High-entropy doped truncated octahedral spinel lithium nickel manganese oxide positive electrode material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of lithium batteries, in particular to a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide positive electrode material and a preparation method and application thereof, and the chemical general formula of the positive electrode material is LiNi < 0.5-a > Mn < 1.5-beta > M < x > O < 4 >, m is selected from at least three of Zr, Nb, Mo, Ta, W, Al, Zn, Mg, Ti, Fe, Cu, Co, Cr, V and Eu, x = a + beta, and x is larger than or equal to 0.01 and smaller than or equal to 0.20. The positive electrode material provided by the invention not only has LNMO particles with a single-crystal structure and regular truncated octahedron morphology and mainly exposes a {111} crystal face with stable thermodynamics, but also remarkably improves the intrinsic stability of the material by utilizing a high-configuration entropy effect through a component complicated region formed on an atomic scale through high-entropy doping. Multiple synergistic effects are generated through a high-entropy strategy, so that the positive electrode material shows excellent long cycle life and high rate performance under high voltage of 4.7 V.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, its preparation method, and its application. Background Technology

[0002] High-voltage spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4, LNMO) cathode materials are used due to their high operating voltage (~4.7V vs. Li). + Lithium-ion batteries, with their cobalt-free and saturated states (e.g., 4-Li₂O₃), are considered ideal candidates for next-generation high-energy-density lithium-ion batteries. However, this ultra-high voltage also pushes the material to the limits of its electrochemical stability, leading to serious intrinsic and interfacial instabilities. In a highly delithiated state, the material faces a thermodynamic tendency to lose lattice oxygen. The released oxygen not only leads to the loss of active materials but also reacts violently with organic electrolytes, becoming a key factor in causing safety hazards such as battery swelling and thermal runaway.

[0003] In addition, Mn in the material 3+ The Jahn-Teller distortion and disproportionation of ions further induced the manganese dissolution problem. Dissolved Mn 2+ Ions not only disrupt the bulk structure of the positive electrode but also migrate to the negative electrode, poisoning the solid electrolyte interphase (SEI). This causes repeated SEI rupture and regeneration, continuously consuming active lithium and electrolyte, ultimately leading to a surge in battery impedance and a sharp drop in capacity. Furthermore, the two-phase transformation, rather than the mild solid solution reaction, that occurs in LNMO during charge and discharge generates significant lattice mismatch and internal stress within the particles. Repeated volume changes and stress accumulation cause microcracks to form in the particles. These newly generated cracks are exposed to the electrolyte, accelerating side reactions and creating a vicious cycle of performance degradation. These intrinsic instabilities directly lead to extremely severe electrode-electrolyte interface problems.

[0004] To address these challenges, traditional elemental doping strategies (such as introducing single or binary dopants like Al and Mg) have limited effectiveness and struggle to solve multiple instability issues simultaneously.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, its preparation method and application, aiming to solve the problems of interface instability and short cycle life of existing spinel-type lithium nickel manganese oxide materials under high voltage.

[0007] The technical solution of the present invention is as follows: A high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, wherein the general chemical formula of the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material is LiNi. 0.5-a Mn 1.5-β M x O4; wherein M is selected from at least three of Zr, Nb, Mo, Ta, W, Al, Zn, Mg, Ti, Fe, Cu, Co, Cr, V, and Eu, and x = a + β and 0.01 ≤ x ≤ 0.20.

[0008] The high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, wherein 0≤a≤0.20, 0≤β≤0.20.

[0009] The high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material has the following properties: 0.01≤a≤0.05, 0.04≤β≤0.15, and 0.08≤x≤0.15.

[0010] The high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, wherein M comprises Zr and Nb, and at least two of Mo, Ta, W, Al, Zn, Mg, Ti, Fe, and Cu.

[0011] The high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material has a particle size of 1μm-10μm and a D50 of 2μm-6μm.

[0012] A method for preparing a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material includes the following steps: A mixture is obtained by mixing a lithium source, a nickel source, a manganese source, and a metal oxide or salt corresponding to the dopant element M. The mixture was subjected to pre-sintering and sintering treatments in sequence, and then ground to obtain a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material. Alternatively, the mixture can be mixed with a eutectic salt, calcined, and then ground to obtain a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material.

[0013] The method for preparing the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, wherein the lithium source is selected from one or more of Li2CO3, LiCH3COO, Li2C2O4, LiOH·H2O, and LiOH; the nickel source is selected from one or more of NiO, Ni(NO3)2·6H2O, Ni(CH3COO)2, Ni(OH)2, and NiCO3; and the manganese source is selected from one or more of MnO2, Mn2O3, MnCO3, Mn(NO3)2·4H2O, and Mn(CH3COO)2.

[0014] The method for preparing the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material includes a pre-sintering treatment temperature of 400℃-650℃ and a pre-sintering treatment time of 4h-6h; and a sintering treatment temperature of 850℃-950℃ and a sintering treatment time of 10h-20h.

[0015] The method for preparing the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, wherein the calcination temperature is 800℃-950℃ and the calcination time is 6h-12h.

