Ion Intercalation Research Articles

Enhanced surface stability of K0.27MnO2·0.54 H2O cathode materials with LiF/LixPFyOz coating for potassium-ion batteries

Manganese based oxides have significant potential as cathode materials for potassium ion batteries (PIB). Unfortunately, the practical application of manganese-based oxides is hindered by severe electrode surface erosion from electrolyte decomposition products and material expansion and collapse during potassium ion intercalation. Consequently, the surface modification strategy is adopted herein to uniformly cover the surface of K0.27MnO2·0.54 H2O (KMO) microspheres with LiF/LixPFyOz coating to effectively protect the electrode surface and significantly inhibit the collapse of the material crystal structure. Additionally, the coating exhibits excellent electron/ion conductivity, enhancing the diffusion efficiency of potassium ions within the electrode material. The existence of LiF/LixPFyOz coating is confirmed by characterization measurements. The LiF/LixPFyOz-coated KMO microspheres (sample LLO@KMO-2) exhibit outstanding cyclic stability (66.3 % capacity retention at 50 mA g−1) and high discharge capacity (100.2 mAh g−1 at 50 mA g−1), demonstrating their excellent cycle stability. The modification strategy of LiPF6-electrolyte-solvothermal coating provides an innovative surface modification method for potassium ion batteries, showcasing its potential for application in future high-performance battery technologies.

Synergism of carbonaceous additives in engineering of the supercapacitive performance of α-and λ-phases of manganese oxide

Owing to the presence of valence shells for charge transfer, a high theoretical specific capacitance, and variable redox properties, MnO2 appears as a promising agent in the realm of energy storage. Crystallographic structures of manganese oxide (MnO2), a transition metal oxide, play a crucial role in determining its capacitive behavior by controlling the ion intercalation and double-layer formation. In this work, two different phases of MnO2 were synthesized using the facile chemical reduction method and biological method, say α-MnO2 and λ-MnO2. The phases were incorporated with different carbonaceous additives including GO and CNT while maintaining a constant weight ratio of 8:1:1 between active materials (MnO2), additive, and PVDF binder. Among different composites formed, the best electrode performance is demonstrated by λ-MnO2/CNT/PVDF composite with an excellent specific capacitance of 356 F/g at a scan rate of 1 A/g. Moreover, the best-performing electrodes are investigated with a symmetrical two-electrode system yielding a wide potential window of 1.8V with an outstanding power density of 13.5 KW/Kg at 5 A/g and an energy density of 53.78 Wh/Kg at 1A/g having a specific capacitance of 190 F/g.

Ultra-fast switching of energy efficient electrochromic nickel oxide thin films for smart window applications

In today's modern world, energy consumption continues to escalate. In such cases, smart windows play a crucial role in reducing energy consumption and enhancing the quality of life. Electrochromic devices (ECDs) -based smart windows rely profoundly on nickel oxide (NiO) thin films, which act as a counter electrode in ECDs. This work aims to fabricate NiO thin films, with the intention of achieving ultrafast ECD. Through the sputtering technique, energy-efficient ECD is obtained with the highest optical modulation of 60 % at a rapid switching speed of 0.55s for bleaching and 0.95s for coloration. We have also investigated the structural, morphological, vibrational, and optical properties of NiO thin films. XRD analysis revealed the less crystalline or near amorphous nature of NiO thin film. XPS, PL, and Raman studies confirm the existence of defects in the film. The favourable, less crystalline nature, along with the presence of defects, facilitates ultra-fast ion intercalation and de-intercalation process. We believe that prepared NiO film can be used as a promising anodic colourant in electrochromic smart windows with applications in energy-efficient buildings.

Recent Progress in our Understanding of the Degradation of Carbon‐Based Electrodes in Vanadium Redox Flow Batteries – Current Status and Next Steps

AbstractThis mini‐review summarises and discusses recent findings form the literature on the degradation of carbon‐based electrodes for vanadium redox flow batteries (VRFBs). It becomes evident that the focus of current investigations is on carbon paper, carbon felt and graphite felt electrodes, which is understandable from a practical point of view. However, the structural complexity of these materials often prohibits doubtless attribution of observed performance reduction (or increase) to changes in the electrode materials. Among the discussed major causes for degradation are formation or change of surface functional groups, changes in the carbon sp2/sp3 ratio, intercalation of ions as well as formation of inhibiting adsorbates. In order to gain deeper insight into the changes of carbon electrodes in VRFBs under relevant operation conditions, the authors suggest reducing complexity of the investigated materials and applying in situ‐studies under well‐defined and controllable conditions on model electrodes. These studies then should be extended towards more practical systems and may finally help to reduce degradation phenomena including enhanced overvoltages and thus could improve cycling and energy efficiency as well as long‐term stability of vanadium redox flow batteries.

