Orthorhombic single-crystal dimanganese trioxide, lithium manganate material and preparation method thereof

Abstract

This invention provides an orthogonal single-crystal manganese trioxide, lithium manganese oxide, and their preparation method, relating to the field of lithium battery technology. The orthogonal single-crystal manganese trioxide comprises mixing single-crystal manganese tetroxide with a dopant to obtain a mixture; the dopant has an ionic radius between 0.5 Å and 0.8 Å and is capable of at least partially replacing Mn. 3+ A metal dopant is introduced into the manganese trioxide lattice; the mixture is calcined at 700℃~900℃ for 3 hours~24 hours to obtain orthorhombic single-crystal manganese trioxide. The method provided by this invention can achieve the structural transformation from manganese tetroxide to manganese trioxide, obtaining orthorhombic single-crystal manganese trioxide with good crystallinity. The introduction of the dopant contributes to lattice stability and reduces oxygen defects. Controlled calcination temperature and time can obtain products with uniform morphology and stable structure, facilitating subsequent material applications.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and more specifically, to an orthogonal single-crystal manganese trioxide and lithium manganese oxide material and their preparation method. Background Technology

[0002] Lithium-ion batteries, as the mainstream energy storage technology, are widely used in portable electronic devices, electric vehicles, and energy storage power stations. Their performance largely depends on the structure and electrochemical properties of the cathode material. Lithium manganese oxide has become a key candidate cathode material for lithium batteries due to its low cost, environmental friendliness, and stable voltage platform. Lithium manganese oxide materials can be classified into polycrystalline and monocrystalline types according to their microstructure, and their preparation methods and precursor properties directly affect key indicators such as the final battery capacity, cycle life, and compaction density.

[0003] In conventional technologies, polycrystalline lithium manganese oxide is typically prepared using polycrystalline precursors, including electrolytic manganese dioxide (EMD) generated from electrolytic manganese sulfate solution, high-purity manganese tetroxide (Mn3O4) formed by hydrolysis of metallic manganese powder, or manganese trioxide (Mn2O3) obtained from the thermal decomposition of manganese carbonate. These precursors are mixed with lithium carbonate and sintered at high temperatures to form polycrystalline lithium manganese oxide materials. In contrast, the precursor for monocrystalline lithium manganese oxide is typically monocrystalline Mn3O4, which undergoes a high-temperature lithiation reaction to produce monocrystalline lithium manganese oxide. The two structures each have their own advantages and disadvantages in performance, and their process routes also differ significantly.

[0004] While polycrystalline lithium manganese oxide exhibits outstanding initial discharge capacity (1C capacity exceeding 115 mAh / g), it suffers from low compaction density (less than 3.0), poor structural thermal stability (resulting in poor high-temperature cycling performance), and susceptibility to manganese dissolution at grain boundaries. These defects lead to rapid capacity decay and short lifespan in practical applications, making it unsuitable for scenarios requiring high stability. Monocrystalline lithium manganese oxide, on the other hand, possesses high compaction density (greater than 3.0) and good cycling performance (capacity retention greater than 94% after 200 cycles), along with strong structural stability. However, its capacity is generally low (1C capacity less than 108 mAh / g), and the limited number of active sites restricts further improvements in energy density.

[0005] In summary, both existing polycrystalline and monocrystalline lithium manganese oxide materials have significant performance limitations, making it difficult to simultaneously meet the comprehensive performance requirements of high capacity, high compaction density, and high cycle life. Given the battery industry's increasing demands for energy density and lifespan, developing lithium manganese oxide materials that combine the high capacity of polycrystalline materials with the high stability of monocrystalline materials has become a crucial area requiring breakthroughs in this technological field. Currently, there is a lack of novel precursors with controllable structure, matched manganese valence states, and the ability to achieve comprehensive performance improvements, along with their corresponding preparation processes.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide orthorhombic single-crystal manganese trioxide (MnO) and lithium manganese oxide materials, and their preparation methods. The method for preparing single-crystal MnO involves mixing single-crystal MnO with a dopant and calcining the mixture at 700℃~900℃ for 3~24 hours, achieving a structural transformation from MnO to MnO, resulting in well-crystallized orthorhombic single-crystal MnO. The introduction of the dopant contributes to lattice stability and reduces oxygen defects. Controlled calcination temperature and time yield products with uniform morphology and stable structure, facilitating subsequent material applications.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0009] In a first aspect, the present invention provides a method for preparing single-crystal manganese trioxide, comprising:

[0010] A mixture is obtained by mixing single-crystal manganese tetroxide with a dopant; the dopant has an ionic radius between 0.5 Å and 0.8 Å and is capable of at least partially replacing Mn. 3+ Metal dopants that enter the manganese trioxide lattice;

[0011] The mixture is calcined at 700℃~900℃ for 3 to 24 hours to obtain single-crystal manganese trioxide.