[0016] Application of a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material in lithium-ion batteries.

[0017] Beneficial effects: This invention provides a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, its preparation method, and its application. The general chemical formula of the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material is LiNi. 0.5- a Mn 1.5-β M x O4; wherein M is selected from at least three elements selected from Zr, Nb, Mo, Ta, W, Al, Zn, Mg, Ti, Fe, Cu, Co, Cr, V, Eu, etc., and x = a + β and 0.01 ≤ x ≤ 0.20. The cathode material provided by this invention has a unique structure, which not only has a single crystal structure and regular truncated octahedral LNMO particles, mainly exposing the thermodynamically stable {111} crystal plane, but also significantly improves the intrinsic stability of the material by utilizing the high configurational entropy effect through the compositional complexity region formed at the atomic scale by high entropy doping. Furthermore, this invention generates multiple synergistic effects through the high entropy strategy, including: a severe lattice effect that reduces the lithium-ion migration barrier and improves rate performance; a hysteresis diffusion effect that significantly inhibits manganese dissolution and oxygen loss; and a thermodynamic stabilization effect that inhibits harmful phase transitions. Under multiple synergistic effects, this cathode material exhibits extremely long cycle life and excellent high-rate performance at a high voltage of 4.7V, fundamentally solving the interface stability problem of high-voltage LNMO cathodes and providing key material support for the development of next-generation lithium-ion batteries with high energy density and high safety. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of a method for preparing a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material according to the present invention. Figure 2 SEM image of the quaternary high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material prepared in Example 1; Figure 3 XRD pattern; Figure 4 This is a discharge rate diagram; Figure 5 This is a long cycle life diagram; Figure 6 For LiNi 0.5 Mn 1.46 M 0.04 SEM image of O4; Figure 7 For LiNi 0.47 Mn 1.41 M 0.12 SEM image of O4; Figure 8 SEM image of undoped octahedral LNMO; Figure 9 SEM image of undoped truncated octahedral LNMO; Figure 10 For LiNi 0.5 Mn 1.48 Al 0.02 SEM image of O4. Detailed Implementation

[0019] This invention provides a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, its preparation method, and its applications. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0020] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0021] Existing spinel lithium nickel manganese oxide cathode materials suffer from instability, directly leading to extremely severe electrode-electrolyte interface problems. The operating voltage of 4.7V far exceeds the electrochemical stability window of conventional carbonate-based electrolytes, causing severe oxidative decomposition of the electrolyte on the cathode surface, forming a thick, porous cathode electrolyte interphase (CEI) film with low ionic conductivity. This unstable CEI film continuously consumes active lithium and electrolyte, significantly increasing interfacial impedance, resulting in increased polarization, decreased rate performance, and accelerated capacity decay.

[0022] Existing elemental doping strategies offer limited benefits and struggle to simultaneously address multiple instabilities. The limited variety of doping elements and low configurational entropy gain are insufficient to effectively suppress elemental segregation and phase transitions. Surface coating is another widely studied strategy; however, its application is significantly limited. Wet chemical methods (such as sol-gel methods) struggle to achieve nanoscale, continuous, and dense coatings on complex particle surfaces, and the coating layer exhibits weak adhesion to the substrate. More critically, while common insulating oxide coatings (such as Al2O3) provide a physical barrier, they severely hinder lithium-ion transport, significantly sacrificing the material's rate performance. Although techniques like atomic layer deposition (ALD) can achieve perfect coating, their expensive equipment and extremely slow deposition rates completely fail to meet the demands of large-scale power battery production.

[0023] Spinel-type LNMO materials suffer from severe interfacial instabilities under high voltage, including severe electrolyte oxidation and decomposition, manganese dissolution, and lattice oxygen loss, leading to short cycle life and safety risks. Traditional single-doping or surface coating strategies suffer from problems such as uneven coating, high interfacial impedance, or difficulty in scaling up processes, failing to fundamentally solve the aforementioned multi-dimensional degradation challenges.

[0024] Therefore, the technological background for developing high-voltage LNMO cathode materials is a series of interconnected problems. The root cause lies in the intrinsic instability of the material under high voltage, which directly triggers severe interfacial side reactions, ultimately leading to rapid degradation of electrochemical performance. Traditional solutions, however, face bottlenecks due to limited effectiveness or difficulty in scaling up. This urgently requires a revolutionary material design strategy and preparation method that can systematically and synergistically solve all stability challenges from the bulk phase to the interface, providing sufficient necessity and rationale for the subsequent innovative approach combining "high-entropy doping" with "truncated octahedral single-crystal substrates."

[0025] Based on this, the present invention provides a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, wherein the chemical formula of the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material is LiNi. 0.5-a Mn 1.5-β M x O4; wherein M is selected from at least three elements such as Zr, Nb, Mo, Ta, W, Al, Zn, Mg, Ti, Fe, Cu, Co, Cr, V, and Eu, and x = a + β and 0.01 ≤ x ≤ 0.20.