Tailoring the ion storage of MXene by aramid nanofibers towards self-standing electrodes for flexible solid-state supercapacitors

Two-dimensional (2D) transition metal carbides and nitrides (MXenes) are a class of 2D nanomaterials that can offer excellent properties for high-performance supercapacitors. Nevertheless, irreversible restacking of MXene sheets decreases the interlayer spacing, which inhibits the ion intercalation between the MXene nanosheets and finally deteriorates the electrochemical performance of supercapacitors. Herein, aramid nanofibers (ANFs) are mixed with Ti3C2T x MXene to prepare MXene/ANFs composite films. The restacking of MXene sheets is inhibited by the electrostatic repulsion between ANFs and MXene. The ANFs act as intercalation agents to increase the interlayer spacing of the composite films, which can improve the ion storage ability of supercapacitors. Furthermore, the ANFs enhance the mechanical strength of the composite films due to the strong hydrogen bonding interaction and nanomechanical interlocking between ANFs and MXene, endowing the composite films with self-standing property. The resultant composite films are used as electrodes for flexible solid-state supercapacitors to achieve high specific capacitance (996.5 mF cm−2 at 5 mV s−1) and outstanding cycling stability. Thus, this work provides a potential strategy to regulate the properties of 2D nanomaterials, which may expand the application of them in energy storage, ionic separation, osmotic energy conversion and beyond.

Pd-intercalated black phosphorus: An efficient electrocatalyst for CO2 reduction.

Nanoconfined catalysts enhance stabilization of reaction intermediates, facilitate electron transfer, and safeguard active centers, leading to superior electrocatalytic activity, particularly in CO2 reduction reactions (CO2RR). Despite their effectiveness, crafting nanoconfined catalysts is challenging due to unclear formation mechanisms. In this study, we introduce an electrochemical method to grow Pd clusters within the interlayers of two-dimensional black phosphorus, creating Pd cluster-intercalated black phosphorus (Pd-i-BP) as an electrocatalyst. Using in situ electrochemical liquid phase transmission electron microscopy (EC-TEM), we revealed the synthesis mechanism of Pd-i-BP, involving electrochemically driven Pd ion intercalation followed by reduction within the BP layers. The Pd-i-BP electrocatalyst exhibits exemplary CO2-to-formate conversion, achieving 90% Faradaic efficiency for formate production, owing to its distinct nanoconfined structure that stabilizes intermediates and enhances electron transfer. Density functional theory (DFT) calculations underscore the structural benefits for enhancing intermediate adsorption and catalyzing the reaction. Our insights deepen understanding of nanoconfined material synthesis, promising advanced, high-efficiency catalysts.

Electrochromic properties of sputter-grown Nb18W16O93 thin films

Large-area electrochromic films with high stability under high temperatures and humid conditions are essential for the commercialization of smart windows. In this paper, we introduce a new cathodic coloration Nb18W16O93 thin film produced using sputtering that exhibits excellent electrochromic modulation, superior chemical stability, and cyclic durability owing to its stable host structure for ion intercalation. The electrochemical properties of the as-grown Nb18W16O93 thin films, including charge density and transmittance modulation, were enhanced with increasing deposition temperatures. The annealed Nb18W16O93 thin films (grown at room temperature) exhibited comparable electrochromic performances to films grown at high temperatures. Electrochromic devices composed of annealed and high-temperature-grown Nb18W16O93 thin films exhibited excellent durability and nearly identical transmittance modulation, even after 10,000 test cycles. Furthermore, degradation of the surface morphology of the Nb18W16O93 thin films after etching in heated water was alleviated, suggesting high stability under hot and humid conditions, whereas the flat surface of the room-temperature-grown WO3 thin films degraded significantly.