[0012] In an optional embodiment, the dopant includes at least one of aluminum source dopant, magnesium source dopant, cobalt source dopant, niobium source dopant, chromium source dopant, or titanium source dopant.

[0013] Wherein, the aluminum source dopant includes at least one of aluminum oxide, aluminum hydroxide, and aluminum nitrate; and / or, the magnesium source dopant includes at least one of magnesium oxide, magnesium hydroxide, magnesium acetate, and magnesium nitrate; and / or, the cobalt source dopant includes at least one of cobalt oxide, cobalt tetroxide, cobalt sulfate, cobalt oxalate, and chromium nitrate; and / or, the niobium source dopant includes at least one of niobium pentoxide, niobium oxalate, and niobium dioxide; and / or, the chromium source dopant includes at least one of chromium oxide and chromium nitrate; and / or, the titanium source dopant includes at least one of titanium oxide and titanate.

[0014] In an optional embodiment, the amount of dopant added is: the mass of the dopant element accounts for 0.1% to 2% of the total mass of the single crystal manganese tetroxide.

[0015] In an optional embodiment, the crystal structure parameters of the single-crystal manganese trioxide include: a=9.4118Å, b=9.4177Å, c=9.4233Å, Vol=835.26Å.3 .

[0016] In an optional embodiment, the method for preparing the single-crystal manganese tetroxide includes:

[0017] High-purity manganese tetroxide is calcined at 1000℃~1500℃ for 4 hours to 24 hours to obtain the single-crystal manganese tetroxide.

[0018] Secondly, the present invention provides an orthogonal single-crystal manganese trioxide, which is prepared by the single-crystal manganese trioxide preparation method described in any of the foregoing embodiments.

[0019] Thirdly, the present invention provides a method for preparing lithium manganese oxide material, comprising:

[0020] Lithium manganese oxide material is prepared by mixing orthogonal single-crystal manganese trioxide as described in the aforementioned embodiments with a lithium source material and calcining it at 600℃~800℃ for 2 hours~36 hours.

[0021] Fourthly, the present invention provides a lithium manganese oxide material, which is prepared by the lithium manganese oxide material preparation method described in the foregoing embodiments.

[0022] Fifthly, the present invention provides a positive electrode comprising the lithium manganese oxide material as described in the foregoing embodiments.

[0023] In a sixth aspect, the present invention provides a battery comprising a positive electrode as described in the foregoing embodiments.

[0024] In a seventh aspect, the present invention provides an electrical device including a battery as described in the foregoing embodiments.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] This application provides orthogonal single-crystal manganese trioxide, lithium manganese oxide materials, and their preparation methods. In the preparation method of the single-crystal manganese trioxide, single-crystal manganese tetroxide is used as the starting material, and is reacted with manganese tetroxide having a specific ionic radius (0.5 Å to 0.8 Å) and capable of partially substituting Mn. 3+ The mixing of metal dopants into the manganese trioxide lattice ensures good lattice compatibility of the dopant elements. Based on this, calcining the resulting mixture at 700℃ to 900℃ for 3 to 24 hours effectively drives the structural transformation of manganese tetroxide to manganese trioxide, simultaneously forming a structurally complete and well-crystallized single-crystal product.

[0027] The starting material is "single-crystal manganese tetroxide," which inherently possesses high crystal integrity. By maintaining the single-crystal growth direction and crystal characteristics under appropriate heat treatment, polymorphism and structural distortion can be avoided, which is beneficial to the structural stability and controllability in subsequent material applications.

[0028] The dopant's limited ionic radius range is similar to that of manganese ions, allowing it to partially enter Mn₂O₃ lattice sites during calcination and act as a lattice stabilizer. On one hand, this helps reduce stress concentration in the lattice caused by phase transitions, preventing particle breakage or grain boundary defects. On the other hand, within this temperature range, the dopant can diffuse smoothly and occupy stable sites, which is beneficial for reducing defect concentration and improving the structural uniformity and internal order of the product.

[0029] A process window of 700℃ to 900℃ and 3 hours to 24 hours satisfies the thermodynamic requirements of material conversion while avoiding problems such as over-sintering and particle agglomeration. This process range helps to produce single-crystal manganese trioxide powder with moderate particle size and uniform morphology, which facilitates subsequent mixing and sintering operations.

