Lithium nickel manganese oxide positive electrode material, preparation method thereof and lithium ion battery

Abstract

The invention belongs to the technical field of lithium batteries, and discloses a lithium nickel manganese oxide positive electrode material, a preparation method thereof and a lithium ion battery. Wherein the lithium nickel manganese oxide positive electrode material has a regular truncated octahedron single crystal structure, and the ratio K of a (111) crystal face orientation parameter to a (100) crystal face orientation parameter in an XRD (X-Ray Diffraction) spectrogram of the lithium nickel manganese oxide positive electrode material is 1-1.6. The lithium nickel manganese oxide positive electrode material provided by the invention has excellent rate capability and cycling stability, and can be well applied to production and manufacturing of lithium ion batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and in particular relates to a lithium nickel manganese oxide positive electrode material and a preparation method thereof, and a lithium ion battery. Background Art

[0002] As a renewable energy storage device, lithium-ion batteries have the advantages of high discharge voltage, low self-discharge, long cycle life, low environmental pollution and high energy density. They have become a new energy technology with broad development prospects and are widely used in portable electronic consumer products, electric vehicles, electric equipment tools, aerospace and other fields. At this stage, especially in the field of electric vehicles, the huge market demand, coupled with the increasing maturity of traditional battery technology, the demand for new technology research and development and the strong support of the industry, have gradually exposed the existing market drawbacks of traditional positive electrode materials, and thus put forward new requirements and challenges for the development of new battery materials with high energy density, good cycle performance and low cost.

[0003] In the above background, in recent years, spinel lithium nickel manganese oxide (LiNi) with the characteristics of high voltage, high energy, stable structure, safety and low manufacturing cost has been widely used. 0.5 Mn 1.5 O4) cathode materials have received extensive attention and are considered to be the most promising and suitable cathode materials for the next generation of high energy density lithium-ion batteries. However, there are some problems in the application of lithium nickel manganese oxide cathode materials. Under high voltage systems, the lithium nickel manganese oxide cathode materials have a high lithium deintercalation potential and are very likely to have serious side reactions with the electrolyte, leading to electrolyte decomposition, Jahn-Teller effect causing structural system damage, Mn 3+ Transition metal dissolution and Li x Ni 1-x O impurity phase generation and other problems, thereby reducing the battery cycle performance and shortening the battery life.

[0004] Therefore, how to improve the rate performance and cycle stability of lithium nickel manganese oxide positive electrode materials is an issue that needs to be studied and solved urgently in this field. Summary of the invention

[0005] The first object of the present invention is to provide a lithium nickel manganese oxide positive electrode material, which has excellent rate performance and cycle stability and can be well applied to the production and manufacture of lithium ion batteries.

[0006] The second object of the present invention is to provide a method for preparing the above-mentioned lithium nickel manganese oxide positive electrode material.

[0007] A third object of the present invention is to provide a lithium ion battery.

[0008] Specifically, the lithium nickel manganese oxide cathode material provided by the present invention has a regular truncated octahedron single crystal structure, and the ratio K of the (111) crystal plane orientation parameter to the (100) crystal plane orientation parameter in the XRD pattern of the lithium nickel manganese oxide cathode material is 1 to 1.6.

[0009] Further, in the XRD pattern of the lithium nickel manganese oxide cathode material, the (111) crystal plane orientation parameter is 270 to 320 nm, and the (100) crystal plane orientation parameter is 210 to 270 nm.

[0010] Further, the ratio K of the (111) crystal plane orientation parameter to the (100) crystal plane orientation parameter in the XRD pattern of the lithium nickel manganese oxide cathode material is 1.1 to 1.5.

[0011] Further, the lithium nickel manganese oxide cathode material includes a compound with the chemical general formula LiNi 0.49 M x Mn 1.49-x / 2 Y z O4; wherein, 0 < x ≤ 0.1, 0.01 < z ≤ 0.05, and M is selected from one or more of strontium, titanium, niobium, molybdenum, tantalum, ruthenium, phosphorus, zinc, and magnesium.

[0012] The preparation method of the above lithium nickel manganese oxide cathode material provided by the present invention specifically includes: S1. Taking a nickel source and a manganese source to carry out a coprecipitation reaction in the presence of an alkaline precipitating agent to obtain a nickel manganese compound precursor; S2. Taking the nickel manganese compound precursor and a lithium source and a crystal plane orientation inducer to carry out a mixing treatment to obtain a mixed material;

[0013] S3. Taking the mixed material to carry out a multi-stage sintering treatment to obtain the lithium nickel manganese oxide cathode material; wherein, the crystal plane orientation inducer includes yttrium element and M element.

[0014] Further, in step S1, the nickel source is selected from one or more of nickel hydroxide, nickel sulfate, nickel carbonate, and nickel acetate.

[0015] Further, in step S1, the manganese source is selected from one or more of manganese hydroxide, manganese sulfate, manganese carbonate, and manganese acetate.

[0016] Further, in step S1, the alkaline precipitating agent is selected from one or more of ammonia, ammonium bicarbonate, sodium bicarbonate, ammonium carbonate, sodium carbonate, and sodium hydroxide.

[0017] Further, in step S1, the molar ratio of nickel ions in the nickel source, manganese ions in the manganese source, and hydroxide ions in the alkaline precipitating agent is 1:(2 to 3.5):(10 to 25).

