Organic-Inorganic Hybrid Solid Composite Electrolytes for High Energy Density Lithium Batteries: Combining Manufacturability, Conductivity, and Stability.

The deployment of solid and quasi-solid electrolytes in lithium metal batteries is envisioned to push their energy densities to even higher levels, in addition to providing enhanced safety. This article discusses a set of hybrid solid composite electrolytes which combine functional properties with electrode compatibility and manufacturability. Their anodic stability >5 V versus Li/Li and compatibility with lithium metal stem from the incorporated ionic liquid electrolyte, whereas the organic-inorganic hybrid host structure boosts their conductivity up to 2.

Reversible Redox Probes to Determine Band-Edge Locations and Dopant Concentrations of Nano-TiO Thin-Films: Settling the Mott-Schottky Conundrum.

Knowing the exact location of the semiconductor band-edges is key for mechanistic insights into their use for water and CO photo/electrocatalysis. In this regard, a reliable strategy for nano-semiconductors did not exist yet. We demonstrate the use of reversible redox probes on nano-semiconductor electrodes to determine their band-edge locations in aqueous solutions.

Nano-TiO/TiN Systems for Electrocatalysis: Mapping the Changes in Energy Band Diagram across the Semiconductor|Current Collector Interface and the Study of Effects of TiO Electrochemical Reduction Using UV Photoelectron Spectroscopy.

TiO is the most widely used material in photoelectrocatalytic systems. A key parameter to understand its efficacy in such systems is the band bending in the semiconductor layer. In this regard, knowledge on the band energetics at the semiconductor/current collector interface, especially for a nanosemiconductor electrode, is extremely vital as it will directly impact any charge transfer processes at its interface with the electrolyte.

Tracking Decomposition Layer Formation in Thin-Film Si Electrodes via Thermogalvanic Profiles.

Si anodes are of great interest for next-generation Li-ion batteries due to their exceptional energy density. One of the problems hindering the adoption of this material is the presence of electrolyte decomposition reactions that result in capacity fade and Coulombic inefficiency. This work studies the influence of the decomposition layer in Si on its electrochemical performance using thermogalvanic profiling, a non-destructive in operando technique.

Effects of Iron Species on Low Temperature CO Electrolyzers.

Electrochemical energy conversion devices are considered key in reducing CO emissions and significant efforts are being applied to accelerate device development. Unlike other technologies, low temperature electrolyzers have the ability to directly convert CO into a range of value-added chemicals. To make them commercially viable, however, device efficiency and durability must be increased.

Titanium Carboxylate Molecular Layer Deposited Hybrid Films as Protective Coatings for Lithium-Ion Batteries.

The lifetime of lithium-ion batteries can be extended by applying protective coatings to the cathode's surface. Many studies explore atomic layer deposition (ALD) for this purpose. However, the complementary molecular layer deposition (MLD) technique might offer the benefit of depositing hybrid coatings that are flexible and can accommodate potential volume changes of the electrode during charging and discharging of the battery.

An IR Spectroscopy Study of the Degradation of Surface Bound Azido-Groups in High Vacuum.

Controlled surface functionalization with azides to perform on surface "click chemistry" is desired for a large range of fields such as material engineering and biosensors. In this work, the stability of an azido-containing self-assembled monolayer in high vacuum is investigated using in situ Fourier transform infrared spectroscopy. The intensity of the antisymmetric azide stretching vibration is found to decrease over time, suggesting the degradation of the azido-group in high vacuum.

Interfacial Conductivity Enhancement and Pore Confinement Conductivity-Lowering Behavior inside the Nanopores of Solid Silica-gel Nanocomposite Electrolytes.

Solid nanocomposite electrolytes (nano-SCEs) that exhibit higher ionic conductivity than the individual confined electrolyte were investigated for high-performance solid-state batteries. Understanding the behavior of Li-ion conduction through the pores is important to design ideal nanoporous structures for nano-SCEs, which are composed of an ionic liquid electrolyte (ILE) in a highly porous (∼90%) silica matrix. To establish the relationship between the pore structure of the silica matrix and the ionic conductivity of the solid nanocomposite, the liquid electrolyte fraction was successfully extracted from the nano-SCE to reveal the fragile porous silica matrix.

Effect of different oxide and hybrid precursors on MOF-CVD of ZIF-8 films.

