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Lithium phosphorus oxynitride (LiPON) is an amorphous solid-state lithium ion conductor displaying exemplary cyclability against lithium metal anodes. There is no definitive explanation for this stability due to the limited understanding of the structure of LiPON. Herein, we provide a structural model of RF-sputtered LiPON. Information about the short-range structure results from 1D and 2D solid-state NMR experiments. These results are compared with first principles chemical shielding calculations of Li-P-O/N crystals and ab initio molecular dynamics-generated amorphous LiPON models to unequivocally identify the glassy structure as primarily isolated phosphate monomers with N incorporated in both apical and as bridging sites in phosphate dimers. Structural results suggest LiPON's stability is a result of its glassy character. Free-standing LiPON films are produced that exhibit a high degree of flexibility, highlighting the unique mechanical properties of glassy materials.

The effects of the coronavirus global pandemic have rippled through many lives and have upended aspects of health care, transportation, and the economy in virtually every country. The energy materials and renewable generation and conversion market, which includes battery-powered electric vehicles, grid storage, and personal electronic devices, is no exception.

During the current pandemic shutdown, everyone has had to make decisions-many of which haven't been easy. For the first time in my life, I experienced what were previously unthinkable-airplanes being grounded, cars being off the roads, all classes and meetings being held virtually. The surreal experience has propelled me to think more deeply about what I do and why it is so important to push forward with doing better materials science to enable breakthroughs in energy technologies and to ensure a robust supply chain of relevant materials for the world.

The recent proliferation of renewable energy generation offers mankind hope, with regard to combatting global climate change. However, reaping the full benefits of these renewable energy sources requires the ability to store and distribute any renewable energy generated in a cost-effective, safe, and sustainable manner. As such, sodium-ion batteries (NIBs) have been touted as an attractive storage technology due to their elemental abundance, promising electrochemical performance and environmentally benign nature. Moreover, new developments in sodium battery materials have enabled the adoption of high-voltage and high-capacity cathodes free of rare earth elements such as Li, Co, Ni, offering pathways for low-cost NIBs that match their lithium counterparts in energy density while serving the needs for large-scale grid energy storage. In this essay, a range of battery chemistries are discussed alongside their respective battery properties while keeping metrics for grid storage in mind. Matters regarding materials and full cell cost, supply chain and environmental sustainability are discussed, with emphasis on the need to eliminate several elements (Li, Ni, Co) from NIBs. Future directions for research are also discussed, along with potential strategies to overcome obstacles in battery safety and sustainable recyclability.

Liquefied gas electrolytes with unique solvation structure enable high ionic conductivity in extended temperature ranges, supporting wide-temperature high-voltage lithium metal batteries.

Electrochemical deposition of metals, such as Li, Na, K, Zn, Mg and alike, are very important for energy storage and rechargeable battery applications. Yet, the fundamental understanding of the deposition process of these metals is surprisingly overlooked and lacking. It is often observed that the deposit’s morphology, microstructure, and the associated properties are often controlled by the kinetic processes that govern the evolution of these properties with time. However, the mechanism and mechanistic processes involved are difficult to characterize to yield quantitative and sufficiently detailed temporal information to help us understand the underlying principles that govern the phase lattice structural and morphological changes. Here, we applied reactive molecular dynamics (r-MD) simulation to model the nucleation and growth processes of Li metal deposition in typical electrochemical cells. Cryo-EM was used to characterize the microstructure, morphology and relevant properties of the Li metal deposits obtained from a range of current density and duration. Both cryo-TEM and r-MD results suggest that the Li deposits are likely amorphous in the initial deposition and such amorphous phase was retained more easily at lower current density such as 0.1 mA cm-2 than those at 1 mA cm-2. The r-MD simulation explained the cause of such amorphous phase retention is due to the significantly longer phase transition time associated with the transition from the disordered amorphous phase to the ordered crystalline phase of body-centered cubic (bcc) lattice structure. Such a long incubation could be easily understood, but hardly emphasized in the literature. Therefore, this critical aspect was often overlooked in the discussion of the experimental results, where kinetic effects are dominating the processes in the observations. We registered similar observations in other electrochemical metal depositions, and this thermal-activation-inhibited incubation process is being observed in all experimental conditions disregarding which elemental metal and lattice structure involved. The implication of this fundamental understanding will be discussed in this presentation.