High Entropy Activated and Stabilized Nickel-based Prussian Blue Analogue for High-performance Aqueous Sodium-ion Batteries

Aqueous sodium-ion batteries (SIBs) represent a cost-effective, safe, and reliable candidate for grid-scale energy storage towards a low-carbon society. The development of cathode materials for aqueous SIBs that have both high capacity and good cycling stability still remains a big challenge. This study proposes a high entropy strategy to boost both specific capacity and capacity retention by introducing equimolar Fe, Co, Mn, and Cu at the Ni sites in the Prussian blue analogue (PBA) frameworks. Attributing to the hybridization of 3d energy levels and improved valence electron concentration deriving from the exotic equimolar four transition metals, significantly increase the number of electrochemically active sites and raised the configuration entropy of PBA frameworks, contributing intensive valence electron transport to faster Faraday reaction and more stable hosts for Na+ ion (de)intercalation. Therefore, the high-entropy PBA (HE-PBA) cathode delivers an enhanced capacity of 118.6 mAh g−1 at the current density of 100 mA g−1, which is nearly 1.6 times higher than that of Ni-PBA, resulting in a high energy density of 74.8 Wh kg−1. Moreover, the HE-PBA demonstrates stable operation over 1800 cycles at a high rate of 5 C. This high entropy strategy provides a feasible strategy for the practical application of aqueous SIBs.

Electrochemical and impedance analysis of nickel oxide nanoflakes-based electrodes for efficient chromo supercapacitors

In response to the dynamic advancement of our growing world, there is a tenacious need for sophisticated technologies and continuous refinement of existing knowledge through rigorous scientific endeavors, all with a focus on achieving sustainable development goals for a cleaner and more prosperous future. In this context, this study involves a novel approach to the synthesis of highly porous and stable nickel oxide (NiO) nanoflakes assembled with stacked nanosheet thin films through hydrothermal methods. These films are in-detail examined for their redox-active chromo-supercapacitive properties. The hydrothermal synthesis technique yields thin films with exceptional adhesion to the electrode surface, remarkable chemical stability, and suitable porous structure. These characteristics are strategically employed to facilitate rapid ion intercalation and deintercalation processes, thereby enhancing electrochemical activity. Notably, films deposited for 6-hour reaction times deliver a higher areal capacitance of 140 mF/cm² (and capacity of 70 mC/cm2) at 0.5 mA/cm², which is higher than other electrodes and earlier reports. In-situ, optical investigations further underscore the high coloration efficiency of 44.14 cm²/C, coupled with large optical modulation of 56.5 % and enduring the electrochemical and electrochromic stability. Further research and optimization of NiO-based materials hold significant potential for the development of efficient, smart, and sustainable energy storage solutions in the evolving field of electrochromic supercapacitors to meet the demands of next-generation electronic systems.

Hexagon MXene based heterojunction interface with high ion adsorption and electron transfer efficiency for soft-package potassium-ions aqueous supercapacitors

Potassium-ion hybrid capacitors (PIHC) are considered as ideal large-scale rechargeable energy storage devices due to their low-cost, high-power density and environmental protection. However, a low energy density is the main factor restricting the practical application of PIHC. The interface is formed on the surface of electrode material of PIHC through strong correlation to construct heterojunction, which can significantly improve the performance of ion energy storage. However, how to reveal the influence of the interfacial state of the heterojunction on the adsorption and electron transmission of energy storage ions at the atomic level is still one of the key scientific problems in this field. In this work, metal ion intercalation and microwave-assisted in-situ etching are used to construct the Hexagon MXene Ti3C2 heterojunction with TiOHO strong correlation. At the interface of heterojunction, TiOHO highway for electron transmission is developed to improve the rate performance of PIHC. Through experimental and theoretical calculation, the optimum adsorption position and maximum adsorption amount of potassium-ion at the single interface of heterojunction are obtained, and the specific energy density of PIHC is increased. This lays a foundation for the practical application of high-performance soft-package PIHC.

