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Despite significant interest toward solid‐state electrolytes owing to their superior safety in comparison to liquid‐based electrolytes, sluggish ion diffusion and high interfacial resistance limit their application in durable and high‐power density batteries. Here, a novel quasi‐solid Li+ ion conductive nanocomposite polymer electrolyte containing black phosphorous (BP) nanosheets is reported. The developed electrolyte is successfully cycled against Li metal (over 550 h cycling) at 1 mA cm−2 at room temperature. The cycling overpotential is dropped by 75% in comparison to BP‐free polymer composite electrolyte indicating lower interfacial resistance at the electrode/electrolyte interfaces. Molecular dynamics simulations reveal that the coordination number of Li+ ions around (trifluoromethanesulfonyl)imide (TFSI−) pairs and ethylene‐oxide chains decreases at the Li metal/electrolyte interface, which facilitates the Li+ transport through the polymer host. Density functional theory calculations confirm that the adsorption of the LiTFSI molecules at the BP surface leads to the weakening of N and Li atomic bonding and enhances the dissociation of Li+ ions. This work offers a new potential mechanism to tune the bulk and interfacial ionic conductivity of solid‐state electrolytes that may lead to a new generation of lithium polymer batteries with high ionic conduction kinetics and stable long‐life cycling. [ABSTRACT FROM AUTHOR]

Understanding the behavior of confined matter within Van der Waals (VdW) materials is complicated due to the interplay of various factors, including the VdW interaction between the interlayers, the layer interaction with the matter, and the bending strain energy of the layers to accommodate encapsulation. Herein, new insight on the magnitude of pressure and density of water entrapped within confined spaces in VdW materials is provided. This is accomplished by studying the plasmon excitation of water encapsulated between two sheets of graphene membranes in an aberration‐corrected scanning transmission electron microscope. The results indicate ≈12% maximum increase in the density of water under tight graphene encasement, where pressure as high as 400 MPa is expected. The pressure estimation from theoretical analysis considering the effect of VdW forces, Laplace pressure, and strain energy is in agreement with the experimental results. The findings of this work open new opportunities to explore the local physical state of not only water but also other liquid materials under high pressure with imaging and analytical resolutions never achieved before. [ABSTRACT FROM AUTHOR]

Abstract: Dendritic growth of lithium (Li) has severely impeded the practical application of Li‐metal batteries. Herein, a 3D conformal graphene oxide nanosheet (GOn) coating, confined into the woven structure of a glass fiber separator, is reported, which permits facile transport of Li‐ions thought its structure, meanwhile regulating the Li deposition. Electrochemical measurements illustrate a remarkably enhanced cycle life and stability of the Li‐metal anode, which is explained by various microscopy and modeling results. Utilizing scanning electron microscopy, focused ion beam, and optical imaging, the formation of an uniform Li film on the electrode surface in the case of GO‐modified samples is revealed. Ab initio molecular dynamics (AIMD) simulations suggest that Li‐ions initially get adsorbed to the lithiophilic GOn and then diffuse through defect sites. This delayed Li transfer eliminates the “tip effect” leading to a more homogeneous Li nucleation. Meanwhile, CC bonds rupture observed in the GO during AIMD simulations creates more pathways for faster Li‐ions transport. In addition, phase‐field modeling demonstrates that mechanically rigid GOn coating with proper defect size (smaller than 25 nm) can physically block the anisotropic growth of Li. This new understanding is a significant step toward the employment of 2D materials for regulating the Li deposition. [ABSTRACT FROM AUTHOR]

The progress on sodium-ion battery technology faces many grand challenges, one of which is the considerably lower rate of sodium insertion/deinsertion in electrode materials due to the larger size of sodium (Na) ions and complicated redox reactions compared to the lithium-ion systems. Here, it is demonstrated that sodium ions can be reversibly stored in Zn-Sb intermetallic nanowires at speeds that can exceed 295 nm s−1. Remarkably, these values are one to three orders of magnitude higher than the sodiation rate of other nanowires electrochemically tested with in situ transmission electron micro­scopy. It is found that the nanowires display about 161% volume expansion after the first sodiation and then cycle with an 83% reversible volume expansion. Despite their massive expansion, the nanowires can be cycled without any cracking or facture during the ultrafast sodiation/desodiation process. In addition, most of the phases involved in the sodiation/desodiation process possess high electrical conductivity. More specifically, the NaZnSb exhibits a layered structure, which provides channels for fast Na+ diffusion. This observation indicates that Zn-Sb intermetallic nanomaterials offer great promise as high rate and good cycling stability anodic materials for the next generation of sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Widespread application of Li‐ion batteries (LIBs) in large‐scale transportation and grid storage systems requires highly stable and safe performance of the batteries in prolonged and diverse service conditions. Oxygen release from oxygen‐containing positive electrode materials is one of the major structural degradations resulting in rapid capacity/voltage fading of the battery and triggering the parasitic thermal runaway events. Herein, the authors summarize the recent progress in understanding the mechanisms of the oxygen release phenomena and correlative structural degradations observed in four major groups of cathode materials: layered, spinel, olivine, and Li‐rich cathodes. In addition, the engineering and materials design approaches that improve the structural integrity of the cathode materials and minimize the detrimental O2 evolution reaction are summarized. The authors believe that this review can guide researchers on developing mitigation strategies for the design of next‐generation oxygen‐containing cathode materials where the oxygen release is no longer a major degradation issue. [ABSTRACT FROM AUTHOR]

