Materials AIILnInO4 with Ruddlesden-Popper Structure for Electrochemical Applications: Relationship between Ion (Oxygen-Ion, Proton) Conductivity, Water Uptake, and Structural Changes

In this paper, the review of the new class of ionic conductors was made. For the last several years, the layered perovskites with Ruddlesden-Popper structure AIILnInO4 attracted attention from the point of view of possibility of the realization of ionic transport. The materials based on Ba(Sr)La(Nd)InO4 and the various doped compositions were investigated as oxygen-ion and proton conductors. It was found that doped and undoped layered perovskites BaNdInO4, SrLaInO4, and BaLaInO4 demonstrate mixed hole-ionic nature of conductivity in dry air. Acceptor and donor doping leads to a significant increase (up to ~1.5–2 orders of magnitude) of conductivity. One of the most conductive compositions BaNd0.9Ca0.1InO3.95 demonstrates the conductivity value of 5∙10−4 S/cm at 500 °C under dry air. The proton conductivity is realized under humid air at low (<500 °C) temperatures. The highest values of proton conductivity are attributed to the compositions BaNd0.9Ca0.1InO3.95 and Ba1.1La0.9InO3.95 (7.6∙10−6 and 3.2∙10−6 S/cm correspondingly at the 350 °C under wet air). The proton concentration is not correlated with the concentration of oxygen defects in the structure and it increases with an increase in the unit cell volume. The highest proton conductivity (with 95−98% of proton transport below 400 °C) for the materials based on BaLaInO4 was demonstrated by the compositions with dopant content no more that 0.1 mol. The layered perovskites AIILnInO4 are novel and prospective class of functional materials which can be used in the different electrochemical devices in the near future.

Phase-locked constructing dynamic supramolecular ionic conductive elastomers with superior toughness, autonomous self-healing and recyclability

Stretchable ionic conductors are considerable to be the most attractive candidate for next-generation flexible ionotronic devices. Nevertheless, high ionic conductivity, excellent mechanical properties, good self-healing capacity and recyclability are necessary but can be rarely satisfied in one material. Herein, we demonstrate a novel ionic conductor design, dynamic supramolecular ionic conductive elastomers (DSICE), via “phase-locked” strategy, wherein “locking soft phase” polyether backbone conducts lithium-ion (Li+) transport and the combination of dynamic disulfide metathesis and stronger supramolecular quadruple hydrogen bonds in the hard domains contributes to the self-healing capacity and mechanical versatility. The dual-phase design performs its own functions and the conflict among ionic conductivity, self-healing capability, and mechanical compatibility can be thus defeated. The well-designed DSICE exhibits high ionic conductivity (3.77×10−3 S m−1 at 30°C), high transparency (92.3%), superior stretchability (2615.17% elongation), strength (27.83 MPa) and toughness (164.36 MJ m−3), excellent self-healing capability (~99% at room temperature) and favorable recyclability. This work provides a new strategy for designing the advanced ionic conductors and offers promise for flexible iontronic devices or solid-state batteries.

The chemistry of melting oxynitride phosphate glasses

Oxide glasses are the most commonly studied non-crystalline materials in Science and Technology, though compositions where part of the oxygen is replaced by other anions, e.g. fluoride, sulfide or nitride, have given rise to a good number of works and several key applications, from optics to ionic conductors. Oxynitride silicate or phosphate glasses stand out among all others because of their higher chemical and mechanical stability and their research continues particularly focused onto the development of solid electrolytes. In phosphate glasses, the easiest way of introducing nitrogen is by the remelting of the parent glass under a flow of ammonia, a method that allows the homogeneous nitridation of the bulk glass and which is governed by diffusion through the liquid-gas reaction between NH3 and the PO4 chemical groupings. After nitridation, two new structural units appear, the PO3N and PO2N2 ones, where nitrogen atoms can be bonded to either two or three neighboring phosphorus, thus increasing the bonding density of the glass network and resulting in a quantitative improvement of their properties. This short review will gather all important aspects of the synthesis of oxynitride phosphate glasses with emphasis on the influence of chemical composition and structure.

Stable near-to-ideal performance of a solution-grown single-crystal perovskite X-ray detector

The ideal photodetector is the one able to detect every single incoming photon. In particular, in X-ray medical imaging, the radiation dose for patients can then approach its fundamentally lowest limit set by the Poisson photon statistics. Such near-to-ideal X-ray detection characteristics have been demonstrated with only a few semiconductor materials such as Si1 and CdTe2; however, their industrial deployment in medical diagnostics is still impeded by elaborate and costly fabrication processes. Hybrid metal halide perovskites – newcomer semiconductors -– make for a viable alternative3,4,5 owing to their scalable, inexpensive, robust, and versatile solution growth and recent demonstrations of single gamma-photon counting under high applied bias voltages6,7. The major hurdle with perovskites as mixed electronic-ionic conductors, however, arises from the rapid material's degradation under high electric field8,9,10,11, thus far used in perovskite X-ray detectors12,13. Here we show that both near-to-ideal and long-term stable performance of perovskite X-ray detectors can be attained in the photovoltaic mode of operation at zero-voltage bias, employing thick and uniform methylammonium lead iodide (MAPbI3) single crystal (SC) films (up to 300 µm), solution-grown directly on hole-transporting electrodes. The operational device stability is equivalent to the intrinsic chemical shelf lifetime of MAPbI3, being at least one year in the studied case. Detection efficiency of 88% and noise equivalent dose of 90 pGyair (lower than the dose of a single incident photon) are obtained with 18 keV X-rays, allowing for single-photon counting, as well as low-dose and energy-resolved X-ray imaging. These findings benchmark hybrid perovskites as practically suited materials for developing low-cost commercial detector arrays for X-ray imaging technologies.