Rechargeable Magnesium Batteries Research Articles

Progress and Challenges of Vanadium Oxide Cathodes for Rechargeable Magnesium Batteries.

Among the challenges related to rechargeable magnesium batteries (RMBs) still not resolved are positive electrode materials with sufficient charge storage and rate capability as well as stability and raw material resources. Out of the materials proposed and studied so far, vanadium oxides stand out for these requirements, but significant further improvements are expected and required. They will be based on new materials and an improved understanding of their mode of operation. This report provides a critical review focused on this material, which is embedded in a brief overview on the general subject. It starts with the main strategic ways to design layered vanadium oxides cathodes for RMBs. Taking these examples in more detail, the typical issues and challenges often missed in broader overviews and reviews are discussed. In particular, issues related to the electrochemistry of intercalation processes in layered vanadium oxides; advantageous strategies for the development of vanadium oxide composite cathodes; their mechanism in aqueous, "wet", and dry non-aqueous aprotic systems; and the possibility of co-intercalation processes involving protons and magnesium ions are considered. The perspectives for future development of vanadium oxide-based cathode materials are finally discussed and summarized.

Advances in ionic-liquid-based eutectic electrolyte for high voltage rechargeable magnesium batteries

Advances in ionic-liquid-based eutectic electrolyte for high voltage rechargeable magnesium batteries

Nucleation Mechanisms of Electrodeposited Magnesium on Metal Substrates

AbstractMagnesium rechargeable batteries (RMBs) are a promising alternative to lithium‐based ones. However, a major challenge in their advance concerns the development of aprotic electrolytes from which magnesium can be electrodeposited with high efficiency and without the formation of dendrites. Of note, the mechanism of the magnesium electrodeposition from aprotic electrolytes remains largely unexplored. In this study, we propose a combined experimental and theoretical approach based on the Scharifker‐Hills (S−H) mathematical model for the potentiostatic transients to analyse the nucleation and growth of magnesium during electrodeposition in order to shed light on the nucleation process and increase battery safety and cycle lifetime. The model is used to investigate the electrodeposition of magnesium from a Magnesocene (MgCp2)‐based electrolyte onto metal current substrates such as copper, nickel, aluminium and stainless steel.

Comparative investigation of Fe2O3 and FeS2 as cathode materials for rechargeable magnesium batteries

Comparative investigation of Fe2O3 and FeS2 as cathode materials for rechargeable magnesium batteries

In-situ dynamic catalysis electrode electrolyte interphase enabling Mg2+ insertion in 2D metal–organic polymer for high-capacity and long-lifespan magnesium batteries

Rechargeable magnesium battery is regarded as the promising candidate for the next generation of high-specific-energy storage systems. Nevertheless, issues related to severe Mg-Cl dissociation at the electrolyte–electrode interface impede the insertion of Mg2+ into most materials, leading to severe polarization and low utilization of Mg-storage electrodes. In this study, a metal–organic polymer (MOP) Ni-TABQ (Ni-coordinated tetramino-benzoquinone) with superior surface catalytic activity is proposed to achieve the high-capacity Mg-MOP battery. The layered Ni-TABQ cathode, featuring a unique 2D π-d linear conjugated structure, effectively reduces the dissociation energy of MgxCly clusters at the Janus interface, thereby facilitating Mg2+ insertion. Due to the high utilization of active sites, Ni-TABQ achieves high capacities of 410 mAh/g at 200 mA g−1, attributable to a four-electron redox process involving two redox centers, benzoid carbonyls, and imines. This research highlights the importance of surface electrochemical processes in rechargeable magnesium batteries and paves the way for future development in multivalent metal-ion batteries.

Initiating cationic-anionic chemistry with stepwise surface-to-inner conversion in copper selenide superstructures for high-energy rechargeable magnesium batteries

Copper selenides are viewed as the most capable cathode materials for rechargeable magnesium batteries, yet suffer from unsatisfactory energy density due to their low operating voltage plateau (∼0.9 V vs. Mg/Mg2+) and insufficient reversible capacity. Herein, a stepwise conversion from surface cationic-anionic redox to inside electrochemical displacement reaction is realized in copper selenide (Cu2-xSe) superstructure cathodes. A highly reversible high-voltage platform at ∼1.6 V is discovered during discharge process. Ex-situ spectroscopy and microscopy results demonstrate that the high-voltage plateau is contributed by surface Cu2+ charge-carrier transformation and anionic Se2– redox reaction while sufficient inner Cu-Mg replacement conversion at low-voltage region. Following the favorable mechanism, the Cu2-xSe superstructure cathodes can present high specific capacity of 385.4 mAh g–1 at 0.1 A g–1 and outstanding energy density of 426.3 Wh kg–1. Moreover, the Cu2-xSe superstructure cathodes also maintain a reversible capacity of 223.6 mAh g–1 over 700 cycles with 0.0147 % capacity degradation per cycle at 1.0 A g–1 and long-term charge-discharge lifetime for 3000 cycles at 5.0 A g–1. This research reports a new Mg2+ storage mechanism for copper selenide cathodes and provides novel route to develop high-energy-density rechargeable magnesium batteries.