Chemical vapor deposition of metal-organic frameworks (MOF-CVD) will facilitate the integration of porous and crystalline coatings in electronic devices. In the two-step MOF-CVD process, a precursor layer is first deposited and subsequently converted to a MOF through exposure to linker vapor. We herein report the impact of different metal oxide and metalcone layers as precursors for zeolitic imidazolate framework ZIF-8 films.

Silica gel solid nanocomposite electrolytes with interfacial conductivity promotion exceeding the bulk Li-ion conductivity of the ionic liquid electrolyte filler.

The transition to solid-state Li-ion batteries will enable progress toward energy densities of 1000 W·hour/liter and beyond. Composites of a mesoporous oxide matrix filled with nonvolatile ionic liquid electrolyte fillers have been explored as a solid electrolyte option. However, the simple confinement of electrolyte solutions inside nanometer-sized pores leads to lower ion conductivity as viscosity increases.

A High-Surface-Area Carbon-Coated 3D Nickel Nanomesh for Li-O Batteries.

Nanostructured electrodes show great promises for application in batteries and could improve their energy and power density. Herein, a carbon-coated 3D Ni nanomesh was used as an air cathode for non-aqueous Li-air (O ) battery applications. A 3 μm thick 3D Ni nanomesh was fabricated, showing an excellent surface area/footprint area ratio (90 cm :1 cm ) and uniformly distributed pores, on which a conformal amorphous carbon coating was applied for the first time.

Combining High Porosity with High Surface Area in Flexible Interconnected Nanowire Meshes for Hydrogen Generation and Beyond.

Nanostructured metals with large surface area have a great potential for multiple device applications. Although various metal architectures based on metal nanoligaments and nanowires are well known, they typically show a tradeoff between mechanical robustness, high surface area, and high (macro)porosity, which, when combined, could significantly improve the performance of devices such as batteries, electrolyzers, or sensors. In this work, we rationally designed templated networks of interconnected metal nanowires, combining for the first time high porosity of metal foams, narrowly distributed macropores, and a very high surface area of nanoporous dealloyed metals.

Nanoscale electrochemical response of lithium-ion cathodes: a combined study using C-AFM and SIMS.

The continuous demand for improved performance in energy storage is driving the evolution of Li-ion battery technology toward emerging battery architectures such as 3D all-solid-state microbatteries (ASB). Being based on solid-state ionic processes in thin films, these new energy storage devices require adequate materials analysis techniques to study ionic and electronic phenomena. This is key to facilitate their commercial introduction.

Bending impact on the performance of a flexible LiTiO-based all-solid-state thin-film battery.

The growing demand of flexible electronic devices is increasing the requirements of their power sources. The effect of bending in thin-film batteries is still not well understood. Here, we successfully developed a high active area flexible all-solid-state battery as a model system that consists of thin-film layers of LiTiO, LiPON, and Lithium deposited on a novel flexible ceramic substrate.

The transformation behaviour of "alucones", deposited by molecular layer deposition, in nanoporous AlO layers.

Nanoporous alumina films can be synthesized from hybrid organic-inorganic "alucone" films deposited by molecular layer deposition (MLD) by wet etching in deionized water or calcination in air at 500 °C. This transformation process was systematically investigated for two alucone chemistries based on ethylene glycol (EG) and glycerol (GL). Ellipsometric porosimetry (EP) was used for the characterization of the porous alumina structures that are formed as a result of the treatments.

Electrolytic Manganese Dioxide Coatings on High Aspect Ratio Micro-Pillar Arrays for 3D Thin Film Lithium Ion Batteries.

In this work, we present the electrochemical deposition of manganese dioxide (MnO₂) thin films on carbon-coated TiN/Si micro-pillars. The carbon buffer layer, grown by plasma enhanced chemical vapor deposition (PECVD), is used as a protective coating for the underlying TiN current collector from oxidation, during the film deposition, while improving the electrical conductivity of the stack. A conformal electrolytic MnO₂ (EMD) coating is successfully achieved on high aspect ratio C/TiN/Si pillar arrays by tailoring the deposition process.

Electrical Characterization of Ultrathin RF-Sputtered LiPON Layers for Nanoscale Batteries.