[0018] Furthermore, in step S1, the coprecipitation reaction comprises: adding an alkaline precipitant to a mixed solution of metal ions including a nickel source and a manganese source at a stirring speed of 20 to 35 Hz and a temperature of 35 to 55° C. to obtain a nickel-manganese compound precursor.

[0019] Furthermore, in step S2, the lithium source is selected from one or more of lithium carbonate, lithium nitrate, lithium hydroxide, lithium acetate, lithium acetate and lithium oxalate.

[0020] Furthermore, in step S2, the molar ratio of lithium ions in the lithium carbonate to the total amount of metal ions in the nickel manganese compound precursor is (0.4-0.6):1.

[0021] Further, in step S2, the crystal plane orientation inducer includes a yttrium inducer and an M inducer, the yttrium inducer is yttrium oxide and / or yttrium hydroxide, and the M inducer is selected from one or more of strontium oxide, titanium oxide, niobium oxide, molybdenum oxide, tantalum oxide, ruthenium oxide, phosphorus oxide, zinc oxide and magnesium oxide.

[0022] Furthermore, in step S2, based on the total mass of the nickel-manganese compound precursor, the added amount of the yttrium inducer is 0.1-1 wt%, and the added amount of the M inducer is 0.0001-0.5 wt%.

[0023] Furthermore, in step S2, the mixing treatment includes: mixing the nickel-manganese compound precursor with a lithium source and a crystal plane orientation inducer, performing a primary mixing treatment at 100-200 rpm for 1-5 min, and performing a secondary mixing treatment at 500-900 rpm for 15-35 min to obtain a mixture.

[0024] Furthermore, in step S3, the multi-stage sintering treatment includes: taking the mixture for a primary sintering treatment at 650-850°C for 2-12 hours, performing a secondary sintering treatment at 850-1050°C for 10-20 hours, and performing an annealing treatment at 600-800°C for 4-8 hours to obtain the lithium nickel manganese oxide positive electrode material.

[0025] The lithium-ion battery provided by the present invention specifically includes the above-mentioned lithium nickel manganese oxide positive electrode material.

[0026] Beneficial effects:

[0027] The ratio K of the (111) crystal plane orientation parameter and the (100) crystal plane orientation parameter in the XRD spectrum of the lithium nickel manganese oxide positive electrode material provided by the present invention is 1 to 1.6. At this time, the surface energy of the regular truncated octahedral single crystal structure of the lithium nickel manganese oxide positive electrode material is low, and it has better stability, so that it has a higher Li under high voltage system. +The diffusion coefficient is beneficial to the deintercalation of lithium ions in the crystal structure during the charge and discharge cycle, improves the deintercalation efficiency of lithium ions and the stability of the contact interface with the electrolyte, greatly reduces the dissolution of transition metals during the charge and discharge cycle, and ultimately achieves the improvement of the rate performance and cycle stability of the lithium nickel manganese oxide positive electrode material.

[0028] In some specific embodiments, the above-mentioned lithium nickel manganese oxide positive electrode material is prepared by a method combining a co-precipitation method and a high-temperature solid phase method. By introducing a mixture including yttrium and strontium as a crystal plane orientation inducer during the material mixing stage, the surface energy of the crystal can be significantly reduced, and the crystal is induced to tend to grow toward the (111) crystal plane and the (100) crystal plane with low surface energy during the growth process, so as to achieve induced regulation of the crystal plane orientation of the positive electrode material, so as to obtain a lithium nickel manganese oxide positive electrode material with a special (111) crystal plane orientation parameter and a (100) crystal plane orientation parameter ratio. The preparation method has the advantages of simple process, few process steps, high product purity, low production cost, excellent electrochemical properties of the prepared material, and suitability for large-scale production, and has good promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a SEM image of the lithium nickel manganese oxide positive electrode material provided in Example 1 of the present invention (scale is 20 μm);

[0030] Figure 2 XRD diagram of the lithium nickel manganese oxide positive electrode material provided in Example 1 of the present invention;

[0031] Figure 3 This is a SEM image of the lithium nickel manganese oxide positive electrode material provided in Example 2 of the present invention (scale is 20 μm);

[0032] Figure 4 XRD diagram of the lithium nickel manganese oxide positive electrode material provided in Example 2 of the present invention;

[0033] Figure 5 This is a SEM image of the lithium nickel manganese oxide positive electrode material provided in Example 3 of the present invention (scale is 20 μm);

[0034] Figure 6 XRD diagram of the lithium nickel manganese oxide positive electrode material provided in Example 3 of the present invention;

[0035] Figure 7 This is a SEM image of the lithium nickel manganese oxide positive electrode material provided in Example 4 of the present invention (scale is 20 μm);

[0036] Figure 8 XRD diagram of the lithium nickel manganese oxide positive electrode material provided in Example 4 of the present invention;

[0037] Fig. 9This is a SEM image of the lithium nickel manganese oxide positive electrode material provided in Example 5 of the present invention (scale is 20 μm);

[0038] Fig.10 XRD diagram of the lithium nickel manganese oxide positive electrode material provided in Example 5 of the present invention;

[0039] Fig.11 This is a SEM image of the lithium nickel manganese oxide positive electrode material provided in Comparative Example 1 (scale is 20 μm);

[0040] Fig.12 XRD diagram of the lithium nickel manganese oxide positive electrode material provided in Comparative Example 1;

[0041] Fig.13 This is a SEM image of the lithium nickel manganese oxide positive electrode material provided in Comparative Example 2 (scale is 20 μm);

