Insights into the LiMnO Cathode Stability in Aqueous Electrolytes.

LiMnO (LMO) cathodes present large stability when cycled in aqueous electrolytes, contrasting with their behavior in conventional organic electrolytes in lithium-ion batteries (LIBs). To elucidate the mechanisms underlying this distinctive behavior, we employ unconventional characterization techniques, including variable energy positron annihilation lifetime spectroscopy (VEPALS), tip-enhanced Raman spectroscopy (TERS), and macro-Raman spectroscopy (with tens of μm-size laser spot). These still rather unexplored techniques in the battery field provide complementary information across different length scales, revealing previously hidden features.

Superior Thermoelectric Performance of SiGe Nanowires Epitaxially Integrated into Thermal Micro-Harvesters.

Semiconductor nanowires have demonstrated fascinating properties with applications in a wide range of fields, including energy and information technologies. Particularly, increasing attention has focused on SiGe nanowires for applications in a thermoelectric generation. In this work, a bottom-up vapour-liquid-solid chemical vapour Deposition methodology is employed to integrate heavily boron-doped SiGe nanowires on thermoelectric generators.

Nanoscaled LiMnO for Extended Cycling Stability in the 3 V Plateau.

Extending the potential window toward the 3 V plateau below the typically used range could boost the effective capacity of LiMnO spinel cathodes. This usually leads to an "overdischarge" of the cathode, which can cause severe material damage due to manganese dissolution into the electrolyte and a critical volume expansion (induced by Jahn-Teller distortions). As those factors determine the stability and cycling lifetime for all-solid-state batteries, the operational window of LiMnO is usually limited to 3.

Photo-enhanced ionic conductivity across grain boundaries in polycrystalline ceramics.

Grain boundary conductivity limitations are ubiquitous in material science. We show that illumination with above-bandgap light can decrease the grain boundary resistance in solid ionic conductors. Specifically, we demonstrate the increase of the grain boundary conductance of a 3 mol% Gd-doped ceria thin film by a factor of approximately 3.

Toward Controlling Filament Size and Location for Resistive Switches via Nanoparticle Exsolution at Oxide Interfaces.

Memristive devices are among the most prominent candidates for future computer memory storage and neuromorphic computing. Though promising, the major hurdle for their industrial fabrication is their device-to-device and cycle-to-cycle variability. These occur due to the random nature of nanoionic conductive filaments, whose rupture and formation govern device operation.

Nanoscale Correlations between Metal-Insulator Transition and Resistive Switching Effect in Metallic Perovskite Oxides.

Strongly correlated perovskite oxides are a class of materials with fascinating intrinsic physical functionalities due to the interplay of charge, spin, orbital ordering, and lattice degrees of freedom. Among the exotic phenomena arising from such an interplay, metal-insulator transitions (MITs) are fundamentally still not fully understood and are of large interest for novel nanoelectronics applications, such as resistive switching-based memories and neuromorphic computing devices. In particular, rare-earth nickelates and lanthanum strontium manganites are archetypical examples of bandwidth-controlled and band-filling-controlled MIT, respectively, which are used in this work as a playground to correlate the switching characteristics of the oxides and their MIT properties by means of local probe techniques in a systematic manner.

Lithium-Battery Anode Gains Additional Functionality for Neuromorphic Computing through Metal-Insulator Phase Separation.

Specialized hardware for neural networks requires materials with tunable symmetry, retention, and speed at low power consumption. The study proposes lithium titanates, originally developed as Li-ion battery anode materials, as promising candidates for memristive-based neuromorphic computing hardware. By using ex- and in operando spectroscopy to monitor the lithium filling and emptying of structural positions during electrochemical measurements, the study also investigates the controlled formation of a metallic phase (Li Ti O ) percolating through an insulating medium (Li Ti O ) with no volume changes under voltage bias, thereby controlling the spatially averaged conductivity of the film device.

Thermoelectric stack sample cooling modification of a commercial atomic force microscopy.

Enabling temperature dependent experiments in Atomic Force Microscopy is of great interest to study materials and surface properties at the nanoscale. By studying Curie temperature of multiferroic materials, temperature dependent phase transitions on crystalline structures or resistive switching phenomena are only a few examples of applications. We present an equipment capable of cooling samples using a thermoelectric cooling stage down to -61.

Electrochemical Tuning of Metal Insulator Transition and Nonvolatile Resistive Switching in Superconducting Films.

Modulation of carrier concentration in strongly correlated oxides offers the unique opportunity to induce different phases in the same material, which dramatically change their physical properties, providing novel concepts in oxide electronic devices with engineered functionalities. This work reports on the electric manipulation of the superconducting to insulator phase transition in YBaCuO thin films by electrochemical oxygen doping. Both normal state resistance and the superconducting critical temperature can be reversibly manipulated in confined active volumes of the film by gate-tunable oxygen diffusion.

Spontaneous formation of spiral-like patterns with distinct periodic physical properties by confined electrodeposition of Co-In disks.

Spatio-temporal patterns are ubiquitous in different areas of materials science and biological systems. However, typically the motifs in these types of systems present a random distribution with many possible different structures. Herein, we demonstrate that controlled spatio-temporal patterns, with reproducible spiral-like shapes, can be obtained by electrodeposition of Co-In alloys inside a confined circular geometry (i.