Layered Cathode Materials Research Articles

Inhomogeneous Coordination in High‐Entropy O3‐Type Cathodes Enables Suppressed Slab Gliding and Durable Sodium Storage

AbstractO3‐type layered oxides are highly promising cathodes for sodium‐ion batteries (SIBs), however they undergo complex phase transitions and exhibit high sensibility to air, leading to subpar cycling performance and commercial viability. In this work, we report a layered cathode material (NaNi0.29Cu0.1Mg0.05Li0.05Mn0.2Ti0.2Sn0.11O2) with a sate‐of‐the‐art high‐entropy compositional design. We unveil that such a configuration featuring inhomogeneous coordination environment of transition metal (TM) elements, can enable enhanced gliding energy (−0.38 vs −0.58 eV) of TMO2 slabs upon desodiation both theoretically and experimentally, which underlies the fundamental origin of the outstanding structural stability of HEO materials. As a consequence, the complex phase transitions (O3−O′3−P3−P′3−P3′−O3′) of conventional O3‐type cathode have been eliminated, and the as‐obtained material demonstrates exceptional structural robustness and integrity with an ultra‐long cycle life in a quasi‐solid‐state cell (maintaining 73.2 % capacity after 1000 cycles at 2 C). Moreover, the material presents satisfactory air stability, with minimal structural and electrochemical degradation when directly exposed to the air. An Ah‐scale pouch cell based on the cathode material is constructed, demonstrating a capacity retention of 83.6 % after 500 cycles, signaling substantial promise for commercial applications.

Inhomogeneous Coordination in High-Entropy O3-Type Cathodes Enables Suppressed Slab Gliding and Durable Sodium Storage.

O3-type layered oxides are highly promising cathodes for sodium-ion batteries (SIBs), however they undergo complex phase transitions and exhibit high sensibility to air, leading to subpar cycling performance and commercial viability. In this work, we report a layered cathode material (NaNi0.29Cu0.1Mg0.05Li0.05Mn0.2Ti0.2Sn0.11O2) with a sate-of-the-art high-entropy compositional design. We unveil that such a configuration featuring inhomogeneous coordination environment of transition metal (TM) elements, can enable enhanced gliding energy (-0.38 vs -0.58 eV) of TMO2 slabs upon desodiation both theoretically and experimentally, which underlies the fundamental origin of the outstanding structural stability of HEO materials. As a consequence, the complex phase transitions (O3-O'3-P3-P'3-P3'-O3') of conventional O3-type cathode have been eliminated, and the as-obtained material demonstrates exceptional structural robustness and integrity with an ultra-long cycle life in a quasi-solid-state cell (maintaining 73.2 % capacity after 1000 cycles at 2 C). Moreover, the material presents satisfactory air stability, with minimal structural and electrochemical degradation when directly exposed to the air. An Ah-scale pouch cell based on the cathode material is constructed, demonstrating a capacity retention of 83.6 % after 500 cycles, signaling substantial promise for commercial applications.

Surface Reconstruction Reduces Internal Stress of Ni-Rich Cathode Particles.

High-voltage Ni-rich layered cathode materials are undoubtedly a powerful driving force for high-energy density lithium batteries. However, residual lithium impurities on the surface of Ni-rich materials can cause more severe side reactions under high-voltage, leading to rapid decay. There is still no reliable mechanistic explanation for this phenomenon. It has been detected that residual alkali on the cathode surface under high voltage can cause obvious side reactions. This side reaction will affect the capacity retention of the material and increase the internal stress of the particles. In addition, the surface reconstruction of Ni-rich cathodes is achieved through simple chemical reactions, turning waste into treasure. The newly generated Ti-based layer not only repairs the structure of the nickel-rich material but also optimizes the material from a dynamic perspective. Removing residual lithium components on the cathode surface effectively reduces the hydrolysis and self-catalytic side reactions of PF6 - at the electrolyte cathode interface and suppresses gas generation during cycling, promoting the application of the next generation of high-energy density Ni-rich layered cathode-based lithium batteries with high-voltage.

Mitigating Mechanical Stress by the Hierarchical Crystalline Domain for High-Energy P2/O3 Biphasic Cathode Materials.

