Lithium-rich disordered rock salt positive electrode material and preparation method and application thereof

Abstract

The invention provides a lithium-rich disordered rock salt positive electrode material as well as a preparation method and application thereof. The chemical general formula of the lithium-rich disordered rock salt positive electrode material is Li (1 + x) MpNqO (2-y) Xy, 0.3 < = x < = 0.6, p + q = 1, 0.5 < = p < = 0.9, 0.1 < = q < = 0.5, 0 < = y < = 0.4, and M comprises Fe and / or Mn; n comprises any one or a combination of at least two of Zr, Ti, Nb, Mo, W or V; x comprises a polyanionic group. The N element with higher valence is introduced into the lithium-rich disordered rock salt positive electrode material, and meanwhile, the polyanion group is introduced to jointly stabilize the crystal structure, so that the oxygen loss under high voltage is effectively inhibited, and the N element with higher valence can also reduce cation mixing and participate and stabilize the anion redox reaction, so that the lithium-rich disordered rock salt positive electrode material is more stable. The polyanion groups and the transition metal ions form strong covalent bonds, so that the cycling stability of the material is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to cathode materials, and more particularly to a lithium-rich disordered rock salt cathode material, its preparation method, and its application. Background Technology

[0002] Currently, the most widely commercialized cathode materials for lithium-ion batteries are lithium cobalt oxide, ternary materials, and lithium-rich manganese-based materials. Cobalt and nickel are key elements in these materials, but they suffer from resource scarcity and high costs. Lithium iron phosphate and lithium manganese iron phosphate have low compaction density and energy density.

[0003] Lithium-rich disordered rock salt cathode materials have attracted widespread attention due to their high capacity and low cost. Unlike ordered layered lithium-rich manganese-based cathode materials, lithium-rich disordered rock salt cathode materials are disordered structures lacking long-range order. Lithium-ion diffusion in this structure follows an "octahedral-tetrahedral-octahedral" jumping pattern: a lithium ion moves from its original octahedral position to an adjacent tetrahedral interstitial position before jumping to the next empty octahedral position. During this jumping process, the lithium ion is strongly electrostatically repelled by the high-charge transition metal ions on the four octahedrons coplanar with the tetrahedral position, significantly hindering the lithium ion jumping. Therefore, lithium-rich rock salt cathode materials typically achieve high reversible capacity by introducing excess lithium ions and selecting high-valence inactive elements to ensure smooth lithium ion migration. However, lithium-rich disordered rock salt cathode materials are prone to oxygen loss and irreversible migration of transition metal ions under high voltage, leading to decreased cycle stability, which has become a key issue restricting their commercial application.

[0004] CN118299558A discloses a composite-coated nickel-based lithium-rich disordered rock salt structure cathode material and its preparation method. The chemical formula of the cathode material is Li. 1.2 Ni 1 / 3 Ti 1 / 3 W 2 / 15 O2. This cathode material has a three-dimensional disordered cation framework structure, which can stabilize the oxygen lattice and oxygen valence change reaction in lithium-rich oxide cathode materials, improve lithium-ion migration ability, and enhance the material's cycle performance. The amorphous carbon and titanium dioxide composite coating layer is prepared in situ using a wet chemical method, which is simple to operate, low in cost, and can avoid problems such as surface structure failure caused by secondary coating treatment.

[0005] CN110350190A discloses a lithium zirconium phosphate surface-modified lithium-rich rock salt oxide cathode material and its preparation method, belonging to the field of electrode technology. This cathode material includes lithium-rich rock salt oxide Li... 4+x Ni 1-xThe surface of WO6 is coated with a layer of lithium zirconium phosphate (LiZr2(PO4)3), which is beneficial to improving the structural stability and electrochemical cycle performance of the battery.

