MgH2@Mg(BH4)2 Core-Shell-like Nanostructures: Synthesis, Hydrolysis Performance, and Promotion Mechanism.

The hydrolysis of hydrides, represented by MgH2, delivers substantial capacity and presents an appealing prospect for an on-site hydrogen supply. However, the sluggish hydrolysis kinetics and low hydrogen yield of MgH2 caused by the formation of a passivation Mg(OH)2 layer hinder its practical application. Herein, we present a dual strategy encompassing microstructural design and compounding, leading to the successful synthesis of a core-shell-like nanostructured MgH2@Mg(BH4)2 composite, which demonstrates excellent hydrolysis performance. Specifically, the optimal composite with a low Ea of 9.05 kJ mol-1 releases 2027.7 mL g-1 H2 in 60 min, and its hydrolysis rate escalates to 1356.7 mL g-1 min-1 H2 during the first minute at room temperature. The nanocoating Mg(BH4)2 plays a key role in enhancing the hydrolysis kinetics through the release of heat and the formation of local concentration of Mg2+ field after its hydrolysis. This work offers an innovative concept for the design of hydrolysis materials.

Recent advances in proton exchange membrane water electrolysis.

Proton exchange membrane water electrolyzers (PEMWEs) are an attractive technology for renewable energy conversion and storage. By using green electricity generated from renewable sources like wind or solar, high-purity hydrogen gas can be produced in PEMWE systems, which can be used in fuel cells and other industrial sectors. To date, significant advances have been achieved in improving the efficiency of PEMWEs through the design of stack components; however, challenges remain for their large-scale and long-term application due to high cost and durability issues in acidic conditions. In this review, we examine the latest developments in engineering PEMWE systems and assess the gap that still needs to be filled for their practical applications. We provide a comprehensive summary of the reaction mechanisms, the correlation among structure-composition-performance, manufacturing methods, system design strategies, and operation protocols of advanced PEMWEs. We also highlight the discrepancies between the critical parameters required for practical PEMWEs and those reported in the literature. Finally, we propose the potential solution to bridge the gap and enable the appreciable applications of PEMWEs. This review may provide valuable insights for research communities and industry practitioners working in these fields and facilitate the development of more cost-effective and durable PEMWE systems for a sustainable energy future.

Unlocking Liquid Sulfur Chemistry for Fast-Charging Lithium-Sulfur Batteries.

A recent study of liquid sulfur produced in an electrochemical cell has prompted further investigation into regulating Li-S oxidation chemistry. In this research, we examined the liquid-to-solid sulfur transition dynamics by visually observing the electrochemical generation of sulfur on a graphene-based substrate. We investigated the charging of polysulfides at various current densities and discovered a quantitative correlation between the size and number density of liquid sulfur droplets and the applied current. However, the areal capacities exhibited less sensitivity. This observation offers valuable insights for designing fast-charging sulfur cathodes. By incorporating liquid sulfur into Li-S batteries with a high sulfur loading of 4.2 mg cm-2, the capacity retention can reach ∼100%, even when increasing the rate from 0.1 to 3 C. This study contributes to a better understanding of the kinetics involved in the liquid-solid sulfur growth in Li-S chemistry and presents viable strategies for optimizing fast-charging operations.

Deciphering Anion-Modulated Solvation Structure for Calcium Intercalation into Graphite for Ca-Ion Batteries.

Co-intercalation reactions make graphite a feasible anode in Ca ion batteries, yet the correlation between Ca ion intercalation behaviors and electrolyte structure remains unclear. This study, for the first time, elucidates the pivotal role of anions in modulating the Ca ion solvation structures and their subsequent intercalation into graphite. Specifically, the electrostatic interactions between Ca ion and anions govern the configurations of solvated-Ca-ion in dimethylacetamide-based electrolytes and graphite intercalation compounds. Among the anions considered (BH4 -, ClO4 -, TFSI- and [B(hfip)4]-), the coordination of four solvent molecules per Ca ion (CN=4) leads to the highest reversible capacities and the fastest reaction kinetics in graphite. Our study illuminates the origins of the distinct Ca ion intercalation behaviors across various anion-modulated electrolytes, employing a blend of experimental and theoretical approaches. Importantly, the practical viability of graphite anodes in Ca-ion full cells is confirmed, showing significant promise for advanced energy storage systems.