Sodium-ion batteries (SIBs) have captured widespread attention for grid-scale energy storage owing to the wide distribution and low cost of sodium resources. Delivery of high energy density with stable retention remains a challenge in developing cathode candidates for rechargeable SIBs. Inspired by the concept of "cationic potential", here, we present a hierarchical crystalline domain in hexagonal particles with target chemical composition (Na0.8Li0.03Mg0.05Ni0.28Fe0.05Mn0.54Ti0.05O2) from the inner bulk O3 phase (71.1 wt %) to the outer P2-type shell (28.9 wt %) of the structure. Benefiting from the mitigated mechanical stress of the predominant bulk O3 phase under the protection of the surficial P2 crystalline domain at the microscale during Na+ (de)intercalation, the brittle fracture, plastic yielding, and structural damage of the bulk O3 phase are effectively prohibited during battery cycling, thereby achieving good structural integrity. As a consequence, the biphasic P2/O3-Na0.8Li0.03Mg0.05Ni0.28Fe0.05Mn0.54Ti0.05O2 material exhibits satisfactory electrochemical properties, with a high energy density of 506 Wh kg-1 and good capacity retention of 85.5% over 200 cycles. This work highlights the importance of tailoring the crystalline domain to mitigate the reaction-induced stress and particle fracture of layered biphasic cathode materials for high-energy SIBs.

Recent progress of ion-doping methods in modifying layered oxide cathode materials for sodium-ion batteries

Typically, the cathode materials contribute the most in achieving the commercialization of sodium-ion batteries (SIBs) as the cathodes take up the most proportion of the full cells cost. Hence, developing cathode materials with a high specific capacity, perfect capacity retention, long cycling lifetime, and strong chemical/environmental stability is of undoubted importance. Researchers are now using many methodologies to improve the performance of different types of cathodes. Among all these, ion-doping used in modifying layered oxide (NaxTMO2, in which TM=transition metal; 0<x≤1) cathode materials seem to be one of the most popular methods. This is because that the NaxTMO2 cathodes offer perfect energy density and Na+ conductivity, while ion-doping methods could help mitigate the phase transition, sluggish kinetics, and air instability challenges. As a result, this review summarizes the recent progress of ion-doped NaxTMO2 cathodes modification strategies, divided into three parts in dealing with the above three challenges respectively. This work targets for facilitating the development of ion-doping methods used in commercial NaxTMO2 modification and pave the way for the next generation of energy storage systems.

Dynamic Transition Metal Network via Orbital Population Design Stabilizes Lattice Oxygen Redox in Stoichiometric Layered Cathodes.

Li-ion batteries employing stoichiometric layered Li metal oxides as cathodes are now reaching the energy density limits due to single cationic redox chemistry. Lattice oxygen redox (LOR) has been discovered in these materials, as a high-energy-density paradigm observed in Li-rich materials. Nevertheless, the origin of this process is not understood, preventing the rational design of better cathode materials. Here, employing stoichiometric Ni-based cathodes, it is demonstrated that LOR originates from a dynamic transition metal (TM) network caused by ion migration during the electrochemical process. This network is confirmed to be ribbon through both ex- and in-situ STEM observations, facilitating reversible LOR. Finally, a t2g orbital population rule is proposed to guide the design of ordered TM networks, supported by calculated structures and the synthesized ordered TM oxides reported. This work explains the mechanism of LOR in stoichiometric layered cathode materials, and sets a promising direction for the design of high-energy-density cathodes through the regulation of TM ordering.

Enhancing the potassium-ion storage performance of potassium manganese oxide cathode by single-element doping strategies

Layered manganese-based oxides are considered as ideal cathode materials for potassium-ion batteries (PIBs) due to their ease of synthesis and relatively large interlayer spacing. Nevertheless, the Jahn-Teller effect of Mn3+ and the irreversible phase transitions in high-voltage regions of layered manganese-based oxide leads to slow diffusion kinetics of potassium ions and severe capacity fading. Herein, a series of single-element doped manganese-based oxide cathodes K0.5Mn0.98X0.02O2 (X = Fe, Mg, Cu, Ti and Zn) are designed and investigated. The results demonstrate that trace doping with these elements stabilizes the layered structure of KMnO2 cathode materials, improves the diffusion coefficient of K+, and effectively suppresses the P3-O3-P3 phase transition in high-voltage regions. Among the doping-samples, the K0.5Mn0.98Fe0.02O2 exhibits outstanding reversible specific capacity of 127 mAh g−1 at a current density of 20 mA g−1. Meanwhile, K0.5Mn0.98Ti0.02O2 demonstrates exceptional cycling stability and rate capability, retaining 83.8 % of its initial capacity after 300 cycles at 200 mA g−1, and maintaining a high specific capacity close to 40 mAh g−1 even at 1000 mA g−1. This study validates the feasibility of trace element doping in enhancing the electrochemical performance of layered Mn-based cathode materials for PIBs.