[0030] Through the synergistic control of doping and heat treatment, this method can obtain orthorhombic single-crystal manganese trioxide with uniform particle size, continuous crystal faces, and regular morphology. Compared with undoped or uncontrolled conversion methods, the single-crystal structure formed by this method is not only more compact but also possesses better crystal integrity and structural stability.

[0031] It should be noted that orthorhombic single-crystal manganese trioxide contains various types of Mn. 3+ The coordination (octahedral + tetragonal pyramidal) results in higher reactivity with lithium salts, leading to higher discharge capacity in the subsequent synthesis of lithium manganese oxide materials. The initial orthogonal distortion of orthogonal single-crystal manganese trioxide partially offsets the structural stress of lithium manganese oxide during cycling through the "pre-distortion" effect, mitigating the Jahn-Teller effect and improving cycling stability.

[0032] In single-crystal manganese trioxide, manganese has a single +3 valence state, which is more compatible with the valence states of single-crystal manganese tetroxide (manganese has a mixed valence state, with an average valence state of +2.67) and lithium manganese oxide (+3 manganese:+4 manganese = 1:1) compared to single-crystal manganese trioxide. This results in a more direct lithiation reaction during the synthesis of lithium manganese oxide, avoiding the Mn... 2+ Residue is reduced, side reactions are minimized, and initial coulombic efficiency and cycle stability are improved. Excellent orthogonal single-crystal manganese trioxide provides a high-quality precursor base for subsequent materials in lithium-ion battery cathode applications.

[0033] In summary, the method provided in this application, while maintaining a simple technical path, achieves stable preparation of orthogonal single-crystal manganese trioxide through a reasonable combination of dopant structural properties and heat treatment parameters, which helps to improve the morphological consistency, crystal quality, and structural stability of the material. This technical solution can serve as a key precursor route for the subsequent preparation of high-performance cathode materials, and has a good foundation for promotion and industrial application value. Attached Figure Description

[0034] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 The image shows the XRD pattern of orthogonal single-crystal manganese trioxide in Example 1 of this invention.

[0036] Figure 2 This is the diffraction ring pattern of orthogonal single-crystal manganese trioxide in Example 1 of the present invention;

[0037] Figure 3 This is a scanning electron microscope image of orthogonal single-crystal manganese trioxide in Example 1 of the present invention;

[0038] Figure 4 The XRD pattern of manganese trioxide in Comparative Example 1 of this invention;

[0039] Figure 5 The image shows the XRD pattern of manganese trioxide in Comparative Example 2 of this invention. Detailed Implementation

[0040] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0041] This application provides a method for preparing single-crystal manganese trioxide, comprising:

[0042] Step S1: Mix single-crystal manganese tetroxide with a dopant to obtain a mixture; the dopant has an ionic radius between 0.5 Å and 0.8 Å and is capable of at least partially replacing Mn. 3+ Metal dopants that enter the manganese trioxide lattice.

[0043] This step involves the physical mixing of two substances: the first is single-crystal manganese tetroxide (Mn3O4), which is the original manganese source and has a fixed crystal morphology.

[0044] The second type is metal dopant, which requires two conditions to be met:

[0045] (1) The ionic radius is between 0.5 Å and 0.8 Å;

[0046] (2) It can at least partially replace Mn 3+ It enters the crystal lattice structure of the final product, manganese trioxide (Mn2O3).

[0047] This step is essentially to form a mixed reaction precursor with controllable composition and structure for structural evolution during subsequent calcination. This can be achieved using conventional physical mixing methods, such as, but not limited to, ball milling, high-speed stirring, wet mixing followed by drying, and ultrasonic dispersion. During mixing, it is necessary to ensure that the dopant is uniformly distributed at the powder scale so that it can be uniformly incorporated into the crystal lattice during subsequent heat treatment.

[0048] By mixing, a "mixture" can be obtained, in which Mn3O4 serves as the main crystalline phase; the dopant is uniformly distributed in space, awaiting subsequent high-temperature conditions to achieve ion diffusion and lattice occupancy.

[0049] Premixing positions the dopant spatially close to the Mn3O4 crystal, facilitating subsequent thermal diffusion; the ionic radius is similar to that of Mn. 3+ Proximity contributes to lattice stability; it is a fundamental condition for achieving structural doping, requires no complex pretreatment, and has strong versatility.

[0050] Step S2: The mixture is calcined at a temperature of 700℃~900℃ for 3 hours to 24 hours to obtain orthogonal single crystal manganese trioxide.