[0006] CN114560514A discloses a high-energy-density layered-rock-salt symbiotic lithium-rich cathode material and its preparation method. The particles of this layered-rock-salt symbiotic lithium-rich cathode material are primary particles, with a main structure of lithium-rich layered structure and local lithium-rich disordered rock-salt structures dispersed within it. The two structures have similar oxygen structure frameworks and exist in a mutually soluble layer as a symbiotic structure. This symbiotic structure endows the prepared cathode material with both the high lithium-ion diffusion rate of the layered structure and the isotropic structural change characteristics of the rock-salt structure during charge and discharge, thereby improving the energy efficiency and cycle stability of the battery.

[0007] Therefore, it is of great significance to provide a lithium-rich disordered rock salt cathode material that can be stably cycled under high voltage and its preparation method. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a lithium-rich disordered rock salt cathode material, its preparation method, and its applications. This invention introduces higher-valence nitrogen elements and polyanionic groups into the lithium-rich disordered rock salt cathode material, which together stabilize the crystal structure, effectively suppressing oxygen loss under high voltage. The higher-valence nitrogen elements also reduce cation mixing and participate in and stabilize anion redox reactions. The polyanionic groups form strong covalent bonds with transition metal ions, enhancing the structural stability of the material and significantly improving its cycle stability.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a lithium-rich disordered rock salt cathode material, wherein the general chemical formula of the lithium-rich disordered rock salt cathode material is Li. (1+x) M p N q O (2-y) X y Wherein, 0.3≤x≤0.6, p+q=1, 0.5≤p≤0.9, 0.1≤q≤0.5, 0≤y≤0.4, M includes Fe and / or Mn; N includes any one or at least two combinations of Zr, Ti, Nb, Mo, W or V; X includes polyanionic groups.

[0011] This invention introduces polyanionic groups to replace oxygen sites in lithium-rich disordered rock salt cathode materials, while simultaneously introducing nitrogen elements with higher valence states. The high-valence nitrogen elements participate in and stabilize the redox reaction of the polyanionic groups. The polyanionic groups form strong covalent bonds with transition metal ions. The two work synergistically to achieve crystal structure stability of the lithium-rich disordered rock salt cathode material, effectively suppressing oxygen loss under high voltage and significantly improving the cycle stability of the material.

[0012] The lithium-rich disordered rock salt cathode material provided by this invention does not include scarce and expensive cobalt and nickel elements, which reduces the cost of raw materials and is conducive to large-scale commercial application.

[0013] In this invention, the N element is preferably a combination of at least two types, more preferably a combination of Ti and Nb, and the molar ratio of Ti to Nb is preferably (1~4):1.

[0014] Preferably, the polyanionic group includes SO4. 2- PO4 3- BO3 3- or SiO4 4- Any one or at least two of the above, preferably PO4 3- BO3 3- or SiO4 4- Any one or at least two of them.

[0015] In a second aspect, the present invention provides a method for preparing the lithium-rich disordered rock salt cathode material as described in the first aspect, the method comprising:

[0016] According to the stoichiometric ratio, Li source, M source, N source and X source are weighed and premixed to obtain premixed raw material. The premixed raw material is subjected to a first ball milling to obtain a first ball milling material. The first ball milling material is pre-sintered to obtain a pre-sintered material. The pre-sintered material is subjected to a second ball milling to obtain a second ball milling material. The second ball milling material is calcined to obtain the lithium-rich disordered rock salt cathode material.

[0017] This invention employs a high-energy ball milling method combined with a solid-state reaction method to prepare lithium-rich disordered rock salt cathode materials. First, pre-mixing and a first ball milling process ensure thorough mixing and particle refinement of the raw materials. This facilitates the removal of moisture from the raw materials during the subsequent pre-sintering process, preventing moisture from adversely affecting the material's performance. The pre-sintered material is then subjected to a second ball milling followed by calcination to ensure complete uniformity of elements and prevent component segregation after pre-sintering.

[0018] Preferably, the premix includes dry mixing.

[0019] Preferably, the first ball milling includes wet ball milling.

[0020] Preferably, the second ball milling includes dry ball milling.

[0021] Preferably, the ball milling medium in the wet ball milling includes ethanol.

[0022] Preferably, the rotation speed of the wet ball mill is 400 rpm to 800 rpm.

[0023] Preferably, the wet ball milling time is 10h to 15h.