High-entropy doping for high-voltage LiCoO2 with enhanced electrochemical performances

Lithium cobalt oxide (LiCoO2), as a pioneering layered oxide cathode material for lithium-ion batteries (LIBs), possesses exceptional theoretical specific capacity and cycling stability, positioning it as a leading candidate for commercial LIB applications. Boosting the upper-limit of charge voltage of LiCoO2 is a promising strategy to increase the capacity of batteries, vital for advancing energy storage solutions from portable electronics to electric vehicles. Nevertheless, hybrid redox reactions at high voltages speed up oxygen evolution, electrolyte decomposition, and irreversible phase transitions, ultimately causing rapid capacity fading.To address these challenges, we present a novel approach to enhance the structural stability and electrochemical performances of LiCoO2 cathode via La-Al-Mg-Y high-entropy doping. This strategy significantly improves the high-voltage cycling stability of the cathode material by retaining 72.5 % of its initial capacity after 500 cycles at 5 C under 4.6 V. Furthermore, the structural change caused by the phase transition between the O3 and H1-3 phases is remarkably suppressed. This advancement in LIB cathode technology paves the way for the development of high performance batteries and it is crucial for meeting the growing demand for sustainable energy storage.

Surface structure reconstruction to suppress heterogeneous phase transformation for air-stable single crystalline O3-type sodium oxide

O3-type layered oxide cathode material for sodium-ion batteries (SIBs) has attracted much attention as one of the most viable candidates due to its high specific capacity and mature synthesis process, while the moisture sensitivity and harmful phase transformation lead to poor processing properties and unsatisfactory life-span, hindering its large-scale and commercial application. Herein, single crystallization strategy is adopted to enhance air stability and processing performance, and surface structure reconstruction for single crystalline cathode material O3-NaNi1/3Fe1/3Mn1/3O2 by ammonium tetraborate pretreatment is employed to further remove residual alkali and improve sodium ions diffusion dynamics and suppress heterogeneous phase transformation, achieving superior structure stability. Surface residual alkali is in-situ converted into a protective coating layer of Na2B4O7 and meanwhile partial B atoms enter into the interstitial site of sub-surface or near surface, which accelerates sodium ions transport as well as enhances TM-O bonding and hybridization of surface O (2p)-Fe (3d-t2g) orbital, inhibits TMO6 slabs gliding and strengthens structure on the surface and near surface. Additionally, the formed boron-rich surface exhibits high stability, effectively alleviating structural degradation from surface to bulk and enhancing air stability. Benefiting from the reconstructed surface structure, the modified single crystalline oxides (NFM@B) exhibit distinguished processing performance and electrochemical properties.

Synthesis of nano cubic microstructure LiNi0.8Co0.1Mn0.1O2 cathode materials via rapid precipitation assisted with hydrothermal treatment

In this work, a modified Ni-rich cathode material LiNi0.8Co0.1Mn0.1O2 with a unique nano cubic microstructure is successfully synthesized via a rapid precipitation assisted with hydrothermal treatment. The formation of this distinctive microstructure is attributed to the homogeneous rapid precipitation in microreactor, which predominantly generates uniform crystal nuclei. The as-prepared material with nano-/microstructure shows superior initial reversible capacity (205.3 mAh·g−1 at 2.7–4.3 V) and rate capability (163.9 mAh·g−1 at 5 C). Additionally, it maintains a high capacity (188.2 mAh·g−1) with a retention of 87.2 % at 1 C after 200 cycles, demonstrating outstanding cycling stability. Our work presents a straightforward and efficient approach for producing nano-cubic microstructure layered cathode materials.

