High Energy Mechanical Milling Research Articles

Temperature-dependent structural and magnetic properties of mechanically alloyed Ni80Co17Mo3powder mixture

Nanostructured materials containing nickel improve the effectiveness of several applications. This study examines the preparation and characterization of nanostructured Ni80Co17Mo3 alloy powders using high-energy mechanical alloying and subsequent annealing. A 72h milling process used pure elemental powders to synthesise nanocrystalline FCC-NiCo(Mo) solid solution. The milled powders were then subjected to annealing at different temperatures:300°C, 500°C, and 750°C. X-ray diffraction, scanning electron microscopy coupled with energy-dispersive spectroscopy, and vibrating sample magnetometry indicated significant changes in the powdered alloy properties. The particles growth occurred as the annealing temperature increased, while the microstrain decreased significantly; 14.30±0.07nm up to 56.30±0.28nm and 0.680±0.003% up to 0.180±0.001%, at 25°C and 750°C respectively. SEM analysis revealed differences in particle size and shape as milling progressed. Surprisingly, the milled powdered alloy displayed improved magnetic properties, manifesting significant magnetic susceptibility and enhanced saturation magnetisation, remanent magnetisation, and coercivity within the temperature range of 300°C to 750°C. These findings indicate the development of a consistent and structured state, accompanied by significant crystal growth due to the annealing temperature. This study highlights the great importance of high-energy mechanical milling and subsequent annealing to tune / tailor the characteristics and subsequently investigate the potential utilization of nanostructured Ni-based alloys.

Advancing room temperature NO2 gas sensing performance through high-energy mechanical milling of Tin-dichalcogenides

Eco-friendly gas sensing devices with simple architecture, reduced cost, and high performance at room temperature are being sought to replace the traditional metallic oxide materials, aiming to address environmental concerns. Lamellae semiconducting materials have shown promising detection properties for this purpose. Here, we investigated the sensing response of SnS2, Sn(S0.5Se0.5)2, and SnSe2 tin-dichalcogenides prepared by high-energy mechanical milling. High RNO2/Rair response signals, from 102 to 106, for 2–100 ppm of NO2 were observed for temperatures between 30 °C and 300 °C. The materials were not sensitive to CO, while H2 detection could only be observed above 200 °C, implying high NO2 selectivity. Additionally, we investigated the influence of samples suspension in water and isopropanol on grain size and morphology. We found that isopropanol crystallizes amorphous selenium phase dispersed in the Sn-Se system and increase the agglomeration in the Sn(S0.5Se0.5)2 system. Deformed and defective particles were observed regardless the preparation methodology. This unique defect-rich morphology might increase surface reactivity for selective NO2 detection by physisorption, owing a high adsorption/desorption rate at room temperature.

A Universal Self-Propagating Synthesis of Aluminum-Based Oxyhalide Solid-State Electrolytes.

Inorganic solid-state electrolytes (SSEs) play a vital role in high-energy all-solid-state batteries (ASSBs). However, the current method of SSE preparation usually involves high-energy mechanical ball milling and/or a high-temperature annealing process, which is not suitable for practical application. Here, a facile strategy is developed to realize the scalable synthesis of cost-effective aluminum-based oxyhalide SSEs, which involves a self-propagating method by the exothermic reaction of the raw materials. This strategy enables the synthesis of various aluminum-based oxyhalide SSEs with tunable components and high ionic conductivities (over 10-3 S cm-1 at 25 °C) for different cations (Li+, Na+, Ag+). It is elucidated that the amorphous matrix, which mainly consists of various oxidized chloroaluminate species that provide numerous sites for smooth ion migration, is actually the key factor for the achieved high conductivities. The application of these aluminum-based oxyhalide SSEs synthesized by our approach further pushes forward their practical application considering their easy synthesis, low cost, and low weight that ensures high-energy-density ASSBs.