Ultrastable and High Energy Calcium Rechargeable Batteries Enabled by Calcium Intercalation in a NASICON Cathode.

Ca-ion batteries (CIBs) have been considered a promising candidate for the next-generation energy storage technology owing to the abundant calcium element and the low reduction potential of Ca2+ /Ca. However, the large size and divalent nature of Ca2+ induce significant volume change and sluggish ion mobility in intercalation cathodes, leading to poor reversibly and low energy/power densities for CIBs. Herein, a polyanionic Na superionic conduction (NASICON)-typed Na-vacant Na1 V2 (PO4 )2 F3 (N1 PVF3 ) with sufficient interstitial spaces is reported as ultra-stable and high-energy Ca ion cathodes. The N1 PVF3 delivers exceptionally high Ca storage capacities of 110 and 65 mAh g-1 at 10 and 500 mA g-1 , respectively, and a record-long cyclability of 2000 cycles. More interestingly, by tailoring the fluorine content in N1 PVFx (1 ≤ x ≤ 3), the high working potential of 3.5 V versus Ca2+ /Ca is achievable. In conjunction with Ca metal anode and a compatible electrolyte, Ca metal batteries with N1 VPF3 cathodes are constructed, which deliver an initial energy density of 342 W h kg-1 , representing one of the highest values thus far reported for CIBs. Origins of the uncommonly stable and high-power capabilities for N1 PVF3 are elucidated as the small volume changes and low cation diffusion barriers among the cathodes.

In Situ Electrochemical Transformation toward Structure Optimized VEG@MXene Cathode for Enhanced Zinc-Ion Storage.

Vanadium-based derivatives, featuring affordable cost and high theoretical capacity, have gathered widespread interest in the context of aqueous zinc-ion batteries (ZIBs). However, the further application of vanadium-based materials is hindered by the limited electrical conductivity and cycling lifespan. Herein, 1D chain-like structure vanadyl ethylene glycolate (VEG, (VO(CH2 O)2 )), growing on the Ti3 C2 Tx MXene nanosheets, is synthesized via a one-step oil-bath heating process as cathode materials for ZIBs. Benefiting from the hybrid structure with high conductivity and abundant reactive sites, the VEG@MXene cathode exhibits a remarkable specific capacity (360.3 mAh g-1 at 0.5 A g-1 ), and impressive capacity retention (up to 85.2% after 3000 cycles at 10 A g-1 ). Mechanism analysis reveals a gradual phase transition from the original VEG on MXene to the stable Zn3 V2 O7 (OH)2 ·2H2 O nanoflakes accompanied by continuous zinc ion intercalation/deintercalation, offering more pathways for zinc ion transport. This work suggests that engineering conductivity-enhanced vanadium-based materials is a rational approach for developing promising cathode materials of ZIBs.

ß-ecdysone promotes osteogenic differentiation of bone marrow mesenchymal stem cells.