Robust interface for O3-type layered cathode towards stable ether-based sodium-ion full batteries

Developing a robust cathode-electrolyte interface (CEI) is crucial for stable layered cathode in sodium-ion batteries (SIBs). A CEI based on ester electrolytes often exhibit poor stability and robustness, which cannot address the issues of structural collapse and material dissolution in layered cathodes. However, there are few reports on constructing a stable CEI for layered cathode based on ether electrolytes. Here we develop a robust CEI for O3-type cathode via DME solvent, which enables a long-term stability of full SIBs. The results indicate that unique decomposition process of DME yields favorable organic component (e.g. RCH2ONa) and high content of inorganic components (e.g. NaF and Na2CO3) in the CEI, which is quite different from ester electrolyte, improving Na+ diffusion kinetic and interfacial stability. Notably, the O3-NaNi0.5Mn0.5O2||Na cell with the designed electrolyte demonstrates outstanding stability up to 500 cycles. Furthermore, the full cell exhibits remarkable cycling performance with a capacity retention of 85% over 200 cycles. This work provides an opportunity for stable operation of layered cathode materials via inexpensive ether electrolytes.

Recent Advances in High-Entropy Layered Oxide Cathode Materials for Alkali Metal-Ion Batteries.

Since the electrochemical de/intercalation behavior is first detected in 1980, layered oxides have become the most promising cathode material for alkali metal-ion batteries (Li+/Na+/K+; AMIBs) owing to their facile synthesis and excellent theoretical capacities. However, the inherent drawbacks of unstable structural evolution and sluggish diffusion kinetics deteriorate their electrochemical performance, limiting further large-scale applications. To solve these issues, the novel and promising strategy of high entropy has been widely applied to layered oxide cathodes for AMIBs in recent years. Through multielement synergy and entropy stabilization effects, high-entropy layered oxides (HELOs) can achieve adjustable activity and enhanced stability. Herein, the basic concepts, design principles, and synthesis methods of HELO cathodes are introduced systematically. Notably, it explores in detail the improvements of the high-entropy strategy on the limitations of layered oxides, highlighting the latest advances in high-entropy layered cathode materials in the field of AMIBs. In addition, it introduces advanced characterization and theoretical calculations for HELOs and proposes potential future research directions and optimization strategies, providing inspiration for researchers to develop advanced HELO cathode materials in the areas of energy storage and conversion.

Machine learning descriptors for crystal materials: applications in Ni-rich layered cathode and lithium anode materials for high-energy-density lithium batteries

Lithium batteries have revolutionized energy storage with their high energy density and long lifespan, but challenges such as energy density limitations, safety, and cost still need to be addressed. Crystalline materials, including Ni-rich cathodes and lithium anodes, play pivotal roles in the performance of high-energy-density lithium batteries. Understanding the micro-scale behavior and degradation mechanisms of these materials is crucial for improving macro-scale battery performance. Simulation methods, particularly machine learning (ML) techniques, have become indispensable tools in elucidating these intricate processes because of great efficiency and acceptable accuracy. ML methods depend on descriptors, which bridge the gap between crystal structures and input matrices of models. These descriptors encode essential atomic-level details in crystal structures, enabling predictions of material properties and behaviors relevant to lithium batteries. This paper reviews and discusses the diverse array of descriptors employed in the simulation of crystalline materials for lithium batteries with high energy density. Case studies highlight the effectiveness of different descriptors in simulating cathode behaviors such as Li/Ni disordering, screening of stable LiNi0.8Co0.1Mn0.1O2 (NMC811) configurations, and lithium deposition behaviors at the anode interface. The discussed descriptors can also be applied to other crystalline cathode, anode, and electrolyte materials in lithium batteries and advance the development of lithium batteries with superior energy density.

Electrochemical performance of ultra-high‑nickel layered oxide cathode synthesized using different lithium sources

Ultra-high‑nickel layered oxide cathodes are extensively explored in lithium-ion battery research owing to their high specific capacity. However, the rapid decline in discharge specific capacity considerably limits their long-term performance. The choice of lithium precursors is crucial in enhancing both the structural and cycle stability of these batteries, yet this aspect has not been adequately addressed in existing studies. In this study, Li2O, LiOH, and Li2CO3 were used as lithium precursors to synthesize LiNi0.92Co0.04Mn0.04O2 (NCM92) cathodes. We compare the structure and electrochemical properties of NCM92 cathode materials prepared with these three lithium precursors, examining a lithium residual layer on the surface of three NCM92 and thus inferring the varying amounts of Li incorporation into the bulk lattice. Our findings highlight the effect of lithium precursors on the rapid degradation of NCM92's discharge capacity. Notably, the NCM92–Li2O cathode demonstrates a higher discharge specific capacity and superior capacity retention after 100 cycles compared to cathodes synthesized with LiOH and Li2CO3. This study provides valuable insights and guidance for further research on ultra-high‑nickel layered oxide cathode materials.

