Integration of LiTiO Crystalline Films on Silicon Toward High-Rate Performance Lithionic Devices.

The growth of crystalline Li-based oxide thin films on silicon substrates is essential for the integration of next-generation solid-state lithionic and electronic devices including on-chip microbatteries, memristors, and sensors. However, growing crystalline oxides directly on silicon typically requires high temperatures and oxygen partial pressures, which leads to the formation of undesired chemical species at the interface compromising the crystal quality of the films. In this work, we employ a 2 nm gamma-alumina (γ-AlO) buffer layer on Si substrates in order to grow crystalline thin films of LiTiO (LTO), a well-known active material for lithium-ion batteries.

High-throughput, combinatorial synthesis of multimetallic nanoclusters.

Multimetallic nanoclusters (MMNCs) offer unique and tailorable surface chemistries that hold great potential for numerous catalytic applications. The efficient exploration of this vast chemical space necessitates an accelerated discovery pipeline that supersedes traditional "trial-and-error" experimentation while guaranteeing uniform microstructures despite compositional complexity. Herein, we report the high-throughput synthesis of an extensive series of ultrafine and homogeneous alloy MMNCs, achieved by 1) a flexible compositional design by formulation in the precursor solution phase and 2) the ultrafast synthesis of alloy MMNCs using thermal shock heating (i.

Ultrafast, Controllable Synthesis of Sub-Nano Metallic Clusters through Defect Engineering.

Supported metallic nanoclusters (NCs, < 2 nm) are of great interests in various catalytic reactions with enhanced activities and selectivities, yet it is still challenging to efficiently and controllably synthesize ultrasmall NCs with a high-dispersal density. Here we report the in situ synthesis of surfactant-free, ultrasmall, and uniform NCs via a rapid thermal shock on defective substrates. This is achieved by using high-temperature synthesis with extremely fast kinetics while limiting the synthesis time down to milliseconds (e.

Stable Multimetallic Nanoparticles for Oxygen Electrocatalysis.

Nanostructured catalysts often face an important challenge: poor stability. Many factors contribute to catalytic degradation, including parasitic chemical reactions, phase separation, agglomeration, and dissolution, leading to activity loss especially during long-term catalytic reactions. This challenge is shared by a new family of catalysts, multimetallic nanoparticles, which have emerged owing to their broad tunability and high activity.

Cellulose ionic conductors with high differential thermal voltage for low-grade heat harvesting.

Converting low-grade heat into useful electricity requires a technology that is efficient and cost effective. Here, we demonstrate a cellulosic membrane that relies on sub-nanoscale confinement of ions in oxidized and aligned cellulose molecular chains to enhance selective diffusion under a thermal gradient. After infiltrating electrolyte into the cellulosic membrane and applying an axial temperature gradient, the ionic conductor exhibits a thermal gradient ratio (analogous to the Seebeck coefficient in thermoelectrics) of 24 mV K-more than twice the highest value reported until now.

Carbothermal shock synthesis of high-entropy-alloy nanoparticles.

The controllable incorporation of multiple immiscible elements into a single nanoparticle merits untold scientific and technological potential, yet remains a challenge using conventional synthetic techniques. We present a general route for alloying up to eight dissimilar elements into single-phase solid-solution nanoparticles, referred to as high-entropy-alloy nanoparticles (HEA-NPs), by thermally shocking precursor metal salt mixtures loaded onto carbon supports [temperature ~2000 kelvin (K), 55-millisecond duration, rate of ~10 K per second]. We synthesized a wide range of multicomponent nanoparticles with a desired chemistry (composition), size, and phase (solid solution, phase-separated) by controlling the carbothermal shock (CTS) parameters (substrate, temperature, shock duration, and heating/cooling rate).

Extrusion-Based 3D Printing of Hierarchically Porous Advanced Battery Electrodes.