[0026] In this embodiment, the provided cathode material possesses a unique structure. It not only exhibits a single-crystal structure and a regular truncated octahedral morphology of LNMO particles, primarily exposing the thermodynamically stable {111} crystal plane, but also significantly enhances the intrinsic stability of the material through high-entropy doping of atomically complex regions, utilizing the high configurational entropy effect. Furthermore, this invention generates multiple synergistic effects through a high-entropy strategy, including: a severe lattice effect lowering the lithium-ion migration barrier and improving rate performance; a hysteresis diffusion effect significantly suppressing manganese dissolution and oxygen loss; and a thermodynamic stabilization effect suppressing harmful phase transitions. Under these multiple synergistic effects, this cathode material exhibits exceptionally long cycle life and outstanding high-rate performance at a high voltage of 4.7V, fundamentally solving the interfacial stability problem of high-voltage LNMO cathodes and providing crucial material support for the development of next-generation lithium-ion batteries with high energy density and high safety.

[0027] Specifically, the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material has an octahedral cross-section and a disordered spinel crystal structure (space group Fd-3m). This invention introduces various heterogeneous elements to generate severe lattice distortion in the spinel lattice, achieving high configurational entropy. This allows for the suppression of element migration and dissolution through its "hysteresis diffusion effect," the suppression of phase transitions and oxygen loss through its "thermodynamic stabilization effect," and the reduction of the lithium-ion migration barrier through its "lattice distortion effect." Simultaneously, it possesses a single-crystal structure and a regular truncated octahedral morphology, primarily exposing the thermodynamically stable {111} crystal plane, laying a solid foundation for intrinsic stability.

[0028] In some implementations, 0 ≤ a ≤ 0.20, 0 ≤ β ≤ 0.20, and a and β are not simultaneously 0. By controlling a and β, high-entropy doping of the dopant element M is achieved, resulting in severe lattice distortion in the spinel lattice and obtaining high configuration entropy. This allows the "hysteresis diffusion effect" to suppress element migration and dissolution, the "thermodynamic stabilization effect" to suppress phase transitions and oxygen loss, and the "lattice distortion effect" to reduce the lithium-ion migration barrier.

[0029] In some implementations, 0.05 ≤ x ≤ 0.20.

[0030] In a preferred embodiment, 0.01≤a≤0.05, 0.04≤β≤0.15, and 0.08≤x≤0.15.

[0031] In some implementations, the elements in the dopant element M are in equimolar ratios.

[0032] In some implementations, M comprises Zr and Nb, and at least two of Mo, Ta, W, Al, Zn, Mg, Ti, Fe, and Cu. When the doping element M is used in this combination, it can produce a significant high-entropy effect and a "cocktail" synergistic effect, perfectly solving the interfacial stability problem of high-voltage LNMO cathodes and achieving a balance between ultra-long cycle life and excellent rate performance.

[0033] In a preferred embodiment, M comprises Zr, Nb, and Mo, as well as at least one of the elements Ta, W, Al, Zn, Mg, Ti, Fe, Cu, Co, Cr, V, and Eu.

[0034] In some embodiments, the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material has a particle size of 1 μm-10 μm and a D50 of 2 μm-6 μm. Furthermore, the cathode material particles have a smooth surface and sharp edges, which is beneficial for exposing the thermodynamically stable {111} crystal planes.

[0035] In a preferred embodiment, the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material has a particle size of 1μm-5μm and a D50 of 2μm-3μm.

[0036] In this embodiment, high-entropy doping optimizes material performance through multi-dimensional synergistic effects. Its specific mechanisms can be divided into the following four aspects, with each mechanism working together to achieve performance improvement: 1. Constructing efficient ion transport channels At the 16d lattice sites of the material, multiple elemental ions with different ionic radii and electronegativity coexist. This mixed distribution of multiple ions induces significant lattice distortion, which effectively weakens the lattice's binding effect on lithium ions and substantially reduces the lithium content. + The migration energy barrier is reduced, which ultimately significantly improves the ionic conductivity inside the material, providing a structural basis for the rapid transport of lithium ions.

[0037] 2. Suppressing side reactions and structural degradation The unique chemical environment created by high-entropy doping significantly reduces the diffusion kinetics of elements in the material. This effect can improve the stability of the material in several ways: firstly, it effectively inhibits the migration and dissolution of transition metal ions into the electrolyte during cycling; secondly, it slows down the phase transition process of the material during charge-discharge cycles, promoting the transformation of the traditional two-phase reaction mode to a more stable solid solution reaction mode, thereby reducing the structural stress and performance degradation caused by phase transition.

[0038] 3. Improve the stability of the system architecture The high configurational entropy of a high-entropy system can significantly reduce the Gibbs free energy of the system through thermodynamic correlation. This thermodynamic property directly improves the intrinsic stability of the material, specifically manifested in two core advantages: first, it effectively suppresses the formation of various impurity phases during the reaction process, ensuring the integrity of the main phase structure; second, it significantly reduces the risk of oxygen precipitation under high temperature or cycling conditions, avoiding structural collapse and performance failure caused by oxygen loss.