High-Entropy Layered Oxide Cathode Materials with Moderated Interlayer Spacing and Enhanced Kinetics for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) with low cost and environmentally friendly features have recently attracted significant attention for renewable energy storage. Sodium layer oxides stand out as a type of promising cathode material for SIBs owing to their high capacity, good rate performance, and high compatibility for manufacturing. However, the poor cycling stability of layer oxide cathodes due to structure distortion greatly impacts their practical applications. Herein, a high entropy doped Cu, Fe, and Mn-based layered oxide (HE-CFMO), Na0.95Li0.05Mg0.05Cu0.20Fe0.22Mn0.35Ti0.13O2 for high-performance SIBs, is designed. The HE-CFMO cathode possesses high-entropy transition metal (TM) layers with a homogeneous stress distribution, providing a moderated interlayer spacing to maintain the structure stability and enhance Na+ ion diffusion. In addition, Li doping in TM layers increases the Mn valence state, which effectively suppresses John-Teller effect, thus stabilizing the layered structure during cycling. Furthermore, the use of nontoxic and low-cost raw materials benefits future commercialization and reduces the risk of environmental pollution. As a result, the HE-CFMO cathode exhibits a super cycling performance with a 95% capacity retention after 300 cycles. This work provides a promising strategy to improve the structure stability and reaction kinetics of cathode materials for SIBs.

Bifunctional modulation of Li-rich layered oxide cathode material via W-modification for improved electrochemical performance

Lithium-rich layered oxides (LRLOs) have raised the greatest attention to the high-energy-density Li-ion batteries. Nevertheless, the undesirable interfacial side reactions and the structure transformation cause fast voltage fading and poor capacity retention of LRLO cathodes, which extremely prevent their practical application. Surface coating or lattice doping has been an effective strategy to improve its electrochemical properties. However, the general performance of the material can only be limitedly promoted. Herein, we proposed a bifunctional modulation of LRLO cathodes coupled by bulk-phase W-doping and surficial Li2WO4 nanocoating of LRLOs using a facile synchronous lithiation strategy under a high-temperature solid-state treatment. The modified material (2 mol% W6+ modified) showed a distinguished discharge capability of 260.5 mAh/g at 0.1 C after 50 cycles. Meanwhile, a competitive capacity retention of 95.38% at 1 C after 100 cycles was achieved. The splendid electrochemical performance can be the result of the increased interlayer spacing for enhancing Li+ diffusion kinetics and the stronger W–O bond for alleviating oxygen release after W-doping and Li2WO4 nanocoating, which not only accelerates the Li+ transfer rate as its fast Li+ transfer channels but also act as a transitional interface layer to restrain the interfacial adverse reactions.

Enhanced cyclability and energy density of mid-nickel layered oxide cathode material LiNi0.55Mn0.25Co0.20O2 by niobium doping via solvothermal method

Ni-based layered oxide materials are among the most promising cathode materials for the next generation of lithium-ion batteries due to their higher energy capacity. However, capacity decay occurs due to degradation mechanisms that reduce the electrochemical performance of this type of material. This work aims to synthesize Nb-doped LiNi0.55Mn0.25Co0.20O2 (Nb-NCM) materials via the solvothermal method to enhance the cyclability and energy density of the layered oxide cathode. The effects of Nb doping on the microstructure and the electrochemical performance of the cathodes are investigated. The introduction of the contents of Nb expands the structural lattice parameters and decreases the Li+/Ni2+ cation mixing degree of the NCM cathode. Furthermore, the Nb doping enhances the electrochemical activity of LiNi0.55Mn0.25Co0.20O2, increasing its initial discharge capacity to 169.61 mAhg−1 when 1% of Nb was used as a dopant (1%Nb-NCM) in contrast to the capacity of 149.45 mAhg−1 presented by the pristine material. The modified 1.0%Nb-NCM material also exhibits remarkable cycling performance with a capacity retention of 92.7% after 100 cycles at the rate of 1 C (2.8–4.3 V). This work suggests a rational strategy for high-performance cathode for lithium-ion batteries, proposing the extension of Nb doping to enhance Ni-mid material's cyclability.