Tuning MgCl2 content in BMIMPF6 to optimize mg-ion battery performance

This study aims to explore magnesium chloride salt-ionic liquid as an efficient electrolyte for Magnesium-ion Batteries (MIBs) using graphite as a cathode material. A complete physicochemical and electrochemical characterizations were performed on a number of electrolyte compositions and important properties including ion solvation, specific conductivity, ion transport behaviour, dominant ionic species, and electrochemical stability were tested. Also, the effect of magnesium salt concentration on specific capacity, reversibility, stability, charge retention, and rate capability were examined. Moreover, the effect of graphite electrodes on Solid Electrolyte Interphase (SEI) layer, its practicality, and cyclability of the different electrolyte compositions afforded interesting conclusions by this comprehensive comparison of electrode-electrolyte pairings. This evaluation is further supported by life cycle analysis, which gave an important information on how to keep electrodes structurally intact even after several uses. Though there were differences in the three electrolyte systems with respect to reversibility, stability, cyclicbility, capacity fading, and unexpected failures, the 0.2 M electrolyte showcased a notable feature of a high ionic conductivity (4.6 × 10−3 mS cm−1) at room temperature and strong anodic stability (4.0 V vs. Mg/Mg2+). Thus, endorsing the developed system as promising lead for further exploration. Additionally, magnesium dissolution and deposition on a Pt working electrode in this electrolyte was also thoroughly examined in this study. The process of PF6¯ ion intercalation and de-intercalation into graphite layer structure was examined using Cyclic Voltammetry (CV). Based on the analysis by Field Emission- Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDS), and X-ray Photoelectron Spectroscopy (XPS), a change in the active-material morphology was observed and we hypothesize that this might be the reason for the improved performance.

Structure-modulation of flower-like VS2 via ammonium ion intercalation for high performance potassium-ion batteries

Transition vanadium sulfide is a promising anode material for potassium-ion batteries (PIBs), but the volume variation during charge-discharge cycling and low electric conductivity seriously hinder its applications. Herein, we designed a multilayer lamellar self-assembled flower-like vanadium sulfide with ammonium ion intercalation (VS2–NF) by a facile and inexpensive hydrothermal method to improve its electrochemical potassium ion storage performance. By introducing ammonia during the hydrothermal synthesis process, the structures of vanadium sulfide transformed to nanoflowers composed by ultrathin nanosheets from the initial nanosphere structures. The intercalation of ammonium ion enlarges the lattice fringes and induces anisotropic growth of vanadium sulfide, resulting in a large number of mesopores and increased specific surface area as well as the reactive sites of vanadium sulfide, which contribute to the enhanced potassium ion storage performance. Consequently, the structure-modulated VS2–NF exhibits a high specific capacity of 507 mAh g−1 after 50 cycles at a current density of 100 mA g−1. This approach provides a new routine for the modification of other transition metal disulfides as anode materials for PIBs.

Intercalation-Induced Localized Conversion Reaction in h-CuSe for Ultrafast-Rechargeable and Long-Cycling Sodium Metal Battery.

Cathode materials of sodium-based batteries with high specific capacity and fast charge-discharge mode, as well as ultralong reversible cycles at wide applied temperatures, are essential for future development of advanced energy storage system. Developing transition metal selenides with intercalation features provides a new strategy for realizing the above cathode materials. Herein, this work reports a storage mechanism of sodium ion in hexagonal CuSe (h-CuSe) based on the density functional theory (DFT) guidance. This work reveals that the two-dimensional ion intercalation triggers localized redox reaction in the h-CuSe bulk phase, termed intercalation-induced localized conversion (ILC) mechanism, to stabilize the sodium storage structure by forming localized Cu7Se4 transition phase and adjusting the near-edge coordination state of the Cu sites to achieve high reversible capacity and ultra-long cycling life, while allowing rapid charge-discharge cycling over a wide temperature range.

Carbon Atom Modulation of 2H‐MoS2 Promotes Sodium Storage Kinetics by a Unique “Intercalation‐Conversion” Mechanism

AbstractHigh theoretical capacity, stabilized and layered 2H phase molybdenum disulfide (2H) is regarded as a promising material for superior kinetics anode in sodium ion battery, but the inherent semiconducting properties and sluggish sodium ions diffusion limit the development of 2H based anode. Hence, this study builds a unique metalloid phase with high electronic conductivity and suitable layer structure by screening non‐metallic carbon atoms doped in 2H (2H‐C). As experimental and simulation results, 2H‐C of metalloid properties after carbon atom modulation exhibit superior sodium storage kinetics and reversibility by a unique mechanism that promotes ion intercalation under high voltage window, and further good for the later uniformly conversion at lower voltage (intercalation‐conversion mechanism). The 2H‐C anode material delivers a remarkable reversible capacity of 156 mAh g−1 at ultra‐high 100.0 A g−1, long‐term life of 6000 cycles, and superior performance at low temperatures of −10 °C. Otherwise, 2H‐C/Na3V2(PO4)3 full cell also performs charge/discharge capacity of 80.0/76.7 mAh g−1 with 87% capacity retention after 140 cycles at 0 °C. This discovery further explores the unique mechanism and application of 2D layered materials in sodium‐ion battery anodes for fast kinetics under extreme conditions.