[0042] Fig.14 XRD diagram of the lithium nickel manganese oxide positive electrode material provided in Comparative Example 2;

[0043] Fig.15 This is a SEM image of the lithium nickel manganese oxide positive electrode material provided in Comparative Example 3 (scale is 20 μm);

[0044] Fig.16 XRD diagram of the lithium nickel manganese oxide positive electrode material provided in Comparative Example 3;

[0045] Fig.17 The test example in the present invention provides an experimental result diagram of the cycle performance test of the lithium nickel manganese oxide positive electrode material. DETAILED DESCRIPTION

[0046] Based on a deep understanding of the effects of high voltage systems on the microstructure and ionic state of lithium nickel manganese oxide positive electrode materials, the inventors of the present invention have found through extensive and in-depth research and a large number of experiments that the crystals of the induced positive electrode materials tend to grow toward the (111) crystal plane and the (100) crystal plane with low surface energy during the growth process, so as to obtain a lithium nickel manganese oxide positive electrode material having a specific ratio of the (111) crystal plane orientation parameter and the (100) crystal plane orientation parameter. The lithium nickel manganese oxide positive electrode material has excellent rate performance and cycle stability, can be well applied to the production and manufacture of lithium ion batteries, and has excellent application prospects. Based on this, the technical solution of the present invention is obtained.

[0047] In the present invention, the lithium nickel manganese oxide positive electrode material has a regular truncated octahedral single crystal structure, and the ratio K of the (111) crystal plane orientation parameter to the (100) crystal plane orientation parameter in the XRD spectrum of the lithium nickel manganese oxide positive electrode material is specifically 1 to 1.6, such as 1, 1.05, 1.1, 1.12, 1.22, 1.25, 1.3, 1.4, 1.41, 1.44, 1.53, 1.6 or any value therebetween.

[0048] In the present invention, the regular truncated octahedron single crystal structure refers to a regular crystal structure formed by stacking truncated octahedrons as basic units in the structure of the lithium nickel manganese oxide positive electrode material in three-dimensional space. This structure is beneficial to the deintercalation of lithium ions in the crystal structure during the charge and discharge cycle process, and can greatly reduce the dissolution of transition metals during the charge and discharge cycle process, thereby giving the lithium nickel manganese oxide material excellent rate performance and cycle stability.

[0049] In some specific embodiments, the (111) crystal plane orientation parameter in the XRD spectrum of the lithium nickel manganese oxide positive electrode material is preferably 280-320nm, such as 280nm, 282.48nm, 285nm, 290nm, 293.65nm, 295nm, 299.86nm, 300nm, 303.87nm, 306.84nm, 310nm, 320nm or any value therebetween; and the (100) crystal plane orientation parameter is preferably 210-270nm, such as 210nm, 211.02nm, 213.31nm, 217.62nm, 235nm, 240nm, 245.79nm, 251.61nm, 260nm, 260.9nm, 270nm or any value therebetween. At this time, the proportion of (111) crystal plane and (100) crystal plane in the crystal structure of the lithium nickel manganese oxide positive electrode material is higher, giving the lithium nickel manganese oxide positive electrode material better rate performance and cycle stability.

[0050] In some preferred embodiments, the ratio K of the (111) crystal plane orientation parameter to the (100) crystal plane orientation parameter in the XRD spectrum of the lithium nickel manganese oxide positive electrode material is more preferably 1.1 to 1.5. The lithium nickel manganese oxide positive electrode material has a more ideal crystal structure, and has excellent rate performance and cycle stability.

[0051] In the present invention, the (111) crystal plane orientation parameters and the (100) crystal plane orientation parameters are obtained based on the original XRD spectrum measured by the XRD test, and the characteristic peaks representing the (111) crystal plane and the (100) crystal plane in the original XRD spectrum are refined and fitted using the Rietveld fitting refinement method.

[0052] In the present invention, the conditions of the XRD test specifically include: the radiation source is Cu-kα; the test angle is 10° to 120°; the step size is The residence time for each step is 0.5 s.

[0053] In the present invention, the Rietveld refinement method specifically includes: (a) Open the TOPAS refinement software and import the original XRD spectrum in the software; (b) After import, select the sample to be refined, perform background subtraction, select the background fitting parameter option (Background) and set the polynomial series Order value to 4, then import the adapted instrument parameters in the Instrument task bar, and check Sampledisplacement in the Corrections of the error calibration parameters; (c) Import the XRD structure file of the corresponding lithium nickel manganese oxide cathode material, select Sites in the structure file and set the structure parameters according to the characteristics of the material, and then you can select the characteristic peaks of the (111) crystal plane and the (100) crystal plane for single-peak fitting to obtain the crystal plane orientation parameters C 111 and C 100 ; (d) Calculate the ratio K of C 111 and C 100 , where K = C 111 / C 100 .

[0054] In the present invention, the lithium nickel manganese oxide cathode material specifically includes a compound with the chemical formula LiNi 0.49 M x Mn 1.49-x / 2 Y z O4. Wherein, 0 < x ≤ 0.1, 0.01 < z ≤ 0.05, and M is selected from one or more of strontium, titanium, niobium, molybdenum, tantalum, ruthenium, phosphorus, zinc and magnesium. In some specific embodiments, M is preferably strontium. At this time, the introduced yttrium and strontium can further optimize the crystal structure of the lithium nickel manganese oxide cathode material to achieve the effect of further improving the rate performance and cycle stability performance of the lithium nickel manganese oxide material.

