with solid electrolytes. [ 3 ] Solid electrolytes offer many advantages and could enable the use of new high capacity electrode materials such as sulfur, [ 4 ] manganese, [5][6][7] and vanadate [ 8,9 ] -based cathodes which may not be stable and safe in the current Li-ion battery technology based on liquid electrolytes. [ 10 ] Furthermore, solid electrolytes have the promise to use directly metallic lithium anodes, i.e., preventing dendritic lithium growth, which enables even higher energy densities. From a practical point of view, one may also highlight that solid electrolytes have much-improved thermal operation windows resulting in a higher chemical and thermal stability, benefi ting the long-term operation and safety when compared to their liquid counterparts. This allows for safe packaging of the cell geometries and enables miniaturized cell architectures while simultaneously reducing the battery weight. [ 11,12 ] Among the oxide solid Li-ionic electrolytes, Li 7 La 3 Zr 2 O 12 (LLZO) garnets and their doped variants show one of the highest Li-ion conductivities in the range of ≈10 −4 S cm −1 at room temperature. [ 13 ] LLZO was fi rst synthesized and characterized in 2007 by Murugan et al. [ 14 ] Not until a few years later Geiger et al. [ 15 ] showed that LLZO appears in two different crystal structures, a cubic and a tetragonal one, with the cubic phase showing a Li-ion conductivity two orders of magnitude higher than the tetragonal phase. Using doping strategies, i.e., by introducing Al 3+ , Ga 3+ , Ta 5+ , Nb 5+ , etc., the high conductive cubic phase can be stabilized at room temperature by introducing vacancies into the Li sublattice of the structures. [16][17][18][19] One of the most commonly used dopants is Al 3+ , which stabilizes the cubic phase by substituting for three Li + , thereby creating two Li vacancies and resulting in the stoichiometry of Li 7−3 x Al x La 3 Zr 2 O 12 for the cubic phase.[ 20 ] Despite the promises, all-solid-state Li-ion batteries based on cubic LLZO solid electrolytes have still challenges in realizing high practical performances due to their high electrode-electrolyte interfacial resistances. For the investigations on all-solid-state batteries based on garnet-type cubic LLZO, most of the current research efforts are concentrated on the cathode material, most prominently on LiCoO 2 . [21][22][23][24][25][26][27] Reasonable electrochemical activities are so far only achieved by vacuum deposition of the cathode as thin fi lms, i.e., by pulsed laser deposition (PLD), because of the resulting good electrolyte-electrode contact. [ 25,26 ] Here, the exact chemical composition of the electrolyte-electrode interface also greatly determines the contact properties, the interfacial

Methanol poisoning causes blindness, organ failure or even death when recognized too late. Currently, there is no methanol detector for quick diagnosis by breath analysis or for screening of laced beverages. Typically, chemical sensors cannot distinguish methanol from the much higher ethanol background. Here, we present an inexpensive and handheld sensor for highly selective methanol detection. It consists of a separation column (Tenax) separating methanol from interferants like ethanol, acetone or hydrogen, as in gas chromatography, and a chemoresistive gas sensor (Pd-doped SnO2 nanoparticles) to quantify the methanol concentration. This way, methanol is measured within 2 min from 1 to 1000 ppm without interference of much higher ethanol levels (up to 62,000 ppm). As a proof-of-concept, we reliably measure methanol concentrations in spiked breath samples and liquor. This could enable the realization of highly selective sensors in emerging applications such as breath analysis or air quality monitoring.

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Isoprene is a versatile breath marker for noninvasive monitoring of high blood cholesterol levels as well as for influenza, end-stage renal disease, muscle activity, lung cancer, and liver disease with advanced fibrosis. Its selective detection in complex human breath by portable devices (e.g., metal-oxide gas sensors), however, is still challenging. Here, we present a new filter concept based on activated alumina powder enabling fast and highly selective detection of isoprene at the ppb level and high humidity. The filter contains high surface area adsorbents that retain hydrophilic compounds (e.g., ketones, alcohols, ammonia) representing major interferants in breath while hydrophobic isoprene is not affected. As a proof-of-concept, filters of commercial activated alumina powder are combined with highly sensitive but rather nonspecific, nanostructured Pt-doped SnO sensors. This results in fast (10 s) measurement of isoprene down to 5 ppb at 90% relative humidity with outstanding selectivity (>100) to breath-relevant acetone, ammonia, ethanol, and methanol, superior to state-of-the-art isoprene sensors. Most importantly, when exposed continuously to simulated breath mixtures (four analytes) for 8 days, this filter-sensor system showed stable performance. It can be incorporated readily into a portable breath isoprene analyzer promising for simple-in-use monitoring of blood cholesterol or other patho/physiological conditions.

Sorption, size-selective & catalytic film or particle-bed filters dramatically enhance gas sensor selectivity. We critically review 300+ articles and tutorially give guidelines for systematic filter design in air quality, health & food applications.

All-solid-state batteries provide new opportunities to realize safe, non-flammable, and temperature-tolerant energy storage and display a huge potential to be the core of future energy storage devices.

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