Preparation of spinel-structured high-voltage composite positive electrode material

Abstract

The invention discloses preparation of a high-voltage composite positive electrode material with a spinel structure, and belongs to the technical field of lithium ion batteries. The spinel structure high-voltage composite positive electrode material comprises a spinel structure matrix phase and a rock salt structure functional phase, the chemical general formula of the matrix phase of the spinel structure is LiNi < 0.5 > Mn < 1.5 > O < 4 > (LNMO); the general chemical formula of the rock salt structure functional phase is LixNi1-xO (LNO), and x is greater than or equal to 0 and less than or equal to 0.3. The LNO component is controllably prefabricated in the product, so that the side reaction of converting LNMO into LNO in the synthesis process is effectively inhibited, the content of Mn < 3 + > in the product is greatly reduced, and the cycling stability of the battery is greatly improved. In addition, the LNO shows metal characteristics and does not influence the electronic conductivity of the composite positive electrode material. The preparation method has the characteristics that the LNO component is controllable, and the content of Mn < 3 + > in LNMO is extremely low.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to the preparation of a spinel-structured high-voltage composite cathode material. Background Technology

[0002] Globally, the emerging energy storage industry has garnered widespread attention and is considered a key pathway to achieving carbon neutrality. In the transportation sector, new energy vehicles powered by lithium-ion batteries are gradually replacing traditional gasoline-powered vehicles, with market sales showing a significant upward trend and demonstrating enormous development potential. Among these, cathode materials, as the core factor determining the energy density and cost of lithium-ion batteries (accounting for approximately 30%-40% of the total battery cost), directly constrain the upper limit of battery performance. Currently, mainstream cathode material systems still face certain development bottlenecks; the energy density of lithium iron phosphate (LFP) is approaching its theoretical limit, while high-nickel ternary materials (NCM / NCA) are limited by the high cost of cobalt resources and the risk of thermal runaway.

[0003] Among them, nickel-manganese spinel cathode material (LiNi 0.5 Mn 1.5 O4 (LNMO) has become an ideal cathode choice for unattended devices (such as field sensor nodes, drones, and mobile robots) due to its advantages such as a high voltage platform (approximately 4.7V), low cost (abundant manganese resources, reducing costs by more than 30% compared to cobalt-based materials), and wide temperature range adaptability. Its theoretical specific energy can reach 689.5 Wh / kg, significantly improving device endurance and supporting rapid charge and discharge, thus meeting the needs of extreme environment applications. However, LNMO materials synthesized using conventional methods currently contain a large amount of Mn. 3+ Mn readily forms at approximately 4.0 V. 4+ / Mn 3+ Redox reaction, Mn in the cycle 3+ It easily triggers the Janteler effect and is reduced to Mn. 2+ This leads to the dissolution of manganese ions, severely damaging the cycle stability of lithium-ion batteries.

[0004] While common material modification strategies can improve performance to some extent, they still have fundamental limitations. Doping can increase the Ni / Mn disorder and lithium-ion diffusion coefficient, thereby improving battery cycle life, but it cannot effectively reduce Mn content. 3+ Content (DOI: 10.1021 / acssuschemeng.3c04620). Surface coating can suppress the contact between the positive electrode and the electrolyte, alleviate HF corrosion of the electrode during battery cycling, and thus improve stability, but it still cannot reduce Mn. 3+Content (DOI:10.1016 / j.cej.2025.162287). While electrolyte formulation optimization helps build a stable electrode-electrolyte interface and improve ion transport, it still cannot solve the problem of Mn content. 3+ The resulting degradation of the material's intrinsic structure (DOI:10.1002 / aenm.201701398) still requires further improvement. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a spinel-structured high-voltage composite cathode material, thereby addressing the aforementioned problems in the prior art. Because the product of this invention already contains a controllable pre-prepared LNO component, the side reaction of LNMO converting to LNO during synthesis is effectively suppressed, resulting in a decrease in Mn content in the product. 3+ The content is significantly reduced, thereby greatly improving the cycle stability of the battery.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] One of the technical solutions of this invention is to provide a spinel-structured high-voltage composite cathode material, comprising a spinel-structured matrix phase and a rock-salt-structured functional phase; the general chemical formula of the spinel-structured matrix phase is LiNi. 0.5 Mn 1.5 O4 (LNMO); the general chemical formula of the rock salt structural functional phase is Li x Ni 1-x O(LNO), where 0≤x≤0.3.

