Rechargeable Magnesium Batteries Research Articles

Unlocking the Power of Magnesium Batteries: Synergistic Effect of InSb-C Composites to Achieve Superior Electrochemical Performance.

Pure magnesium anode used in rechargeable magnesium batteries (RMB) exhibits high theoretical capacity but has been challenged by the passivation issue with conventional electrolytes. Alloy-type anodes have the potential to surpass this issue and have attracted increasing attention. However, the kinetic performance and stabilities of conventional alloy anodes are still constrained. In this study, the InSb-10%C anode is synthesized by a two-step high-energy ball milling process. The InSb-10%C anode exhibits a remarkably high capacity of up to 448 mA h g-1, significantly improved cycle performance (234 mA h g-1 at 100 cycles) and rate performance (168 mA h g-1 at 500 mA g-1). The above-mentioned superior performance of the InSb-10%C anode for RMBs is attributed to the cellular graphitized amorphous carbon composite structure (CGA) which effectively refines the particle size and restricts the volume expansion. Additionally, the reduced surface electron density of InSb combined with the high conductivity resulting from graphitization enhances the Mg2+ diffusion performance. Notably, the InSb-10%C anode demonstrates good compatibility with conventional halogen-free salt ether-based electrolytes in the full battery configuration.

From Bulk to Interface: Solvent Exchange Dynamics and Their Role in Ion Transport and the Interfacial Model of Rechargeable Magnesium Batteries.

Multivalent battery chemistries have been explored in response to the increasing demand for high-energy rechargeable batteries utilizing sustainable resources. Solvation structures of working cations have been recognized as a key component in the design of electrolytes; however, most structure-property correlations of metal ions in organic electrolytes usually build upon favorable static solvation structures, often overlooking solvent exchange dynamics. We here report the ion solvation structures and solvent exchange rates of magnesium electrolytes in various solvents by using multimodal nuclear magnetic resonance (NMR) analysis and molecular dynamics/density functional theory (MD/DFT) calculations. These magnesium solvation structures and solvent exchange dynamics are correlated to the combined effects of several physicochemical properties of the solvents. Moreover, Mg2+ transport and interfacial charge transfer efficiency are found to be closely correlated to the solvent exchange rate in the binary electrolytes where the solvent exchange is tunable by the fraction of diluent solvents. Our primary findings are (1) most battery-related solvents undergo ultraslow solvent exchange coordinating to Mg2+ (with time scales ranging from 0.5 μs to 5 ms), (2) the cation transport mechanism is a mixture of vehicular and structural diffusion even at the ultraslow exchange limit (with faster solvent exchange leading to faster cation transport), and (3) an interfacial model wherein organic-rich regions facilitate desolvation and inorganic regions promote Mg2+ transport is consistent with our NMR, electrochemistry, and cryogenic X-ray photoelectron spectroscopy (cryo-XPS) results. This observed ultraslow solvent exchange and its importance for ion transport and interfacial properties necessitate the judicious selection of solvents and informed design of electrolyte blends for multivalent electrolytes.

Outstanding specific capacitance of air plasma exposed MgCoSiO4 cathode in the rechargeable magnesium batteries

Outstanding specific capacitance of air plasma exposed MgCoSiO4 cathode in the rechargeable magnesium batteries

Ternary Mg alloy-based artificial interphase enables high-performance rechargeable magnesium batteries

Rechargeable magnesium batteries (RMBs) provide potential advantages over lithium-ion batteries in terms of high volumetric capacity, natural abundance, and high safety. However, the rational design of high-performance magnesium-based metal anodes compatible with conventional electrolytes is a big challenge for the viability of RMBs. In this work, an in-situ formed ternary alloy-based artificial interphase layer on Mg foil as an anode was successfully prepared through a facile and universal electrodeposition strategy. The Mg-Sn-Bi@Mg anode provides high charge transfer dynamics for Mg deposition and constructs a reduced energy barrier for Mg2+ ions desolvation. Thanks to the unique Mg deposition behaviors, the Mg-Sn-Bi@Mg alloy anode demonstrates a low overpotential of 39.4 mV and a long cycle life of >2000 h. The transfer kinetics for RMBs can be largely improved due to the unique alloying reactions. Density functional theory (DFT) calculations demonstrate that the designed ternary alloy-based artificial interphase layer enables faster Mg2+ ion migration than the bare Mg electrode. Full cells with Mo6S8 cathode also show ultra-stable cycling performance over 2400 cycles at 1C in a conventional all-phenyl complex (APC) electrolyte. This facile interface modification strategy sheds light on the development of advanced RMBs and also provides a promising direction for the design of high-performance Mg-based alloy anodes for high-performance RMBs and beyond.