[0051] This step is a high-temperature heat treatment step (i.e., calcination), the purpose of which is to promote the phase transformation reaction of Mn3O4 → Mn2O3; and at the same time, to allow the dopant M to undergo a phase transformation. n+ It can diffuse into the crystal lattice to form stable doped products; and enable the reactive crystal to maintain a single crystal structure growth under high temperature conditions.

[0052] The calcination temperature can be 700℃, 750℃, 800℃, 850℃, 900℃, etc.

[0053] The calcination time can be 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 12 hours, 14 hours, 15 hours, 16 hours, 20 hours, 22 hours, 24 hours, etc.

[0054] This step can be achieved using conventional solid-state material calcination methods, including but not limited to: static heating in an air atmosphere in a muffle furnace, with the heating rate controlled within a suitable range (e.g., 3~10℃ / min); and natural cooling after holding at a set temperature (700℃~900℃) for 3~24 hours. The calcination vessel can be made of heat-resistant materials such as alumina boats or quartz crucibles.

[0055] Through this chemical transformation, the original manganese tetroxide is converted into manganese trioxide (Mn₂O₃) via oxidation and rearrangement; Mn₂O₃ contains various Mn groups. 3+ Coordination (octahedral + tetragonal pyramidal) results in higher reactivity with lithium salts; doped ions enter the crystal lattice and occupy Mn 3+ Site; the product has a single-crystal morphology of manganese trioxide structure, excluding polycrystalline or amorphous phases.

[0056] The above calcination process can be represented by the following reaction:

[0057] 2Mn3O4+ O2→3Mn2O3;

[0058] Among them, Mn 2+ It is further oxidized to Mn in high-temperature air. 3+ The crystal structure was reconstructed into a stable manganese trioxide phase.

[0059] In this step, the temperature range of 700℃~900℃ covers the effective phase transition region of Mn3O4→Mn2O3, and the time range of 3~24 hours ensures sufficient reaction and structure formation time, which helps to obtain products with good crystal continuity and uniform doping.

[0060] In an optional embodiment, the dopant includes at least one of aluminum source dopant, magnesium source dopant, cobalt source dopant, niobium source dopant, chromium source dopant, or titanium source dopant.

[0061] The aluminum source dopant includes at least one of aluminum oxide, aluminum hydroxide, and aluminum nitrate;

[0062] And / or, the magnesium source dopant includes at least one of magnesium oxide, magnesium hydroxide, magnesium acetate, and magnesium nitrate;

[0063] And / or, the cobalt source dopant includes at least one of cobalt oxide, cobalt tetroxide, cobalt sulfate, cobalt oxalate, and chromium nitrate;

[0064] And / or, the niobium source dopant includes at least one of niobium pentoxide, niobium oxalate, and niobium dioxide;

[0065] And / or, the chromium source dopant includes at least one of chromium oxide and chromium nitrate;

[0066] And / or, the titanium source dopant includes at least one of titanium oxide and titanate.

[0067] In an optional embodiment, the amount of dopant added is: the mass of the dopant element accounts for 0.1% to 2% of the total mass of the single crystal manganese tetroxide.

[0068] In an optional embodiment, the crystal structure parameters of the single-crystal manganese trioxide include: a=9.4118Å, b=9.4177Å, c=9.4233Å, Vol=835.26Å. 3 .

[0069] In an optional embodiment, the method for preparing the single-crystal manganese tetroxide includes:

[0070] High-purity manganese tetroxide is calcined at 1000℃~1500℃ for 4 hours to 24 hours to obtain the single-crystal manganese tetroxide.

[0071] For example, the temperature conditions can be 1000℃, 2000℃, 3000℃, 4000℃, 5000℃, etc. The calcination time can be 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 12 hours, 14 hours, 15 hours, 16 hours, 20 hours, 22 hours, 24 hours, etc.

[0072] The above-mentioned methods for preparing high-purity manganese tetroxide include:

[0073] Metallic manganese powder and a catalyst are added to deionized water; wherein the catalyst includes at least one of ammonium chloride, ammonium sulfate, ammonium acetate and ammonium oxalate.

[0074] High-purity manganese tetroxide was prepared by reacting in a constant temperature water bath at 40℃~150℃ (2 hours~72 hours), followed by crushing and sieving.

[0075] It should be noted that the transformation from one crystal form to another (phase transition) is usually accompanied by lattice rearrangement and volume changes. This invention provides a process for oxidizing manganese tetroxide to manganese trioxide. This includes:

[0076] (1) Crystal Lattice Reconstruction: This process is not simply about filling the existing lattice with oxygen atoms, but involves a change in the valence state of manganese ions (Mn). 2+ Oxidized to Mn 3+ And a fundamental rearrangement of the entire crystal structure.