[0008] The presence of LNO effectively reduces Mn in LNMO. 3+ The content of these components solves the problem of poor battery cycle stability. A heterogeneous interface can be formed between the spinel matrix phase and the rock salt functional phase.

[0009] Preferably, the rock salt structure functional phase accounts for 4-30% of the mass of the spinel structure high voltage composite cathode material, more preferably 4-15%.

[0010] The chemical formula of the spinel-structured high-voltage composite cathode material of this invention is γLi. x Ni 1-x O+(1-y)LiNi 0.5 Mn 1.5 O4, where y is the mass percentage of the rock salt structural functional phase in the material, 4%≤y≤30%.

[0011] The second technical solution of the present invention provides a method for preparing the above-mentioned spinel structure high-voltage composite cathode material, comprising the following steps:

[0012] The lithium source, nickel source and manganese source are mixed and sintered to obtain the spinel structure high voltage composite cathode material.

[0013] Preferably, the lithium source is lithium carbonate and / or lithium oxide.

[0014] Preferably, the nickel source is nickel monoxide and / or nickel trioxide.

[0015] Preferably, the manganese source is at least one of manganese carbonate, manganese dioxide, and manganese acetate.

[0016] Preferably, the sintering temperature is 700~1000℃, more preferably 800~900℃, the heating rate is 2~10℃ / min, and the time is 2~24 h, more preferably 4~12 h.

[0017] Preferably, the atmosphere for the sintering process is at least one of air, oxygen, and argon, and more preferably an air atmosphere.

[0018] Preferably, the mixing method is wet ball milling, which includes the following steps: ball milling the raw material system at a speed of 200~800 rpm / min for 2~24 h to make the raw materials mix evenly, and then drying it at 60~120℃.

[0019] More preferably, the wet ball milling includes the following steps: ball milling the raw material system at a speed of 300~500 rpm / min for 2~6 h to make the raw material uniformly mixed, and then drying it at 70~120℃ for 2~12 h.

[0020] The third technical solution of the present invention provides an application of the above-mentioned spinel structure high-voltage composite cathode material in the field of lithium-ion battery cathode materials.

[0021] Traditional methods for synthesizing lithium nickel manganese oxide (LNMO) electrode materials primarily focus on controlling the introduction of Li, Ni, and Mn, hoping to synthesize a pure LNMO phase, which involves maximizing the LNMO content and minimizing the LNO content in the product. However, this method cannot suppress the side reaction of LNMO converting to LNO during synthesis, and the LNO composition is uncontrollable, leading to an imbalance in the Mn content of the product. 3+ Excessive content leads to Mn 3+ The Janteler effect and Mn in the cyclic process 3+ Generate Mn 2+ And leading to Mn 2+The dissolution problem is a significant issue, which is why traditional lithium nickel manganese oxide electrode materials, despite their high initial discharge specific capacity, suffer from extremely poor cycle stability. This invention, however, prepares an LNMO-LNO composite material through pre-synthesizing LNO. Because the product already contains a controllable pre-introduced LNO component, the side reaction of LNMO to LNO conversion during synthesis is effectively suppressed based on Le Chatelier's principle, resulting in a decrease in Mn content in the product. 3+ The content is significantly reduced, thereby greatly improving the cycle stability of the battery. Furthermore, LNO exhibits metallic properties and does not affect the electronic conductivity of the composite cathode material. This invention features controllable LNO composition and controllable Mn content in LNMO. 3+ It is characterized by its extremely low content.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] This invention provides a low Mn 3+ High-voltage composite cathode material with spinel structure and high content, made of LiNi 0.5 Mn 1.5 O4 (LNMO) and Li x Ni 1-x The composition is O(LNO). The presence of LNO reduces the Mn content of LNMO. 3+ The content increased Mn 4+ The content of [something] is increased, thereby improving cycle stability.