Bimetallic Selenide CuFeSe2 as Mg‐Storage Material for Rechargeable Magnesium Batteries

AbstractRechargeable magnesium batteries (RMBs) are appealing alternatives for energy storage systems based on the high theoretical capacity, low price and high security of the Mg metal anode. Nevertheless, the shortage of high‐performance cathode materials severely obstructs its development. As an important conversion material, transition metal selenides, with desirable theoretical capacity and weak bond energy (Mg−Se), have attracted more attention in recent years. In this study, CuFeSe2 (CFS) nanoparticles were produced by a hydrothermal approach and its feasibility as a cathode material for RMBs was further investigated. Given the synergistic effect between Cu and Fe, the optimized CFS shows a reversible capacity of 120 mAh g−1 at 100 mA g−1, outstanding long‐term cyclability (86 mAh g−1 at 1 A g−1 after 600 cycles), and prominent rate capability (85 mAh g−1 at 1 A g−1). Density functional theory (DFT) computations conclude CFS exhibits a suitable migration barrier for Mg2+ along the tunnel of 0.92 eV. An in‐depth investigation of the mechanism demonstrates that the Mg storage process can be divided into solid solution reaction and the conversion processes by ex‐situ techniques. This work contributes to further investigate the Mg2+ storage mechanism of cathode materials for RMBs.

Machine learning molecular dynamics insight into high interface stability and fast kinetics of low-cost magnesium chloride amine electrolyte for rechargeable magnesium batteries

The development of rechargeable magnesium batteries (RMBs) is hindered by the lack of long-lifespan and low-cost electrolytes. Moreover, due to lacking of an in-depth understanding of accurate dynamic solvation structures, the relationship between the interface kinetics behavior and a stable anode interface is still unclear. Herein, we develop a novel low-cost electrolyte containing the MgCl2 salt and the 3-methoxypropylamine solvent (denoted as the MgCl2-S2 electrolyte), which exhibits higher interface stability and faster kinetics compared to the reference Mg(TFSI)2-S2 electrolyte. The powerful machine learning molecular dynamics (MLMD) is employed to systematically investigate the differences of the fine solvation structures and explore the fundamental reason for better interfacial dynamics processes. The results show that the degree of dissociation in MgCl2-S2 electrolyte is less than 1 %, much lower than 95.1 % in Mg(TFSI)2-S2 electrolyte. The solvation structures dominated by Cl− ions can induce Mg2+ ions to preferentially acquire electrons in both kinetics and thermodynamics, which thus improving the deposition kinetics and enhancing the stability of the anode interface. This work inspires a new paradigm from MLMD to investigate the relationship between interface stability and accurate solvation structures for RMBs.

A New Cathode for Rechargeable Magnesium Batteries

A New Cathode for Rechargeable Magnesium Batteries

Utilization of Delithiation-Induced Amorphous Oxide as a Cathode for Rechargeable Magnesium Batteries

Utilization of Delithiation-Induced Amorphous Oxide as a Cathode for Rechargeable Magnesium Batteries

A Microporous Gel Polymer Electrolyte with High Mg2+ Ionic Conductivity at Room Temperature

Rechargeable magnesium batteries have attracted much attention due to the high theoretical volumetric capacity, abundance, and safety. However, solid‐state Mg batteries have been rarely studied because of limited choices of solid‐state electrolyte materials. In this research, poly(vinylidene fluoride)/poly(propylene carbonate) (PVDF/PPC) as matrix were prepared using a simple solution casting method. Ethylene carbonate (EC), diethyl carbonate (DEC), and magnesium(II) bis(trifluoromethanesulfonyl) imide [Mg(TFSI)2] were selected to prepare liquid electrolyte. A classification of novel gel polymer electrolytes (GPEs), PVDF/PPC/Mg(TFSI)2, was synthesized and investigated. The electrochemical measurements show that PVDF/PPC/Mg(TFSI)2 polymer electrolytes exhibit a high ionic conductivity, close to 10‐2 S cm‐1, at room temperature. The electrochemical stability window of PVDF/PPC‐based GPE was up to 3 V (versus Mg2+/Mg). Materials characterization shows that these GPEs have a porous structure, providing a pathway for magnesium ion transport. Thermal analysis and crystal structure results indicate that PVDF crystallinity was affected by the addition of PPC. Additionally, the ion transport mechanism in the gel polymer electrolyte has been discussed.