High-Volumetric-Energy-Density Cathode Material from Single-Sized Precursor via Precise Additive Control

To overcome the energy density limitations of current layered cathode materials, high-nickel cathode materials with a bimodal distribution composed of ∼ 15um-sized secondary particles and micron-sized single crystals are synthesized from a single-sized high-nickel precursor by incorporating the grain-growth promoting/inhibiting additive. Synthesized cathode material effectively reduces the pores within the electrode and shows an excellent electrode density of > 3.9 g/cm3, exceeding ∼ 80 % of the theoretical density. In addition, due to efficient contact between large secondary particles and small single crystals, bimodal particles with additives show higher electrical conductivity compared to additive-free monomodal secondary particles, and a capacity of ∼ 220 mAh/g is achieved even at a high loading level of ∼ 30 mg/cm2 and 96 % active-material fraction. Based on remarkable electrode density and high capacity, it is possible to realize a volumetric energy density of more than 700 mAh/cm3. To the best of our knowledge, this is the highest energy density result for electrodes made from layered cathode materials. Moreover, through the synergistic effect of morphology control by selective additives and surface coating, the synthesized bimodal cathode simultaneously exhibits excellent capacity as well as improved cycle-life performance compared to a bare cathode without additives. The enhanced electrochemical performance is attributed to increased connectivity between individual cathode particles, decreased bulk/surface resistance, and reduced intergranular cracks after cycling through structure design by additives, which is confirmed through various electrochemical analyses and electrode observations.

Effect of Rare Earth Ion Doping on the Performance of Lithium-Rich Cathode Materials for Lithium-Ion Batteries

Lithium-rich layered oxide cathode materials have the advantages of a high voltage and a high specific capacity. Their commercial applications have however been impeded by some disadvantages such as low initial coulombic efficiency and low cycle life. To overcome these issues, rare earth ion-doped lithium-rich layered oxide cathode materials are investigated in this work. The irreversible release of O2- in Li2MnO3 is suppressed by rare earth ions doping, which enhanced the initial coulombic efficiency of the materials. Meanwhile, the rare-earth ion radius used for doping is larger than the Mn4+ radius, which enlarges the (003)-crystalline plane spacing, resulting in a significant enhancement of the rate performance of the material.

Low-crystalline 1T/2H-MoSe2 heterostructure as the high-rate and ultra-long-lifespan cathode materials for magnesium ion batteries

Two-dimensional layered-like materials are attracted extensive attention to be the potential cathode materials for magnesium ion batteries because of the wide layer distances and high capacities. Whereas such strong interaction between bivalent Mg2+ and layered cathode materials is prone to cause the slow diffusion kinetics, and irreversible electrochemical reaction, finally bringing about the low specific capacity and inferior rate capability. Meanwhile, limited by the inherent crystal structure of MoSe2 and unsuitable electrolyte, the magnesium storage properties are not ideal. Herein, the low-crystalline 1T/2H-MoSe2 heterostructure (LC-MoSe2) is synthesized via one-step hydrothermal method. Such low-crystalline feature of LC-MoSe2 and MgCl+ in the electrolyte significantly decrease the Mg2+ diffusion barrier, and largely promote the Mg2+ diffusion kinetics. The rich heterogeneous interfaces in the 1T/2H-MoSe2 boost the electron/ion transfer kinetics and endow plentiful active sites for the Mg2+ storage. As expected, the LC-MoSe2 exhibits a high discharge capacity (257.4 mAh g−1/0.5 A g−1/200 cycles) and stable long-span cyclic life of 2000/1000 loops even at 2/5 A g−1, distinctly transcending those of relatively high-crystalline MoSe2 (HC-MoSe2). Such electrode can also surprisingly cycle at an ultra-high rate of 10 A g−1. Meanwhile, the charge transfer/ion diffusion kinetics along with charge storage mechanism of LC-MoSe2 are carried out by various kinetics strategies from experimental and theoretical aspects. The reaction mechanism has also been discussed by some ex-situ characterization techniques. The remarkable Mg2+ storage properties of LC-MoSe2 cathode materials provide new ideas for the long-run development of MIBs.