LiCoO2 is a prime example of widely used cathodes that suffer from the structural/thermal instability issues that lead to the release of their lattice oxygen under nonequilibrium conditions and safety concerns in Li‐ion batteries. Here, it is shown that an atomically thin layer of reduced graphene oxide can suppress oxygen release from LixCoO2 particles and improve their structural stability. Electrochemical cycling, differential electrochemical mass spectroscopy, differential scanning calorimetry, and in situ heating transmission electron microscopy are performed to characterize the effectiveness of the graphene‐coating on the abusive tolerance of LixCoO2. Electrochemical cycling mass spectroscopy results suggest that oxygen release is hindered at high cutoff voltage cycling when the cathode is coated with reduced graphene oxide. Thermal analysis, in situ heating transmission electron microscopy, and electron energy loss spectroscopy results show that the reduction of Co species from the graphene‐coated samples is delayed when compared with bare cathodes. Finally, density functional theory and ab initio molecular dynamics calculations show that the rGO layers could suppress O2 formation more effectively due to the strong COcathode bond formation at the interface of rGO/LCO where low coordination oxygens exist. This investigation uncovers a reliable approach for hindering the oxygen release reaction and improving the thermal stability of battery cathodes. [ABSTRACT FROM AUTHOR]

LiCoO2 is a prime example of widely used cathodes that suffer from the structural/thermal instability issues that lead to the release of their lattice oxygen under nonequilibrium conditions and safety concerns in Li‐ion batteries. Here, it is shown that an atomically thin layer of reduced graphene oxide can suppress oxygen release from LixCoO2 particles and improve their structural stability. Electrochemical cycling, differential electrochemical mass spectroscopy, differential scanning calorimetry, and in situ heating transmission electron microscopy are performed to characterize the effectiveness of the graphene‐coating on the abusive tolerance of LixCoO2. Electrochemical cycling mass spectroscopy results suggest that oxygen release is hindered at high cutoff voltage cycling when the cathode is coated with reduced graphene oxide. Thermal analysis, in situ heating transmission electron microscopy, and electron energy loss spectroscopy results show that the reduction of Co species from the graphene‐coated samples is delayed when compared with bare cathodes. Finally, density functional theory and ab initio molecular dynamics calculations show that the rGO layers could suppress O2 formation more effectively due to the strong COcathode bond formation at the interface of rGO/LCO where low coordination oxygens exist. This investigation uncovers a reliable approach for hindering the oxygen release reaction and improving the thermal stability of battery cathodes. [ABSTRACT FROM AUTHOR]

Electronic properties of silicon, the most important semiconductor material, are controlled through doping. The range of achievable properties can be extended by hyperdoping, i.e., doping to concentrations beyond the nominal equilibrium solubility of the dopant. Here, hyperdoping is achieved in a laser pyrolysis reactor capable of providing nonequilibrium conditions, where doping is governed by kinetics rather than thermodynamics. High resolution scanning transmission electron microscopy (TEM) with energy‐dispersive X‐ray spectroscopy shows that the boron atom distribution in the hyperdoped nanoparticles is relatively uniform. The hyperdoped nanoparticles demonstrate tunable localized surface plasmon resonance (LSPR) and are stable in air for periods of at least one year. The hyperdoped nanoparticles are also stable upon annealing at temperatures up to 600 °C. Furthermore, boron hyperdoping does not change the diamond cubic crystal structure of silicon, as demonstrated in detail by high flux synchrotron X‐ray diffraction and pair distribution function (PDF) analysis, supported by high‐resolution TEM analysis. Boron‐hyperdoped silicon nanocrystals produced by laser pyrolysis of silane and diborane maintain the crystal structure of silicon with uniformly distributed boron, revealed by high‐resolution scanning transmission electron microscopy and high flux synchrotron X‐ray diffraction with pair distribution function analysis. As‐synthesized nanoparticles with 0.4–42.5 atom percent boron exhibit stable and tunable localized surface plasmon resonance at mid‐infrared wavelengths. [ABSTRACT FROM AUTHOR]