[0024] The composite cathode material of the present invention is prepared by a solid-state method, which is simple in preparation process, low in cost, easy to be mass-produced industrially, and has good application prospects. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 The charge-discharge curves of the button batteries assembled using the cathode materials of Examples 1-5 and Comparative Example 1 are shown for the first cycle at 0.1C.

[0027] Figure 2 The graph shows the cycle stability of button batteries assembled using the cathode materials of Examples 1-5 and Comparative Example 1 at a 1C charge-discharge rate. Detailed Implementation

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0029] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. It should be noted that any aspects of this invention not described in detail are conventional practices in the art and are not the focus of this invention.

[0031] The terms “comprising,” “including,” “having,” “containing,” etc., used in this invention are all open-ended terms, meaning that they include but are not limited to.

[0032] This invention utilizes the product to convert Mn during recycling. 4+ / Mn 3+ The specific capacity provided by the redox reaction, and the Mn content in the XPS analysis results. 3+ The content of Mn in the material is used to jointly assess and explain its presence. 3+ The level of content.

[0033] All raw materials used in the following embodiments and comparative examples of the present invention are commercially available products.

[0034] Example 1

[0035] A spinel-structured high-voltage composite cathode material with the chemical formula γLi x Ni 1-x O+(1-y)LiNi 0.5 Mn 1.5 O4, where y is Li x Ni 1-x The mass percentage of O in the material is y=28.30% and x=0.05.

[0036] The specific preparation steps are as follows:

[0037] (1) 0.78 g lithium carbonate, 2.09 g nickel monoxide, 0.08 g nickel trioxide and 3.45 g manganese carbonate were placed in a ball mill jar and ball milled at 400 rpm / min for 4 h in anhydrous ethanol medium to mix the raw materials evenly. Then the raw materials were dried at 80℃ for 12 h to obtain the precursor.

[0038] (2) In an air atmosphere, the precursor is heated to 800°C at a heating rate of 5°C / min and then kept at that temperature for 12 hours to obtain the cathode material.

[0039] X-ray photoelectron spectroscopy (XPS) analysis was performed on the spinel-structured high-voltage composite cathode material prepared in this embodiment to analyze the Mn content. 3+ The content and results are shown in Table 1.

[0040] Example 2

[0041] A spinel-structured high-voltage composite cathode material with the chemical formula γLi x Ni 1-x O+(1-y)LiNi 0.5 Mn 1.5 O4, where y is Li x Ni 1-x The mass percentage of O in the material is y=14.47% and x=0.05.

[0042] The specific preparation steps are as follows:

[0043] (1) 0.75 g lithium carbonate, 1.32 g nickel monoxide, 0.03 g nickel trioxide and 3.45 g manganese carbonate were placed in a ball mill jar and ball milled at 400 rpm / min for 4 h in anhydrous ethanol medium to make the raw materials uniformly mixed. Then the raw materials were dried at 80℃ for 12 h to obtain the precursor.

[0044] (2) In an air atmosphere, the precursor is heated to 800°C at a heating rate of 5°C / min and then kept at that temperature for 12 hours to obtain the cathode material.

[0045] X-ray photoelectron spectroscopy (XPS) analysis was performed on the spinel-structured high-voltage composite cathode material prepared in this embodiment to analyze the Mn content. 3+ The content and results are shown in Table 1.

[0046] Example 3

[0047] A spinel-structured high-voltage composite cathode material with the chemical formula γLi x Ni 1-x O+(1-y)LiNi 0.5 Mn 1.5O4, where y is Li x Ni 1-x The mass percentage of O in the material is y=4.20% and x=0.05.