Large-Scale Integration of the Ion-Reinforced Phytic Acid Layer Stabilizing Magnesium Metal Anode.

Rechargeable magnesium batteries (RMBs) have garnered significant attention for their potential in large-scale energy storage applications. However, the commercial development of RMBs has been severely hampered by the rapid failure of large-sized Mg metal anodes, especially under fast and deep cycling conditions. Herein, a concept proof involving a large-scale ion-reinforced phytic acid (PA) layer (100 cm × 7.5 cm) with an excellent water-oxygen tolerance, high Mg2+ conductivity, and favorable electrochemical stability is proposed to enable rapid and uniform plating/stripping of Mg metal anode. Guided by even distributions of Mg2+ flux and electric field, the as-prepared large-sized PA-Al@Mg electrode (5.8 cm × 4.5 cm) exhibits no perforation and uniform Mg plating/stripping after cycling. Consequently, an ultralong lifespan (2400 h at 3 mA cm-2 with 1 mAh cm-2) and high current tolerance (300 h at 9 mA cm-2 with 1 mAh cm-2) of the symmetric cell using the PA-Al@Mg anode could be achieved. Notably, the PA-Al@Mg//Mo6S8 full cell demonstrates exceptional stability, operating for 8000 cycles at 5 C with a capacity retention of 99.8%, surpassing that of bare Mg (3000 cycles, 74.7%). Moreover, a large-sized PA-Al@Mg anode successfully contributes to the stable pouch cell (200 and 750 cycles at 0.1 and 1 C), further confirming its significant potential for practical utilization. This work provides valuable theoretical insights and technological support for the practical implementation of RMBs.

Deep cycling magnesium metal anode enabled by a robust Mg2+-Conducting and electron-insulating interphase

Rechargeable magnesium batteries (RMBs) have garnered significant attention due to the abundant natural availability, safety and high volumetric capacity of magnesium (Mg) anode. However, the practical application has been hindered by the pronounced passivation layer and sluggish charge transfer kinetics of Mg anode in commercial conventional electrolytes. Herein, a superb Mg2+-conducting and electron-blocking interphase is in-situ constructed on Mg anode facilely through the spontaneous magnetization reaction with SbBr3 added in cost-effective Mg(TFSI)2 electrolyte. The interphase with high ionic conductivity and electronic resistivity endows Mg anode a stable long-cycling lifespan of 1600 h with a low overpotential (<0.3 V) at 0.5 mA cm−2 and 0.5 mAh cm−2. Benefitting from the deep cycling Mg anode, the Mg||CuS cell delivers an impressive specific capacity 85.2 mAh g−1 over 300 cycles at 1000 mA g−1 with a capacity retention of 82.8 %, as well as the Mg||Mo6S8 cell can be cycled over 500 cycles at 2C. This research provides valuable insight into the interphase construction and presents a feasible way to develop reliable Mg metal anode for high-performance RMBs.

Amorphous Cobalt Polyselenides with Hyperbranched Polymer Additive as High-Capacity Magnesium Storage Cathode Materials Through Cationic and Anionic Co-Redox Mechanism.

Rechargeable magnesium batteries (RMBs) are a promising energy-storage technology with low cost and high reliability, while the lack of high-performance cathodes is impeding the development. Herein, a series of amorphous cobalt polyselenides (CoSex, x>2) is synthesized with the assistance of organic amino-terminal hyperbranched polymer (AHP) additive and investigated as cathodes for RMBs. The coordination of cobalt cations with the amino groups of AHP leads to the formation of amorphous CoSex rather than crystalline CoSe2. The amorphous structure is favorable for magnesium-storage reaction kinetics, and the polyselenide anions provide extra capacities besides the redox of cobalt cations. Moreover, the organic AHP molecules retained in CoSex-AHP provide an elastic matrix to accommodate the volume change of conversion reaction. With a moderate x value (2.73) and appropriate AHP content (11.58%), CoSe2.7-AHP achieves a balance between capacity and cycling stability. Amorphous CoSe2.7-AHP provides high capacities of 246.6 and 94 mAh g‒1, respectively, at 50 and 2000 A g‒1, as well as a capacity retention rate of 68.5% after 300 cycles. The mechanism study demonstrates CoSex-AHP undergoes reversible redox of Co2+/3+↔Co0 and Sen 2‒↔Se2‒. The present study demonstrates amorphous polyselenides with cationic-anionic redox activities is as a feasible strategy to construct high-capacity cathode materials for RMBs.