BACKGROUND: ß-ecdysone (ßEcd) has numerous pharmacological effects, although its role in the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) has not yet been explored. METHODS: In cell experiments, BMSCs were induced to differentiate by osteogenic induction medium (OIM) or ßEcd. In animal experiments, an osteonecrosis of the femoral head (ONFH) rat model was established using lipopolysaccharide plus methylprednisolone and treating the rats with ßEcd. The osteogenic differentiation capacity of human BMSCs (hBMSCs) was analyzed by alkaline phosphatase and alizarin red S staining. Histopathological changes in rat femoral head tissues were observed by hematoxylin and eosin staining. The expression levels of RUNX2, COL1A1, OCN and phosphorylated Akt in BMSCs from rat femoral head tissues were measured by a quantitative real-time polymerase chain reaction or western blot analysis. RESULTS: Alkaline phosphatase activity and calcium nodules in the ßEcd-treated BMSC group dose-dependently increased compared to those in the control and OIM groups. The hematoxylin and eosin staining results indicated that femoral head tissues of ONFH rats showed typical osteonecrosis, which could be ameliorated by ßEcd. Western blot, quantitative real-time polymerase chain reaction and immunohistochemistry assays demonstrated that the expression levels of RUNX2, COL1A1 and OCN in hBMSCs and femoral head tissue models were obviously increased after ßEcd treatment, and phosphoinositide 3-kinase and Akt phosphorylation were also increased. CONCLUSIONS: ßEcd may be beneficial for the recovery of ONFH patients by accelerating osteogenic differentiation of BMSCs, which may be a novel therapy for related diseases.

Characterization of Fractional Polysaccharides from Gleditsia sinensis and Gleditsia microphylla Gums.

The seeds of Gleditsia sinensis and Gleditsia microphylla, widespread in China, are an important source of galactomannans. G. sinensis gum (GSG) and G. microphylla gum (GMG) were purified and precipitated using different concentrations of ethanol and isopropanol. The GSG and GMG, precipitated in different stages, presented different characteristics, including polymer recovery, mannose/galactose ratio, chemical composition, molecular weight, and morphological appearance. The galactomannan recovery of GSG and GMG in 33.3% ethanol was 81.7% and 82.5%, respectively, while that in 28.8% isopropanol was 81.3% and 82.9%, respectively. To achieve similar precipitation efficiency, the amount of isopropanol should be lower than that of ethanol because of the lower dielectric constant of isopropanol (20 vs. 25 for ethanol). The precipitation behavior of galactomannans in polar organic solvents was dependent on the molecular structures and properties of the solvent. A higher mannose/galactose ratio and a higher molecular weight was obtained in a lower concentration of alcohols.

Visualizing the Interfacial Chemistry in Multivalent Metal Anodes by Transmission Electron Microscopy.

Multivalent metal batteries (MMBs) have been considered potentially high-energy and low-cost alternatives to commercial Li-ion batteries, thus attracting tremendous research interest for energy-storage applications. However, the plating and stripping of multivalent metals (i.e., Zn, Ca, Mg) suffer from low Coulombic efficiencies and short cycle life, which are largely rooted in the unstable solid electrolyte interphase. Apart from exploring new electrolytes or artificial layers for robust interphases, fundamental works on deciphering interfacial chemistry have also been conducted. This work is dedicated to summarizing the state-of-the-art advances in understanding the interphases for multivalent metal anodes revealed by transmission electron microscopy (TEM) methods. Operando and cryogenic TEM with high spatial and temporal resolutions realize the dynamic visualization of the vulnerable chemical structures in interphase layers. Following a scrutinization of the interphases on different metal anodes, we elucidate their features for appealing multivalent metal anodes. Finally, perspectives are proposed for the remaining issues on analyzing and regulating interphases for practical MMBs.

Plant Transpiration-Inspired Biomass-Based Device with Underwater Oleophobicity for Efficient General-Purpose Solar-Driven Oily Wastewater Purification.

The remediation of wastewater containing oily pollutants is imperative to mitigate the serious threats posed to the safety of fresh water, human well-being, and the environment. Current membrane separation technologies are severely restricted by their limitations for separating various types of oily pollutants with low sustainability. Herein, by imitating the plant transpiration in nature, we designed a solar-driven device composed of natural biomass sugar cane stem, chitosan/carboxymethyl cellulose, and graphite powders to separate versatile oily pollutants from the wastewater. Owing to its superior solar absorption capacity, microchannels for water transportation, and underwater oleophobicity, the resultant evaporator not only exhibited an excellent evaporation rate of 1.41 kg m-2 h-1 but also demonstrated an admirable purification efficiency of 99.9% for oily wastewater. Moreover, the device can maintain a stable evaporation rate and the original structure even in oily wastewater containing strong acid, alkali, or hypersaline components. Therefore, this work provides an effective approach to producing clean water from versatile wastewater.