[0055] In the present invention, the above-mentioned lithium nickel manganese oxide cathode material can be prepared by one or more methods of co-precipitation method, microemulsion method, high-temperature solid-phase method, hydrothermal method / solvothermal method and sol-gel method, as long as the corresponding lithium nickel manganese oxide cathode material can be prepared, and the present invention does not particularly limit the specific preparation scheme.

[0056] Based on the realization of more precise induction and control of the crystal plane orientation of the lithium nickel manganese oxide positive electrode material, the inventors of the present invention further conducted research and experiments and creatively found that the method of combining the coprecipitation method and the high temperature solid phase method, and introducing a compound / mixture including yttrium and one or more of strontium, titanium, niobium, molybdenum, tantalum, ruthenium, phosphorus, zinc and magnesium into the nickel manganese compound precursor before high temperature sintering, can well reduce the surface energy of the crystal, thereby inducing the crystal to tend to grow towards the (111) crystal plane and (100) crystal plane with low surface energy during the growth process, which can play an excellent crystal plane orientation induction effect, and thus better obtain the lithium nickel manganese oxide positive electrode material with a special (111) crystal plane orientation parameter and (100) crystal plane orientation parameter ratio. Based on this, a preparation method that can well prepare the above-mentioned lithium nickel manganese oxide positive electrode material is obtained.

[0057] In the present invention, the preparation method specifically includes: S1, taking a nickel source and a manganese source to carry out a co-precipitation reaction in the presence of an alkaline precipitant to obtain a nickel-manganese compound precursor; S2, taking the nickel-manganese compound precursor and a lithium source and a crystal plane orientation inducer to mix them to obtain a mixture; S3, taking the mixture to carry out a multi-stage sintering treatment to obtain the nickel manganese oxide lithium positive electrode material; wherein the crystal plane orientation inducer includes yttrium element and M element.

[0058] In the present invention, in step S1, the nickel source is a type of reagent conventionally used in the preparation of existing nickel manganese oxide positive electrode materials. The present invention does not impose any special limitation on it. Specific examples thereof include but are not limited to: one or more of nickel hydroxide, nickel sulfate, nickel carbonate and nickel acetate.

[0059] In the present invention, in step S1, the manganese source is a type of reagent commonly used in the preparation of existing nickel manganese oxide positive electrode materials. The present invention does not impose any special limitation on it. Specific examples thereof include but are not limited to: one or more of manganese hydroxide, manganese sulfate, manganese carbonate and manganese acetate.

[0060] In the present invention, in step S1, the alkaline precipitant is used to provide OH - The compound used to precipitate nickel ions and manganese ions to obtain a nickel-manganese compound precursor includes, but is not limited to, one or more of ammonia, ammonium bicarbonate, sodium bicarbonate, ammonium carbonate, sodium carbonate and sodium hydroxide.

[0061] In some preferred embodiments, in step S1, the molar ratio of the nickel ions in the nickel source, the manganese ions in the manganese source and the hydroxide ions in the alkaline precipitant is preferably 1:(2-3.5):(10-25), such as 1:2:10, 1:2:10.3, 1:2.6:19, 1:3:20, 1:3.5:25 or any value therebetween. At this time, the obtained nickel-manganese compound precursor has a relatively ideal state, which is conducive to the final preparation of a nickel-manganese-oxide lithium positive electrode material having a regular truncated octahedral single crystal structure and a specific crystal plane orientation parameter ratio.

[0062] In the present invention, in step S1, the coprecipitation reaction is a conventional technical means used in the preparation of existing lithium nickel manganese oxide positive electrode materials, and is limited to being able to obtain the nickel manganese compound precursor, and the present invention does not impose any special limitation on it.

[0063] In some specific embodiments, in step S1, the coprecipitation reaction specifically includes: adding an alkaline precipitant to a mixed solution of metal ions including a nickel source and a manganese source under stirring to obtain a nickel-manganese compound precursor. The stirring speed of adding the alkaline precipitant to the mixed solution of metal ions including a nickel source and a manganese source is preferably 28 to 35 Hz, such as 28 Hz, 30 Hz, 32 Hz, 35 Hz or any value therebetween; the temperature is preferably 35 to 45°C, such as 35°C, 37°C, 40°C, 45°C or any value therebetween.

[0064] In the present invention, in step S2, the lithium source is a type of reagent conventionally used in the preparation of existing lithium nickel manganese oxide positive electrode materials. The present invention does not impose any special limitation on it. Specific examples include but are not limited to: one or more of lithium carbonate, lithium nitrate, lithium hydroxide, lithium acetate, lithium acetate and lithium oxalate.

[0065] In some specific embodiments, in step S2, the molar ratio of lithium ions in the lithium carbonate to the total amount of metal ions in the nickel manganese compound precursor is preferably (0.4-0.6):1, such as 0.4:1, 0.43:1, 0.45:1, 0.49:1, 0.5:1, 0.55:1, 0.6:1 or any value therebetween.

