Microscopic Behavior of Active Materials Inside a TCNQ-Based Lithium-Ion Rechargeable Battery by in Situ 2D ESR Measurements.

Real-time spectroscopic measurements in rechargeable batteries are important to understand the electrochemistry of the batteries at the molecular level and improve relevant functionalities. We have applied in situ two-dimensional (2D) electron spin resonance (ESR) spectroscopy to a well-known organic lithium-ion battery, which is composed of 7,7,8,8-tetracyanoquinodimethane (TCNQ) as the cathode-active material and a lithium metal anode electrode. The TCNQ rechargeable battery is suitable for investigating electrochemistry in the battery in terms of behavior of electron spin at microscopic levels on both the cathode and anode electrodes. We have discussed two-stage oxidation/reduction reactions of TCNQ, Li deposited/stripped process and their resulting dendritic and/or mossy microstructures, clearly elucidating the cause of the cell capacity degradation upon the charge-discharge cycles. The observed in situ ESR spectra showed that the degradation of the cell capacity was due to the elution of the active molecules, which caused the increase of ion conductivity by the substitution of the electrolyte solution for the adsorbed active materials on the conductive carbon surface. To discriminate paramagnetic species during the charge-discharge process, the generalized 2D correlation spectroscopy has been applied to characterize time-dependent in situ ESR spectra. The correlation analysis with in situ ESR helps us identify the paramagnetic species occurring in the battery cell in a straightforward manner.

Metal-free aqueous redox capacitor via proton rocking-chair system in an organic-based couple.

Safe and inexpensive energy storage devices with long cycle lifetimes and high power and energy densities are mandatory for the development of electrical power grids that connect with renewable energy sources. In this study, we demonstrated metal-free aqueous redox capacitors using couples comprising low-molecular-weight organic compounds. In addition to the electric double layer formation, proton insertion/extraction reactions between a couple consisting of inexpensive quinones/hydroquinones contributed to the energy storage. This energy storage mechanism, in which protons are shuttled back and forth between two electrodes upon charge and discharge, can be regarded as a proton rocking-chair system. The fabricated capacitor showed a large capacity (>20 Wh/kg), even in the applied potential range between 0-1 V, and high power capability (>5 A/g). The support of the organic compounds in nanoporous carbon facilitated the efficient use of the organic compounds with a lifetime of thousands of cycles.

[Basic research for development of pinhole camera using a Geiger Mueller counter].

To visualize the scattered X-ray distribution in the diagnosis domain, we examined whether a Geiger Mueller (GM) counter could be applied to a pinhole camera as an X-ray detector. The GM counter detects radiation at certain detection points. To obtain two-dimensional images using the GM counter, the detector needs to be moved two-dimensionally. We constructed an apparatus using industrial actuators to move the detector. To investigate the usability of the developed apparatus, the scattered X-rays from the phantom were measured using the GM counter. The images obtained were then compared with those measured using the phosphor plate. Our results demonstrated that the GM counter can detect low count-rate radiation, but further research will be needed to obtain clear two-dimensional images. In this paper, we propose that the GM counter can be used as a complementary detector to a phosphor plate.