[0039] 4. Achieve comprehensive performance optimization In high-entropy systems, multiple dopants do not simply stack up, but rather exert their combined effectiveness through a "cocktail"-like synergistic effect: for example, Zr 4+ With Nb 5+ Its inherent properties can strengthen the crystal lattice structure and improve the mechanical stability of materials; Mo 6+ It can precisely adjust the electronic band structure of materials and optimize electron transport performance; Al 3+ With Mg 2+ The strong interaction between these elements and oxygen atoms stabilizes the oxygen lattice and suppresses the generation of oxygen defects. The synergistic effect of these elements comprehensively enhances the overall performance of the material.

[0040] In addition, such as Figure 1 As shown, the present invention also provides a method for preparing a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, comprising the following steps: Step S10: Mix the lithium source, nickel source, manganese source, and the metal oxide or salt corresponding to the doping element M to obtain a mixture; Step S20: The mixture is subjected to pre-sintering and sintering treatments in sequence, and after grinding, a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material is obtained. Alternatively, the mixture can be mixed with a eutectic salt, calcined, and then ground to obtain a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material.

[0041] In this embodiment, a one-step high-temperature solid-state sintering method or molten salt method is employed. By controlling the stoichiometric ratio of lithium, nickel, manganese, and various dopant sources, and after thorough mixing, high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material is directly synthesized through a "pre-sintering + sintering" or calcination process. This method is simple, easy to scale up, and achieves uniform solid solution of multiple elements at the atomic scale and controllable growth of truncated octahedral morphology. Furthermore, the cathode material prepared using this method exhibits multiple synergistic effects through a high-entropy strategy, including: a severe lattice effect that lowers the lithium-ion migration barrier and improves rate performance; a hysteresis diffusion effect that significantly inhibits manganese dissolution and oxygen loss; and a thermodynamic stabilization effect that suppresses harmful phase transitions. Under these multiple synergistic effects, the cathode material exhibits extremely excellent long cycle life and outstanding high-rate performance at a high voltage of 4.7V, fundamentally solving the interfacial stability problem of high-voltage LNMO cathodes and providing key material support for the development of next-generation lithium-ion batteries with high energy density and high safety.

[0042] Specifically, this preparation method systematically introduces the material design concept of "high entropy effect" into the high-pressure spinel cathode material system. By introducing four or more heterogeneous elements to synergistically modify the crystal lattice, the resulting ultra-high configurational entropy is used to significantly reduce the Gibbs free energy of the system. Thermodynamically, this drives the material to tend towards the formation of a stable and uniform solid solution phase, rather than an unfavorable precipitated phase. The "severe lattice distortion" and "hysteresis diffusion effect" induced by the high entropy environment fundamentally suppress transition metal ions (especially Mn). 3+ The migration and dissolution of lithium ions, as well as the phase transition kinetics during charging and discharging, have led to a breakthrough improvement in the bulk stability of the material. Furthermore, through the synergistic design of "high-entropy doping" and "single-crystal truncated octahedral matrix," the stability of both the bulk and interface is simultaneously enhanced. While stabilizing the bulk phase, high-entropy doping also effectively reduces the lithium-ion migration energy barrier through its "lattice distortion effect," avoiding the inherent defect of sacrificing rate performance in traditional insulating coatings. The pre-constructed single-crystal truncated octahedral matrix, with its inherently low-surface-energy stable crystal planes (such as the {111} plane), lays the foundation for intrinsic interface stability, producing a synergistic effect of "1+1>2" with the interface stabilization effect of high-entropy doping, thus systematically solving the problem of multiple failures under high voltage. Meanwhile, in terms of preparation technology, the traditional and complex two-step route of "synthesis first, coating later" has been abandoned. Instead, a high-temperature solid-state sintering method or molten salt method is innovatively adopted to directly achieve atomic-level uniform solid solution of multiple elements and controllable growth of truncated octahedral single crystal morphology through a one-step reaction. This method is simple, reproducible, and easy to scale up, cleverly solving the technical problem of component segregation and second-phase precipitation caused by multi-element doping. It provides a reliable technical path for the efficient and low-cost preparation of high-entropy materials.

[0043] In some embodiments, the lithium source is selected from, but not limited to, one or more of Li2CO3, LiCH3COO, Li2C2O4, LiOH·H2O, and LiOH; the nickel source is selected from, but not limited to, one or more of NiO, Ni(NO3)2·6H2O, Ni(CH3COO)2, Ni(OH)2, and NiCO3; and the manganese source is selected from, but not limited to, one or more of MnO2, Mn2O3, MnCO3, Mn(NO3)2·4H2O, and Mn(CH3COO)2.

[0044] In some embodiments, the molar ratio between the lithium source, nickel source, manganese source, and the metal oxide or salt corresponding to the dopant element M is expressed by the general chemical formula LiNi. 0.5-a Mn 1.5-β M x O4 is used for calculation; preferably, the lithium salt can be in excess by 2%-5% to compensate for sintering losses.