[0077] (2) Internal Stress: This intense structural rearrangement generates enormous stress inside the crystal. If the starting material is a complete single crystal particle, this stress can easily cause the crystal to crack and break from the inside, thereby destroying the integrity of the single crystal and ultimately resulting in an aggregate of polycrystalline powder.

[0078] The insight from the embodiments of this application is that adding dopants with specific ionic radii helps to "reduce stress concentration in the lattice caused by phase transitions, and avoid particle breakage or grain boundary defects." This indirectly confirms that, in conventional methods without such "lattice stabilizers," single crystals are extremely prone to breakage during phase transitions, which is one of the core reasons why it is difficult to produce single-crystal manganese trioxide.

[0079] Secondly, to transform a single crystal Mn3O4 into a single crystal Mn2O3, the ideal reaction process should resemble a "template-based" transformation, meaning the reaction starts from the crystal surface, extends slowly and uniformly inward, and does not generate new crystal nuclei. This is extremely difficult to control kinetically.

[0080] In traditional techniques, the precursors for preparing manganese trioxide are often polycrystalline, such as those obtained through the thermal decomposition of manganese carbonate. Starting from polycrystalline powder, regardless of the sintering process, only polycrystalline products can be obtained. This embodiment emphasizes that it must start from "single-crystal manganese tetroxide," illustrating the crucial importance of the crystal morphology of the starting material.

[0081] The rate of phase transition reactions is extremely sensitive to temperature. If the temperature is too low, the reaction is incomplete, resulting in a mixed phase (as shown in Comparative Example 1, where manganese tetroxide residue remains after calcination at 600℃). If the temperature is too high, the reaction is too vigorous, atomic diffusion is too rapid, and multiple new crystal nuclei easily form inside the crystal, thereby destroying the single-crystal structure or causing reverse decomposition (Mn₂O₃ decomposes into Mn₃O₄ at higher temperatures, as shown in Comparative Example 2, which contains a large amount of manganese tetroxide after calcination at 1000℃). Therefore, to maintain the single-crystal morphology, slow and gentle calcination must be carried out within a very narrow and precise process window (700℃~900℃ as proposed in this example).

[0082] Furthermore, manganese (Mn) is an element that can form a variety of stable oxides (such as MnO, Mn2O3, Mn3O4, MnO2, etc.). The transformation between these oxides is closely related to temperature and oxygen partial pressure. Under specific temperatures and atmospheres, multiple manganese oxides may coexist. Precisely obtaining pure-phase, specific-crystal-system (orthorhombic) Mn2O3 without the formation of other impurity phases is itself a thermodynamic challenge.

[0083] Manganese trioxide itself can exist in different crystal forms. To stably obtain a crystal phase with a specific "orthorhombic distortion," the control of process conditions is even more demanding. This invention points out that this orthorhombic structure, through a "pre-distortion" effect, helps improve the cycle stability of the final lithium manganese oxide material. This indicates that obtaining this specific crystal phase is key to achieving excellent performance, while also highlighting the difficulty of its preparation.

[0084] In summary, the difficulty in preparing orthorhombic single-crystal manganese trioxide using conventional techniques stems from the need to simultaneously address multiple physical, technological, and chemical challenges. Specifically, the phase transition from manganese tetroxide to manganese trioxide (MnO) generates significant internal stress due to lattice reconstruction, easily leading to single-crystal fracture. Technologically, extremely precise and gentle kinetic control (such as strict temperature and time windows) is required to maintain the integrity of the single crystal and prevent the formation of new nuclei or reverse reactions. Furthermore, from a chemical perspective, the complexity of the manganese oxide system makes obtaining a pure, single target crystalline phase (orthorhombic phase) very difficult. Therefore, the combined strategy proposed in this application—"selecting a single-crystal precursor, stabilizing the lattice through specific ion doping, and supplementing with precise calcination process control"—effectively overcomes these challenges, thus providing a feasible technical path for the stable preparation of orthorhombic single-crystal manganese trioxide.

[0085] This application provides an orthogonal single-crystal manganese trioxide, which is prepared by the single-crystal manganese trioxide preparation method described in any of the foregoing embodiments.

[0086] This application provides a method for preparing lithium manganese oxide material, including:

[0087] Lithium manganese oxide material is prepared by mixing orthogonal single-crystal manganese trioxide as described in the aforementioned embodiments with a lithium source material and calcining it at 600℃~800℃ for 2 hours~36 hours.

[0088] For example, the temperature conditions can be 600℃, 700℃, 800℃, etc. The calcination time can be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 12 hours, 14 hours, 15 hours, 16 hours, 20 hours, 22 hours, 24 hours, 30 hours, 36 hours, etc.