Haptic devices are in general more adept at mimicking the bulk properties of materials than they are at mimicking the surface properties. This paper describes a haptic glove capable of producing sensations reminiscent of three types of near-surface properties: hardness, temperature, and roughness. To accomplish this mixed mode of stimulation, three types of haptic actuators were combined: vibrotactile motors, thermoelectric devices, and electrotactile electrodes made from a stretchable conductive polymer synthesized in our laboratory. This polymer consisted of a stretchable polyanion which served as a scaffold for the polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). The scaffold was synthesized using controlled radical polymerization to afford material of low dispersity, relatively high conductivity (0.1 S cm-1), and low impedance relative to metals. The glove was equipped with flex sensors to make it possible to control a robotic hand and a hand in virtual reality (VR). In psychophysical experiments, human participants were able to discern combinations of electrotactile, vibrotactile, and thermal stimulation in VR. Participants trained to associate these sensations with roughness, hardness, and temperature had an overall accuracy of 98%, while untrained participants had an accuracy of 85%. Sensations could similarly be conveyed using a robotic hand equipped with sensors for pressure and temperature.

According to the US Department of Energy’s Energy Infomation Administration (EIA) (International Energy Outlook 2017), world energy consumption will increase 28% between 2015 and 2040, rising from 575 quadrillion Btu (∼606 quadrillion kJ) in 2015 to 736 quadrillion Btu (∼776 quadrillion kJ) in 2040. EIA predicts increases in consumption for all energy sources (excluding coal, which is estimated to remain flat)—fossil (petroleum and other liquids, natural gas), renewables (solar, wind, hydropower), and nuclear. Although renewables are the world’s fastest growing form of energy, fossil fuels are expected to continue to supply more than three-quarters of the energy used worldwide. Among the various fossil fuels, natural gas is the fastest growing, with a projected increase of 43% from 2015 to 2040. As the use of fossil fuels increases, the EIA projects world energy-related carbon dioxide emission to grow from ∼34 billion metric tons in 2015 to ∼40 billion metric tonnes in 2040 (an average 0.6% increase per year).

Thermoregulation has substantial implications for energy consumption and human comfort and health. However, cooling technology has remained largely unchanged for more than a century and still relies on cooling the entire space regardless of the number of occupants. Personalized thermoregulation by thermoelectric devices (TEDs) can markedly reduce the cooling volume and meet individual cooling needs but has yet to be realized because of the lack of flexible TEDs with sustainable high cooling performance. Here, we demonstrate a wearable TED that can deliver more than 10°C cooling effect with a high coefficient of performance (COP > 1.5). Our TED is the first to achieve long-term active cooling with high flexibility, due to a novel design of double elastomer layers and high-ZT rigid TE pillars. Thermoregulation based on these devices may enable a shift from centralized cooling toward personalized cooling with the benefits of substantially lower energy consumption and improved human comfort.

State-of-the-art lithium (Li)-ion batteries are approaching their specific energy limits yet are challenged by the ever-increasing demand of today’s energy storage and power applications, especially for electric vehicles. Li metal is considered an ultimate anode material for future high-energy rechargeable batteries when combined with existing or emerging high-capacity cathode materials. However, much current research focuses on the battery materials level, and there have been very few accounts of cell design principles. Here we discuss crucial conditions needed to achieve a specific energy higher than 350 Wh kg −1 , up to 500 Wh kg −1 , for rechargeable Li metal batteries using high-nickel-content lithium nickel manganese cobalt oxides as cathode materials. We also provide an analysis of key factors such as cathode loading, electrolyte amount and Li foil thickness that impact the cell-level cycle life. Furthermore, we identify several important strategies to reduce electrolyte-Li reaction, protect Li surfaces and stabilize anode architectures for long-cycling high-specific-energy cells.

Lithium metal is viewed as the ultimate battery anode because of its high theoretical capacity and low electrode potential, but its implementation has been limited by low Coulombic efficiency and dendrite formation above a critical current density. Determining the fundamental properties dictating lithium metal plating-stripping behavior is challenging because characterization techniques are limited by the sensitivity of lithium metal to damage by external probes, which regularly results in altered morphology and chemistry. Motivated by recent application of cryogenic transmission electron microscopy (cryo-TEM) to characterize lithium metal at the atomic scale, we explore the cryogenic focused ion beam (cryo-FIB) method as a quantitative tool for characterizing the bulk morphology of electrochemically deposited lithium and as a technique that enables TEM observation of Li-metal/solid-state electrolyte interfaces. This work highlights the importance of cryo-FIB methodology for preparing sensitive battery materials and elucidates the impact of electrolyte selection on the density and morphology of plated lithium.

