Hyperbolic polariton modes are highly appealing for a broad range of applications in nanophotonics, including surfaced enhanced sensing, sub-diffractional imaging, and reconfigurable metasurfaces. Here we show that attenuated total reflectance (ATR) micro-spectroscopy using standard spectroscopic tools can launch hyperbolic polaritons in a Kretschmann–Raether configuration. We measure multiple hyperbolic and dielectric modes within the naturally hyperbolic material hexagonal boron nitride as a function of different isotopic enrichments and flake thickness. This overcomes the technical challenges of measurement approaches based on nanostructuring, or scattering scanning near-field optical microscopy. Ultimately, our ATR approach allows us to compare the optical properties of small-scale materials prepared by different techniques systematically.

Solid inorganic and polymeric electrolytes have the potential to enable rechargeable batteries with higher energy densities, compared to current lithium-ion technology, which uses liquid electrolyte. Inorganic materials such as ceramics and glasses conduct lithium ions well, but they are brittle, which makes incorporation into a battery difficult. Polymers have the flexibility for facile use in a battery, but their transport properties tend to be inferior to inorganics. Thus, there is growing interest in composite electrolytes with inorganic and organic phases in intimate contact. This article begins with a discussion of ion transport in single-phase electrolytes. A dimensionless number (the Newman number) is presented for quantifying the efficacy of electrolytes. An effective medium framework for predicting transport properties of composite electrolytes containing only one conducting phase is then presented. The opportunities and challenges presented by composite electrolytes containing two conducting phases are addressed. Finally, the importance and status of reaction kinetics at the interfaces between solid electrolytes and electrodes are covered, using a lithium-metal electrode as an example.

Solid-state batteries are promising candidates for energy storage due to their potential advantages in safety, working temperature range, and energy density compared to traditional liquid-electrolyte-based batteries. Rational battery architecture design and a scalable fabrication approach are critical to realize solid-state batteries. In this article, we present the architecture, fabrication procedure, and related challenges of sulfide and oxide electrolyte-based solid-state batteries. Approaches toward intimate solid−solid contact, thin solid-electrolyte fabrication, and scale-up production are discussed. Finally, we discuss the future research directions of solid-state batteries.

Solid-state electrolytes can offer improved lithium-ion battery safety while potentially increasing the energy density by enabling alkali metal anodes. There have been significant research efforts to improve the ionic conductivity of solid-state electrolytes and the electrochemical performance of all-solid-state batteries; however, the root causes of their poor performance—interfacial reaction and subsequent impedance growth—are poorly understood. This is due to the dearth of effective characterization techniques for probing these buried interfaces. In situ and operando methodologies are currently under development for solid-state interfaces, and they offer the potential to describe the dynamic interfacial processes that serve as performance bottlenecks. This article highlights state-of-the-art solid–solid interface probing methodologies, describes practical limitations, and describes a future for dynamic interfacial characterization.

All-solid-state batteries utilizing a ceramic instead of an organic liquid as an electrolyte have the potential to be safer and more energy dense than traditional rechargeable lithium-ion batteries. This emergent energy-storage technology, however, is still critically limited by the performance of the solid electrolyte and its interface with electrodes. Here, we present a review of recent efforts in predictive modeling and materials design for lithium and sodium solid electrolytes using advanced computational approaches. These approaches have enabled the efficient design and discovery of new functional materials with desired properties, such as high alkali ionic conductivity, good phase and electrochemical stability, and low cost, accelerating the development of all-solid-state alkali batteries.

We report on reliability testing of vertical GaN (v-GaN) devices under continuous switching conditions of 500, 750, and 1000 V. Using a modified double-pulse test circuit, we evaluate 1200 V-rated v-GaN PiN diodes fabricated by Avogy. Forward current–voltage characteristics do not change over the stress period. Under the reverse bias, the devices exhibit an initial rise in leakage current, followed by a slower rate of increase with further stress. The leakage recovers after a day's relaxation which suggests that trapping of carriers in deep states is responsible. Overall, we found the devices to be robust over the range of conditions tested.