Large Conjugated Polyimide Cathodes of Rechargeable Magnesium Batteries: Electron Delocalization Induced by Bivalent Magnesium Cations

Large Conjugated Polyimide Cathodes of Rechargeable Magnesium Batteries: Electron Delocalization Induced by Bivalent Magnesium Cations

Understanding the Cathode-Electrolyte Interfacial Chemistry in Rechargeable Magnesium Batteries.

Rechargeable magnesium batteries (RMBs) have garnered significant attention due to their potential to provide high energy density, utilize earth-abundant raw materials, and employ metal anode safely. Currently, the lack of applicable cathode materials has become one of the bottleneck issues for fully exploiting the technological advantages of RMBs. Recent studies on Mg cathodes reveal divergent storage performance depending on the electrolyte formulation, posing interfacial issues as a previously overlooked challenge. This minireview begins with an introduction of representative cathode-electrolyte interfacial phenomena in RMBs, elaborating on the unique solvation behavior of Mg2+, which lays the foundation for interfacial chemistries. It is followed by presenting recently developed strategies targeting the promotion of Mg2+ desolvation in the electrolyte and alternative cointercalation approaches to circumvent the desolvation step. In addition, efforts to enhance the cathode-electrolyte compatibility via electrolyte development and interfacial engineering are highlighted. Based on the abovementioned discussions, this minireview finally puts forward perspectives and challenges on the establishment of a stable interface and fast interfacial chemistry for RMBs.

Accessing Mg‐Ion Storage in V2PS10 via Combined Cationic‐Anionic Redox with Selective Bond Cleavage

AbstractMagnesium batteries attract interest as alternative energy‐storage devices because of elemental abundance and potential for high energy density. Development is limited by the absence of suitable cathodes, associated with poor diffusion kinetics resulting from strong interactions between Mg2+ and the host structure. V2PS10 is reported as a positive electrode material for rechargeable magnesium batteries. Cyclable capacity of 100 mAh g−1 is achieved with fast Mg2+ diffusion of 7.2 10−11–4 10−14 cm2 s−1. The fast insertion mechanism results from combined cationic redox on the V site and anionic redox on the (S2)2− site; enabled by reversible cleavage of S−S bonds, identified by X‐ray photoelectron and X‐ray absorption spectroscopy. Detailed structural characterisation with maximum entropy method analysis, supported by density functional theory and projected density of states analysis, reveals that the sulphur species involved in anion redox are not connected to the transition metal centres, spatially separating the two redox processes. This facilitates fast and reversible Mg insertion in which the nature of the redox process depends on the cation insertion site, creating a synergy between the occupancy of specific Mg sites and the location of the electrons transferred.

Accessing Mg-Ion Storage in V2PS10 via Combined Cationic-Anionic Redox with Selective Bond Cleavage.

Magnesium batteries attract interest as alternative energy-storage devices because of elemental abundance and potential for high energy density. Development is limited by the absence of suitable cathodes, associated with poor diffusion kinetics resulting from strong interactions between Mg2+ and the host structure. V2PS10 is reported as a positive electrode material for rechargeable magnesium batteries. Cyclable capacity of 100 mAh g-1 is achieved with fast Mg2+ diffusion of 7.2 10-11-4 10-14 cm2 s-1. The fast insertion mechanism results from combined cationic redox on the V site and anionic redox on the (S2)2- site; enabled by reversible cleavage of S-S bonds, identified by X-ray photoelectron and X-ray absorption spectroscopy. Detailed structural characterisation with maximum entropy method analysis, supported by density functional theory and projected density of states analysis, reveals that the sulphur species involved in anion redox are not connected to the transition metal centres, spatially separating the two redox processes. This facilitates fast and reversible Mg insertion in which the nature of the redox process depends on the cation insertion site, creating a synergy between the occupancy of specific Mg sites and the location of the electrons transferred.