Direct crystallization of deep eutectic solvent into solid-state electrolyte for magnesium metal batteries

Solid-state magnesium rechargeable battery is a promising post-Li battery technology due to the high abundance of Mg element, the competitive volumetric capacity and enhanced safety of Mg metal anodes. However, current solid electrolyte formulas failed to realize considerably reversible Mg anodes caused by the passive layer formed on their surface. Herein, a novel Mg2+-conducting solid-state electrolyte (MCE) is proposed by directly crystalizing deep eutectic solvents composing of Mg(TFSI)2 and urea at room temperature. Experimental and simulation results indicate the formation of anion-rich groups in urea-Mg2+ coordination structures, facilitating rapid Mg2+ migration in the MCE. When applied in the Mg//Mg symmetric cells, the new electrolyte derives a macroporous and fluoride-rich organic/inorganic hybrid interface layer on the Mg metal surface. The unique interfacial structure endows the interface layer with Mg2+ diffusion capability for reversible Mg metal stripping/plating. The practical feasibility of MCE is finally demonstrated by cycling in Mg//V2O5 full cells with competitive electrochemical performance. This work illustrates a new concept of crystalizing deep eutectic solvents into solid-state electrolytes at room temperature for multivalent metal batteries.

Constructing Cu9S5@CuSe heterostructures under microwave irradiation for rechargeable magnesium batteries

Copper chalcogenides are believed as the prospective cathode materials for rechargeable magnesium batteries. However, their practical application is seriously restricted by slow diffusion and reaction kinetics due to the large charge/radius ratio of divalent Mg2+ ions. Herein, a simple two-step microwave-assisted synthesis method is rationally developed to construct Cu9S5@CuSe heterostructures as the capable cathode materials for rechargeable magnesium batteries. Two-dimensional CuSe nanosheets are vertically grown on the surface of single-crystal Cu9S5 substrate through selenation reaction under microwave irradiation to form the mixed-dimensional heterostructures. Electrochemical measurements reveal that the as-synthesized Cu9S5@CuSe heterostructures show high reversible capacity of 240 mAh g−1 and good long-term cyclic stability with approximate 0.013 % capacity decay per cycle at 500 mA g−1 within 1000 cycles. Furthermore, the obviously enhanced rate capability can be achieved in comparison with that of single-crystal Cu9S5 substrate and CuSe nanoparticles. Ex-situ X-ray photoelectron spectroscopy and X-ray diffraction characterizations reveal favourable electrochemical conversion reaction over the Cu9S5@CuSe heterostructure cathode. The superior electrochemical properties are attributed to the optimized diffusion kinetics within the unique heterostructure. This research offers a valuable strategy to develop high-performance cathode materials with favourable kinetics for magnesium batteries.

Magnesium-eutectic electrolyte as a winning combination for sustainable battery

Eutectic-Magnesium electrolytes are sparsely used electrolytes in Magnesium ion batteries. In this context, readily available less toxic precursors based eutectic electrolytes are attracting increasing interest owing to the focus of sustainable battery development. The unique benefits of magnesium such as high specific capacity, low reduction potential, and remarkable reversibility without dendrimer formation are highly advantages when compare to lithium based batteries. Developing an optimal electrolyte composition is a key area of study in the field of battery technology. With improved cell performance, stability across cycles, and general safety, we hope to reduce unwanted interfacial reactions. In this study, we examined eutectic combination of trimethylamine hydrochloride and aluminium chloride (TMA: AlCl3 = TMA) along with magnesium perchlorate to understand ion-solvation, complexation, thermal stability, ion transport and conduction, and electrochemical stability, certain physico-chemical and electrochemical parameters were evaluated prior to assessing the cell's performance. The salient features being an ionic conductivity (σ) of 6.25×10−3 mS cm−1 at 30 °C, remarkable performance retention with over 90 cycles of operation with the electrolyte and an impressive capacity of 90 mAh/g. The behaviour of ionic conductivity with temperature followed the Vogel-Tammann-Fulcher (VTF) equation. Moreover, the anodic stability around 2.5 V (Mg/Mg2+) when platinum is used as the working electrode endorses the suitability of the electrolyte for use in Rechargeable Magnesium Batteries (RMBs).The promising results of this first investigation open up new possibilities for investigating complementary pairings with the aim of improving the efficiency of magnesium-ion cells.

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.

Materials and manufacturing process of anode for low-cost, high-performance magnesium rechargeable batteries

Materials and manufacturing process of anode for low-cost, high-performance magnesium rechargeable batteries

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.

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.

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.

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.

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

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.