Cytomegalovirus-vectored COVID-19 vaccines elicit neutralizing antibodies against the SARS-CoV-2 Omicron variant (BA.2) in mice.

IMPORTANCE: Cytomegalovirus (CMV) has been used as a novel viral vector for vaccine development and gene therapy. Coronavirus disease 2019 is an infectious disease caused by the SARS-CoV-2 virus, which is highly mutable and is still circulating globally. The study showed that the CMV viral vector caused transient systemic infection and induced robust transgene expression in vivo. CMV vectors expressing different SARS-CoV-2 proteins were immunogenic and could elicit neutralizing antibodies against a highly mutated Omicron variant (BA.2). The expression level of receptor-binding domain (RBD) protein was higher than that of full-length S protein using CMV as a vaccine vector, and CMV vector expression RBD protein elicited higher RBD-binding and neutralizing antibodies. Moreover, the study showed that CMV-vectored vaccines would not cause unexpected viral transmission, and pre-existing immunity might impair the immunogenicity of subsequent CMV-vectored vaccines. These works provide meaningful insights for the development of a CMV-based vector vaccine platform and the prevention and control strategies for SARS-CoV-2 infection.

Ti2C3Tx/Polyurethane Constructed by Gas-Liquid Interface Self-Assembly for Underwater Sensing.

Nowadays, multifunctional, easily prepared, and highly sensitive flexible sensors have attracted extensive attention and are gradually used in various scenarios. Here, we report the design of the Ti2C3Tx/polyurethane composites prepared by a facile gas-liquid interface self-assembly. The obtained flexible sensor has a wide detection range (∼900%), a low-stress detection limit (<1%), a high sensitivity (GF = 1.3, strain from 0 to 100%), and a fast response time (<140 ms). The multifunctional stress sensor can be applied to not only wearable motion monitoring and detection of various signals but also the detection of underwater human motion, as well as different motion states and swimming frequencies of toy fish in water, demonstrating its great prospects in a variety of applications, such as human movement monitoring and marine biological detection and research.

Lithiophilic Mo3N2/MoN as multifunctional interlayer for dendrite-free and ultra-stable lithium metal batteries.

The formation of lithium dendrite and the unstable electrode/electrolyte interface, especially at high rates, are the dominant obstacles impeding the implementation of lithium metal batteries (LMBs). To tackle these fundamental challenges, here we propose a lithiophilic Mo3N2/MoN heterostructure (designated as MoNx) interlayer for dendrite-free and ultra-stable lithium metal anodes for the first time. The MoNx interlayer presents excellent electrolyte wettability, fast lithium diffusion kinetics and strong mechanical strength, which function synergistically to inhibit lithium dendrite growth. During cycling, an in-situ formation of Li3N-rich solid electrolyte interphase layer and metallic Mo phase can regulate the Li-ion conductivity and Li metal deposition, thus indicating uniform and compact Li plating. Above ameliorating features accompany an ultra-long-life of 2000 h at a high current density of 5 mA cm-2 for the MoNx-Li anode. The feasibility of the MoNx-Li anode in LMB is further confirmed in conjunction with LiFePO4 cathodes. The full cells deliver exceptionally high-capacity retentions of above 82.0% after 500 cycles at 1C and 425 cycles at 3C, which are among the best thus far reported for LMBs. This work provides both new insights towards functional interlayer design and effective transition-metal nitrides for practical LMBs.

Loofah Sponge-Derived Hygroscopic Photothermal Absorber for All-Weather Atmospheric Water Harvesting.