[0089] This application provides a lithium manganese oxide material, which is prepared by the lithium manganese oxide material preparation method described in the foregoing embodiments.

[0090] This application provides a positive electrode comprising the lithium manganese oxide material as described in the foregoing embodiments.

[0091] The aforementioned positive electrode may include lithium manganese oxide material as the active material, as described above, and may further include, but is not limited to, conventional components such as conductive agents, binders, and metal current collectors. The conductive agent is used to improve the overall conductivity of the electrode and may be materials such as acetylene black, carbon black, or conductive graphite. The binder is used to enhance the bonding force between materials and between the binder and the current collector, and may be polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), etc. The current collector is typically aluminum foil, used to support the electrode active layer and collect electrons. The above components can be mixed according to conventional proportions in the art and prepared into a positive electrode sheet with lithium-ion intercalation / deintercalation function through coating, electrode rolling, etc., suitable for the structure of various lithium-ion batteries.

[0092] This application provides a battery that includes a positive electrode as described in the foregoing embodiments.

[0093] The aforementioned battery includes the positive electrode described above and is suitable for various electrochemical energy storage systems that use lithium ions as carriers for charge transfer. Specifically, it can be a cylindrical battery, a prismatic battery, a coin cell battery, or a pouch cell. In addition to the positive electrode, the battery may also include, but is not limited to, conventional components such as a negative electrode, a separator, an electrolyte, and a casing. The negative electrode can typically be made of graphite or silicon-based materials, the separator is a porous polyolefin film with ion permeability and electronic insulation, and the electrolyte can be a mixture of organic solvents and lithium salts, such as carbonate electrolytes combined with lithium salts like LiPF6. The components can be assembled into a complete battery cell through processes such as winding, stacking, electrolyte injection, and encapsulation.

[0094] This application provides an electrical device, including a battery as described in the foregoing embodiments.

[0095] The aforementioned electrical equipment may include the batteries described above, and is suitable for various electronic, electrical, or power devices that require electrochemical energy supply. Specifically, this includes, but is not limited to, portable electronic devices such as smartphones, laptops, tablets, and wearable devices; transportation vehicles such as electric vehicles, electric bicycles, and electric motorcycles; stationary energy storage systems such as home energy storage, grid frequency regulation energy storage, and power station backup power; and industrial equipment such as drones, power tools, and medical equipment. The batteries used in these devices employ lithium manganese oxide as the positive electrode, possessing characteristics such as high safety, low cost, and excellent cycle performance, and can meet the energy density, power output, and lifespan requirements of different application scenarios.

[0096] The present invention will be further illustrated below with specific embodiments. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0097] Table 1. Key process parameters of the examples and comparative examples

[0098]

[0099] In Table 1, the mass ratio represents the mass ratio of the dopant element to manganese tetroxide; "real" represents an example, such as "real 1" representing example 1; "compare" represents a comparative example, such as "compare 1" representing comparative example 1.

[0100] Example 1

[0101] In this embodiment, an orthogonal single-crystal manganese trioxide and its lithium manganese oxide are prepared.

[0102] Experimental methods:

[0103] Step 1: Preparation of high-purity manganese tetroxide: Add 100g of metallic manganese powder and 1g of ammonium chloride catalyst to deionized water, react in a constant temperature water bath at 100℃ for 24 hours, and then pulverize and sieve to prepare high-purity manganese tetroxide.

[0104] Step 2: Preparation of single-crystal manganese tetroxide: The above-mentioned high-purity manganese tetroxide is calcined at 1200℃ for 6 hours to prepare single-crystal manganese tetroxide.

[0105] Step 3: Preparation of orthorhombic single-crystal manganese trioxide: The above-mentioned single-crystal manganese trioxide and aluminum hydroxide were mixed at a mass ratio of Al:Mn3O4 = 1:100, and then calcined at 750℃ for 8 hours to prepare aluminum-doped single-crystal manganese trioxide. Figure 1 The XRD pattern of the prepared orthogonal single-crystal manganese trioxide is shown in the figure. It can be seen from the figure that the prepared manganese trioxide material has complete peak shapes and high crystallinity. The fitted cell parameters are a=9.4118Å, b=9.4177Å, c=9.4233Å, and Vol=835.26Å. 3 ; Figure 2 and Figure 3 The images show the diffraction ring pattern and scanning electron microscope (SEM) image of orthorhombic single-crystal manganese trioxide, respectively. It can be seen from the images that the prepared manganese trioxide material has a single-crystal structure and intact particles.

