Temperature-responsive phase separations of poly(N-isopropylacrylamide) (PNiPAm)/dimethylsulfoxide (DMSO)/water mixtures have been investigated by infrared and confocal micro-Raman spectroscopy. The ternary mixtures exhibited lower critical solution temperature (LCST) and upper critical solution temperature (UCST) phenomena at low and high DMSO concentrations, respectively. The amide I band of PNiPAm consists of two components; the intensity of the 1650 cm-1 component increased, and that of the 1625 cm-1 component decreased with increasing temperature during both LCST and UCST phase transitions. Gradual red shifts of the C-H stretching and the amide II bands with increasing temperature or increasing DMSO concentration indicate a removal of water molecules from the alkyl and N-H groups. Raman microscopic measurements showed that DMSO is excluded from the polymer-rich phases upon both LCST and UCST phase separation. On the basis of the experimental results and the quantum chemical calculations, a model that explains the solvation change of the polymer during phase transitions was proposed.

Hydration changes of poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMoEoEMa) during thermosensitive phase separation in water have been investigated by infrared spectroscopy. The C=O stretching band can be separated into three components assigned to non-hydrated carbonyl groups and singly and doubly hydrogen-bonded carbonyl groups (1728, 1709, and 1685 cm-1, respectively). Relatively large parts of the carbonyl groups (50% in 30 wt % solution) do not form hydrogen bonds even below the transition temperature (Tp) probably because they possess crowded positions near the backbone. The fraction of hydrogen-bonding carbonyl groups decreased during phase separation by approximately 0.2. Among five nu(C-H) bands, the highest- and the lowest-frequency bands (nu(C-H)A and nu(C-H)E) exhibited relatively large red shifts of 8 and 11 cm(-1), respectively. DFT calculations indicate that the formation of a H-bond between the ether oxygen and water leads to blue shifts of nu(C-H) of adjacent alkyl groups and has a larger effect than a direct H-bond to the alkyl groups, namely, C-H...O H-bonds. The fraction of hydrogen-bonding methoxy oxygens estimated from the position of the nu(C-H)A is 1 at Tp. This result indicates that the methoxy oxygens and the carbonyl are more favorably hydrated than the other at Tp, respectively.

The performance of a lithium-ion battery (LiB) fabricated with a tin-phosphate glass anode was studied as well as the characteristics of the anode. It was confirmed that the total positive charge of Sn2+ ions in the glass anode is compensated by a reaction with lithium during the first charge by forming tin crystals. It was observed after the first charge that the glass is converted into a nanocomposite in which the metallic crystals are embedded in an amorphous lithium phosphate matrix. A half-cell fabricated with the glass anode showed a reproducible capacity of 550 mAh/g at room temperature, which was much higher than that of the cell with a graphite anode. The cell also showed a steady capacity of 160 mAh/g even at −20°C with no deposition of lithium dendrites. A full-cell fabricated with the glass anode and LiMn2O4 cathode showed a good life cycle performance at 60°C along with no degradation in its life cycle performance. The tin-phosphate glass is a promising candidate as a new anode material that realizes LiBs with a high energy density that can be used over a wide temperature range.

In recent years, the expansion of demand for lithium ion batteries has resulted in soaring prices of the constituent resources. From the viewpoint of safety, studies on all‐solid‐state batteries are actively being carried out. In this study, we succeeded in driving all‐solid‐state batteries derived from nontoxic oxide glasses at room temperature without requiring scarce resources such as lithium and cobalt. The main structure of the ceramic batteries with a simple structure in which Na2FeP2O7 crystallized glass and β″‐alumina solid solution are joined by pressureless cofiring at 550°C. During the crystallization of Na2O‐Fe2O3‐P2O5 glass, fusion with the β″‐alumina solid solution is achieved. Reversible charge and discharge of 80 mAh/g were achieved at room temperature. It is not necessary to apply pressure during cell preparation or the use of the batteries. Furthermore, the strong junction at the cathode and electrolyte interface does not peel off during charge and discharge over a long period of 623 cycles. Ex situ X‐ray photoelectron spectroscopy revealed partial Fe4+ induction and a reversible charge and discharge reaction even after overcharging to 9 V. It was demonstrated that Na2FeP2O7 is very stable against overcharging to 9 V.

An all-solid-state battery (ASSB) with a new structure based on glass-ceramic that forms Na2FeP2O7 (NFP) crystals, which functions as an active cathode material, is fabricated by integrating it with a β″-alumina solid electrolyte. Two important factors that influence the rate capability of this ASSB were optimised. First, the particle size of the precursor glass powder from which the NFP crystals are formed was decreased. Consequently, the onset temperature of crystallisation shifts to a lower temperature, which enables the softening of NFP crystals and their integration with β″-alumina at a low temperature, without the interdiffusion of different crystal phases or atoms. Second, the interface between the β″-alumina solid electrolyte and cathode active materials which consisted of the NFP-crystallised glass and acetylene black used as a conductive additive, is increased to increase the insertion/release of ions and electrons from the active material during charge/discharge processes. Thus, the internal resistance of the battery is reduced considerably to 120 Ω. Thus, an ASSB capable of rapid charge/discharge that can operate not only at room temperature (30 °C) but also at −20 °C is obtained. This technology is an innovative breakthrough in oxide-based ASSBs, considering that the internal resistance of liquid electrolyte-based Li-ion batteries and sulphide-based ASSBs is ~10 Ω.