Porous Si/Ca-Si-O nanocomposite lithium storage materials by calciothermic reduction of Si with CaH2

Silicon monoxide (SiO)-based anode materials are one of the most intensively investigated class of materials for use as high-capacity anodes in lithium-ion batteries. However, their low initial Coulombic efficiency (ICE), resulting from the irreversible electrochemical reaction of the amorphous SiO2 (a-SiO2) phase in the SiO, restricts the wide-spread adoption of SiO-based anode materials in lithium-ion batteries. Pre-emptive formation of an irreversible phase that converts a-SiO2 to a non-reactive state with lithium prior to cell assembly has received much attention for enhancing ICE. However, this process has the drawback of not ensuring long-term cycle performance. Herein, the pre-emptive formation of irreversible phase combined with the high-energy mechanical milling (HEMM) process is proposed to simultaneously improve both the ICE and long-term cycle performance. The resulting porous Si/Ca-Si-O nanocomposite electrode exhibits an impressive ICE of 86.4 % and maintains 55 % of its capacity over 200 cycles. The key factor in the significant ICE improvement is the irreversible Ca-Si-O phase, which is formed by the calciothermic reduction of Si with CaH2. In addition, the microstructural changes induced by the HEMM process effectively mitigate the volume expansion of Si during cycling, resulting in improved long-term cycle stability.

Oxidation behavior of lightweight Al2NbTi3V2Zr high entropy alloy at 1000°C

AbstractLightweight high entropy alloy (LWHEA) has great potential in aeroengine hot component applications. Anticorrosion property of LWHEA at high temperatures is one of the key determining factors. In this study, an LWHEA containing Al, Nb, Ti, V, and Zr elements with a molar ratio of 2: 1: 3: 2: 1 was designed and prepared by low energy (LE) and high energy (HE) mechanical milling followed by vacuum hot pressing. The sintered LE alloy consisted of a simple cubic matrix and α intermetallic while the BCC matrix along with α and β intermetallic phases were observed in HE alloy. The oxidation of LE and HE at 1000°C for 48 h was mainly concentrated on α and β phases, and the resultant oxides were ZrO2 and TiO2. Weight gain curve of HE sample within oxidation time of 48 h followed the parabolic law while a two‐stage parabola was found in LE bulk. The steady‐state oxidation of α precipitate was dominant within 12 h and showed a preferential oxidation mode. High temperature induced simple cubic matrix to stable BCC phase transformation and thus LE alloy with longer oxidation time and HE exhibited a similar uniform oxidation. The oxidation rate of the alloy is related to the content of α and β phases.

Chromium tetraphosphide (CrP4) as a high-performance anode for Li ion and Na ion batteries

The CrP4 nanoparticles and CrP4/C nanocomposite were synthesized via high-energy mechanical milling and applied as anodes for LIBs and SIBs.

A Near Dimensionally Invariable Electrode Material: Li8/7Ti2/7V4/7O2

Our group has reported that Li-excess V-based oxide with Nb ions, Li1.25Nb0.25V0.25O2, delivers a large reversible capacity of over 250 mA g-1 with V3+/V5+ two-electron redox reaction.[1] Recently, Li8/7Ti2/7V4/7O2 has been also synthesized and examined as high-capacity positive electrode materials with V cationic redox.[2] Nanosized Li8/7Ti2/7V4/7O2 was also synthesized by high-energy mechanical milling. Nanosized Li8/7Ti2/7V4/7O2 delivers a high reversible capacity of ~300 mA h g-1 with no capacity deterioration for 100 cycles, which originates from a near dimensionally invariable nature as high-capacity electrode materials. Moreover, Li8/7Ti2/7V4/7O2 is used for as positive electrode materials for all-solid-state batteries with argyrodite-type electrolyte, Li6PS5Cl. An all-solid-state cell with Li8/7Ti2/7V4/7O2 and Li6PS5Cl delivers a large reversible capacity of 300 mA h g-1 with excellent retention for 700 cycles. From these results, the importance of a near dimensionally invariable character is discussed in detail.[1] M. Nakajima and N. Yabuuchi, Chem. Mater., 29, 6927 (2017)[2] I. Konuma et al. and N. Yabuuchi, Nat. Mater., 22, 225 (2023)