Ultrathin lithium phosphorus oxynitride glass (LiPON) films with thicknesses down to 15 nm, deposited by reactive sputtering in nitrogen plasma, were found to be electronically insulating. Such ultrathin electrolyte layers could lead to high power outputs and increased battery energy densities. The effects of stoichiometry, film thickness, and substrate material on the ionic conductivity were investigated.

Molecular layer deposition of "titanicone", a titanium-based hybrid material, as an electrode for lithium-ion batteries.

Molecular layer deposition (MLD) of hybrid organic-inorganic thin films called "titanicones" was achieved using tetrakisdimethylaminotitanium (TDMAT) and glycerol (GL) or ethylene glycol (EG) as precursors. For EG, in situ ellipsometry revealed that the film growth initiates, but terminates after only 5 to 10 cycles, probably because both hydroxyls react with the surface. GL has a third hydroxyl group, and in that case steady state growth could be achieved.

Characterization of thin films of the solid electrolyte Li(x)Mg(1-2x)Al(2+x)O4 (x = 0, 0.05, 0.15, 0.25).

RF-sputtered thin films of spinel Li(x)Mg(1-2x)Al(2+x)O4 were investigated for use as solid electrolyte. The usage of this material can enable the fabrication of a lattice matched battery stack, which is predicted to lead to superior battery performance. Spinel Li(x)Mg(1-2x)Al(2+x)O4 thin films, with stoichiometry (x) ranging between 0 and 0.

High Cycling Stability and Extreme Rate Performance in Nanoscaled LiMn2O4 Thin Films.

Ultrathin LiMn2O4 electrode layers with average crystal size of ∼15 nm were fabricated by means of radio frequency sputtering. Cycling behavior and rate performance was evaluated by galvanostatic charge and discharge measurements. The thinnest films show the highest volumetric capacity and best cycling stability, retaining the initial capacity over 70 (dis)charging cycles when manganese dissolution is prevented.

Synthesis of a 3D network of Pt nanowires by atomic layer deposition on a carbonaceous template.

The formation of a 3D network composed of free standing and interconnected Pt nanowires is achieved by a two-step method, consisting of conformal deposition of Pt by atomic layer deposition (ALD) on a forest of carbon nanotubes and subsequent removal of the carbonaceous template. Detailed characterization of this novel 3D nanostructure was carried out by transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS). The characterization showed that this pure 3D nanostructure of platinum is self-supported and offers an enhancement of the electrochemically active surface area by a factor of 50.

Electrochemical deposition of subnanometer Ni films on TiN.

In this paper, we show the electrochemical deposition of a subnanometer film of nickel (Ni) on top of titanium nitride (TiN). We exploit the concept of cluster growth inhibition to enhance the nucleation of new nuclei on the TiN substrate. By deliberately using an unbuffered electrolyte solution, the degree of nucleation is enhanced as growth is inhibited more strongly.

First-principles material modeling of solid-state electrolytes with the spinel structure.

Ionic diffusion through the novel (AlxMg1-2xLix)Al2O4 spinel electrolyte is investigated using first-principles calculations, combined with the Kinetic Monte Carlo algorithm. We observe that the ionic diffusion increases with the lithium content x. Furthermore, the structural parameters, formation enthalpies and electronic structures of (AlxMg1-2xLix)Al2O4 are calculated for various stoichiometries.

Selective actuation of arrays of carbon nanotubes using magnetic resonance.

We introduce the use of ferromagnetic resonance (FMR) to actuate mechanical resonances in as grown arrays of carbon nanotubes (CNTs) loaded with Ni particles (Ni-CNTs). This contactless method is closely related to the magnetic resonance force microscopy technique and provides spatial selectivity of actuation along the array. The Ni-CNT arrays are grown by chemical vapor deposition and are composed of homogeneous CNTs with uniform length (~600 nm) and almost equal diameter (~20 nm), which are loaded with Ni catalyst particles at their tips due to the tip growth mode.

Carbon nanotube growth from Langmuir-Blodgett deposited Fe3O4 nanocrystals.

We investigate colloidal Fe(3)O(4) nanocrystals as a catalyst system for carbon nanotube (CNT) growth that allows for decoupling the CNT growth step from the catalyst shaping and activation step. The system consists of 6.4 nm Fe(3)O(4) nanocrystals synthesized using a solution-based thermal decomposition reaction and, subsequently, transferred as hexagonally ordered Langmuir-Blodgett (LB) monolayers on TiN substrates.