Ferric manganese phosphate precursor and preparation method thereof, lithium ferric manganese phosphate positive electrode material and preparation method thereof, lithium ion battery and electric equipment

Abstract

The invention provides an iron manganese phosphate precursor and a preparation method thereof, a lithium iron manganese phosphate positive electrode material and a preparation method thereof, a lithium ion battery and electric equipment, and relates to the technical field of new energy. The ferromanganese phosphate precursor provided by the invention comprises secondary particles composed of a plurality of primary particles, the primary particles are nano dotted particles, the diameter of the primary particles is 20-300nm, the secondary particles are of a blocky structure, and the morphology of the ferromanganese phosphate precursor can improve the electrochemical performance and the compaction density of the material. According to the preparation method of the ferromanganese phosphate precursor provided by the invention, a salt solution is taken as a base solution, and a phosphorus source solution, an oxidizing agent and a pH regulator are jointly fed, so that uniform precipitation of Mn and Fe is realized; regulation and control of nucleation, growth process, crystallinity and dotted primary particle size are realized by regulating and controlling the reaction temperature, the adding rate of the oxidant and the phosphorus source and the reaction pH value.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and in particular to a ferromanganese phosphate precursor and a preparation method thereof, a lithium ferromanganese phosphate positive electrode material and a preparation method thereof, a lithium ion battery and electrical equipment. Background Art

[0002] As an important cathode material, lithium iron manganese phosphate has become a hot topic in lithium-ion battery research due to its environmental friendliness, low raw material cost and high theoretical specific capacity. However, the existing technology still has some problems and limitations in improving the electrochemical performance and compaction density of lithium iron manganese phosphate cathode materials.

[0003] First, the precursors prepared by the traditional co-precipitation method often have problems such as difficult to control morphology, which ultimately affects the compaction density of the material. Secondly, although the existing sand milling process can control the particle size of the material, it is also easy to destroy the integrity of the primary particles, thereby reducing the electrochemical performance of the material. Therefore, how to improve the electrochemical performance and compaction density of lithium manganese iron phosphate positive electrode materials by optimizing the preparation process of the precursor is the main problem facing the current technology. Summary of the invention

[0004] The purpose of the present application is to provide a ferromanganese phosphate precursor and a preparation method thereof, a lithium ferromanganese phosphate positive electrode material and a preparation method thereof, a lithium ion battery and electrical equipment, aiming to solve the problem that the existing ferromanganese phosphate precursor cannot take into account both electrochemical performance and compaction density.

[0005] To achieve the above objectives, the present application provides a ferromanganese phosphate precursor, which is a crystalline material. The ferromanganese phosphate precursor includes secondary particles composed of multiple primary particles, the primary particles are nano-dot particles, the average diameter of the primary particles is 20-300nm, and the secondary particles are block structures.

[0006] In some embodiments, at least one of the following conditions is met:

[0007] A. In the X-ray diffraction spectrum of the ferromanganese phosphate precursor, the main peak intensity is 500-4000;

[0008] B. The average grain size of the ferromanganese phosphate precursor is

[0009] C. The crystallinity of the ferromanganese phosphate precursor is 15-80%.

[0010] In some embodiments, at least one of the following conditions is met:

[0011] A. The chemical formula of the manganese ferrophosphate precursor is Mn x Fe1-x PO4·H2O, where 0.2≤x≤0.9;

[0012] Optional, 0.4≤x≤0.8;

[0013] B. The D50 of the ferromanganese phosphate precursor is 1-25 μm;

[0014] C. The specific surface area of ​​the ferromanganese phosphate precursor is 5-100m 2 / g;

[0015] D. The tap density of the ferromanganese phosphate precursor is 0.3-2.0 g / cm 3 ;

[0016] E. The diameter of the primary particles is 50-150 nm;

[0017] F. The Mn / Fe ratio of the ferromanganese phosphate precursor is 1.45 to 1.55.

[0018] The present application also provides a method for preparing the above-mentioned ferromanganese phosphate precursor, comprising:

[0019] A mixed salt solution including a manganese source and an iron source is used as a bottom liquid of a reaction kettle;

[0020] Adding an oxidant solution, a pH regulator and a phosphorus source solution to the bottom liquid of the reaction kettle in parallel to perform a co-precipitation reaction to obtain a slurry;

[0021] The slurry is subjected to solid-liquid separation, drying and calcination to obtain the ferromanganese phosphate precursor.