Novel CuSi2P3-Based Semi-Solid Anolyte for Redox Flow Batteries

Introduction Redox flow batteries (RFBs), as a kind of low-cost, high-efficiency energy storage system, have received increasing attention in recent years. However, the energy density of RFBs is much lower than that of most commercialized lithium-ion batteries, which not only makes RFBs inconvenient in stationary energy storage but also greatly limits their application in many fieldsIn this work, a low-potential CuSi2P3-based composite is synthesized through a simple high-energy mechanical ball milling and impregnation method; then, it is used to prepare a semisolid anolyte, which is able to achieve a high volumetric capacity (320- 400 Ah L-1). The effect of adding binder to a composite is also discussed for the first time. The synthesis method of adding a binder to the composite provides a direction for optimizing the suspension for other active materials to be applied to semi-solid flow battery.Results and DiscussionFigure 1 compares the 1st and 10th galvanostatic discharge-charge cycling tests of two semisolid anolytes, 8 vol% CSP@C-10 vol% Super P (8CSP@C-10SP) and 8 vol% CSP@C-LiPAA-10 vol% Super P (8CSP@C-LiPAA-10SP). The specific capacity of 8CSP@CLiPAA-10SP anolyte at the first cycle can reach up to >2000 mAh g-1, which approaches the theoretical capacity (2079 mAh g-1) based on the corresponding binary Li-alloy products (Li3.75Si and Li3P), with the capacity retention greater than 98% from the 2nd to the 10th cycle. However, the specific capacity of 8CSP@C-10SP anolyte without LiPAA at the first cycle is only about 1000 mAh g-1, and severe capacity fading is encountered. Only a specific capacity of 420 mAh g-1 is left at the 10th cycle, leading to capacity retention of only 40%. The presence of LiPAA makes a more stable CSP composite, which can obtain a better cycling performance. We concluded that the cycling stability of LiPAA binder-based CSP composite is much better for RFBs compared with the one without binder.Figure 1b-e reveals the comparison of SEM images between 8CSP@C-10SP and 8CSP@C-LiPAA-10SP at pristine stage and after cycles respectively. It can be seen from the images that these two semisolid anolytes present very porous structure at the pristine stage (Figure 1b, d). However, after cycles, the surface of 8CSP@C-10SP produces very large film-like precipitates (Figure 1c), which greatly hinders the reaction of active materials in the subsequent cycles and further results in serious capacity fading. On the other hand, the porous structure of the 8CSP@C-LiPAA-10SP after cycles enables sound performance of the anolyte during the continuous cycles. The addition of LiPAA in the CSP composite can improve the contact between CSP and carbon, which confirms the electrical conductivity uniformity of CSP-based suspension.The addition of LiPAA binder to the composite enables the CSP semisolid anolytes to maintain better uniformity and rheological performance. Figure 2 shows the viscosity test results of electrolyte (1 M LiPF6 EC/DEC) and various CSP-based semisolid anolytes. It is indicated in the results that the non-Newtonian fluid semisolid anolytes present greater viscosity than the Newtonian fluid electrolytes, which results in larger flow resistance and more pump loss; therefore, viscosity is an important issue to be considered in the application of SSFBs. We find the viscosity of CSP@C-LiPAA anolyte significantly smaller than that of CSP@C anolyte at the same concentration, which is favorable to reduce the flow loss of the anolyte. The addition of LiPAA binder improves the rheological performance of the semisolid anolyte in an effective way and enormously enhances its cycling stability. Further investigations on the electrochemical reversibility, energy efficiency, cycle life, full cell design, and flow cell performance will be discussed. Acknowledgments The work described was substantially supported by a grant from the the Natural Science Foundation of Guangdong Province (2023A1515010954) and the Shenzhen Science and Technology Fund (JCYJ20220531101801002). Figure 1

The Analysis of the Application of Using Nanoceramic Oxides in Fire-resistant Coatings

The increased demand for enhanced fire safety in various industries has spurred interest in the properties and applications of nanoceramic oxide materials. This paper provides a thorough examination of the fundamental attributes of nanoceramic oxides, showcasing their exceptional temperature, corrosion, and wear resistance. The paper discusses synthesis methods like evaporation condensation, high-energy mechanical ball milling, and both vapor and liquid phase chemical techniques. The paper further explicates the underlying mechanisms that enable fire-resistant coatings to retard flames, highlighting thermal insulation, intumescence, and more. Of significance is the potential of nanoceramic oxides to augment the performance of these coatings, evidenced by applications like tunnel fire retardant coatings and steel structure coatings that integrate materials such as Mg (OH)2, nano-SiO2, and TiO2. While challenges in raw material sourcing, eco-friendliness, production, and expertise arise, solutions are proposed. Conclusively, the study underscores the transformative potential of nanoceramic oxides in the realm of fire-resistant coatings, pushing boundaries in fire safety across sectors.

Synthesis of Graphitic Carbon Coated ZnPS3 and its Superior Electrochemical Properties for Lithium and Sodium Ion Storage.

