Nature of Li2O2 and its relationship to the mechanisms of discharge/charge reactions of lithium-oxygen batteries.

Lithium-air batteries (LABs) are considered one of the most promising energy storage devices because of their large theoretical energy density. However, low cyclability caused by battery degradation prevents its practical use. Thus, to realize practical LABs, it is essential to improve cyclability significantly by understanding how the degradation processes proceed. Here, we used online mass spectrometry for real-time monitoring of gaseous products generated during charging of lithium-oxygen batteries (LOBs), which was operated with pure oxygen not air, with 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) tetraethylene glycol dimethyl ether (TEGDME) electrolyte solution. Linear voltage sweep (LVS) and voltage step modes were employed for charge instead of constant current charge so that the energetics of the product formation during the charge process can be understood more quantitatively. The presence of two distinctly different types of Li2O2, one being decomposed in a wide range of relatively low cell voltages (2.8-4.16 V) (l-Li2O2) and the other being decomposed at higher cell voltages than ca. 4.16 V (h-Li2O2), was confirmed by both LVS and step experiments. H2O generation started when the O2 generation rate reached a first maximum and CO2 generation took place accompanied by the decomposition of h-Li2O2. Based on the above results and the effects of discharge time and the use of isotope oxygen during discharge on product distribution during charge, the generation mechanism of O2, H2O, and CO2 during charging is discussed in relation to the reactions during discharge.

Evaluation of performance metrics for high energy density rechargeable lithium-oxygen batteries.

The demand for practical implementation of rechargeable lithium-oxygen batteries (LOBs) has grown owing to their extremely high theoretical energy density. However, the factors determining the performance of cell-level high energy density LOBs remain unclear. In this study, LOBs with a stacked-cell configuration were fabricated and their performance evaluated under different experimental conditions to clarify the unique degradation phenomenon under lean-electrolyte and high areal capacity conditions. First, the effect of the electrolyte amount against areal capacity ratio (E/C) on the battery performance was evaluated, revealing a complicated voltage profile for an LOB cell operated under high areal capacity conditions. Second, the impact of different kinds of gas-diffusion layer materials on the "sudden death" phenomenon during the charging process was investigated. The results obtained in the present study reveal the importance of these factors when evaluating the performance metrics of LOBs, including cycle life, and round-trip energy efficiency. We believe that adopting a suitable experimental setup with appropriate technological parameters is crucial for accurately interpreting the complicated phenomenon in LOBs with cell-level high energy density.

CD69 Is Indispensable for Development of Functional Local Immune Memory in Murine Contact Hypersensitivity.

Local immune memory develops at the site of antigen exposure and facilitates a rapid and strong local adaptive defense upon re-exposure. Resident memory T (TRM) cells play a role in local immune memory, and their cell-surface molecules CD69 and CD103 promote their tissue residency. However, the contribution of these molecules to skin immune memory remains unclear. In this study, by inducing contact hypersensitivity (CHS) in CD69KO (CD69-deficient) and CD103-deficient mice, where different degrees of TRM cell contribution are observed by repeated challenges on the right ear and a single challenge on the left ear, we found that the deficiency of CD69 but not CD103 leads to impaired CHS upon repeated antigen challenges, even although TRM cells-like CD8 T cells developed at the challenged site of CD69KO. CHS responses in both ears were diminished in CD69KO by FTY720 or CD8 neutralization, suggesting that CHS in CD69KO is ascribed to circulating CD8 T cells and that the developed TRM cell-like CD8 T cells do not behave as TRM cells. The infiltration of macrophages was reduced in the rechallenged site of CD69KO, along with the downregulation of Cxcl1 and Cxcl2. Thus, CD69 is considered essential for an effective recall response, involving the development of functional TRM cells and the recruitment of macrophages.

Poor Cycling Performance of Rechargeable Lithium-Oxygen Batteries under Lean-Electrolyte and High-Areal-Capacity Conditions: Role of Carbon Electrode Decomposition.

There is growing demand for practical implementation of lithium-oxygen batteries (LOBs) due to their superior potential for achieving higher energy density than that of conventional lithium-ion batteries. Although recent studies demonstrate the stable operation of 500 Wh kg-1 -class LOBs, their cycle life remains fancy. For further improving the cycle performance of LOBs, the complicated chemical degradation mechanism in LOBs must be elucidated. In particular, the quantitative contribution of each cell component to degradation phenomenon in LOBs under lean-electrolyte and high-areal-capacity conditions should be clarified. In the present study, the mass balance of the positive-electrode reaction in a LOB under lean-electrolyte and high-areal-capacity conditions is quantitatively evaluated. The results reveal carbon electrode decomposition to be the critical factor that prevents the prolonged cycling of the LOB. Notably, the carbon electrode decomposition occur during charging at voltages higher than 3.8 V through the electrochemical decomposition of solid-state side products. The findings of this study highlight the significance of improving the stability of the carbon electrode and/or forming Li2 O2 , which can decompose at voltages lower than 3.8 V, to realize high-energy-density LOBs with long cycle life.