[0066] In the present invention, in step S2, the crystal plane orientation inducer specifically includes a yttrium inducer and an M inducer. Among them, the yttrium inducer specifically refers to a class of compounds including yttrium elements, and the M inducer specifically refers to a class of compounds including M elements, and the M element can be completely identical, partially identical, or completely different from the M element of the above-mentioned lithium nickel manganese oxide positive electrode material, and will not be repeated. At this time, the introduced yttrium inducer and M inducer can significantly reduce the surface energy of the crystal during the high-temperature solid phase sintering process, thereby inducing the crystal to tend to grow toward the (111) crystal plane and (100) crystal plane with low surface energy during the growth process, thereby forming a stable regular truncated octahedral single crystal structure, and the regular truncated octahedral single crystal structure is conducive to the deintercalation of lithium ions in the crystal structure during the charge and discharge cycle process, and can greatly reduce the dissolution of transition metals during the charge and discharge cycle process, thereby improving the rate performance and cycle stability of the lithium nickel manganese oxide material.

[0067] In some specific embodiments, in step S2, specific examples of the yttrium inducing agent include but are not limited to: yttrium oxide and / or yttrium hydroxide.

[0068] In some specific embodiments, in step S2, specific examples of the M inducing agent include but are not limited to: one or more of strontium oxide, titanium oxide, niobium oxide, molybdenum oxide, tantalum oxide, ruthenium oxide, phosphorus oxide, zinc oxide and magnesium oxide.

[0069] In some specific embodiments, in step S2, based on the total mass of the nickel manganese compound precursor, the addition amount of the yttrium inducer is preferably 0.1-1wt%, such as 0.1wt%, 0.15wt%, 0.2wt%, 0.3wt%, 0.5wt%, 0.75wt%, 1wt% or any value therebetween; the addition amount of the M inducer is preferably 0.0001-0.5wt%, such as 0.0001wt%, 0.005wt%, 0.01wt%, 0.1wt%, 0.2wt%, 0.38wt%, 0.5wt% or any value therebetween. At this time, the yttrium inducer and the M inducer can better cooperate with each other to achieve a more ideal crystal plane orientation induction effect, and finally obtain a nickel manganese oxide lithium positive electrode material with better rate performance and cycle stability.

[0070] In the present invention, in step S2, the mixing treatment is a technical means conventionally used in the prior art, which is limited to achieving sufficient mixing of the nickel-manganese compound precursor, the lithium source and the crystal plane orientation inducer, and the present invention does not impose any special limitation thereto.

[0071] In some specific embodiments, in step S2, the mixing treatment preferably includes: mixing the nickel-manganese compound precursor with a lithium source and a crystal plane orientation inducing agent, and performing a primary mixing treatment and a secondary mixing treatment in sequence to obtain a mixture. Wherein, the stirring speed of the primary mixing treatment is specifically 100-200 rpm, such as 100 rpm, 110 rpm, 125 rpm, 150 rpm, 180 rpm, 200 rpm or any value therebetween; the time is specifically 1-5 min, such as 1 min, 1.3 min, 1.5 min, 1.8 min, 2 min, 2.5 min, 3 min, 4 min, 5 min or any value therebetween. The stirring speed of the secondary mixing treatment is specifically 500-900rpm, such as 500rpm, 530rpm, 560rpm, 600rpm, 700rpm, 800rpm, 900rpm or any value therebetween; the time is specifically 15-35min, such as 15min, 18min, 20min, 28min, 30min, 35min or any value therebetween. At this time, the mixing treatment can not only achieve full mixing of the nickel-manganese compound precursor, the lithium source and the crystal plane orientation inducer, but also the obtained mixture has a more ideal ion distribution morphology and chemical bonding force, which is conducive to the formation of the material crystal structure during the subsequent high-temperature calcination process.

[0072] In the present invention, in step S3, the multi-stage sintering treatment specifically includes: taking the mixed material and sequentially performing a primary sintering treatment, a secondary sintering treatment and an annealing treatment to obtain the lithium nickel manganese oxide positive electrode material. Wherein, the temperature of the primary sintering treatment is preferably 650-850°C, such as 650°C, 680°C, 700°C, 750°C, 800°C, 850°C or any value therebetween; the time is preferably 2-12h, such as 2h, 4h, 6h, 8h, 10h, 12h or any value therebetween. The temperature of the secondary sintering treatment is preferably 850-1050°C, such as 850°C, 880°C, 900°C, 950°C, 1000°C, 1050°C or any value therebetween; the time is preferably 10-20h, such as 10h, 12h, 15h, 18h, 20h or any value therebetween. The annealing temperature is preferably 600-800°C, such as 600°C, 630°C, 650°C, 700°C, 750°C, 800°C or any value therebetween; the annealing time is preferably 4-8h, such as 4h, 4.3h, 4.8h, 5h, 5.5h, 6h, 7h, 8h or any value therebetween.

[0073] Based on the excellent rate performance and cycle stability of the above-mentioned lithium nickel manganese oxide positive electrode material and its application potential in the preparation of lithium ion batteries, the present invention also provides a lithium ion battery.

[0074] In the present invention, the lithium ion battery specifically includes the above-mentioned lithium nickel manganese oxide positive electrode material. The lithium ion battery is a conventional device in the field of lithium battery technology, and the present invention does not impose any particular limitation on its specific structure, reagents and size.

[0075] Embodiments of the present invention are described in detail below, and the examples of the embodiments are intended to be used to explain the present invention, but should not be construed as limiting the present invention. In the embodiments, if specific techniques or conditions are not specified, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not specified for reagents or instruments used, they are all conventional products that can be obtained commercially.