To enable next-generation high-energy-density lithium (Li)-metal batteries (LMBs), an electrolyte that has simultaneous high Li-metal Coulombic efficiency (CE) and high anodic stability on cathodes is of significant importance. Sulfones are known for strong resistance against oxidation, yet their application in LMBs is restricted because of their poor compatibility with Li-metal anodes, high viscosity, and poor wettability. Here, we demonstrate that a high Li CE over 98% can be achieved in concentrated sulfone-based electrolytes. Furthermore, the viscosity and wettability issues of sulfones are resolved by the addition of a fluorinated ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, to form a localized high-concentration electrolyte (LHCE), which not only provides further improvement in Li CE (98.8%) but also remains anodically stable with high-voltage cathodes, suppresses Al corrosion, and enables LMBs to operate in a wide temperature range. As a result, significantly improved cycling performance of LMBs has been realized with sulfone-based LHCE. For high-voltage rechargeable lithium (Li)-metal batteries (LMBs), electrolytes with good stabilities on both the highly oxidative cathodes and the highly reductive Li-metal anodes are urgently desired. Sulfones have excellent oxidative stability, yet their high viscosity, poor wettability, and, in particular, incompatibility with Li anodes greatly hinder their applications in LMBs. Here, we demonstrate that a high Li Coulombic efficiency (CE) of 98.2% during repeated Li plating and stripping cycles can be realized in concentrated lithium bis(fluorosulfonyl)imide (LiFSI)-tetramethylene sulfone electrolyte. More importantly, the localized high-concentration electrolyte, formed by the dilution of the high-concentration electrolyte with a non-solvating fluorinated ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, solves the viscosity and wettability issues, further improves Li CE (98.8%), and improves the high-voltage (4.9 V) performance of LMBs with effective Al protection. High-voltage batteries with Li-metal anodes can offer desirable high energy densities. Despite their excellent oxidative stability, sulfones have various limitations to be useful in Li-metal batteries, in particular their instability with Li metal. Here, we achieved a high Li Coulombic efficiency of nearly 99% in a sulfone-based localized high-concentration electrolyte (LHCE) with the addition of a non-solvating co-solvent. In addition, this co-solvent is highly beneficial for realizing stable battery cycling up to 4.9 V.

In the current study, through a set of nail penetration and impact tests on modified lithium-ion battery coin half-cells, we examine the effects of electrode pattern on the heat generation behaviors associated with internal shorting. The results show that the temperature profile is quite insensitive to the openings in cathode layer, which may be attributed to the high specific energy as well as the secondary conductive paths. This finding will considerably influence the study in the area of thermal runaway mitigation of energy storage systems.

The performance of many technologies, such as Li- and Na-ion batteries as well as some two-dimensional (2D) electronics, is dependent upon the reversibility of stacking-sequence-change phase transformations. However, the mechanisms by which such transformations lead to degradation are not well understood. This study explores lattice-invariant shear as a source of irreversibility in stacking-sequence changes, and through an analysis of crystal symmetry shows that common electrode materials (graphitic carbon, layered oxides, and layered sulfides) are generally susceptible to lattice-invariant shear. The resulting irreversible changes to microstructure upon cycling ("electrochemical creep") could contribute to the degradation of the electrode and capacity fade.

The semiconductor industry has seen tremendous progress over the last few decades with continuous reduction in transistor size to improve device performance. Miniaturization of devices has led to changes in the dopants and dielectric layers incorporated. As the gradual shift from two-dimensional metal-oxide semiconductor field-effect transistor to three-dimensional (3D) field-effect transistors (finFETs) occurred, it has become imperative to understand compositional variability with nanoscale spatial resolution. Compositional changes can affect device performance primarily through fluctuations in threshold voltage and channel current density. Traditional techniques such as scanning electron microscope and focused ion beam no longer provide the required resolution to probe the physical structure and chemical composition of individual fins. Hence advanced multimodal characterization approaches are required to better understand electronic devices. Herein, we report the study of 14 nm commercial finFETs using atom probe tomography (APT) and scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy (STEM-EDS). Complimentary compositional maps were obtained using both techniques with analysis of the gate dielectrics and silicon fin. APT additionally provided 3D information and allowed analysis of the distribution of low atomic number dopant elements (e.g., boron), which are elusive when using STEM-EDS.

Electrochemical capacitors and lithium-ion batteries have seen little change in their electrolyte chemistry since their commercialization, which has limited improvements in device performance. Combining superior physical and chemical properties and a high dielectric-fluidity factor, the use of electrolytes based on solvent systems that exclusively use components that are typically gaseous under standard conditions show a wide potential window of stability and excellent performance over an extended temperature range. Electrochemical capacitors using difluoromethane show outstanding performance from -78° to +65°C, with an increased operation voltage. The use of fluoromethane shows a high coulombic efficiency of ~97% for cycling lithium metal anodes, together with good cyclability of a 4-volt lithium cobalt oxide cathode and operation as low as -60°C, with excellent capacity retention.