[0045] In some embodiments, the metal oxides corresponding to the dopant element M include, but are not limited to, ZrO2, Nb2O5, MoO3, Ta2O5, WO3, Al2O3, ZnO, MgO, TiO2, Fe3O4, CuO, etc.; the salts corresponding to the dopant element M include, but are not limited to, carbonates and oxalates; carbonates include, but are not limited to, ZnCO3, MgCO3, CuCO3, etc.; oxalates include, but are not limited to, MgC2O4·2H2O, ZrOC2O4·nH2O, [NbO(C2O4)2]·nH2O, Al2(C2O4)3·xH2O, ZnC2O4·2H2O, etc.

[0046] In some embodiments, the pre-sintering treatment temperature is 400℃-650℃, and the pre-sintering treatment time is 4h-6h; the sintering treatment temperature is 850℃-950℃, and the sintering treatment time is 10h-20h. Pre-sintering decomposes organic matter and nitrates; then, sintering provides the necessary oxidation state basis for constructing a high-voltage spinel LNMO structure. The sintering temperature and time are crucial to ensuring sufficient element diffusion, forming a high-entropy solid solution rather than an impurity phase. Preferably, the pre-sintering treatment temperature is 500℃-600℃.

[0047] Specifically, the high-temperature solid-state synthesis of LNMO materials involves two key heat treatment stages: pre-sintering and main sintering. The primary function of pre-sintering is to induce preliminary thermal decomposition and oxidation reactions of the lithium, nickel, and manganese sources in the mixture. Within this temperature range, the carbonate precursor releases gases such as CO2 and H2O, transforming into the corresponding transition metal oxides. XRD analysis indicates that some intermediate phases, such as layered P2-type structures or spinel-type impurity phases (e.g., LiMn2O4), begin to form at this stage. Simultaneously, the valence state of manganese undergoes a significant change during this stage, from the initial Mn... 2+ or Mn 3+ Gradually oxidized by oxygen in the air to Mn 4+ This provides the necessary oxidation state basis for constructing the high-voltage spinel LNMO structure in the subsequent main sintering stage.

[0048] The main calcination stage (850–950°C) involves prolonged high-temperature calcination (typically 10–20 hours) in an air or oxygen atmosphere. This is a crucial step in the final formation and refinement of the LNMO spinel structure. At this high temperature, sufficient solid-state diffusion and chemical reactions occur between the lithium source and the transition metal oxide, generating thermodynamically stable LiNi. 0.5 Mn 1.5 O4 phase. Sintering temperature has a decisive influence on the crystal structure of the final product: when the temperature is ≥800°C, atomic migration ability is enhanced, and Ni and Mn tend to be randomly distributed at 16d octahedral sites, forming a disordered Fd-3m space group structure; while if the sintering temperature is lower (≤700°C), it is easier to form a Ni / Mn ordered P4332 space group structure. Current research shows that the disordered Fd-3m phase has become a research focus of high-performance LNMO cathode materials due to its higher lithium-ion diffusion coefficient and better cycle stability. At the same time, high temperature also promotes grain growth and improves crystallinity, making diffraction peaks sharper and reducing lattice defects. However, with increasing temperature, the tendency for oxygen vacancies to form also increases—this is due to the partial escape of lattice oxygen at high temperatures, and the increase in oxygen vacancy concentration will directly affect the valence state balance of transition metals, which may lead to a small amount of Mn. 4+ Reduced to Mn³ + This can affect the electrochemical platform and structural stability of the material. Therefore, while ensuring sufficient reaction and high crystallinity, it is necessary to precisely control the sintering temperature, holding time, and oxygen partial pressure in the atmosphere to achieve the best balance between phase purity, order, oxygen content, and electrochemical performance.

[0049] In some embodiments, the calcination temperature is 800℃-950℃, and the calcination time is 6h-12h. During the calcination process, molten salt is used as the reaction medium, which can promote ion diffusion and anisotropic crystal growth, making it easier to obtain truncated octahedral particles with regular morphology; and the molten salt needs to be removed after calcination.

[0050] Specifically, this temperature range and a sufficiently long holding time facilitate the dissolution and re-precipitation of metal ions in the molten salt medium, thereby enabling preferential growth along specific crystal planes to form a truncated octahedral morphology composed of 8 {111} triangular facets and 6 {100} tetrahedrons. Increasing the molten salt ratio or introducing trace amounts of surfactants such as citric acid can further regulate the crystal facet exposure behavior. After the reaction is complete, the mixture is naturally cooled to room temperature, repeatedly washed with boiling water to thoroughly remove the eutectic salt, and then centrifuged or filtered before being vacuum dried at 60°C to obtain a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material.

[0051] In some embodiments, the eutectic salt includes, but is not limited to, NaCl-KCl eutectic salt, KCl-ZnCl2 eutectic salt, NaCl-KCl-ZnCl2 eutectic salt, and MgCl2-KCl-NaCl eutectic salt.

[0052] In some embodiments, before calcination, the mixture and the eutectic salt mixture are kept at 400-650°C for 1-2 hours in an air or oxygen atmosphere to complete dehydration and nitrate decomposition.