[0024] Preferably, the rotation speed of the dry ball mill is 200 rpm to 600 rpm.

[0025] Preferably, the dry ball milling time is 2h to 6h.

[0026] Preferably, the pre-sintering temperature is 500℃~750℃.

[0027] Preferably, the pre-sintering time is 4h to 8h.

[0028] Preferably, the pre-sintering atmosphere includes an inert atmosphere.

[0029] Preferably, the inert atmosphere includes nitrogen and / or an inert gas.

[0030] Preferably, the calcination temperature is 900℃~1100℃.

[0031] Preferably, the calcination time is 10h to 15h.

[0032] Preferably, the calcination atmosphere includes an inert atmosphere.

[0033] Preferably, the inert atmosphere includes nitrogen and / or an inert gas.

[0034] Preferably, the preparation method further includes sequentially subjecting the lithium-rich disordered rock salt cathode material to roller crushing and air jet milling.

[0035] Thirdly, the present invention provides a positive electrode sheet comprising the lithium-rich disordered rock salt positive electrode material as described in the first aspect.

[0036] Fourthly, the present invention provides a lithium-ion battery comprising a lithium-rich disordered rock salt cathode material as described in the first aspect, or a cathode sheet as described in the third aspect.

[0037] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] This invention introduces polyanionic groups to replace oxygen sites in lithium-rich disordered rock salt cathode materials, while simultaneously introducing nitrogen elements with higher valence states. The high-valence nitrogen elements participate in and stabilize the redox reaction of the polyanionic groups. The polyanionic groups form strong covalent bonds with transition metal ions. The two work synergistically to achieve crystal structure stability of the lithium-rich disordered rock salt cathode material, effectively suppressing oxygen loss under high voltage and significantly improving the cycle stability of the material. Attached Figure Description

[0040] Figure 1 This is a SEM image of the lithium-rich disordered rock salt cathode material provided in Example 1.

[0041] Figure 2 These are the rate performance test results of the lithium-rich disordered rock salt cathode materials provided in Examples 1 to 3.

[0042] Figure 3 The charge-discharge curves of the lithium-rich disordered rock salt cathode material provided in Example 1 at a rate of 0.1C are shown. Detailed Implementation

[0043] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. In this invention, "a combination of at least two" means, unless otherwise specified, a quantity greater than or equal to two. For example, "any combination of one or at least two" means one or more of two. It is understood that when referring to "a combination of at least two," it means any suitable combination of multiple items, i.e., a combination of "at least two" items carried out in a manner that does not conflict with and allows for the implementation of the invention.

[0045] In the description of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0046] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0047] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0048] In one specific embodiment, the present invention provides a lithium-rich disordered rock salt cathode material, wherein the general chemical formula of the lithium-rich disordered rock salt cathode material is Li. (1+x) M p N q O (2-y) X y , 0.3≤x≤0.6, for example, can be 0.3, 0.35, 0.4, 0.45, 0.5 or 0.55; 0.5≤p≤0.9, for example, can be 0.6, 0.7, 0.75, 0.8 or 0.85; 0.1≤q≤0.5, for example, can be 0.1, 0.2, 0.3, 0.4; 0≤y≤0.4, for example, can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 or 0.38; M includes Fe and / or Mn; N includes any one or at least two combinations of Zr, Ti, Nb, Mo, W or V, typically but not limited to combinations of Ti and Nb, Ti and Mo, or W and V; X includes polyanionic groups.

[0049] This invention introduces polyanionic groups to replace oxygen sites in lithium-rich disordered rock salt cathode materials, while simultaneously introducing nitrogen elements with higher valence states. The high-valence nitrogen elements participate in and stabilize the redox reaction of the polyanionic groups. The polyanionic groups form strong covalent bonds with transition metal ions. The two work synergistically to achieve crystal structure stability of the lithium-rich disordered rock salt cathode material, effectively suppressing oxygen loss under high voltage and significantly improving the cycle stability of the material.