The loofah gourd is like a natural water tank that stores underground water and drains it out after aging, leaving only a three-dimensional network consisting of hollow and interconnected fibers. This phenomenon inspired us to fabricate a solar-energy-powered sorption-based atmospheric water harvesting device using a loofah sponge. Herein, moisture absorption and photothermal conversion strategies are rationally designed to fast release the absorbed water. This is accomplished by filling the hollow and connected loofah fiber with LiCl and replacing the original luffa peel with a bacterial cellulose (BC)/carbon nanotube (CNT) photothermal conversion membrane. As a result, loofah/BC/CNT (LBC)@LiCl presents a high water absorption capacity of 2.65 g g-1 at 90% relative humidity (RH) and fast water release performance of 1.33 kg m-2 h-1 under 1.0 sun. Noticeably, ∼1.92-2.40 kg LBC@LiCl can produce daily drinking water for adults (2000-2500 mL) in one night outdoors at ∼66% RH, proving that it is a feasible method to overcome the drinking water shortage of poor and arid areas using cheap and renewable biomass material.

Stable Liquid-Sulfur Generation on Transition-Metal Dichalcogenides toward Low-Temperature Lithium-Sulfur Batteries.

The electrochemical formation of liquid sulfur at room temperature on the basal plane of MoS2 has attracted much attention due to the high areal capacity and rapid kinetics of lithium-liquid sulfur chemistry. However, the liquid sulfur is converted to the solid phase once it contacts the solid sulfur crystals generated from the edge of MoS2. Thus, stable liquid sulfur cannot be formed on the entire MoS2 surface. Herein, we report entire liquid sulfur generation on hydrogen-annealed MoS2 (H2-MoS2), even under harsh conditions of large overpotentials and low working temperatures. The origins of the solely liquid sulfur formation are revealed to be the weakened interactions between H2-MoS2 and sulfur molecules and the decreased electrical polarization on the edges of the H2-MoS2. Progressive nucleation and droplet-merging growth behaviors are observed during the sulfur formation on H2-MoS2, signifying high areal capacities by releasing active H2-MoS2 surfaces. To demonstrate the universality of this strategy, other transition-metal dichalcogenides (TMDs) annealed in hydrogen also exhibit similar sulfur growth behaviors. Furthermore, the H2 annealing treatment can induce sulfur vacancies on the basal plane and partial oxidation on the edge of TMDs, which facilitates liquid sulfur formation. Finally, liquid sulfur can be generated on H2-MoS2 flakes at an ultralow temperature of -50 °C, which provides a possible development of low-temperature lithium-sulfur batteries. This work demonstrates the potential of a pure liquid sulfur-lithium electrochemical system using functionalized two-dimensional materials.

Curculigoside promotes osteogenic differentiation of ADSCs to prevent ovariectomized-induced osteoporosis.