[0048] The specific preparation steps are as follows:

[0049] (1) 0.74 g lithium carbonate, 0.90 g nickel monoxide, 0.01 g nickel trioxide and 3.45 g manganese carbonate were placed in a ball mill jar and ball milled at 400 rpm / min for 4 h in anhydrous ethanol medium to mix the raw materials evenly. Then the raw materials were dried at 80℃ for 12 h to obtain the precursor.

[0050] (2) In an air atmosphere, the precursor is heated to 800°C at a heating rate of 5°C / min and then kept at that temperature for 12 hours to obtain the cathode material.

[0051] X-ray photoelectron spectroscopy (XPS) analysis was performed on the spinel-structured high-voltage composite cathode material prepared in this embodiment to analyze the Mn content. 3+ The content and results are shown in Table 1.

[0052] Example 4

[0053] A spinel-structured high-voltage composite cathode material with the chemical formula γLi x Ni 1-x O+(1-y)LiNi 0.5 Mn 1.5 O4, where y is Li x Ni 1-x The mass percentage of O in the material is y=13.11% and x=0.2.

[0054] The specific preparation steps are as follows:

[0055] (1) 0.80 g lithium carbonate, 1.13 g nickel monoxide, 0.14 g nickel trioxide and 3.45 g manganese carbonate were placed in a ball mill jar and ball milled at 400 rpm / min for 4 h in anhydrous ethanol medium to mix the raw materials evenly. Then the raw materials were dried at 80℃ for 12 h to obtain the precursor.

[0056] (2) In an air atmosphere, the precursor is heated to 800°C at a heating rate of 5°C / min and then kept at that temperature for 12 hours to obtain the cathode material.

[0057] X-ray photoelectron spectroscopy (XPS) analysis was performed on the spinel-structured high-voltage composite cathode material prepared in this embodiment to analyze the Mn content. 3+ The content and results are shown in Table 1.

[0058] Example 5

[0059] A spinel-structured high-voltage composite cathode material with the chemical formula γLi x Ni 1-x O+(1-y)LiNi 0.5 Mn 1.5 O4, where y is Li x Ni 1-x The mass percentage of O in the material is y=12.19% and x=0.3.

[0060] The specific preparation steps are as follows:

[0061] (1) 0.83 g lithium carbonate, 1.00 g nickel monoxide, 0.21 g nickel trioxide and 3.45 g manganese carbonate were placed in a ball mill jar and ball milled at 400 rpm / min for 4 h in anhydrous ethanol medium to mix the raw materials evenly. Then the raw materials were dried at 80℃ for 12 h to obtain the precursor.

[0062] (2) In an air atmosphere, the precursor is heated to 800°C at a heating rate of 5°C / min and then kept at that temperature for 12 hours to obtain the cathode material.

[0063] X-ray photoelectron spectroscopy (XPS) analysis was performed on the spinel-structured high-voltage composite cathode material prepared in this embodiment to analyze the Mn content. 3+ The content and results are shown in Table 1.

[0064] Comparative Example 1 (rock salt phase omitted)

[0065] A spinel-structured cathode material with the chemical formula LiNi 0.5 Mn 1.5 O4 is prepared with a molar ratio of Li:Ni:Mn:O = 1.0:0.5:1.5:4.0.

[0066] The specific preparation steps are as follows:

[0067] (1) Place 0.74 g lithium carbonate, 0.75 g nickel monoxide and 3.45 g manganese carbonate in a ball mill jar and ball mill at 400 rpm / min for 4 h in anhydrous ethanol medium to mix the raw materials evenly. Then dry at 80℃ for 12 h to obtain the precursor.

[0068] (2) In an air atmosphere, the precursor is heated to 800°C at a heating rate of 5°C / min and then kept at that temperature for 12 hours to obtain the cathode material.