[0053] In this embodiment, the method is simple, abandoning the complex multi-step coating process, and is easily scaled up to industrial production. It perfectly achieves uniform solid solution of multiple elements at the atomic scale and controllable growth of truncated octahedral morphology. The material prepared by the above process exhibits a unique microstructure. Scanning electron microscopy observation shows that the obtained material consists of regular truncated octahedral single crystal particles with a particle size of 1.0 to 5.0 micrometers. More importantly, elemental mapping analysis clearly shows that various doping elements (such as Zr, Nb, Mo, Al, Fe, Cu, Co, Cr, V, Eu, etc.) are uniformly distributed at the atomic level within the particle, successfully forming a high-entropy solid solution rather than heterogeneous precipitation. Furthermore, this unique structure translates into excellent electrochemical performance. In half-cell tests (3.5-4.9V), the material exhibits extremely excellent long cycle life and rate performance. For example, after 1000 cycles at 1C, the capacity retention exceeds 90%, significantly better than undoped samples (approximately 64.5%) and traditional single-doped samples (approximately 70%). Meanwhile, the capacity retention at a high 5C rate reaches over 86% of the 0.1C discharge capacity, demonstrating that the material design provides protection without sacrificing kinetic performance.

[0054] In some embodiments, in step S20, after grinding, the material is passed through a 200-mesh sieve to obtain a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material.

[0055] In addition, the present invention also provides the application of a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material in lithium-ion batteries.

[0056] In this embodiment, the cathode material is applied to lithium-ion batteries, exhibiting extremely long cycle life and excellent high-rate performance at a high voltage of 4.7V. This fundamentally solves the interfacial stability problem of high-voltage LNMO cathodes and provides key material support for the development of next-generation lithium-ion batteries with high energy density and high safety.

[0057] In some embodiments, the lithium-ion battery includes a positive electrode; the positive electrode contains the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide positive electrode material.

[0058] In summary, the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material provided by this invention has the following effects: 1) Significantly improves structural stability: The high entropy effect strongly suppresses the two-phase transformation during the charging and discharging process, making it more inclined to solid solution reaction, greatly reducing volumetric strain and mechanical stress, and effectively preventing particle cracking.

[0059] 2) Effectively inhibits manganese dissolution and oxygen loss: The delayed diffusion effect significantly reduces the migration and dissolution rate of Mn ions; multiple doping elements work together to stabilize the oxygen lattice, inhibit oxygen release, and improve the safety of the material.

[0060] 3) Enhanced ionic conductivity and rate performance: Severe lattice distortion in Li + It provides a more relaxed migration channel and reduces the diffusion barrier, thereby improving the rate performance of the material.

[0061] 4) Simple and controllable process: The one-step sintering process is mature and easy to scale up, overcoming the cumbersome and high-cost problems of complex multi-layer coating processes.

[0062] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0063] Example 1 This embodiment provides a quaternary high-entropy doped (Zr, Nb, Mo, Al) truncated octahedral spinel lithium nickel manganese oxide cathode material with a chemical composition of LiNi.0.48 Mn 1.42 Zr 0.02 Nb 0.02 Mo 0.02 Al 0.02 O4 (total doping amount x=0.08) was used in a high-temperature solid-state method. Li2CO3 (5wt% excess), NiO, MnO2, ZrO2, Nb2O5, MoO3, and Al2O3 were weighed according to the stoichiometric ratio, ball-milled and mixed for 12 hours, then pressed into tablets, pre-calcined at 450℃ in air for 5 hours, and then sintered at 900℃ for 15 hours. After furnace cooling, the cathode material was obtained.

[0064] The SEM image of the cathode material prepared in this embodiment is shown below. Figure 2 As shown, the product consists of regular truncated octahedral particles with a particle size of 1-5 μm. The XRD pattern is shown below. Figure 3 As shown, it exhibits a pure spinel phase (Fd-3m) with no impurity peaks. Rietveld refinement indicates a slight increase in lattice parameter a. EDS surface scanning confirms that Zr, Nb, Mo, and Al are uniformly distributed within the grain.

[0065] Discharge rate diagram as follows Figure 4 As shown, the long cycle life diagram is as follows: Figure 5 As shown, half-cell testing (3.5-4.9V) revealed that the material's initial discharge capacity was 135mAh / g, and its capacity retention rate was as high as 92.5% after 1000 cycles at 1C. At a high 5C rate, the capacity retention rate was 87% of the 0.1C discharge capacity.

[0066] Example 2 This embodiment studies the effect of total doping amount on the structural stability and electrochemical performance of the material, as detailed below: The doping elements are fixed at Zr, Nb, Mo, and Al (equal molar ratio), and the total doping amount x is varied. The remaining preparation process is the same as in Example 1. This includes: Example 2a: Low-entropy doping, x=0.04 (LiNi) 0.5 Mn 1.46 M 0.04 O4).

[0067] Example 2b: High-entropy doping, x=0.12 (LiNi) 0.47 Mn 1.41 M 0.12 O4).