Microwave-induced defect-rich vanadium sulfide cathodes for highly reversible electrochemical magnesium storage

Vanadium sulfide (VS4) demonstrates the most prospect as the cathode materials for rechargeable magnesium battery due to its special one-dimensional linear crystal structure. However, VS4 cathode still suffers from sluggish kinetics, irreversible structural change, short cycle life, and low capacity. Herein, a microwave-induced synthesis method is presented to fabricate VS4 nanosheets with rich sulfur vacancies and high V3+/V4+ ratio. When serviced as the cathode material for rechargeable magnesium battery, the VS4 nanosheets display excellent electrochemical performances with large specific capacity of 701 mAh/g at 200 mA g−1 current density. In addition, the VS4 nanosheets cathodes also show long-term operating stability over 600 cycles at 1.0 A/g current density with only 0.3 % capacity decay per cycle. Our experimental results show that the improved electrochemical reaction kinetics is ascribed to the defect-rich structure and the reversible anionic redox reactions between S2−/S22− of the VS4 nanosheets. This work offers a meaningful way to design high-performance Mg2+ ion storage cathode materials with favorable diffusion kinetics.

Ternary Eutectic Electrolyte-Assisted Formation and Dynamic Breathing Effect of the Solid-Electrolyte Interphase for High-Stability Aqueous Magnesium-Ion Full Batteries.

Aqueous rechargeable magnesium batteries hold immense potential for intrinsically safe, cost-effective, and sustainable energy storage. However, their viability is constrained by a narrow voltage range and suboptimal compatibility between the electrolyte and electrodes. Herein, we introduce an innovative ternary deep eutectic Mg-ion electrolyte composed of MgCl2·6H2O, acetamide, and urea in a precisely balanced 1:1:7 molar ratio. This formulation was optimized by leveraging competitive solvation effects between Mg2+ ions and two organic components. The full batteries based on this ternary eutectic electrolyte, Mn-doped sodium vanadate (Mn-NVO) anode, and copper hexacyanoferrate cathode exhibited an elevated voltage plateau and high rate capability and showcased stable cycling performance. Ex-situ characterizations unveiled the Mg2+ storage mechanism of Mn-NVO involving initial extraction of Na+ followed by subsequent Mg2+ intercalation/deintercalation. Detailed spectroscopic analyses illuminated the formation of a pivotal solid-electrolyte interphase on the anode surface. Moreover, the solid-electrolyte interphase demonstrated a dynamic adsorption/desorption behavior, referred to as the "breathing effect", which substantially mitigated undesired dissolution and side reactions of electrode materials. These findings underscore the crucial role of rational electrolyte design in fostering the development of a favorable solid-electrolyte interphase that can significantly enhance compatibility between electrode materials and electrolytes, thus propelling advancements in aqueous multivalent-ion batteries.

Mo3S13 Cluster-Based Cathodes for Rechargeable Magnesium Batteries: Reversible Magnesium Association/Dissociation at the Bridging Disulfur along with Sulfur–Sulfur Bond Break/Formation

Mo₃S₁₃ Cluster-Based Cathodes for Rechargeable Magnesium Batteries: Reversible Magnesium Association/Dissociation at the Bridging Disulfur along with Sulfur–Sulfur Bond Break/Formation

Pillar-Structured Ti3 C2 Tx MXene with Engineered Interlayer Spacing for High-Performance Magnesium Batteries.

Two-dimentional (2D)Ti3 C2 Tx MXene has attracted significant attention in non-lithium-ion batteries due to its excellent electrical conductivity, high volumetric capacity, and ability to accommodate intercalants. Rechargeable magnesium batteries with Mg metal anodes are noted for their high theoretical energy density, potential safety, earth abundance, dendrite-free Mg2+ plating/stripping mechanism on the anode side, and low cost. Nevertheless, owing to the large polarity of divalent Mg2+ ions, the insertion of Mg2+ into the MXene layers suffers from sluggish kinetics, limiting the performance for storage of Mg2+ ions. Herein, a simple self-assembly strategy is demonstrated to achieve high magnesium ion storage capability with pillar-structured Ti3 C2 Tx MXene by intercalating a hyperbranched polyethylene ionomer containing quaternary ammonium ions. The ionomer intercalation/modification leads to the expansion of interlayer spacing of the MXene and, meanwhile, improves its affinity to low-polarity THF-based electrolyte.The delaminated ionomer-modified MXene shows significantly improved electrochemical performance as a cathode material for Mg batteries. It shows a promising cycling stability with a capacity retention of 86% after 400 cycles at 200mAg-1 , as well as outstanding high-rate performance with a capacity of 110mAhg-1 retained at 1,000mAg-1 relative to 213mAhg-1 at 20mAg-1 .