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A combination of cryogenic electron microscopy and cryogenic focused ion beam enabled the characterization of the interface between Li metal and lithium phosphorous oxynitride, one of the well-known interfaces to exhibit exemplary electrochemical stability with a lithium metal anode. The probed structural and chemical information leads to a more comprehensive understanding of the underlying cause for the interfacial stability and its formation mechanism.

N95 decontamination protocols and KN95 respirators have been described as solutions to a lack of personal protective equipment. However, there are a few material science studies that characterize the charge distribution and physical changes accompanying disinfection treatments, particularly heating. Here, we report the filtration efficiency, dipole charge density, and fiber integrity of N95 and KN95 respirators before and after various decontamination methods. We found that the filter layers in N95 and KN95 respirators maintained their fiber integrity without any deformations during disinfection. The filter layers of N95 respirators were 8-fold thicker and had 2-fold higher dipole charge density than that of KN95 respirators. Emergency Use Authorization (EUA)-approved KN95 respirators showed filtration efficiencies as high as N95 respirators. Interestingly, although there was a significant drop in the dipole charge in both respirators during decontamination, there was no remarkable decrease in the filtration efficiencies due to mechanical filtration. Cotton and polyester face masks had a lower filtration efficiency and lower dipole charge. In conclusion, a loss of electrostatic charge does not directly correlate to the decreased performance of either respirator.

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Lithium phosphorus oxynitride (LiPON) is an amorphous solid-state lithium ion conductor displaying exemplary cyclability against lithium metal anodes.T here is no definitive explanation for this stability due to the limited understanding of the structure of LiPON.H erein, we provide astructural model of RF-sputtered LiPON.Information about the short-range structure results from 1D and 2D solid-state NMR experiments.T hese results are compared with first principles chemical shielding calculations of LiP -O/N crystals and ab initio molecular dynamics-generated amorphous LiP-ON models to unequivocally identify the glassy structure as primarily isolated phosphate monomers with Ni ncorporated in both apical and as bridging sites in phosphate dimers. Structural results suggest LiPON'ss tability is ar esult of its glassy character.Free-standing LiPON films are produced that exhibit ah igh degree of flexibility,h ighlighting the unique mechanical properties of glassy materials.

high energy density LIBs is increasing. [2] Lithium-rich layered oxide (LRLO) as a high-energy cathode material has attracted many interests due to its large specific capacity (over 300 mAh g −1 ). [3,4] Accompanied by Li extraction/insertion during charge and discharge, LRLO experiences not only the transition metal (TM) redox but also the oxygen redox which contributes a large portion to its high capacity. [5,6] Despite its high capacity, the practical deployment of LRLO is hindered by voltage fade and capacity decay during electrochemical cycling. [7,8] These two issues are correlated to the activation of oxygen redox at high voltage (>4.5 V versus Li + /Li 0 ), which leads to surface and structure degradation during cycling, such as the formation of oxygen vacancies and irreversible oxygen loss, [8,9] the migration and the dissolution of TM, [10,11] the formation of spinel-like phase, [4] and the accumulation of microstrain. [12] Intensive materials modification efforts have been devoted to addressing the capacity and voltage decay issues in LRLO. Surface coating with oxides or fluorides such as Al 2 O 3 and AlF 3 was applied to reduce the oxygen release and protect the surface from acidic species in the electrolyte. [13][14][15] Both cation and anion doping such as Mg, Mo, F were also designed to mitigate the capacity and voltage decay through the altering of electronic structure and the suppression of structural degradation. [16][17][18] Heat treatment and re-lithiation on cycled LRLO materials were also studied to recover the capacity and voltage decay after electrochemical cycling through the recovery of the honeycomb ordering in the TM layer. [19,20] Besides the modification on active materials, many cell components have also been optimized for high-voltage operation such as the binder and conductive agents. [21] However, the compatibility of the electrolyte with the charged state of LRLO is often neglected in the literature. The activation step ubiquitously seen in anionic redox materials occurs at 4.5 V versus Li + / Li 0 . For the commonly used carbonate-based liquid electrolytes, when the voltage is pushed above this limit (4.5 V), the electrolytes decompose through the following processes: carbonatebased organic solvents such as ethylene carbonate (EC) oxidize and decompose at high voltage, accompanied by dehydrogenation reaction as the protons attached to the carbon in the carbonate solvents are dissociated. [22] The protons may further Lithium-rich layered oxides (LRLO) have attracted great interest for high-energyLi-ion batteries due to their high theoretical capacity. However, capacity decay and voltage fade during the cycling impede the practical application of LRLO. Herein, the use of lithium bis-(oxalate)borate (LiBOB) as an electrolyte additive is reported to improve the cycling stability in high voltage LRLO/graphite full cells. The cell with LiBOB-containing electrolyte delivers 248 mAh g −1 initial capacity and shows no capacity decay after 70 cycles as well as 95.5% retention after 150 c...

Lithium/fluorinated graphite (Li/CFx) primary batteries show great promise for applications in a wide range of energy storage systems due to their high energy density (>2100 Wh kg–1) and low self‐discharge rate (<0.5% per year at 25 °C). While the electrochemical performance of the CFx cathode is indeed promising, the discharge reaction mechanism is not thoroughly understood to date. In this article, a multiscale investigation of the CFx discharge mechanism is performed using a novel cathode structure to minimize the carbon and fluorine additives for precise cathode characterizations. Titration gas chromatography, X‐ray diffraction, Raman spectroscopy, X‐ray photoelectron spectroscopy, scanning electron microscopy, cross‐sectional focused ion beam, high‐resolution transmission electron microscopy, and scanning transmission electron microscopy with electron energy loss spectroscopy are utilized to investigate this system. Results show no metallic lithium deposition or intercalation during the discharge reaction. Crystalline lithium fluoride particles uniformly distributed with <10 nm sizes into the CFx layers, and carbon with lower sp2 content similar to the hard‐carbon structure are the products during discharge. This work deepens the understanding of CFx as a high energy density cathode material and highlights the need for future investigations on primary battery materials to advance performance.

Flexible solid-state zinc-air batteries (ZABs) generally suffer from poor electrolyte/electrode contact and mechanical degradation in practical applications. In addition, CO 2 corrosion is also a common issue for ZABs with alkaline electrolyte. Herein, we report a thermoreversible alkaline hydrogel electrolyte that can simultaneously solve the aforementioned problems. Through a simple cooling process, the hydrogel electrolyte transforms from solid state to liquid state that can not only restore the deformed electrolyte layer to its original state but also rebuild intimate contact between electrode and electrolyte. Moreover, the ZAB based on this hydrogel electrolyte exhibits an unprecedented anti-CO 2 property. As a result, such a battery shows almost 2.5 times discharge duration than that of ZAB based on liquid electrolyte.