High-Efficiency Near-Infrared-to-Visible Photon Upconversion in Poly(vinyl alcohol) Porous Film.

Triplet-triplet annihilation photon upconversion (TTA-UC) has received significant attention in energy harvesting applications such as solar cells. The realization of high upconversion (UC) performance in the form of films is a crucial factor for the incorporation of this technology into large-area devices. Herein, we propose a porous UC film prepared by an emulsification method with a poly(vinyl alcohol) (PVA) aqueous solution and a toluene solution of chromophores (rubrene/Pd-tetraphenyltetraanthraporphyrin pair) that achieved considerable UC performance in the near-infrared (NIR) (810 nm) to visible (560 nm) range with a maximum quantum yield of 3.7% (out of 50%). Notably, the films displayed a UC emission when using an NIR light-emitting diode as a low-power-density noncoherent light source, which was confirmed by the naked eye. Excitation-power-dependent time-resolved photoluminescence measurements showed almost identical triplet lifetimes of emitter species for the films and toluene solutions; however, lower threshold intensities (Ith = 1-2 W/cm2) were observed for the films than those of the solutions (Ith = ∼10 W/cm2). An evaluation of the remaining toluene in the film and UC emission behavior in liquid nitrogen suggested that the chromophores exist as an amorphous solid in the pores, thus enabling hybrid triplet energy transfer (chromophore mobility based and exciton migration) in this unique film. The presented methodology can be generalized to other wavelengths and can enable diverse applications of the TTA-UC technology.

CNT-MXene ultralight membranes: fabrication, surface nano/microstructure, 2D-3D stacking architecture, ion-transport mechanism, and potential application as interlayers for Li-O2 batteries.

Multiwalled carbon nanotubes (MWCNTs) have shown effectiveness in improving the suitability of MXenes for energy-related applications. However, the ability of individually dispersed MWCNTs to control the structure of MXene-based macrostructures is unclear. Here, the correlation among composition, surface nano- and microstructure, MXenes' stacking order, structural swelling, and Li-ion transport mechanisms and properties in individually dispersed MWCNT-Ti3C2 films was investigated. The compact surface microstructure of MXene film, characterized by prominent wrinkles, is dramatically changed as MWCNTs occupy MXene/MXene edge interfaces. The 2D stacking order is preserved up to 30 wt% MWCNTs despite a significant swelling of ∼400%. Such alignment is completely disrupted at 40 wt%, and a more pronounced surface opening and internal expansion of ∼770% are realized. Both 30 wt% and 40 wt% membranes show stable cycling performance under a significantly higher current density due to faster transport channels. Notably, for the 3D membrane, the overpotential during repeated Li deposition/dissolution reactions is further reduced by ∼50%. Ion-transport mechanisms in the absence and presence of MWCNTs are discussed. Furthermore, ultralight yet continuous hybrid films comprising up to ∼0.027 mg cm-2 Ti3C2 can be prepared using aqueous colloidal dispersions and vacuum filtration for specific applications. The potential application of such ultralight membranes as interlayers for Li-O2 batteries is briefly examined.

VGLL3 is a mechanosensitive protein that promotes cardiac fibrosis through liquid-liquid phase separation.

Myofibroblasts cause tissue fibrosis by producing extracellular matrix proteins, such as collagens. Humoral factors like TGF-ß, and matrix stiffness are important for collagen production by myofibroblasts. However, the molecular mechanisms regulating their ability to produce collagen remain poorly characterised. Here, we show that vestigial-like family member 3 (VGLL3) is specifically expressed in myofibroblasts from mouse and human fibrotic hearts and promotes collagen production. Further, substrate stiffness triggers VGLL3 translocation into the nucleus through the integrin ß1-Rho-actin pathway. In the nucleus, VGLL3 undergoes liquid-liquid phase separation via its low-complexity domain and is incorporated into non-paraspeckle NONO condensates containing EWS RNA-binding protein 1 (EWSR1). VGLL3 binds EWSR1 and suppresses miR-29b, which targets collagen mRNA. Consistently, cardiac fibrosis after myocardial infarction is significantly attenuated in Vgll3-deficient mice, with increased miR-29b expression. Overall, our results reveal an unrecognised VGLL3-mediated pathway that controls myofibroblasts' collagen production, representing a novel therapeutic target for tissue fibrosis.