[0076] Example 1

[0077] This embodiment is used to illustrate the preparation of a lithium nickel manganese oxide positive electrode material, which specifically includes:

[0078] S1. Weigh 237.95 g of manganese sulfate and 122.74 g of nickel sulfate in a stoichiometric ratio of 3:1 and dissolve them in 724.63 mL of deionized water to obtain a metal ion solution;

[0079] According to the stoichiometric ratio of the total amount of metal ions to hydroxide ions in the metal ion solution of 1:3, 252 mL of a 10 mol / L sodium hydroxide solution was weighed as a precipitant, and under the conditions of pH 10.6, temperature 35°C, stirring speed 30 Hz and N2 atmosphere, the sodium hydroxide solution was slowly added to the metal ion solution at a dropping speed of 35 mL / min to carry out a coprecipitation reaction to obtain a suspension, and the suspension was filtered, washed and dried to obtain a nickel manganese compound precursor.

[0080] S2, lithium carbonate, yttrium oxide, strontium oxide and nickel manganese compound precursor are mixed, mixed at 200 rpm for 5 min, and then mixed at 700 rpm for 20 min to obtain a mixture;

[0081] The molar ratio of lithium ions in lithium carbonate to the total amount of metal ions in the nickel-manganese compound precursor is 0.5:1; based on the mass of the nickel-manganese compound precursor, the added amount of yttrium oxide is 0.3wt%, and the added amount of strontium oxide is 0.2wt%.

[0082] S3. The mixed material is placed in an air atmosphere sintering furnace, and a primary sintering treatment is performed at 700°C for 6 hours, followed by a secondary sintering treatment at 950°C for 12 hours, and finally an annealing treatment is performed at 700°C for 4 hours. After cooling to room temperature, the mixed material is gas-broken and sieved to obtain a lithium nickel manganese oxide positive electrode material.

[0083] Figure 1This is the SEM image of the lithium nickel manganese oxide positive electrode material prepared in this example. Figure 2 XRD pattern of lithium nickel manganese oxide positive electrode material (Bruker D8ADVANCE equipment, radiation source is Cu-kɑ, angle is 10°~120°, step size is The dwell time of each step is 0.5s). Figure 1 and 2 The results shown show that the lithium nickel manganese oxide positive electrode material has a regular truncated octahedral single crystal structure.

[0084] Example 2

[0085] This embodiment adopts the method provided in Example 1 to prepare a lithium nickel manganese oxide positive electrode material, except that in step S2, based on the mass of the nickel manganese compound precursor, the amount of yttrium oxide added is 0.5wt%, the amount of strontium oxide added is 0.3wt%, and other conditions are the same to obtain a lithium nickel manganese oxide positive electrode material.

[0086] Figure 3 This is the SEM image of the lithium nickel manganese oxide positive electrode material prepared in this example. Figure 4 XRD pattern of lithium nickel manganese oxide positive electrode material (Bruker D8ADVANCE equipment, radiation source is Cu-kɑ, angle is 10°~120°, step size is The dwell time of each step is 0.5s). Figure 3 and 4 The results shown show that the lithium nickel manganese oxide positive electrode material has a regular truncated octahedral single crystal structure.

[0087] Example 3

[0088] This embodiment adopts the method provided in Embodiment 1 to prepare a lithium nickel manganese oxide positive electrode material, except that in step S2, an equal amount of magnesium oxide is added instead of strontium oxide, and other conditions are the same to obtain a lithium nickel manganese oxide positive electrode material.

[0089] Figure 5 This is the SEM image of the lithium nickel manganese oxide positive electrode material prepared in this example. Figure 6 XRD pattern of lithium nickel manganese oxide positive electrode material (Bruker D8ADVANCE equipment, radiation source is Cu-kɑ, angle is 10°~120°, step size is The dwell time of each step is 0.5s). Figure 5 and 6 The results shown show that the lithium nickel manganese oxide positive electrode material has a regular truncated octahedral single crystal structure.

[0090] Example 4

[0091] This embodiment adopts the method provided in Embodiment 1 to prepare a lithium nickel manganese oxide positive electrode material, except that in step S2, an equal amount of titanium oxide is added instead of strontium oxide, and other conditions are the same to obtain a lithium nickel manganese oxide positive electrode material.

[0092] Figure 7 This is the SEM image of the lithium nickel manganese oxide positive electrode material prepared in this example. Figure 8 XRD pattern of lithium nickel manganese oxide positive electrode material (Bruker D8ADVANCE equipment, radiation source is Cu-kɑ, angle is 10°~120°, step size is The dwell time of each step is 0.5s). Figure 7 and 8 The results shown show that the lithium nickel manganese oxide positive electrode material has a regular truncated octahedral single crystal structure.

[0093] Example 5

[0094] This embodiment adopts the method provided in Example 1 to prepare a lithium nickel manganese oxide positive electrode material, except that in step S2, lithium carbonate, yttrium oxide, strontium oxide and a nickel manganese compound precursor are mixed at 700 rpm for 25 minutes to obtain a mixture, and other conditions are the same to obtain a lithium nickel manganese oxide positive electrode material.

[0095] Fig. 9 This is the SEM image of the lithium nickel manganese oxide positive electrode material prepared in this example. Fig.10 XRD pattern of lithium nickel manganese oxide positive electrode material (Bruker D8ADVANCE equipment, radiation source is Cu-kɑ, angle is 10°~120°, step size is The dwell time of each step is 0.5s). Fig. 9 and 10 The results shown show that the lithium nickel manganese oxide positive electrode material has a regular truncated octahedral single crystal structure.