Unmodified α-LiFe5O8 as potential anode material of lithium ion battery and the revelation of conversion mechanism

Spinel structured α-LiFe5O8 were prepared via ball milling combined with a straightforward solid-phase method, using Fe2O3 and Li2CO3 as the raw materials. The material maintained a stable capacity of 440 mAh g−1 after 200 cycles at 900 mA g−1 with Coulomb efficiency more than 95 % and also showed facile lithium ion diffusion dynamics. The calculated diffusion coefficient of α-LiFe5O8 ranged around 10−10-10−12 cm2 s−1. Diffusion controlled contribution was dominant over capacitive contribution in the sweeping range 0.1–1.5 mV s−1. A new intercalation-decomposition-conversion mechanism was proposed on the basis that there existed a small pit at the initial stage of the discharge plateau and a significantly low initial discharge plateau voltage was observed compared with the followed discharge cycles. Based on the DFT calculations and the phase diagram of the Li–Fe–O system, we supposed that for the initial discharge of the material, after 1 mol of lithium ion intercalation per unit formula, α-LiFe5O8 decomposed to LiFeO2 and Fe3O4. The followed discharge was the conversion of both LiFeO2 and Fe3O4 to metal Fe and Li2O. Thereafter, the system cycled between Fe2O3 at the fully charged state and metal Fe and Li2O at the fully discharged state.

Nanostructured MoS2 grafted by anthraquinone for energy storage

Two-dimensional materials such as molybdenum disulfide (MoS2) can be employed as an electrode material in energy systems due its good electrical conductivity and high reachable capacity/capacitance. We demonstrate the concept of a covalent modification of nanostructured MoS2 with anthraquinone (AQ) molecules through diazonium salt chemistry for electrochemical capacitors and lithium-ion storage. AQ molecules are chemically bonded to MoS2 which was proved experimentally by spectroscopic techniques. Here, AQ is grafted (ca. 20 wt%) to the outer surface of nanostructured MoS2, but also confined within the MoS2 interlayer spacing. Modified AQ-MoS2 exhibited faradaic response which improved the overall charge stored from 191 F g−1 (461 F cm−3) to 263 F g−1 (631 F cm−3) at 0.2 A g−1 in 1 M H2SO4. The process of intercalation of ions within interlayer spacing of AQ-MoS2 was not hindered by the presence of confined AQ molecules. Impedance spectroscopy and voltammetry analysis revealed comparable non-diffusion limited response of MoS2 before and after modification. The MoS2 modification was likely conducted on the defect sites limiting the catalytic activity of MoS2 towards hydrogen evolution improving stability of electrodes. In organic medium, the pseudocapacitive response of MoS2, enhanced by additional redox reactions of grafted AQ was observed during lithium-ion storage.

Boosting Li-ion storage kinetics via constructing layered TiO2 anode

Due to the typical intercalation-deintercalation mechanism, TiO2 holds great promise as a sustainable anode for next-generation lithium-ion batteries (LIBs). However, commercial TiO2 (C–TiO2) is granular and shows slow ionic conductivity, which greatly hinders its development due to sluggish kinetics, leading to low reversible capacity and inferior rate capability. In this study, a two-dimensional layered TiO2 (L-TiO2) anode is prepared via a one-step calcination process, which can effectively shorten the lithium ions diffusion path and improve its lithium ions conductivity. We elucidated the enhanced electrochemical performance of L-TiO2 as an anode in LIBs through pseudocapacitive acceleration of lithium ions intercalation and deintercalation using various characterization techniques, including different scan rate cyclic voltammetry tests, in situ electrochemical impedance spectroscopy, in situ Raman spectroscopy, and in situ X-ray diffraction. In comparison to C–TiO2 material, L-TiO2 material showcases remarkable electrochemical performance, achieving a capacity of 166 mAh/g after 100 cycles at 0.1 C. Additionally, the lithium-ion diffusion coefficient calculated for the L-TiO2 is two orders of magnitude greater, underscoring its potential as a negative electrode material for LIBs.