[0106] Step 4: Preparation of lithium manganese oxide material: The single-crystal manganese trioxide and lithium carbonate doped with the above-mentioned elements are mixed in a molar ratio of Li::Mn=1.095:1 and then calcined at 750℃ for 18 hours to prepare lithium manganese oxide cathode material.

[0107] Examples 2 to 5

[0108] In the examples, a single-crystal manganese trioxide and its lithium manganese oxide were prepared respectively.

[0109] The experimental methods are basically the same as those in Example 1, and the differences are shown in Table 1.

[0110] Comparative Examples 1 to 3

[0111] In the comparative example, manganese trioxide and its lithium manganese oxide were prepared.

[0112] The experimental methods are basically the same as in Example 1, except that Comparative Example 3 did not include the treatment in step 2. See Table 1 for details.

[0113] Figure 4 The XRD pattern of manganese trioxide prepared in Comparative Example 1 (4M: 18.2%, 3M: 81.8%) shows that the prepared manganese trioxide material contains a small amount of diffraction peaks of manganese tetroxide.

[0114] Figure 5 The XRD pattern of manganese trioxide prepared in Comparative Example 2 (4M: 69.7%, 3M: 30.3%) shows that the prepared manganese trioxide material contains a large number of diffraction peaks of manganese tetroxide. The above results indicate that neither too low nor too high sintering temperature can synthesize a pure phase manganese trioxide material with high crystallinity.

[0115] Comparative Example 4

[0116] In the comparative example, a single-crystal manganese tetroxide and its lithium manganese oxide were prepared.

[0117] The experimental method is basically the same as in Example 1. The difference is that step 3 was not performed in this comparative example. Please refer to Table 1 for details.

[0118] Test experiment:

[0119] 1. Testing method:

[0120] (1) Test 1:

[0121] The lithium manganese oxide cathode materials prepared in the above embodiments and comparative examples were used to make batteries, and the performance of the batteries was tested. The test results are shown in Table 2.

[0122] Battery assembly methods include:

[0123] Using the lithium manganese oxide cathode material prepared in Examples 1-5 and Comparative Examples 1-4 as the cathode and lithium metal as the anode, and using 1.0 mol / L LiPF6 / EC (ethylene carbonate) + DMC (dimethyl carbonate) + FEC (fluoroethylene carbonate) (EC, DMC and FEC volume ratio 4.5:4.5:1) as the electrolyte, CR2032 button batteries were assembled in an argon glove box.

[0124] The testing methods include:

[0125] Room temperature cycle test: The button cell battery was subjected to one constant current charge-discharge cycle at a current density of 0.1C, and then to 200 constant current charge-discharge cycles at a current density of 1C, with a voltage range of 3~4.3V.

[0126] 55℃ high temperature cycle test: The button battery was subjected to one constant current charge-discharge cycle at a current density of 0.1C, and then to 200 constant current charge-discharge cycles at a current density of 1C, with a voltage range of 3~4.3V.

[0127] (2) Test 2:

[0128] The compaction density of the lithium manganese oxide cathode materials prepared in each embodiment and comparative example was tested. The test method is as follows: the powder was placed on a tablet press, a pressure of 222 MPa was applied, and the pressure was held for 1 minute. The compaction density was then obtained. The results are shown in Table 2.

[0129] 2. Test Results:

[0130] Table 2. Compact density, charge / discharge capacity, and capacity retention of lithium manganese oxide synthesized in the examples and comparative examples.

[0131]

[0132] In Table 2, “real” represents an embodiment, such as “real 1” representing embodiment 1; “compare” represents a comparative example, such as “compare 1” representing comparative example 1.

[0133] analyze:

[0134] As can be clearly seen from the results in Table 2, the batteries prepared using lithium manganese oxide obtained in Examples 1-5 show significant advantages in terms of compaction density, charge / discharge capacity, and room temperature and high temperature cycling performance compared to the materials prepared in Comparative Examples 1-4.

[0135] Batteries prepared from the lithium manganese oxide materials obtained in Comparative Examples 1 and 2 exhibited low charge-discharge capacity and poor cycle performance. This is mainly due to the impurity of their manganese trioxide precursor phase. According to Table 1, Comparative Example 1 was calcined at 600°C, while Comparative Example 2 was calcined at 1000°C. Both temperatures deviate from the optimal process window of 700°C to 900°C defined in this invention. From the XRD patterns (...) Figure 4 and Figure 5 It can be seen that neither too low nor too high calcination temperature can synthesize pure phase manganese trioxide with high crystallinity. The product contains obvious manganese tetroxide impurity phase, which directly affects the electrochemical performance of the final lithium manganese oxide material.