Graphitic carbon-coated ZnPS3 is prepared via direct phosphosulfurization and high energy mechanical milling (HEMM) with multiwall carbon nanotubes (MWCNTs) and first introduced as an anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The HEMM process with MWCNTs reduces the particle size of as-synthesized ZnPS3 bulk to 100-500nm and yields the ≈5nm thick graphitic carbon coated ZnPS3 nanoparticles, which are the nanocomposites of 5nm sized nanocrystallites embedded in the amorphous matrix. The ZnPS3 electrode undergoes the combined conversion and alloying reactions with Li and Na ions and exhibits high initial discharge and charge capacities in both LIBs and SIBs. The graphitic carbon-coated ZnPS3 electrode exhibits excellent high-rate capability and long-term cyclability. The superior electrochemical properties can be attributed to high electrical conductivity, high Li ion mobility, and high reversibility and structural stability derived from the graphitic carbon-coated nanoparticles. This study demonstrates that the novel graphitic carbon-coated ZnPS3 is a promising anode material for both LIBs and SIBs and the graphitic carbon coating methodology by HEMM is expected to apply to the various metal oxides, sulfides, and phosphides.

Effect of high-energy mechanical milling on the physicochemical and rheological properties of chayotextle (Sechium edule Sw.) starch.

This work evaluates the effect of high-energy mechanical milling time (7 levels, 20-80min) on amylose content, crystallinity pattern, temperature and gelatinization enthalpy, morphology, and rheological properties of chayotextle (Sechium edule Sw.) starch. After 30min of milling, granular structure was affected, and amylose values were the highest while crystallinity and gelatinization enthalpy decreased significantly. These changes allowed to obtain gels with viscoelastic properties where the elastic character (Ǵ) prevailed upon the viscous modulus (Ǵ́). Native starch showed Tan δ values of 0.6, increased significantly (0.9) after 30min of milling due to the surge in linear chains (amylose) and loss of granular structure. Native and modified starches showed high dependence on cutting or shear speed, presenting a non-Newtonian behavior (reofluidizers). These results indicate that mechanical grinding is an alternative to obtain modified starches with applications in the food industry.

Facile synthesis of BiSb/C composite anodes for high‐performance and long‐life lithium‐ion batteries

AbstractAlloy‐type antimony (Sb) is considered as an attractive candidate anode for high‐energy lithium‐ion batteries (LIBs) because of its high theoretical specific capacity and volumetric capacity. However, Sb suffers from enormous volume variation during cycling, which causes electrode cracking and pulverization, and hence the fast capacity decay and poor cyclability, limiting its practical applications as a LIB anode. Herein, we report a facile, scalable, low‐cost, and efficient route to successfully fabricate BiSb/C composites via a two‐step high‐energy mechanical milling (HEMM) process. The as‐prepared BiSb/C composites consist of nanosized BiSb totally embedded in a conductive carbon matrix. As LIB anodes, BiSb/C‐73 (with 30 wt% carbon) electrodes exhibit excellent Li‐storage properties in terms of stable high reversible capacities, long‐cycle life, and high‐rate performance. Reversible capacities of ∼583, ∼466, ∼433, and ∼425 mAh g−1 at a current density of 500 mA g−1 after 100, 300, 500, and 1000 cycles, respectively, were achieved. In addition, a high capacity of ∼380 mAh g−1 can still be retained at a high rate of 5 A g−1. Such outstanding cycling stability and rate capability could be mainly attributed to the synergistic effects between the ability of nanosized BiSb particles to withstand electrode fracture during Li insertion/extraction and the buffering effect of the carbon matrix. The as‐prepared BiSb/C composites are based on commercially available and low‐cost Bi, Sb, and graphite materials. Interestingly, HEMM is a more convenient, efficient, scalable, green, and mass‐production route, making as‐prepared materials attractive for high‐energy LIBs.

