Stable and High-Power Calcium-Ion Batteries Enabled by Calcium Intercalation into Graphite

Calcium-ion batteries (CIBs) are considered to be promising next-generation energy storage systems because of the natural abundance of calcium and the multivalent calcium ions with low redox potential close to that of lithium. However, the practical realization of high-energy and high-power CIBs is elusive owing to the lack of suitable electrodes and the sluggish diffusion of calcium ions in most intercalation hosts. Herein, it is demonstrated that calcium-ion intercalation can be remarkably fast and reversible in natural graphite, constituting the first step toward the realization of high-power calcium electrodes. It is shown that a graphite electrode exhibits an exceptionally high rate capability up to 2 A g(-1), delivering approximate to 75% of the specific capacity at 50 mA g(-1) with full calcium intercalation in graphite corresponding to approximate to 97 mAh g(-1). Moreover, the capacity stably maintains over 200 cycles without notable cycle degradation. It is found that the calcium ions are intercalated into graphite galleries with a staging process. The intercalation mechanisms of the "calciated" graphite are elucidated using a suite of techniques including synchrotron in situ X-ray diffraction, nuclear magnetic resonance, and first-principles calculations. The versatile intercalation chemistry of graphite observed here is expected to spur the development of high-power CIBs.

Distorted policy transfer? South Korea’s adaptation of UK social enterprise policy

This study draws upon communicative processes in policy transfer to consider the ways in which policy may be adapted to context or distorted. The theoretical framework is used to investigate exactly what the South Korean government borrowed from UK social enterprise policy. Despite claims that the UK was the source of both the general policy direction and the particular regulatory device, the Korean government did not learn about the specific contexts of the British policy, nor attempt two-way communication with domestic stakeholders. Rather, the UK policy was interpreted in accordance with the Korean government’s own ideas about how to utilize social enterprise. Historical legacies of top-down decision-making played an important role in this process, as did the state’s role as a regulator which mobilizes the private sector to achieve policy goals. The consequences have been negative for those organizations refused social enterprise status under the Ministry of Labor’s strict approval system, as well as for the original target population: the socially disadvantaged and vulnerable. It is suggested that the model advanced may help to illuminate the reasons why some borrowed policies differ considerably from the originals, and the use of policy transfer as a means of legitimizatio

Identification of gut dysbiosis in axial spondyloarthritis patients and improvement of experimental ankylosing spondyloarthritis by microbiome-derived butyrate with immune-modulating function

IntroductionDysbiosis is an environmental factor that affects the induction of axial spondyloarthritis (axSpA) pathogenesis. In the present study, we investigated differences in the gut microbiota of patients with axSpA and revealed an association between specific gut microbiota and their metabolites, and SpA pathogenesis.MethodUsing 16S rRNA sequencing data derived from feces samples of 33 axSpA patients and 20 healthy controls (HCs), we examined the compositions of their gut microbiomes.ResultsAs a result, axSpA patients were found to have decreased α-diversity compared to HCs, indicating that axSpA patients have less diverse microbiomes. In particular, at the species level, Bacteroides and Streptococcus were more abundant in axSpA patients than in HCs, whereas Faecalibacterium (F). prausnitzii, a butyrate-producing bacteria, was more abundant in HCs. Thus, we decided to investigate whether F. prausnitzii was associated with health conditions by inoculating F. prausnitzii (0.1, 1, and 10 μg/mL) or by administrating butyrate (0.5 mM) into CD4+ T cells derived from axSpA patients. The levels of IL-17A and IL-10 in the CD4+ T cell culture media were then measured. We also assessed osteoclast formation by administrating butyrate to the axSpA-derived peripheral blood mononuclear cells. The CD4+ IL-17A+ T cell differentiation, IL-17A levels were decreased, whereas IL-10 was increased by F. prausnitzii inoculation. Butyrate reduced CD4+ IL-17A+ T cell differentiation and osteoclastogenesis.DiscussionWe found that CD4+ IL-17A+ T cell polarization was reduced, when F. prausnitzii or butyrate were introduced into curdlan-induced SpA mice or CD4+ T cells of axSpA patient. Consistently, butyrate treatment was associated with the reduction of arthritis scores and inflammation levels in SpA mice. Taken together, we concluded that the reduced abundance of butyrate-producing microbes, particularly F. prausnitzii, may be associated with axSpA pathogenesis

Solvated Ion Intercalation in Graphite: Sodium and Beyond

Reversible intercalation of guest ions in graphite is the key feature utilized in modern battery technology. In particular, the capability of Li-ion insertion into graphite enabled the successful launch of commercial Li-ion batteries 30 years ago. On the road to explore graphite as a universal anode for post Li-ion batteries, the conventional intercalation chemistry is being revisited, and recent findings indicate that an alternative intercalation chemistry involving the insertion of solvated ions, designated as co-intercalation, could overcome some of the obstacles presented by the conventional intercalation of graphite. As an example, the intercalation of Na ions into graphite for Na-ion batteries has been perceived as being thermodynamically impossible; however, recent work has revealed that a large amount of Na ions can be reversibly inserted in graphite through solvated-Na-ion co-intercalation reactions. More recently, it has been extensively demonstrated that with appropriate electrolyte selection, not only Na ions but also other ions such as Li, K, Mg, and Ca ions can be co-intercalated into a graphite electrode, resulting in high capacities and power capabilities. The co-intercalation reaction shares a lot in common with the conventional intercalation chemistry but also differs in many respects, which has attracted tremendous research efforts in terms of both fundamentals and practical applications. Herein, we aim to review the progress made in understanding the solvated-ion intercalation mechanisms in graphite and to comprehensively summarize the state-of-the-art achievements by surveying the correlations among the guest ions, co-intercalation conditions, and electrochemical performance of batteries. In addition, the advantages and challenges related to the practical application of graphite undergoing co-intercalation reactions are presented11Nsciescopu