A highly porous 2D nanomaterial, holey graphene oxide (hGO), is synthesized directly from holey graphene powder and employed to create an aqueous 3D printable ink without the use of additives or binders. Stable dispersions of hydrophilic hGO sheets in water (≈100 mg mL ) can be readily achieved. The shear-thinning behavior of the aqueous hGO ink enables extrusion-based printing of fine filaments into complex 3D architectures, such as stacked mesh structures, on arbitrary substrates.

Textile Inspired Lithium-Oxygen Battery Cathode with Decoupled Oxygen and Electrolyte Pathways.

The lithium-air (Li-O ) battery has been deemed one of the most promising next-generation energy-storage devices due to its ultrahigh energy density. However, in conventional porous carbon-air cathodes, the oxygen gas and electrolyte often compete for transport pathways, which limit battery performance. Here, a novel textile-based air cathode is developed with a triple-phase structure to improve overall battery performance.

Tree-Inspired Design for High-Efficiency Water Extraction.

The solar steam process, akin to the natural water cycle, is considered to be an attractive approach to address water scarcity issues globally. However, water extraction from groundwater, for example, has not been demonstrated using these existing technologies. Additionally, there are major unaddressed challenges in extracting potable water from seawater including salt accumulation and long-term evaporation stability, which warrant further investigation.

Highly Anisotropic Conductors.

Composite materials with ordered microstructures often lead to enhanced functionalities that a single material can hardly achieve. Many biomaterials with unusual microstructures can be found in nature; among them, many possess anisotropic and even directional physical and chemical properties. With inspiration from nature, artificial composite materials can be rationally designed to achieve this anisotropic behavior with desired properties.

Universal, In Situ Transformation of Bulky Compounds into Nanoscale Catalysts by High-Temperature Pulse.

The synthesis of nanoscale metal compound catalysts has attracted much research attention in the past decade. The challenges of preparation of the metal compound include the complexity of the synthesis process and difficulty of precise control of the reaction conditions. Herein, we report an in situ synthesis of nanoparticles via a high-temperature pulse method where the bulk material acts as the precursor.

Inverted battery design as ion generator for interfacing with biosystems.

In a lithium-ion battery, electrons are released from the anode and go through an external electronic circuit to power devices, while ions simultaneously transfer through internal ionic media to meet with electrons at the cathode. Inspired by the fundamental electrochemistry of the lithium-ion battery, we envision a cell that can generate a current of ions instead of electrons, so that ions can be used for potential applications in biosystems. Based on this concept, we report an 'electron battery' configuration in which ions travel through an external circuit to interact with the intended biosystem whereas electrons are transported internally.

High Temperature Synthesis of Single-Component Metallic Nanoparticles.

Nanoparticles (NPs) dispersed within a conductive host are essential for a range of applications including electrochemical energy storage, catalysis, and energetic devices. However, manufacturing high quality NPs in an efficient manner remains a challenge, especially due to agglomeration during assembly processes. Here we report a rapid thermal shock method to synthesize well-dispersed NPs on a conductive fiber matrix using metal precursor salts.

Toward garnet electrolyte-based Li metal batteries: An ultrathin, highly effective, artificial solid-state electrolyte/metallic Li interface.

Solid-state batteries are a promising option toward high energy and power densities due to the use of lithium (Li) metal as an anode. Among all solid electrolyte materials ranging from sulfides to oxides and oxynitrides, cubic garnet-type LiLaZrO (LLZO) ceramic electrolytes are superior candidates because of their high ionic conductivity (10 to 10 S/cm) and good stability against Li metal. However, garnet solid electrolytes generally have poor contact with Li metal, which causes high resistance and uneven current distribution at the interface.

Mesoporous, Three-Dimensional Wood Membrane Decorated with Nanoparticles for Highly Efficient Water Treatment.

Wood, an earth-abundant material, is widely used in our everyday life. With its mesoporous structure, natural wood is comprised of numerous long, partially aligned channels (lumens) as well as nanochannels that stretch along its growth direction. This wood mesostructure is suitable for a range of emerging applications, especially as a membrane/separation material.