[0050] In this invention, the introduction of polyanionic groups, compared to monoatomic anions, such as O, provides advantages over monoatomic anions. 2- or F - It can better stabilize the structure of lithium-rich rock salt materials during Li ion insertion and extraction, which is more conducive to improving cycle performance.

[0051] In this invention, high-valence elements are introduced to participate in and stabilize anionic redox reactions. During charging, the high-valence elements themselves do not undergo redox reactions, but their high valence states raise the energy level (O2p band center) of the oxygen atoms they coordinate with, making it easier and more controllable for the polyanion clusters to undergo reversible oxygen redox reactions during charging. When the polyanion clusters participate in the reaction, the stable framework formed by these high-valence elements can accommodate changes in the electronic states of the elements within the polyanion cluster without causing structural collapse, thereby improving the reversibility of the redox reactions of the polyanion clusters.

[0052] In this invention, the introduction of an appropriate amount of nitrogen (N) element is beneficial to improving the structural stability and electrical properties of lithium-rich rock salt materials. However, excessive introduction of N element may lead to low reversible capacity and poor rate performance. In this invention, the N element is preferably a combination of at least two types, more preferably a combination of Ti and Nb. The molar ratio of Ti to Nb is preferably (1~4):1, for example, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1 or 4:1.

[0053] In this invention, the amount of polyanionic groups introduced is 0≤y≤0.4. If too much polyanionic group is introduced, impurities may be generated, and pure-phase lithium-rich disordered rock salt cathode material cannot be obtained.

[0054] The lithium-rich disordered rock salt cathode material provided by this invention does not include scarce and expensive cobalt and nickel elements, which reduces the cost of raw materials and is conducive to large-scale commercial application.

[0055] In some embodiments, the polyanionic group includes SO4. 2- PO4 3- BO3 3- or SiO4 4- Any one or at least two of the following, typical but not limited combinations include PO4. 3- BO3 3- The combination of SiO4 4- and PO4 3- Combinations, BO3 3- and SiO4 4- Combinations of these, preferably PO4. 3- BO3 3- or SiO4 4- Any one or at least two of them.

[0056] In another specific embodiment, the present invention provides a method for preparing a lithium-rich disordered rock salt cathode material as described in the foregoing specific embodiment, the preparation method comprising:

[0057] According to the stoichiometric ratio, Li source, M source, N source and X source are weighed and premixed to obtain premixed raw material. The premixed raw material is subjected to a first ball milling to obtain a first ball milling material. The first ball milling material is pre-sintered to obtain a pre-sintered material. The pre-sintered material is subjected to a second ball milling to obtain a second ball milling material. The second ball milling material is calcined to obtain the lithium-rich disordered rock salt cathode material.

[0058] This invention employs a high-energy ball milling method combined with a solid-state reaction method to prepare lithium-rich disordered rock salt cathode materials. First, pre-mixing and a first ball milling process ensure thorough mixing and particle refinement of the raw materials. This facilitates the removal of moisture from the raw materials during the subsequent pre-sintering process, preventing moisture from adversely affecting the material's performance. The pre-sintered material is then subjected to a second ball milling followed by calcination to ensure complete uniformity of elements and prevent component segregation after pre-sintering.

[0059] In some embodiments, the Li source includes any one or a combination of at least two of lithium oxalate, lithium carbonate, lithium nitrate, lithium hydroxide, or lithium acetate.

[0060] In some embodiments, the M source includes any one or a combination of at least two of ferric nitrate, ferric oxide, ferric oxide, ferrous oxide, manganese nitrate, manganese acetate, manganese dioxide, and manganese tetroxide.

[0061] In some embodiments, the N source includes any one or a combination of at least two of zirconium dioxide, titanium dioxide, niobium pentoxide, molybdenum trioxide, tungsten trioxide, or vanadium pentoxide.

[0062] In some embodiments, the X source includes any one or a combination of at least two of ammonium sulfate, lithium sulfate, ammonium dihydrogen phosphate, ammonium phosphate, monohydrogen phosphate, lithium dihydrogen phosphate, lithium phosphate, lithium borate, boron trioxide, silicon dioxide, and lithium silicate.