[0136] Although the lithium manganese oxide material prepared in Comparative Example 3 had a high initial capacity, its cycling performance was poor, and its compaction density was the lowest (2.82 g / cm³). 3The main reason is that, according to Table 1, this method does not involve the high-temperature treatment (1000℃~1500℃) in step two to form a single-crystal phase. The lack of a single-crystal precursor results in insufficient structural stability of the material, making it prone to damage during repeated charge-discharge cycles, thus leading to rapid capacity decay.

[0137] Although the battery prepared in Comparative Example 4 exhibited good cycle performance, its charge-discharge capacity was significantly low. This is because its precursor was single-crystal manganese tetroxide, which was not converted to manganese trioxide in step three. While the single-crystal structure ensured good cycle stability, the average valence state of manganese in manganese tetroxide was +2.67, which did not match the +3.5 valence state of manganese in lithium manganese oxide, resulting in incomplete lithiation and low initial coulombic efficiency and discharge capacity.

[0138] Examples 1-5 strictly followed the key technical solutions of this invention: First, single-crystal manganese tetroxide was prepared by high-temperature calcination at 1000℃~1500℃. Then, after mixing with a specific dopant, it was calcined at a temperature of 700℃~900℃ to successfully prepare a pure, highly crystalline orthorhombic single-crystal manganese tetroxide precursor. This precursor not only maintained the complete morphology and structural stability of the single crystal, but its +3 manganese valence state was also more compatible with the requirements for subsequent synthesis of lithium manganese oxide. Therefore, the final lithium manganese oxide material possessed high solid density, high charge-discharge capacity, and excellent cycle stability.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing orthogonal single-crystal manganese trioxide, characterized in that, include: A mixture is obtained by mixing single-crystal manganese tetroxide with a dopant; the dopant has an ionic radius between 0.5 Å and 0.8 Å and is capable of at least partially replacing Mn. 3+ Metal dopants that enter the manganese trioxide lattice; The mixture is calcined at 700℃~900℃ for 3 to 24 hours to obtain single-crystal manganese trioxide.

2. The method for preparing orthogonal single-crystal manganese trioxide as described in claim 1, characterized in that, The dopant includes at least one of aluminum source dopant, magnesium source dopant, cobalt source dopant, niobium source dopant, chromium source dopant or titanium source dopant; The aluminum source dopant includes at least one of aluminum oxide, aluminum hydroxide, and aluminum nitrate; And / or, the magnesium source dopant includes at least one of magnesium oxide, magnesium hydroxide, magnesium acetate, and magnesium nitrate; And / or, the cobalt source dopant includes at least one of cobalt oxide, cobalt tetroxide, cobalt sulfate, cobalt oxalate, and chromium nitrate; And / or, the niobium source dopant includes at least one of niobium pentoxide, niobium oxalate, and niobium dioxide; And / or, the chromium source dopant includes at least one of chromium oxide and chromium nitrate; And / or, the titanium source dopant includes at least one of titanium oxide and titanate.

3. The method for preparing orthogonal single-crystal manganese trioxide as described in claim 1, characterized in that, The amount of dopant added is: the mass of the dopant element accounts for 0.1% to 2% of the total mass of the single-crystal manganese tetroxide; and / or, The crystal structure parameters of the single-crystal manganese trioxide include: a=9.4118Å, b=9.4177Å, c=9.4233Å, Vol=835.26Å. 3 .

4. The method for preparing orthogonal single-crystal manganese trioxide as described in claim 1, characterized in that, The method for preparing the single-crystal manganese tetroxide includes: High-purity manganese tetroxide is calcined at 1000℃~1500℃ for 4 hours to 24 hours to obtain the single-crystal manganese tetroxide.

5. An orthogonal single-crystal manganese trioxide, characterized in that, It is prepared by the method for preparing single-crystal manganese trioxide as described in any one of claims 1-4.

6. A method for preparing lithium manganese oxide material, characterized in that, include: Lithium manganese oxide material is prepared by mixing the orthogonal single-crystal manganese oxide as described in claim 5 with a lithium source material and calcining it at 600℃~800℃ for 2 hours~36 hours.

7. A lithium manganese oxide material, characterized in that, The lithium manganese oxide material was prepared by the method described in claim 6.

8. A positive electrode, characterized in that, Including the lithium manganese oxide material as described in claim 7.

9. A battery, characterized in that, Includes the positive electrode as described in claim 8.

10. An electrical-related device, characterized in that, Includes the battery as described in claim 9.

Images