[0068] LiNi 0.5 Mn 1.46 M 0.04 SEM image of O4 as follows Figure 6 As shown, LiNi 0.47 Mn 1.41M 0.12 SEM image of O4 as follows Figure 7 As shown.

[0069] XRD characterization results are as follows Figure 3 As shown, XRD revealed that all samples were of the spinel phase. With increasing x, the diffraction peaks broadened slightly and shifted to lower angles, indicating increased lattice expansion and distortion.

[0070] Discharge rate diagram as follows Figure 4 As shown, the long cycle life diagram is as follows: Figure 5 As shown, cycling performance tests revealed that the capacity retention (80% after 1000 cycles) of Example 2a (x=0.04) was lower than that of Example 1 (x=0.08), indicating insufficient doping and inadequate high-entropy effect. Example 2b (x=0.12) exhibited comparable cycling stability (91% after 1000 cycles) to Example 1, but its initial capacity decreased slightly (130 mAh / g). This demonstrates that a total doping amount x within the range of 0.05 to 0.20, preferably 0.08 to 0.12, achieves an optimal balance between high stability and high capacity.

[0071] Example 3 This embodiment explores the "cocktail" effect of different element combinations, as detailed below: The total doping amount was fixed at x=0.08, using different combinations of four elements in equimolar ratios. The remaining preparation process was the same as in Example 1. This included: Example 3a: Combination 1 (Zr, Nb, Mo, Ti) Example 3b: Combination 2 (Zr, Ta, W, Mg) Both combinations significantly improved cycling stability (capacity retention >90% after 1000 cycles), but their optimal performance values ​​differed. The material in Example 3a (containing Mo) exhibited the highest rate performance (88% 5C retention), likely attributable to Mo. 6+ The material exhibits improved electronic conductivity. The material in Example 3b (containing Mg) shows greater stability and slower capacity decay during high-temperature cycling (55°C), possibly due to the presence of Mg. 2+ It is related to the role of stabilizing the oxygen framework.

[0072] Different combinations of elements affect different aspects of the material's properties through a unique "cocktail effect." Zr and Nb are the basic elements for strengthening the crystal lattice, while the selection of the third and fourth elements can be flexibly designed and optimized according to specific performance requirements (focusing on rate performance or high-temperature performance).

[0073] Example 4 This embodiment provides a pentagonal ultra-high entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material with a chemical composition of LiNi. 0.475 Mn1.40 Zr 0.01 Nb 0.01 Mo 0.01 Ti 0.01 Mg 0.01 O4 (x=0.05), the rest of the preparation process is the same as in Example 1.

[0074] The material exhibits extremely stable cycling performance, retaining more than 92% of its capacity after 1000 cycles at a 1C rate, demonstrating the enormous potential of ultra-high entropy systems in suppressing capacity decay.

[0075] Example 5 This embodiment provides a ternary high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material with a chemical composition of LiNi. 0.48 Mn 1.46 Zr 0.02 Nb 0.02 Mo 0.02 O4 (x=0.06), the rest of the preparation process is the same as in Example 1.

[0076] The material exhibits relatively stable cycling performance, retaining more than 85% of its capacity after 1000 cycles at a 1C rate.

[0077] Example 6 This embodiment provides a ternary high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material with a chemical composition of LiNi. 0.47 Mn 1.44 Zr 0.03 Nb 0.03 Mo 0.03 O4 (x=0.09), the rest of the preparation process is the same as in Example 1.

[0078] The material exhibits relatively stable cycling performance, with a capacity retention of over 88% after 1000 cycles at a 1C rate.

[0079] Comparative Example 1 This comparative example provides an undoped octahedral LNMO as a benchmark for performance comparison, with a chemical composition of pure-phase LiNi. 0.5 Mn 1.5 O4, its SEM image is as follows Figure 8 As shown.

[0080] Discharge rate diagram as follows Figure 4 As shown, the long cycle life diagram is as follows: Figure 5 As shown, its capacity decays the fastest, with a capacity retention of only 58.2% after 1000 cycles, and the interface impedance increases significantly.

[0081] Comparative Example 2 This comparative example provides an undoped truncated octahedral LNMO as a benchmark for performance comparison, with a chemical composition of pure-phase LiNi. 0.5 Mn 1.5 O4, its SEM image is as follows Figure 9 As shown.

[0082] Discharge rate diagram as follows Figure 4 As shown, the long cycle life diagram is as follows: Figure 5 As shown, its capacity decays more slowly than that of the octahedron, with a capacity retention rate of 64.5% after 1000 cycles, but the interfacial impedance still increases significantly.

[0083] Comparative Example 3 This comparative example provides an Al-doped LNMO and a high-entropy doped LNMO for direct comparison, with the chemical composition being LiNi. 0.5 Mn 1.48 Al 0.02 O4 (x=0.02), its SEM image is as follows Figure 10 As shown.

[0084] Discharge rate diagram as follows Figure 4 As shown, the long cycle life diagram is as follows: Figure 5 As shown, its cycle stability and rate performance are significantly lower than all high-entropy doping examples, demonstrating that multi-element high-entropy doping has unparalleled synergistic advantages over traditional single-element doping.