[0063] In some embodiments, the premixing includes dry mixing.

[0064] In some embodiments, the first ball milling includes wet ball milling.

[0065] In some embodiments, the second ball milling includes dry ball milling.

[0066] In some embodiments, the milling media for the wet ball milling includes ethanol.

[0067] In some embodiments, the rotational speed of the wet ball mill is 400 rpm to 800 rpm, for example, it can be 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 780 rpm or 800 rpm.

[0068] In some embodiments, the wet ball milling time is 10h to 15h, for example, 10h, 11h, 12h, 13h, 14h or 15h.

[0069] In some embodiments, the rotational speed of the dry ball mill is 200 rpm to 600 rpm, for example, it can be 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm or 600 rpm.

[0070] In some embodiments, the dry ball milling time is 2h to 6h, for example, it can be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h.

[0071] In this invention, the pre-sintering temperature affects the phase structure of the pre-sintered material, which in turn affects the structure and performance of the lithium-rich disordered rock salt cathode material.

[0072] In some embodiments, the pre-sintering temperature is 500°C to 750°C, for example, it can be 500°C, 550°C, 600°C, 650°C or 700°C.

[0073] In some embodiments, the pre-sintering time is 4h to 8h, for example, it can be 4h, 5h, 6h, 7h or 8h.

[0074] In some embodiments, the pre-sintering atmosphere includes an inert atmosphere.

[0075] In some embodiments, the inert atmosphere includes nitrogen and / or an inert gas.

[0076] In some embodiments, the calcination temperature is 900°C to 1100°C, for example, 900°C, 950°C, 1000°C, 1050°C or 1100°C.

[0077] In some embodiments, the calcination time is 10h to 15h, for example, 10h, 11h, 12h, 13h, 14h or 15h.

[0078] In some embodiments, the calcination atmosphere includes an inert atmosphere.

[0079] In some embodiments, the inert atmosphere includes nitrogen and / or an inert gas.

[0080] In some embodiments, the preparation method further includes sequentially subjecting the lithium-rich disordered rock salt cathode material to roller crushing and air jet milling.

[0081] In yet another embodiment, the present invention provides a positive electrode sheet comprising the lithium-rich disordered rock salt positive electrode material described in one of the preceding embodiments.

[0082] In another specific embodiment, the present invention provides a lithium-ion battery, the lithium-ion battery comprising the lithium-rich disordered rock salt cathode material described in one of the preceding specific embodiments, or comprising the cathode sheet described in yet another of the preceding specific embodiments.

[0083] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0084] Example 1

[0085] This embodiment provides a lithium-rich disordered rock salt cathode material, the general chemical formula of which is Li. 1.5 Mn 0.7 Ti 0.3 O 1.9 (PO4) 0.1 SEM image as follows Figure 1 As shown.

[0086] The preparation method of the lithium-rich disordered rock salt cathode material includes:

[0087] According to the stoichiometric ratio, lithium carbonate, manganese oxide, titanium dioxide, and ammonium dihydrogen phosphate were weighed and dry-mixed to obtain a premixed raw material. Using ethanol as the medium, the premixed raw material was wet-milled at 600 rpm for 12 hours to obtain a first ball milling material. Under a nitrogen atmosphere, the first ball milling material was pre-sintered at 650°C for 6 hours to obtain a pre-sintered material. The pre-sintered material was then ball-milled at 400 rpm for 6 hours to obtain a second ball milling material. Under a nitrogen atmosphere, the second ball milling material was calcined at 980°C for 12 hours to obtain the lithium-rich disordered rock salt cathode material.

[0088] Example 2

[0089] This embodiment provides a lithium-rich disordered rock salt cathode material, the general chemical formula of which is Li. 1.55 Fe 0.75 Zr 0.25 O 1.95 (BO3) 0.05 .