[0096] Comparative Example 1

[0097] This comparative example adopts the method provided in Example 1 to prepare a lithium nickel manganese oxide positive electrode material, except that, in step S2, based on the mass of the nickel manganese compound precursor, the amount of yttrium oxide added is 0wt%, and the amount of strontium oxide added is 0wt%, that is, yttrium oxide and strontium oxide are not added in step S2, and other conditions are the same to obtain a lithium nickel manganese oxide positive electrode material.

[0098] Fig.11 This is the SEM image of the lithium nickel manganese oxide positive electrode material prepared in this comparative example. Fig.12 XRD pattern of lithium nickel manganese oxide positive electrode material (Bruker D8ADVANCE equipment, radiation source is Cu-kɑ, angle is 10°~120°, step size is The dwell time of each step is 0.5s). Fig.11and 12 The results shown show that the lithium nickel manganese oxide positive electrode material has a regular truncated octahedral single crystal structure.

[0099] Comparative Example 2

[0100] This comparative example adopts the method provided in Example 1 to prepare a lithium nickel manganese oxide positive electrode material, except that in step S2, based on the mass of the nickel manganese compound precursor, the amount of strontium oxide added is 0wt%, that is, no strontium oxide is added in step S2, and other conditions are the same to obtain a lithium nickel manganese oxide positive electrode material.

[0101] Fig.13 This is the SEM image of the nickel manganese oxide positive electrode material prepared in this comparative example. Fig.14 XRD pattern of lithium nickel manganese oxide positive electrode material (Bruker D8ADVANCE equipment, radiation source is Cu-kɑ, angle is 10°~120°, step size is The dwell time for each step is 0.5s). Fig.13 and 14 The results shown show that the lithium nickel manganese oxide positive electrode material has a regular truncated octahedral single crystal structure.

[0102] Comparative Example 3

[0103] This comparative example adopts the method provided in Example 1 to prepare a lithium nickel manganese oxide positive electrode material, except that in step S2, based on the mass of the nickel manganese compound precursor, the amount of yttrium oxide added is 0wt%, that is, yttrium oxide is not added in step S2, and other conditions are the same to obtain a lithium nickel manganese oxide positive electrode material.

[0104] Fig.15 This is the SEM image of the nickel manganese oxide positive electrode material prepared in this comparative example. Fig.16 XRD pattern of lithium nickel manganese oxide positive electrode material (Bruker D8ADVANCE equipment, radiation source is Cu-kɑ, angle is 10°~120°, step size is The dwell time for each step is 0.5s). Fig.15 and 16 The results shown show that the lithium nickel manganese oxide positive electrode material has a regular truncated octahedral single crystal structure.

[0105] Test Case

[0106] This test example is used to illustrate the relevant performance of the lithium nickel manganese oxide positive electrode material provided in the above embodiments and comparative examples. The test specifically includes:

[0107] 1. Microstructure testing

[0108] Based on the original XRD spectra measured in the above embodiments and comparative examples, the characteristic peaks representing the (111) crystal plane and the (100) crystal plane in the original XRD spectra were refined and fitted by the Rietveld fitting refinement method to obtain the (111) crystal plane orientation parameter C 111 and (100) crystal plane orientation parameter C 100 , and the ratio K of the (111) crystal orientation parameter and the (100) crystal orientation parameter of each nickel manganese oxide positive electrode material is calculated according to the following formula, that is, K = C 111 / C 100 The test results are shown in Table 1.

[0109] Table 1.

[0110]

[0111]

[0112] 2. Test of electrochemical performance

[0113] (1) Preparation of button-type full battery: lithium nickel manganese oxide positive electrode material, conductive agent Super P and binder PVDF were mixed in a mass ratio of 9:0.4:0.6, and the slurry was adjusted in a degassing machine to control the viscosity of the slurry to 8000 mPa·s. Then, the slurry was evenly coated on a carbon-coated aluminum foil using an automatic coating machine to form an original electrode sheet, which was placed in a vacuum oven at 130°C for 4 hours and then placed in a blast oven at 80°C for 12 hours to obtain a test piece; a punching die with a diameter of 14 mm was used to cut out several small electrode sheets at different positions of the above test piece, and small electrode sheets with regular morphology, smooth surface and edges were selected and weighed using a 1 / 10,000 balance. The weighed small electrode sheet was placed in a vacuum drying oven and evacuated to 0.1 MPa to obtain a positive electrode sheet, which was stored for later use; in an inert gas glove box with a water and oxygen mass content of less than or equal to 0.0005%, button batteries were assembled according to the battery specifications of CR2023; wherein the negative electrode was a lithium sheet, the separator was a polypropylene film, the electrolyte solvent was a mixed solution of ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and the conductive salt was 1M lithium hexafluorophosphate. After the assembly was completed, it was packaged at 800 Pa for 5s to obtain a button battery.

[0114] (2) Electrochemical performance test: A button cell test system was used to conduct constant current charge and discharge tests at different current densities. The test temperature was 25°C, the charge and discharge range was 3.0 to 4.9V, and the rate performance in the 0.1 to 3C rate range and the 0.1C cycle performance test were conducted. The test results are as follows: Fig.17 And as shown in Table 2.

[0115] Table 2.