BACKGROUND: Curculigoside is a natural phenolic glycoside compound produced by Curculigo orchioides Gaertn. This study aimed to explore the effects of curculigoside in promoting the osteogenic differentiation of adipose-derived stem cells (ADSCs) as well as the underlying mechanism. METHODS: ADSCs were treated with curculigoside at different concentrations (0 µmol/L, 1 µmol/L, 2.5 µmol/L, 5 µmol/L, 10 µmol/L, and 20 µmol/L), and cell viability was assessed by CCK-8 assay. Then, the alkaline phosphatase (ALP) activity was determined, and alizarin red S (ARS) staining was performed to measure the extracellular mineralization of curculigoside. Information about protein-chemical interactions is provided by the search tool for interactions of chemicals (STITCH) database. Then, LY294002 was administered to explore the mechanism by which curculigoside promotes the osteogenic differentiation of ADSCs. Western blot assays were performed to assess changes in the expression of osteogenic-related markers and the phosphorylation of PI3K and AKT. Finally, we established an ovariectomized (OVX)-induced osteoporosis mouse model and administered curculigoside to explore the effects of curculigoside in preventing bone loss in vivo. RESULTS: The CCK-8 assay indicated that curculigoside did not induce cytotoxicity at a concentration of 5 µmol/L after 48 h. The ALP and ARS results revealed that the induced group had higher ALP activity and calcium deposition than the control group. Moreover, the curculigoside group exhibited increased biomineralization, ALP activity, and ARS staining compared to the induced and control groups, and these effects were partially inhibited by LY294002. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that the target genes of curculigoside were mainly involved in the PI3K-Akt signaling pathway. PCR and western blot analysis showed that the expression of RUNX2, ALP, and Osterix was upregulated in curculigoside-treated ADSCs, but this effect was partially reversed by the PI3K inhibitor LY294002. Moreover, the curculigoside-treated group exhibited significantly increased phosphorylation of AKT to P-AKT compared with the osteogenic induction group. After treatment with curculigoside, the mice had a higher bone volume than the OVX mice, suggesting partial protection from cancellous bone loss. In addition, when LY294002 was added, the protective effects of curculigoside could be neutralized. CONCLUSIONS: Curculigoside could induce the osteogenic differentiation of ADSCs and prevent bone loss in an OVX model through the PI3K/Akt signaling pathway.

Nanostructure-Mediated Phase Evolution in Lithiation/Delithiation of Co3O4.

Nanostructured transition-metal oxides have been under intensive investigation for their tantalizing potential as anodes of next-generation lithium-ion batteries (LIBs). However, the exact mechanism for nanostructures to influence the LIB performance remains largely elusive. In this work, we discover the nanostructure-mediated lithiation mechanism in Co3O4 anodes using ex situ transmission electron microscopy (TEM) and X-ray diffractometry: while Co3O4 nanosheets exhibit a typical two-step conversion reaction (from Co3O4 to CoO and then to Co0), Co3O4 nanoarrays can go through a direct conversion from Co3O4 to Co0 at a high discharge rate. Such nanostructure-dependent lithiation can be rationalized by the slow lithiation kinetics intrinsic to Co3O4 nanoarrays, which at a high discharge rate may cause local accumulation of lithium to initiate a one-step Co3O4-to-Co0 conversion. Combined with the larger volume change observed in Co3O4 nanoarrays, the slow lithiation kinetics can lead to inhomogeneous expansion with large stress developed at the reaction front, which can eventually cause structure failure and irreversible capacity loss, as explicitly observed by in situ TEM as well as galvanostatic discharge-charge measurement. Our observation resolves the nanostructure-dependent lithiation mechanism of Co3O4 and provides important insights into the interplay among lithiation kinetics, phase evolution, and lithium-storage performance, which can be translated into electrode design strategies for next-generation LIBs.

A new high-voltage calcium intercalation host for ultra-stable and high-power calcium rechargeable batteries.

Rechargeable calcium batteries have attracted increasing attention as promising multivalent ion battery systems due to the high abundance of calcium. However, the development has been hampered by the lack of suitable cathodes to accommodate the large and divalent Ca2+ ions at a high redox potential with sufficiently fast ionic conduction. Herein, we report a new intercalation host which presents 500 cycles with a capacity retention of 90% and a remarkable power capability at ~3.2 V (vs. Ca/Ca2+) in a calcium battery. The cathode material derived from Na0.5VPO4.8F0.7 is demonstrated to reversibly accommodate a large amount of Ca2+ ions, forming a series of CaxNa0.5VPO4.8F0.7 (0 < x < 0.5) phases without any noticeable structural degradation. The robust framework enables one of the smallest volume changes (1.4%) and the lowest diffusion barriers for Ca2+ among the cathodes reported to date, offering the basis for the outstanding cycle life and power capability.

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 presented.

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 ≈75% of the specific capacity at 50 mA g-1 with full calcium intercalation in graphite corresponding 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.