Ultrahigh-Capacity Lithium-Oxygen Batteries Enabled by Dry-Pressed Holey Graphene Air Cathodes.

Lithium-oxygen (Li-O) batteries have the highest theoretical energy density of all the Li-based energy storage systems, but many challenges prevent them from practical use. A major obstacle is the sluggish performance of the air cathode, where both oxygen reduction (discharge) and oxygen evolution (charge) reactions occur. Recently, there have been significant advances in the development of graphene-based air cathode materials with a large surface area and catalytically active for both oxygen reduction and evolution reactions, especially with additional catalysts or dopants.

Dry-Processed, Binder-Free Holey Graphene Electrodes for Supercapacitors with Ultrahigh Areal Loadings.

For commercial applications, the need for smaller footprint energy storage devices requires more energy to be stored per unit area. Carbon nanomaterials, especially graphene, have been studied as supercapacitor electrodes and can achieve high gravimetric capacities affording high gravimetric energy densities. However, most nanocarbon-based electrodes exhibit a significant decrease in their areal capacitances when scaled to the high mass loadings typically used in commercially available cells (∼10 mg/cm).

Tuning two-dimensional nanomaterials by intercalation: materials, properties and applications.

2D materials have attracted tremendous attention due to their unique physical and chemical properties since the discovery of graphene. Despite these intrinsic properties, various modification methods have been applied to 2D materials that yield even more exciting results in terms of tunable properties and device performance. Among all modification methods, intercalation of 2D materials has emerged as a particularly powerful tool: it provides the highest possible doping level and is capable of (ir)reversibly changing the phase of the material.

Transition from Superlithiophobicity to Superlithiophilicity of Garnet Solid-State Electrolyte.

All-solid-state Li-batteries using solid-state electrolytes (SSEs) offer enhanced safety over conventional Li-ion batteries with organic liquid electrolytes due to the nonflammable nature of SSEs. The superior mechanical strength of SSEs can also protect against Li dendrite penetration, which enables the use of the highest specific capacity (3861 mAh/g) and lowest redox potential (-3.04 V vs standard hydrogen electrode) anode: Li metal.

Rapid, in Situ Synthesis of High Capacity Battery Anodes through High Temperature Radiation-Based Thermal Shock.

High capacity battery electrodes require nanosized components to avoid pulverization associated with volume changes during the charge-discharge process. Additionally, these nanosized electrodes need an electronically conductive matrix to facilitate electron transport. Here, for the first time, we report a rapid thermal shock process using high-temperature radiative heating to fabricate a conductive reduced graphene oxide (RGO) composite with silicon nanoparticles.

Transient Rechargeable Batteries Triggered by Cascade Reactions.

Transient battery is a new type of technology that allows the battery to disappear by an external trigger at any time. In this work, we successfully demonstrated the first transient rechargeable batteries based on dissoluble electrodes including V2O5 as the cathode and lithium metal as the anode as well as a biodegradable separator and battery encasement (PVP and sodium alginate, respectively). All the components are robust in a traditional lithium-ion battery (LIB) organic electrolyte and disappear in water completely within minutes due to triggered cascade reactions.

Atomic force microscopy studies on molybdenum disulfide flakes as sodium-ion anodes.

A microscale battery comprised of mechanically exfoliated molybdenum disulfide (MoS2) flakes with copper connections and a sodium metal reference was created and investigated as an intercalation model using in situ atomic force microscopy in a dry room environment. While an ethylene carbonate-based electrolyte with a low vapor pressure allowed topographical observations in an open cell configuration, the planar microbattery was used to conduct in situ measurements to understand the structural changes and the concomitant solid electrolyte interphase (SEI) formation at the nanoscale. Topographical observations demonstrated permanent wrinkling behavior of MoS2 electrodes upon sodiation at 0.