Hydrolytic hydrogen production behavior in NaCl solution of Mg and Mg-GO composite synthesized by mechanochemical reaction

With the help of the mechanochemical reaction (MCR) strategy, the composition optimization, structure regulation and surface modification of metallic Mg are realized by introducing GO in the high energy mechanical ball milling process to enhance the hydrogen production performance in NaCl solution. The synthetic process of Mg and Mg-GO composite by MCR is systematically optimized and the microstructure evolution as well as the hydrolytic hydrogen production behavior are investigated. Phase composition optimization and microstructure regulation can be effectively implemented during the MCR process. The response rate of the repeated hydrogen-filling MCR sample is faster than that of the single hydrogen-filling MCR sample. The hydrogen production rates at 298 K of 4, 8, 12, 16 and 20 h MCR Mg with repeated H2-filling can reach to 922, 934, 890, 917 and 1131 mL/g/min, respectively. The internal microstructure refinement, surface modification, moderate activity, appropriate particle size, surface defects and reasonable mass transfer channels of MCR 8 h Mg-GO composite are the reasons for the fast rates and high yields of hydrolytic hydrogen production. 365.3, 864.4 and 933.8 mL/g H2 can be produced by 8 h MCR Mg-GO composite within 1, 3 and 10 min, respectively. The hydrogen production rate of 8 h MCR Mg-GO composite is as high as ∼600 mL/g/min. Mechanochemical reaction strategy with catalyst is a useful method to improve the hydrolysis hydrogen production performance of metallic Mg when well matched with the added catalyst.

Silicon infused Molybedenum di-selinide (MoSe2) nanosheets for enhanced hydrogen evolution reaction (HER) and lithium-ion battery (LIB) applications

The systematized design of two-dimensional (2D) nanocatalysts for sensible energy-efficient reactions is quite a puzzling prospective aspect in energy-related applications. In this current work, we used a top-down strategy to synthesize silicon (Si) nanoparticles using a high-energy mechanical ball milling technique. In hydrothermal reaction, these Si nanoparticles were introduced into the 2D MoSe2 matrix sequence based on varying the percentages of silicon (0–15%) vs Selinium content. The high crystalline phases of the synthesized 10% Si:MoSe2 exhibited the sheet-like morphology and silicon inserted layered structure. The pristine MoSe2@CC & Si:MoSe2@CC electrodes were prepared by tape casting method. During HER reaction, the miniscule insertion of Si into MoSe2 matrix amplified the current density until 10% addition and moved the reduction curves towards lower onset overpotential (76.23 mV) in addition to the significant Tafel value (112.3 mV/decade). The potential of the better performed electrode in HER was explored as an anode for Lithium-ion battery (LIB) applications. The electrode delivered a discharge capacity of 406.7 mAh g−1 at a current density of 100 mA/g after 100 charge-discharge cycles. Furthermore, the rationally constructed bifunctional electrode (Si:MoSe2@CC) showed strong physicochemical stability, which can be used in future sustainable energy generation and storage devices.

Microstructure and kinetics/thermodynamics of environmentally friendly and recyclable grain regulated Pr-Mg-Ni-based hydrogen storage alloys

The high-energy mechanical milling procedure was used to manufacture the as-milled Pr5Mg85Ni10 alloys of 5 h, 10 h, 20 h, and 30 h respectively. We have been successful in obtaining a variety of nanocrystalline and amorphous alloys with varying amounts of each. The primary phase in the interior structure of the alloys is still Mg2Ni and Mg, which corresponds to the second phase PrMg12. The products of saturated hydrogen absorption include MgH2, Mg2NiH4, and PrH2.93, while the products of complete hydrogen release include Mg, Mg2Ni, and PrH2. According to the findings, the amount of time spent ball-milling the alloys is the primary component that determines how well they function in terms of the dynamic performance of hydrogen absorption and desorption. The dynamic performance of the alloy in terms of hydrogen absorption and desorption is enhanced with the increasing time spent ball-milling the material. In the same vein, the alloy that has been milled for ten hours has the most desirable thermodynamic characteristics.

Investigation and production of non-cytotoxic TixNbxSn (x = 5,10,15,20) alloys by high-energy mechanical milling with antibacterial activity

In this research, TixNbxSn (x = 5, 10, 15, 20 wt%) alloys were produced by high-energy mechanical alloying, and their potential applications as biomaterial were investigated through the microstructural characterizations (via XRD, SEM, and EDS analyses), mechanical tests (via hardness and elastic modulus tests), and biological studies (via antibacterial and cytotoxic tests). The alloying studies were carried out at room temperature in a high-energy ball milling for 8 h followed by a consolidation using a uniaxial pressing and 2 h pressureless sintering at 1150 °C. The XRD and EDS analyses showed that α-Ti, β-Ti, and TiC phases were present in the microstructure after sintering at high-temperature. Hardness tests revealed a wide range of values between 384 and 723 HV depending on the alloy compositions. That is, the volume fraction of TiC phase formed during processing and the ratio of α-Ti/β-Ti phases appear to control the hardness of the alloys. The elastic modulus was determined ranging from 70 to 103 GPa as a function of compositions with Ti15Nb15Sn alloy having the closest elastic modulus to the bone. The biological investigations revealed that TiNbSn alloys exhibited antibacterial properties against Staphylococcus aureus (S. aureus) and were not cytotoxic to healthy cells, regardless of their compositions. Furthermore, the findings indicated that when the cells were subjected to various dilutions of alloy extracts, there was a noticeable enhancement in both cell proliferation and viability. These findings have the potential to pave the way for novel approaches in the creation of TiNbSn alloys as biomaterials.