[0090] The preparation method of the lithium-rich disordered rock salt cathode material includes:

[0091] According to the stoichiometric ratio, nitric acid, ferric oxide, zirconium dioxide, and sodium borate were weighed and dry-mixed to obtain a premixed raw material. Using ethanol as the medium, the premixed raw material was wet-milled at 400 rpm for 10 hours to obtain a first ball milling material. Under an argon atmosphere, the first ball milling material was pre-sintered at 500°C for 4 hours to obtain a pre-sintered material. The pre-sintered material was then ball-milled at 200 rpm for 6 hours to obtain a second ball milling material. Under an argon atmosphere, the second ball milling material was calcined at 900°C for 15 hours to obtain the lithium-rich disordered rock salt cathode material.

[0092] Example 3

[0093] This embodiment provides a lithium-rich disordered rock salt cathode material, the general chemical formula of which is Li. 1.5 Mn 0.85 W 0.15 O 1.95 (SiO4) 0.05 .

[0094] The preparation method of the lithium-rich disordered rock salt cathode material includes:

[0095] According to the stoichiometric ratio, lithium carbonate, manganese oxide, tungsten trioxide, and sodium silicate were weighed and dry-mixed to obtain a premixed raw material. Using ethanol as the medium, the premixed raw material was wet-milled at 800 rpm for 15 hours to obtain a first ball milling material. Under a nitrogen atmosphere, the first ball milling material was pre-sintered at 750°C for 8 hours to obtain a pre-sintered material. The pre-sintered material was then ball-milled at 600 rpm for 2 hours to obtain a second ball milling material. Under a nitrogen atmosphere, the second ball milling material was calcined at 1100°C for 12 hours to obtain the lithium-rich disordered rock salt cathode material.

[0096] Example 4

[0097] This embodiment provides a lithium-rich disordered rock salt cathode material, except that the general chemical formula of the lithium-rich disordered rock salt cathode material is Li. 1.5 Mn 0.7 Ti 0.2 Nb 0.1 O 1.9 (PO4) 0.1 During the preparation process, the pre-sintering temperature was 450°C, and all other processes were the same as in Example 1.

[0098] Example 5

[0099] This embodiment provides a lithium-rich disordered rock salt cathode material, which is the same as that in Example 1 except that the pre-sintering temperature is 450°C during the preparation process.

[0100] Example 6

[0101] This embodiment provides a lithium-rich disordered rock salt cathode material, which is the same as that in Example 1 except that the pre-sintering temperature is 800℃ during the preparation process.

[0102] Example 7

[0103] This embodiment provides a lithium-rich disordered rock salt cathode material, which is the same as that in Example 1 except that the calcination temperature is 850°C during the preparation process.

[0104] Example 8

[0105] This embodiment provides a lithium-rich disordered rock salt cathode material, which is the same as that in Example 1 except that the calcination temperature is 1150℃ during the preparation process.

[0106] Example 9

[0107] This embodiment provides a lithium-rich disordered rock salt cathode material, which is the same as that in Example 1 except that the first ball milling is not performed during the preparation process.

[0108] Example 10

[0109] This embodiment provides a lithium-rich disordered rock salt cathode material, which is the same as that in Example 1 except that a second ball milling is not performed during the preparation process.

[0110] Example 11

[0111] This embodiment provides a lithium-rich disordered rock salt cathode material, which is the same as that in Example 1 except that pre-sintering and second ball milling are not performed during the preparation process.

[0112] Comparative Example 1

[0113] This comparative example provides a cathode material, except that the general chemical formula of the lithium-rich disordered rock salt cathode material is Li. 1.3 Mn 0.7 Ti 0.3 O 1.8 (PO4) 0.1 Except for the above, everything else is the same as in Example 1.

[0114] Comparative Example 2

[0115] This comparative example provides a lithium-rich disordered rock salt cathode material, except that the general chemical formula of the lithium-rich disordered rock salt cathode material is Li. 1.6 Mn 0.7 Ti 0.3 O 1.95 (PO4) 0.1 Except for the above, everything else is the same as in Example 1.

[0116] Comparative Example 3

[0117] This comparative example provides a lithium-rich disordered rock salt cathode material, except that the general chemical formula of the lithium-rich disordered rock salt cathode material is Li. 1.5 Mn 0.7 Ti 0.3 O 1.3 (PO4) 0.5 Except for the above, everything else is the same as in Example 1.