Reconfiguring Sodium Intercalation Process of TiS2 Electrode for Sodium-Ion Batteries by a Partial Solvent Cointercalation

Titanium disulfide (TiS2), a first-generation cathode in lithium batteries, has also attracted a broad interest as a sodium-ion battery electrode due to fast sodium intercalation kinetics and large theoretical capacity. However, the reversibility of sodium de/ intercalation is far inferior to that of lithium because of the unfavorable intermediate phase formation. Herein, we demonstrate that reconfiguring sodium intercalation via partial solvent cointercalation alters the phasetransition paths for the entire reactions of NaxTiS2 (0 < x < 1), detouring the formation of the unfavorable intermediates. Additionally, it unexpectedly results in a remarkable enhancement of sodium intercalation reversibility, boosting the cycle stability (1000 cycles) accompanying high power capability (10C rate). Comparative investigations reveal that the sodium intercalation in ether-based electrolyte involves a preintercalation of solvent molecules, which is subsequently dissimilar to the bare sodium intercalation in conventional electrolytes. Rediscovery of the intercalation behavior of TiS2 offers a new insight in revisiting the reversibility and kinetics of the commonly known electrodes for batteries.11Nsciescopu

Inverse Magnus effect on a rotating sphere: when and why

In some specific conditions, a flying spinning ball deflects in a direction opposite to that predicted by the Magnus effect, which is known as the inverse Magnus effect. To elucidate when and why this effect occurs, we measure the variations of the drag and lift forces on a rotating sphere and the corresponding flow field with the spin ratio (the ratio of the rotational velocity to the translational one). This counterintuitive phenomenon occurs because the boundary layer flow moving against the surface of a rotating sphere undergoes a transition to turbulence, whereas that moving with the rotating surface remains laminar. The turbulence energizes the flow and thus the main separation occurs farther downstream, inducing faster flow velocity there and generating negative lift force. Empirical formulae are derived to predict the location where the flow separates as a function of the Reynolds number and the spin ratio. Using the formulae derived, the condition for the onset of the inverse Magnus effect is suggested based on the negative lift generation mechanism.close0

Graphitic Carbon Materials for Advanced Sodium-Ion Batteries

Lithium-ion batteries (LIBs) have dominated the energy storage market for more than two decades; however, the quest for lower-cost battery alternatives is rapidly expanding, especially for large-scale applications. Sodium-ion batteries (SIBs) have recently experienced an impressive resurgence owing to the earth's abundance of sodium resources and the similar electrochemistry of SIBs and the well-established LIBs. Nonetheless, whereas cost-effective and reliable graphite anodes have served as a cornerstone in current LIB technology, one of the major limitations of SIBs has been the inability to exploit graphite as an electrode because of its negligible sodium storage capability. Recently, however, dear progress has been made in preparing high-performance graphitic carbon anodes for SIBs with new findings on the mechanisms of sodium storage. Herein, this paper aims to review the progress made in understanding the sodium storage mechanisms in graphitic carbon materials and comprehensively summarize the start-of-the-art achievements by surveying the correlations among the type of graphitic material, microstructure, sodium storage mechanisms, and electrochemical performance in SIBs. In addition, perspectives related to practical applications, including the electrolyte, coulombic efficiency, and applicability in sodium-ion full cells, are also presented.

Tailoring ion-conducting interphases on magnesium metals for high-efficiency rechargeable magnesium metal batteries

Magnesium (Mg) rechargeable batteries are one of the promising highenergy post-lithium battery chemistries exploiting the multivalent charge carrier. However, the use of magnesium metal has been challenging due to the formation of the ion-blocking passivation layer on magnesium metal in most organic electrolytes. Herein, we propose a new strategy to transform the passivating film into a Mg2+- conductive interphase via simple chemisorption of sulfur dioxide molecules on magnesium metal. The facile chemical tuning converts the magnesium oxide-based passivation layer into a magnesium sulfate-like phase, which greatly enhances the chargetransfer capability of multivalent Mg2+ ions. The reduced surface resistance of the magnesium metal results in efficient magnesium stripping/deposition reactions even under conventional ether-based electrolytes. Theoretical calculations support that the facile ionic conduction is attributed to the relatively low Mg2+ dissociation and migration energies in the tailored interphases. Furthermore, we elucidate the degradation mechanism of magnesium electrodes by combining various experimental analyses with computational calculations.11Nsciescopu