[0069] X-ray photoelectron spectroscopy (XPS) analysis was performed on the spinel-structured high-voltage composite cathode material prepared in this comparative example to analyze the Mn content. 3+The content and results are shown in Table 1.

[0070] Table 1

[0071] sample Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 <![CDATA[Mn 3+ Content 16.0 mol% 13.6 mol% 27.0 mol% 18.3 mol% 22.2 mol% 29.7 mol%

[0072] Effect verification

[0073] The cathode materials prepared in Examples 1-5 and Comparative Example 1 were assembled into lithium-ion button batteries, and charge-discharge tests and cycle performance tests were conducted.

[0074] The assembly steps for lithium-ion button batteries are as follows:

[0075] The above-mentioned positive electrode material, conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were weighed at a mass ratio of 8:1:1, and thoroughly ground and mixed. The mixture was then dissolved in an N-methylpyrrolidone (NMP) solution and magnetically stirred for 4 hours to form a uniform slurry. The slurry was then evenly coated onto aluminum foil using a scraper method and dried at 80°C for 12 hours under vacuum. The foil was then sliced ​​and used as the positive electrode. A lithium foil was used as the negative electrode. The electrolyte was 1 mol / L lithium hexafluorophosphate (LiPF6) dissolved in a 1:1:1 volume ratio of ethylene carbonate / dimethyl carbonate / diethyl carbonate (EC / DMC / DEC) system. The separator was polypropylene (PP). The cells were assembled into a 2032-type lithium-ion button battery in an argon-filled glove box.

[0076] Battery performance testing: The testing was conducted using the Landian testing system, model CT3001A, manufactured by Wuhan Landian Electronics Co., Ltd.

[0077] Cyclic performance test conditions: 300 cycles at a current density of 1C (1C=146.7 mAh / g) within a voltage range of 3.0~4.95 V.

[0078] The first charge-discharge curves and capacity retention rates are shown below. Figure 1 and Figure 2 .

[0079] Figure 1 The charge-discharge curves of the button batteries assembled using the cathode materials of Examples 1-5 and Comparative Example 1 are shown for the first cycle at 0.1C.

[0080] Figure 2 The graph shows the cycle stability of button batteries assembled using the cathode materials of Examples 1-5 and Comparative Example 1 at a 1C charge-discharge rate.

[0081] Based on the treatment effects of Examples 1-5 and Comparative Example 1, the formulation of the present invention is effective for Mn 3+ The reduction in content is beneficial, proving that it can effectively reduce Mn. 4+ / Mn3+ Electron transfer improves the cycle stability of the battery.

[0082] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A spinel-structured high-voltage composite cathode material, characterized in that, The chemical general formula of the spinel structure base phase is LiNi 0.5 Mn 1.5 O4; the chemical general formula of the rock salt structure functional phase is Li x Ni 1-x O, wherein 0≤x≤0.

3.

2. The spinel structured high voltage composite cathode material of claim 1, wherein, The mass ratio of the rock salt structure functional phase in the spinel structure high-voltage composite positive electrode material is 4-30%.

3. A method for preparing the spinel-structured high-voltage composite cathode material according to any one of claims 1-2, characterized in that, The method comprises the following steps: Mixing a lithium source, a nickel source and a manganese source, and performing sintering treatment to obtain the spinel structure high-voltage composite positive electrode material.

4. The production method according to claim 3, characterized by, The lithium source is lithium carbonate and / or lithium oxide.

5. The preparation method according to claim 3, characterized in that, The nickel source is nickel monoxide and / or nickel sesquioxide.

6. The preparation method according to claim 3, characterized in that, The manganese source is at least one of manganese carbonate, manganese dioxide and manganese acetate.

7. The preparation method according to claim 3, characterized in that, The sintering treatment is performed at a temperature of 700-1000 DEG C, a heating rate of 2-10 DEG C / min and a time of 2-24 h.

8. Application of the spinel structure high-voltage composite positive electrode material in the field of lithium ion battery positive electrode materials.

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