[0118] Comparative Example 4

[0119] This comparative example provides a lithium-rich disordered rock salt cathode material, except that the general chemical formula of the lithium-rich disordered rock salt cathode material is Li. 1.5 Mn 0.7 Ti 0.3 O2F 0.1 Except for the above, everything else is the same as in Example 1.

[0120] Comparative Example 5

[0121] This comparative example provides a lithium-rich disordered rock salt cathode material, except that the general chemical formula of the lithium-rich disordered rock salt cathode material is Li. 1.5 MnO 1.6 (PO4) 0.1 Except for the above, everything else is the same as in Example 1.

[0122] Comparative Example 6

[0123] This comparative example provides a lithium-rich disordered rock salt cathode material, except that the general chemical formula of the lithium-rich disordered rock salt cathode material is Li. 1.5 Mn 0.4 Ti 0.6 O 2.2 (PO4) 0.1 Except for the above, everything else is the same as in Example 1.

[0124] Performance testing:

[0125] The positive electrode materials provided in all the above embodiments and comparative examples are dispersed in NMP with conductive carbon black and PVDF at a mass ratio of 8:1:1, coated on the surface of aluminum foil to prepare a positive electrode sheet, and a lithium sheet is used as the negative electrode to prepare a coin cell lithium-ion battery.

[0126] The lithium-ion battery was charged and discharged at a rate of 0.1C under a voltage range of 1.5V to 4.8V at 25℃. The initial coulombic efficiency and discharge specific capacity were tested. The charge and discharge curves of the lithium-rich disordered rock salt cathode material provided in Example 1 at a rate of 0.1C are shown below. Figure 1 As shown.

[0127] The rate performance of the above-mentioned lithium-ion batteries was tested at 25℃ and a voltage range of 1.5V to 4.8V, at rates of 0.2C, 0.5C, 1C, 2C, and 5C.

[0128] The cycle performance of the above-mentioned lithium-ion battery was tested at 25℃ and a voltage range of 1.5V to 4.8V, at a rate of 1C, and the capacity retention rate was tested after 50 cycles.

[0129] The test results are shown in Table 1. The discharge specific capacity of the lithium-rich disordered rock salt cathode materials provided in Examples 1 to 3 at rates of 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, and 0.1C is as follows: Figure 2 As shown; the charge-discharge curves of the lithium-rich disordered rock salt cathode material provided in Example 1 at a 0.1C rate are as follows. Figure 1 As shown.

[0130] Table 1

[0131]

[0132] According to the test results in Table 1, this invention introduces higher valence N elements into lithium-rich disordered rock salt cathode materials, and simultaneously introduces polyanionic groups to jointly stabilize the crystal structure, effectively suppressing oxygen loss under high voltage. The higher valence N elements can also reduce cation mixing and participate in and stabilize anionic redox reactions. The polyanionic groups form strong covalent bonds with transition metal ions, enhancing the structural stability of the material and significantly improving the cycle stability of the material.

[0133] According to the test results of Example 1, Comparative Example 1, and Comparative Example 2, if Li is not excessive in the material, a lithium-rich disordered rock salt cathode material cannot be obtained, the capacity of the material cannot be fully improved, and the discharge specific capacity of the material decreases significantly. However, if Li is excessive, the structure of the material will be unstable, and a lithium-rich disordered rock salt cathode material that meets the chemical formula of the present invention cannot be obtained, resulting in poor electrical performance.

[0134] According to the test results of Example 1 and Comparative Example 3, if too many polyanionic groups are introduced, impurities will be generated, and pure-phase lithium-rich disordered rock salt cathode material cannot be obtained.

[0135] According to the test results of Example 1 and Comparative Example 4, if only fluoride ions are introduced without introducing polyanionic groups, the cycling performance of the material deteriorates significantly.

