etching and precise XRD measurement.

We carried out the characterization of the crystallinity of the solution growth self-standing silicon carbide (SiC) crystals, which were grown from Si-C-Ti ternary solution with Accelerated Crucible Rotation Technique (ACRT). The self-standing crystal exhibited homogeneous green color without cracks and inclusions. The crystallinity of the self-standing crystal was characterized by various precise XRD diffraction measurements, such as の-scan rocking curve measurement, X-ray topography and reciprocal lattice mapping. The Full Width at Half Maximum (FWHM) of the の-scan rocking curves was about 20 arcsec. The X-ray topography showed a large area with a homogeneous orientation. The reciprocal lattice mapping exhibited a sharp single peak indicating the excellent crystallinity. Finally we confirmed rather high crystallinity of the self-standing crystals by etch pits measurement using molten KOH etching.

We have grown AlN single crystal on 6H-SiC substrate using Al-Cu solution of 1500-1600 °C. Nitrogen is supplied from gas phase under atmospheric pressure and the cold crucible technique is applied. Thickness of AlN reached 40 μm with the growth rate of 10 μm/h. Rather high growth rate in solution method is due to the increase in the melt surface area, dynamic convection of the melt and high temperature gradient along the seeded axis, which are easily realized in cold crucible technique. TEM observation reveals that the dislocation density beyond 10μm from the interface decreases by a factor of 10 to the power of -1 or -2. The melt included in between the substrate and AlN epi-layer eases stress in epi-layer and reduces cracks. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We performed solution growth of SiC single crystals from Si-Ti-C ternary solution using the accelerated crucible rotation technique (ACRT). It was confirmed that the growth rate exceeding 200 μm/hr was achievable by several ACRT conditions. This high growth rate might be due to the enhancement of the carbon transport from the graphite crucible to the growth interface using the ACRT. Moreover, the incorporation of inclusions of the Si-Ti solvent in the grown crystal was significantly suppressed by using the ACRT. It was thought that the intensive convection near the growth interface resulted in not only the marked increase of SiC growth rate but also the superior homogeneity in the surface morphology. It was concluded that faster stable growth can be accomplished in the SiC solution growth using the ACRT.

We carried out the growth of single crystalline silicon carbide (SiC) from Si-C-X (X= Co, Fe) ternary solutions. These ternary solutions are expected to show large carbon solubility compared with Si solvent (self-flux) by means of CALPHAD (CALculation of PHAse Diagrams) method. We investigated the growth rate and the polytype of the grown crystal from the ternary solutions. Then we found that the growth rate from the ternary solutions is much larger than that from the self-flux. The growth rate from Si-C-Co (Si-C-Fe) system was about 6mm/hr (12mm/hr) while that from the self-flux was only 2mm/hr. The grown crystal from the ternary solutions is classified into 6H that takes over the seed polytype.

Taste dysfunction is not rare in chronic pain patients. In the treatment of chronic pain, we employ multidisciplinary interventions such as pharmacological treatment, relaxation techniques such as autogenic training and biofeedback training (BFT), and soft massage for home practice. We noted that complex symptoms of the eyes, ears, tongue and nose improved on treatment for chronic pain. It seemed that relaxation training on tongue-related muscles improved the capacity to taste sweetness. This study was performed to examine whether muscle relaxation had any subjective or physiological effects on taste dysfunction.

Monoclonal antibodies (TB1 & TB2), which were obtained by immunization of 24 amino acids in BALB/c mice, bound specifically to the amyloid senile plaque and amyloid-angiopathic lesions of brain tissues of patients with Alzheimer's disease (AD) or with senile dementia of Alzheimer type (SDAT), and strongly reacted with the 1st part (Asp-Ala-Glu-Phe-Arg-His-Asp) of beta-protein. Western blotting and two-dimensional immunoelectrophoresis of cerebrospinal fluid (CSF) and serum revealed bands of 125 and 20 kilodaltons. The positive frequency of 125 and 20 KD bands detected by two-dimensional immunoelectrophoresis was higher in the serum of AD and SDAT patients (12 cases) than in that of normal control patients. ELISA employing various anti-amyloid precursor protein (APP) antibodies was performed using the extract of the human neuroblastoma cell line (NB39) which produces APP. In the near future, we hope to measure APP in CSF and sera from patients with Alzheimer's disease.