Lithium-Ion-Conducting Ceramics-Coated Separator for Stable Operation of Lithium Metal-Based Rechargeable Batteries.

Lithium metal anode is regarded as the ultimate negative electrode material due to its high theoretical capacity and low electrochemical potential. However, the significantly high reactivity of Li metal limits the practical application of Li metal batteries. To improve the stability of the interface between Li metal and an electrolyte, a facile and scalable blade coating method was used to cover the commercial polyethylene membrane separator with an inorganic/organic composite solid electrolyte layer containing lithium-ion-conducting ceramic fillers. The coated separator suppressed the interfacial resistance between the Li metal and the electrolyte and consequently prolonged the cycling stability of deposition/dissolution processes in Li/Li symmetric cells. Furthermore, the effect of the coating layer on the discharge/charge cycling performance of lithium-oxygen batteries was investigated.

Criteria for evaluating lithium-air batteries in academia to correctly predict their practical performance in industry.

Although the market share for Li-ion batteries (LiBs) has continuously expanded, the limited theoretical energy density of conventional LiBs will no longer meet the advanced energy storage requirements. Lithium-air batteries (LABs) are potential candidates for next-generation rechargeable batteries because of their extremely high theoretical energy density. However, the reported values for the actual energy density of LABs are much lower than those for LiBs, mainly due to the excess amount of electrolyte in the cell. In the present review article, the practical energy density is estimated for the representative LABs reported in academia, and the critical factors for improving the energy density of LABs are summarized. The criteria for evaluating LABs in laboratory-based experiments are also proposed for accurately predicting the performance of practical cells in industry.

Induction of alopecia areata in C3H/HeJ mice using cryopreserved lymphocytes.

BACKGROUND: Alopecia areata (AA) is an autoimmune disease resulting in non-scarring hair loss. Animal models are useful means to identify candidates for therapeutic agents. The C3H/HeJ mouse AA model induced via transferring cultured lymphoid cells isolated from AA-affected mice is widely used for AA research. However, this conventional method requires the continuous breeding of AA mice. OBJECTIVE: We aimed to establish a new method to generate AA model using the transfer of cryopreserved cells, which allows the rapid induction of a large number of AA mice when needed. METHODS: We cryopreserved lymph node cells soon after isolation from AA-affected mice and injected thawed-cultured cells into recipient mice. H&E staining, immunohistochemical staining, quantitative real-time PCR and ELISA were conducted to identify pathological characteristics. Flow cytometry was performed to reveal the profile of transferred cells. RESULTS: More than 90 % of recipient mice developed AA-like hair loss and showed inflammatory cell infiltration around anagen hair follicles, markedly increased mRNA expressions of interferon-γ, CXCL11, and granzyme B, and elevated interferon-α protein levels in the skin compared with naïve mice. Higher percentages of effector memory T cells and dendritic cells in transferred cells resulted in a higher incidence of AA. CONCLUSION: This is the first report to establish a method for generating AA mice using cryopreserved lymphocytes. These AA mice have similar pathological characteristics to AA mice generated with the conventional method and AA patients. This convenient and reproducible method is expected to be valuable for AA study.

Material balance in the O2 electrode of Li-O2 cells with a porous carbon electrode and TEGDME-based electrolytes.

This work figures out the material balance of the reactions occurring in the O2 electrode of a Li-O2 cell, where a Ketjenblack-based porous carbon electrode comes into contact with a tetraethylene glycol dimethyl ether (TEGDME)-based electrolyte under more practical conditions of less electrolyte amount and high areal capacity. The ratio of electrolyte weight to cell capacity (E/C, g A h-1) is a good parameter to correlate with cycle life. Only 5 cycles were obtained at an areal capacity of 4 mA h cm-2 (E/C = 10) and a discharge/charge current density of 0.4 mA cm-2, which corresponds to the energy density of 170 W h kg-1 at a complete cell level. When the areal capacity was decreased to half (E/C = 20) by setting a current density at 0.2 mA cm-2, the cycle life was extended to 18 cycles. However, the total electric charge consumed for parasitic reactions was 35 and 59% at the first and the third cycle, respectively. This surprisingly large amount of parasitic reactions was suppressed by half using redox mediators at 0.4 mA cm-2 while keeping a similar cycle life. Based on by-product distribution, we will propose possible mechanisms of TEGDME decomposition and report a water breathing behavior, where H2O is produced during charge and consumed during discharge.