Synthesis of Tungsten Carbides in a Copper Matrix by Spark Plasma Sintering: Microstructure Formation Mechanisms and Properties of the Consolidated Materials.

In this study, the synthesis of tungsten carbides in a copper matrix by spark plasma sintering (SPS) is conducted and the microstructure formation mechanisms of the composite materials are investigated. The reaction mixtures were prepared by the high-energy mechanical milling (MM) of W, C and Cu powders. The influence of the MM time and SPS temperature on the tungsten carbide synthesis in an inert copper matrix was analyzed. It was demonstrated that the milling duration is a critical factor for creating the direct contacts between the W and C reactants and increasing the reactive transformation degree. A WC-W2C-Cu composite was fabricated from the W-C-3Cu powder mixture milled for 10 min and subjected to SPS at a temperature of 980 °C for 5 min. The formation of unconventional microstructures with Cu-rich regions is related to inter-particle melting during SPS. The WC-W2C-Cu composite showed a promising combination of mechanical and functional properties: a hardness of 300 HV, an electrical conductivity of 24% of the International Annealed Copper Standard, a residual porosity of less than 5%, a coefficient of friction in pair with a WC-6Co counterpart of 0.46, and a specific wear rate of the material of 0.52 × 10-5 mm3 N-1 m-1.

Electrochemical properties of mechanically milled Ni-20Cr for H2 oxidation in alkaline fuel cells

The electrochemical properties of Ni-20Cr alloy subject to high-energy mechanical milling were investigated to analyze its potential as a catalyst in fuel cells for hydrogen oxidation reaction (HOR) in an alkaline medium. The kinetic properties of Ni-20Cr alloy decorated with Pt are also reported. Results showed that as the milling time increases, the HOR kinetics improve. Pt particles grow mainly on the surface of highly deformed Ni-20Cr particles. Ni-20Cr and Ni-20Cr/Pt with 12 and 8 h of milling, respectively, are good candidates for HOR in an alkaline medium.

Influence of process conditions on the mechanical and microstructural features of milled Al sintered with rapid heating

The present work explores the impact of the involved sintering conditions (temperature, pressure and sintering time) via rapid induction heating on the mechanical and microstructural properties of milled aluminum powders. The results indicate that induction heating retains the highly refined microstructure generated by high-energy mechanical milling, obtaining higher yield strength, hardness, and densification rates in sintered samples than the conventional method. The above suggests that induction sintering could be a viable solution for producing high-quality sintered nanocrystalline materials with improved mechanical properties in three minutes and 450 MPa of pressure.

Durable Manganese-Based Li-Excess Electrode Material without Voltage Decay: Metastable and Nanosized Li2MnO1.5F1.5

Li-excess manganese-based oxides have been proposed as high-capacity positive electrode materials, but voltage decay associated with gradual oxygen loss hinders its use for practical applications. Herein, Li-excess manganese oxides with different fluorine contents are synthesized by high-energy mechanical milling. Although Li2MnOF2 with only divalent manganese ions cannot be synthesized, Li2MnO2F and Li2MnO1.5F1.5 are successfully synthesized. When the samples are charged to 5.0 V, both oxyfluorides deliver large reversible capacities, ∼350 mA h g–1 and ∼1000 mWh g–1. However, insufficient capacity retention is also observed because of the instability of anionic redox. In contrast, better capacity retention and higher energy density (730 mWh g–1) are obtained for Li2MnO1.5F1.5 with a 4.4 V cutoff because of the enrichment of fluoride ions and activation of Mn2+/Mn4+ cationic redox. Moreover, electrode durability is significantly improved by using a highly concentrated electrolyte, and good capacity retention without voltage decay is achieved for >180 cycles.