[0085] Comparative Example 4 Polycrystalline spherical LNMO substrates were prepared by coprecipitation-solid-state sintering and then subjected to the same high-entropy doping treatment as in Example 1.

[0086] Electrochemical testing showed that the capacity retention of the polycrystalline material (88%) after long-term cycling was lower than that of the single-crystal material in Example 1 (92.5%). SEM revealed grain boundary cracks in the polycrystalline particles after cycling, while the single-crystal particles remained intact. This demonstrates that the single-crystal truncated octahedral matrix can more effectively resist cycling stress and achieve superior long-lifetime performance in synergy with high-entropy doping.

[0087] Specifically, the key performance of the embodiments and comparative examples is summarized in Table 1: Table 1

[0088] Through the above systematic embodiments and comparative examples, the superiority and necessity of the "single-crystal truncated octahedral matrix + multi-element high-entropy doping" technical solution provided by this invention are fully demonstrated from multiple dimensions such as total doping amount, element combination, and matrix morphology. When the total doping amount x = 0.05~0.20, preferably containing Zr, Nb, and two or more other elements, this material can produce a significant high-entropy effect and a "cocktail" synergistic effect, perfectly solving the interface stability problem of high-voltage LNMO cathodes and achieving a balance between ultra-long cycle life and excellent rate performance.

[0089] In summary, this invention provides a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, its preparation method, and its application. The general chemical formula of the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material is LiNi. 0.5-a Mn 1.5-β M x O4; wherein M is selected from at least three elements selected from Zr, Nb, Mo, Ta, W, Al, Zn, Mg, Ti, Fe, Cu, Co, Cr, V, Eu, etc., and x = a + β and 0.01 ≤ x ≤ 0.20. The cathode material provided by this invention has a unique structure, which not only has a single crystal structure and regular truncated octahedral LNMO particles, mainly exposing the thermodynamically stable {111} crystal plane, but also significantly improves the intrinsic stability of the material by utilizing the high configurational entropy effect through the compositional complexity region formed at the atomic scale by high entropy doping. Furthermore, this invention generates multiple synergistic effects through the high entropy strategy, including: a severe lattice effect that reduces the lithium-ion migration barrier and improves rate performance; a hysteresis diffusion effect that significantly inhibits manganese dissolution and oxygen loss; and a thermodynamic stabilization effect that inhibits harmful phase transitions. Under multiple synergistic effects, this cathode material exhibits extremely long cycle life and excellent high-rate performance at a high voltage of 4.7V, fundamentally solving the interface stability problem of high-voltage LNMO cathodes and providing key material support for the development of next-generation lithium-ion batteries with high energy density and high safety.

[0090] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material, characterized in that, The chemical formula of the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material is LiNi. 0.5-a Mn 1.5-β M x O4; wherein M is selected from at least three of Zr, Nb, Mo, Ta, W, Al, Zn, Mg, Ti, Fe, Cu, Co, Cr, V, and Eu, and x = a + β and 0.01 ≤ x ≤ 0.

20.

2. The high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material according to claim 1, characterized in that, 0≤a≤0.20，0≤β≤0.20。 3. The high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material according to claim 2, characterized in that, 0.01≤a≤0.05, 0.04≤β≤0.15, 0.08≤x≤0.

15.

4. The high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material according to claim 1, characterized in that, M includes Zr and Nb, and at least two of Mo, Ta, W, Al, Zn, Mg, Ti, Fe, and Cu.

5. The high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material according to claim 1, characterized in that, The high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material has a particle size of 1μm-10μm.

6. A method for preparing a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material as described in any one of claims 1-5, characterized in that, Including the following steps: A mixture is obtained by mixing a lithium source, a nickel source, a manganese source, and a metal oxide or salt corresponding to the dopant element M. The mixture was subjected to pre-sintering and sintering treatments in sequence, and then ground to obtain a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material. Alternatively, the mixture can be mixed with a eutectic salt, calcined, and then ground to obtain a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material.

7. The method for preparing the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material according to claim 6, characterized in that, The lithium source is selected from one or more of Li2CO3, LiCH3COO, Li2C2O4, LiOH·H2O, and LiOH; the nickel source is selected from one or more of NiO, Ni(NO3)2·6H2O, Ni(CH3COO)2, Ni(OH)2, and NiCO3; and the manganese source is selected from one or more of MnO2, Mn2O3, MnCO3, Mn(NO3)2·4H2O, and Mn(CH3COO)2.

8. The method for preparing the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material according to claim 6, characterized in that, The pre-sintering temperature is 400℃-650℃, and the pre-sintering time is 4h-6h; the sintering temperature is 850℃-950℃, and the sintering time is 10h-20h.

9. The method for preparing the high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material according to claim 6, characterized in that, The calcination temperature is 800℃-950℃, and the calcination time is 6h-12h.

10. The application of a high-entropy doped truncated octahedral spinel lithium nickel manganese oxide cathode material as described in any one of claims 1-5 in lithium-ion batteries.

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