Intermolecular Interaction Mediated Potassium Ion Intercalation Chemistry in Ether‐Based Electrolyte for Potassium‐Ion Batteries

AbstractElectrolyte design is indeed a highly effective strategy to improve battery performance. However, identifying the intermolecular interaction in electrolyte solvation structure is rarely reported in potassium‐ion batteries. Herein, it is discovered that a solvent‐solvent intermolecular interaction can be formed when introducing the cyclopentylmethyl ether (CPME) solvent into the commonly used 1,2‐dimethoxyethane (DME)‐based electrolytes. Such interaction is not only analyzed by 2D 1H‐1H correlation spectroscopy for the first time but also found that it can weaken the K+‐DME interaction significantly, consequently enabling a reversible K+ (de‐)intercalation within the graphite. By employing this strategy without using any fluorine‐based solvent, a new fluorine‐free and low‐concentration ether‐based electrolyte is designed, which is not only compatible with graphite but also facilitates the design of high‐energy‐density and safe potassium ion sulfur batteries. A novel molecular interfacial model is further presented to analyze the interfacial behaviors of K+‐solvent‐anion complexes on the electrode surface that are affected by intermolecular interactions, elucidating the reasons behind the superior electrolyte compatibility and graphite electrode performance at the molecular scale. This work sheds some light on the critical role of solvent–solvent interactions in electrolyte design for potassium‐ion batteries and provides valuable insights for engineering and enhancing the performance of electrolytes and batteries.

Conjugated polyaniline as “conveyor” in tungstate boosting cation storage for high-performance aqueous batteries

Aqueous ion storage systems have motivated great interest by virtue of low reduction, high eco-sustainability and safety. Among various cathode candidates, transition metal compounds are featured with easy dissolution in aqueous solutions and inferior conductivity, which severely hinder their application. Herein, advantages are taken of the “conveyor effect” of conjugated polyaniline to prepare an oxygen defective tungstate-linked polyaniline (Od-WOP) material with chrysanthemum-like microstructure. By virtue of the high electronic conductivity derived from conductive conjugated polyaniline skeleton, unbalanced charge distribution triggered by the defective structure, and reversibly rapid ion (de)intercalation benefited from the open framework with porous chrysanthemum-like microstructure, it delivers outstanding rate capability with a maximum specific capacity of 162.2 mAh g−1 and great cycle stability for storing NH4+. Additionally, it also adopts a high reversible capacity of 140.4 mAh g−1 and outstanding cycling performance to store Ca2+. Consequently, the assembled Od-WOP//PTCDI flexible aqueous ammonium ion batteries and calcium ion batteries exhibit superior capacities, energy densities and flexibilities. Od-WOP achieves the NH4+ and Ca2+ storage capability by interacting with them through hydrogen and ionic bonds, respectively. The deep insight from this work sheds light upon a novel strategy to excavate greater potential of transition metal compounds for aqueous ion batteries.

Lithium insertion/extraction mechanism in Mg2Sn anode for lithium-ion batteries

Due to its high capacity and excellent voltage properties, the Mg2Sn intermetallic phase is considered a promising anode material for next-generation lithium-ion batteries. However, the rapid capacity loss with cycling presently limits the application of Mg2Sn-based anodes. In this work, the Mg2Sn intermetallic phase was synthesized via a conventional casting method, and mechanisms of lithium ions intercalation into Mg2Sn alloy anodes were systematically studied. Density functional theory (DFT) calculations and electrochemical analyses identified two pathways involving four electrochemical reactions for Li+ intercalation/extraction in the Mg2Sn phase. The first pathway involves the insertion reaction of lithium ions into the octahedral sites of the Mg2Sn face center cubic (FCC) matrix, whilst the second involves the substitution of Mg by Li ions (releasing Mg metal). Furthermore, ex-situ EIS analysis and DFT calculations verified that adjusting the cut-off voltage range could control the reaction pathways. Excessively high or low cut-off voltages adversely impact the stability of the Mg2Sn anode. At cut-off voltages between 0.1 and 1 V, Mg2Sn anodes show very good capacity retention (78 % after 50 cycles), benefiting from the minimized formation of metallic Mg and Sn phases.