High-throughput combinatorial screening of multi-component electrolyte additives to improve the performance of Li metal secondary batteries.

Data-driven material discovery has recently become popular in the field of next-generation secondary batteries. However, it is important to obtain large, high quality data sets to apply data-driven methods such as evolutionary algorithms or Bayesian optimization. Combinatorial high-throughput techniques are an effective approach to obtaining large data sets together with reliable quality. In the present study, we developed a combinatorial high-throughput system (HTS) with a throughput of 400 samples/day. The aim was to identify suitable combinations of additives to improve the performance of lithium metal electrodes for use in lithium batteries. Based on the high-throughput screening of 2002 samples, a specific combination of five additives was selected that drastically improved the coulombic efficiency (CE) of a lithium metal electrode. Importantly, the CE was remarkably decreased merely by removing one of these components, highlighting the synergistic basis of this mixture. The results of this study show that the HTS presented herein is a viable means of accelerating the discovery of ideal yet complex electrolytes with multiple components that are very difficult to identify via conventional bottom-up approach.

Potassium Ions Promote Solution-Route Li2O2 Formation in the Positive Electrode Reaction of Li-O2 Batteries.

Lithium-oxygen system has attracted much attention as a battery with high energy density that could satisfy the demands for electric vehicles. However, because lithium peroxide (Li2O2) is formed as an insoluble and insulative discharge product at the positive electrode, Li-O2 batteries have poor energy capacities. Although Li2O2 deposition on the positive electrode can be avoided by inducing solution-route pathway using electrolytes composed of high donor number (DN) solvents, such systems generally have poor stability. Herein we report that potassium ions promote the solution-route formation of Li2O2. The present findings suggest that potassium or other monovalent ions have the potential to increase the volumetric energy density and life cycles of Li-O2 batteries.

Phagocytosis Assay of Necroptotic Cells by Cardiac Myofibroblasts.

In myocardial infarction (MI), a plenty of cardiomyocytes undergo necrosis and necroptosis due to the lack of oxygen and nutrients. The dead cardiomyocytes are promptly engulfed by phagocytes. When the dead cells are not engulfed, the noxious contents of the cells are released outside, and thus, induce inflammation, and obstruct the function of organs. Therefore, phagocytosis is crucial for maintaining homeostasis of organs. Herein, we describe a protocol of an in vitro phagocytosis assay of necroptotic cells.

An Assay to Determine Phagocytosis of Apoptotic Cells by Cardiac Macrophages and Cardiac Myofibroblasts.

In myocardial infarction (MI), a number of cardiomyocytes undergo apoptosis. These apoptotic cardiomyocytes are promptly engulfed by phagocytes. If the dead cells are not engulfed, their noxious contents are released outside, resulting in induction of inflammation. Therefore, the removal of these dead cells is necessary. However, the contribution of each phagocyte type to the removal of apoptotic cells in infarcted hearts remains unresolved. Here, we describe an in vitro protocol for a phagocytosis assay to compare the engulfment ability of cardiac macrophages and cardiac myofibroblasts.

Cardiac myofibroblast engulfment of dead cells facilitates recovery after myocardial infarction.

Myocardial infarction (MI) results in the generation of dead cells in the infarcted area. These cells are swiftly removed by phagocytes to minimize inflammation and limit expansion of the damaged area. However, the types of cells and molecules responsible for the engulfment of dead cells in the infarcted area remain largely unknown. In this study, we demonstrated that cardiac myofibroblasts, which execute tissue fibrosis by producing extracellular matrix proteins, efficiently engulf dead cells. Furthermore, we identified a population of cardiac myofibroblasts that appears in the heart after MI in humans and mice. We found that these cardiac myofibroblasts secrete milk fat globule-epidermal growth factor 8 (MFG-E8), which promotes apoptotic engulfment, and determined that serum response factor is important for MFG-E8 production in myofibroblasts. Following MFG-E8-mediated engulfment of apoptotic cells, myofibroblasts acquired antiinflammatory properties. MFG-E8 deficiency in mice led to the accumulation of unengulfed dead cells after MI, resulting in exacerbated inflammatory responses and a substantial decrease in survival. Moreover, MFG-E8 administration into infarcted hearts restored cardiac function and morphology. MFG-E8-producing myofibroblasts mainly originated from resident cardiac fibroblasts and cells that underwent endothelial-mesenchymal transition in the heart. Together, our results reveal previously unrecognized roles of myofibroblasts in regulating apoptotic engulfment and a fundamental importance of these cells in recovery from MI.