[0116]

[0117] It can be seen from the test results shown in Tables 1 and 2 that compared with Comparative Examples 1 to 3, the crystal plane orientation parameter ratio K of the nickel manganese oxide positive electrode material provided by the present invention is in the range of 1.0 to 1.6, especially in the range of 1.1 to 1.5. The 0.1C first discharge gram capacity of the nickel manganese oxide positive electrode material is 136.87 to 136.92 mAh / g, the 3C / 0.1C reversible specific capacity retention rate is 98.71 to 99.89%, and the 0.1C-25°C cycle capacity retention rate is 97.67 to 98.69%. The rate performance and cycle performance have been significantly improved, and it has excellent electrochemical properties.

[0118] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A lithium nickel manganese oxide positive electrode material, characterized in that: The lithium nickel manganese oxide positive electrode material has a regular truncated octahedral single crystal structure, and the ratio K of the (111) crystal plane orientation parameter to the (100) crystal plane orientation parameter in the XRD spectrum of the lithium nickel manganese oxide positive electrode material is 1 to 1.

6.

2. The lithium nickel manganese oxide positive electrode material according to claim 1, characterized in that: In the XRD spectrum of the lithium nickel manganese oxide positive electrode material, the (111) crystal plane orientation parameter is 270 to 320 nm, and the (100) crystal plane orientation parameter is 210 to 270 nm; Optionally, the ratio K of the (111) crystal orientation parameter to the (100) crystal orientation parameter in the XRD spectrum of the lithium nickel manganese oxide positive electrode material is 1.1 to 1.

5.

3. The lithium nickel manganese oxide positive electrode material according to claim 1, characterized in that: The lithium nickel manganate cathode material includes a compound with the chemical general formula LiNi 0.49 M x Mn 1.49-x / 2 Y z O4; wherein, 0 < x ≤ 0.1, 0.01 < z ≤ 0.05, and M is selected from one or more of strontium, titanium, niobium, molybdenum, tantalum, ruthenium, phosphorus, zinc, and magnesium.

4. The method for preparing the lithium nickel manganese oxide positive electrode material according to any one of claims 1 to 3, characterized in that: The preparation method comprises: S1, taking a nickel source and a manganese source to carry out a co-precipitation reaction in the presence of an alkaline precipitant to obtain a nickel-manganese compound precursor; S2, taking the nickel-manganese compound precursor and a lithium source and a crystal plane orientation inducer to mix them to obtain a mixture; S3, taking the mixture to carry out a multi-stage sintering treatment to obtain the lithium nickel manganese oxide positive electrode material; wherein the crystal plane orientation inducer comprises yttrium element and M element.

5. The method for preparing the lithium nickel manganese oxide positive electrode material according to claim 4, characterized in that: In step S1, the nickel source is selected from one or more of nickel hydroxide, nickel sulfate, nickel carbonate and nickel acetate; Optionally, the manganese source is selected from one or more of manganese hydroxide, manganese sulfate, manganese carbonate and manganese acetate; Optionally, the alkaline precipitant is selected from one or more of ammonia, ammonium bicarbonate, sodium bicarbonate, ammonium carbonate, sodium carbonate and sodium hydroxide; Optionally, the molar ratio of nickel ions in the nickel source, manganese ions in the manganese source and hydroxide ions in the alkaline precipitant is 1:(2-3.5):(10-25).

6. The method for preparing the lithium nickel manganese oxide positive electrode material according to claim 4, characterized in that: In step S1, the coprecipitation reaction comprises: adding an alkaline precipitant to a metal ion mixed solution including a nickel source and a manganese source at a stirring speed of 20 to 35 Hz and a temperature of 35 to 55° C. to obtain a nickel-manganese compound precursor.

7. The method for preparing a lithium nickel manganese oxide positive electrode material according to claim 4, characterized in that: In step S2, the lithium source is selected from one or more of lithium carbonate, lithium nitrate, lithium hydroxide, lithium acetate, lithium acetate and lithium oxalate; Optionally, the molar ratio of lithium ions in the lithium carbonate to the total amount of metal ions in the nickel manganese compound precursor is (0.4-0.6):1; Optionally, the crystal plane orientation inducer includes a yttrium inducer and an M inducer, the yttrium inducer is yttrium oxide and / or yttrium hydroxide, and the M inducer is selected from one or more of strontium oxide, titanium oxide, niobium oxide, molybdenum oxide, tantalum oxide, ruthenium oxide, phosphorus oxide, zinc oxide and magnesium oxide; Optionally, based on the total mass of the nickel-manganese compound precursor, the added amount of the yttrium inducer is 0.1-1 wt %, and the added amount of the M inducer is 0.0001-0.5 wt %.

8. The method for preparing a lithium nickel manganese oxide positive electrode material according to claim 4, characterized in that: In step S2, the mixing treatment includes: mixing the nickel-manganese compound precursor with a lithium source and a crystal plane orientation inducer, performing a primary mixing treatment at 100-200 rpm for 1-5 min, and performing a secondary mixing treatment at 500-900 rpm for 15-35 min to obtain a mixture.

9. The method for preparing a lithium nickel manganese oxide positive electrode material according to claim 4, characterized in that: In step S3, the multi-stage sintering treatment includes: taking the mixed material for a primary sintering treatment at 650-850°C for 2-12 hours, performing a secondary sintering treatment at 850-1050°C for 10-20 hours, and performing an annealing treatment at 600-800°C for 4-8 hours to obtain the lithium nickel manganese oxide positive electrode material.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the lithium nickel manganese oxide positive electrode material according to any one of claims 1 to 3.

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