[0136] According to the test results of Example 1, Comparative Examples 5 and 6, if high-valence elements are not introduced or too many high-valence elements are introduced, it is impossible to obtain lithium-rich disordered rock salt cathode material that meets the chemical formula of the present invention. If high-valence elements are not introduced, the structural stability and electrical performance of lithium-rich rock salt material cannot be effectively improved. If too many high-valence elements are introduced, it will lead to low reversible capacity and poor rate performance.

[0137] Based on the test results of Examples 1 and 4, when the N element is selected as a combination of Ti and Nb, the synergistic effect between the two elements further improves the cycle stability of the capacity of the lithium-rich rock salt material.

[0138] According to the test results of Examples 1, 5 and 6, both excessively high and low pre-sintering temperatures affect the phase structure of the pre-sintered material, thereby affecting the structural stability of the cathode material and causing a decrease in the electrical performance of the cathode material.

[0139] Based on the test results of Examples 1, 7, and 8, both excessively high and excessively low calcination temperatures are detrimental to improving the electrical performance of the cathode material.

[0140] Based on the test results of Examples 1 and 9 to 11, this invention utilizes a combined process of first ball milling, pre-sintering, and secondary ball milling to thoroughly mix and refine the raw materials into fine particles. Pre-sintering removes moisture from the raw materials, preventing it from adversely affecting the material's performance. The pre-sintered material is then subjected to a second ball milling followed by calcination to ensure complete uniformity of elements and prevent component segregation after pre-sintering. Failure to follow this process will hinder the performance of the cathode material, leading to a decline in electrical performance.

[0141] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A lithium-rich disordered rock salt cathode material, characterized in that, The general chemical formula of the lithium-rich disordered rock salt cathode material is Li. (1+x) M p N q O (2-y) X y Wherein, 0.3≤x≤0.6, p+q=1, 0.5≤p≤0.9, 0.1≤q≤0.5, 0≤y≤0.4, M includes Fe and / or Mn; N includes any one or at least two combinations of Zr, Ti, Nb, Mo, W or V; X includes polyanionic groups.

2. The lithium-rich disordered rock salt cathode material as described in claim 1, characterized in that, The polyanionic group includes SO4. 2- PO4 3- BO3 3- or SiO4 4- Any one or at least two of them.

3. A method for preparing the lithium-rich disordered rock salt cathode material as described in claim 1 or 2, characterized in that, The preparation method includes: According to the stoichiometric ratio, Li source, M source, N source and X source are weighed and premixed to obtain premixed raw material. The premixed raw material is subjected to a first ball milling to obtain a first ball milling material. The first ball milling material is pre-sintered to obtain a pre-sintered material. The pre-sintered material is subjected to a second ball milling to obtain a second ball milling material. The second ball milling material is calcined to obtain the lithium-rich disordered rock salt cathode material.

4. The preparation method according to claim 3, characterized in that, The premix includes dry mixing; And / or, the first ball milling includes wet ball milling; And / or, the second ball milling includes dry ball milling.

5. The preparation method according to claim 4, characterized in that, The ball milling media for the wet ball milling includes ethanol; And / or, the rotation speed of the wet ball mill is 400 rpm to 800 rpm; And / or, the wet ball milling time is 10h~15h; And / or, the rotation speed of the dry ball mill is 200 rpm to 600 rpm; And / or, the dry ball milling time is 2h~6h.

6. The preparation method according to any one of claims 3 to 5, characterized in that, The pre-sintering temperature is 500℃~750℃; And / or, the pre-sintering time is 4h~8h; And / or, the pre-sintering atmosphere includes an inert atmosphere.

7. The preparation method according to any one of claims 3 to 6, characterized in that, The calcination temperature is 900℃~1100℃; And / or, the calcination time is 10h~15h; And / or, the calcination atmosphere includes an inert atmosphere.

8. The preparation method according to any one of claims 3 to 7, characterized in that, The preparation method further includes sequentially crushing the lithium-rich disordered rock salt cathode material by roller crushing and air jet milling.

9. A positive electrode plate, characterized in that, The cathode material comprises the lithium-rich disordered rock salt cathode material as described in claim 1 or 2.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the lithium-rich disordered rock salt cathode material as described in claim 1 or 2, or includes the cathode sheet as described in claim 9.

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