[0022] In some embodiments, at least one of the following conditions is met:

[0023] A. The iron source includes at least one of ferrous sulfate, a byproduct of titanium dioxide, industrial-grade ferrous sulfate, battery-grade ferrous sulfate, ferrous nitrate, ferrous chloride, ferrous oxalate, and ferrous acetate;

[0024] B. the manganese source comprises at least one of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate and manganese acetate;

[0025] C. The total molar concentration of manganese and iron in the mixed salt solution is 0.2 to 2.0 mol / L;

[0026] D. The molar ratio of manganese to iron in the mixed salt solution is (1-2):1;

[0027] E. In the oxidant solution, the ratio of the molar amount of the oxidant to the total molar amount of manganese and iron is (1.1-1.5):1; the oxidant includes at least one of hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, ozone, nitric acid, ammonium nitrate, potassium nitrate, sodium nitrate, and potassium permanganate;

[0028] F. The pH regulator includes at least one of aqueous ammonia, diammonium phosphate, diammonium hydrogen phosphate, and sodium hydroxide solution;

[0029] G. In the phosphorus source solution, the ratio of the molar amount of the phosphorus source to the total molar amount of manganese and iron is (1-1.5):1; the phosphorus source includes at least one of phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium phosphate.

[0030] In some embodiments, at least one of the following conditions is met:

[0031] A. The temperature of the coprecipitation reaction is 70-95°C;

[0032] B. the pH value of the coprecipitation reaction is 1.5-5;

[0033] C. The feed flow rates of the oxidant solution and the phosphorus source solution are independently 50-2000 ml / min;

[0034] D. The drying temperature is 90-150°C;

[0035] E. The calcination temperature is 200-600°C.

[0036] The present application also provides a lithium manganese iron phosphate positive electrode material, which is prepared from the above-mentioned lithium manganese phosphate precursor.

[0037] The present application also provides a method for preparing a lithium iron manganese phosphate positive electrode material, comprising: mixing a lithium source and a carbon source with the ferromanganese phosphate precursor, sand grinding, spray drying, and sintering at 550-750° C. for 3-8 hours to obtain the lithium iron manganese phosphate positive electrode material.

[0038] The present application also provides a lithium-ion battery, comprising the above-mentioned lithium iron manganese phosphate positive electrode material.

[0039] The present application also provides an electrical device, comprising the above-mentioned lithium-ion battery.

[0040] Compared with the prior art, the beneficial effects of this application include:

[0041] The ferromanganese phosphate precursor provided by the present application includes secondary particles composed of multiple primary particles, the primary particles are nano-dot particles, the average diameter of the primary particles is 20-300nm, and the secondary particles are block structures. The ferromanganese phosphate precursor of the present application shortens the lithium ion transmission distance by regulating the primary particles to be nano-dot morphology, and the nanostructure has a high BET value, which can increase the contact area between the material and the electrolyte, thereby improving the electrochemical performance. At the same time, the nano primary particles have the characteristics of high activity, and are easy to melt during the positive electrode sintering process to form spherical particles with high roundness, thereby increasing the compaction density.

[0042] The preparation method of the ferromanganese phosphate precursor provided in the present application uses a salt solution as the base liquid, and a phosphorus source solution, an oxidant, and a pH adjuster are fed together to achieve uniform precipitation of Mn and Fe; by regulating the reaction temperature, the addition rate of the oxidant and the phosphorus source, and the reaction pH value, the nucleation, growth process, crystallinity, and point-like primary particle size are regulated, and finally the particle uniformity and morphology are regulated.

[0043] The lithium manganese iron phosphate positive electrode material provided in the present application is prepared from the manganese iron phosphate of the present application and has excellent electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0045] Figure 1 Schematic diagram of the process for preparing the ferromanganese phosphate precursor of the present application;

[0046] Figure 2 This is the XRD result diagram of the ferromanganese phosphate precursor of Example 1;

[0047] Figure 3 This is a SEM image of the ferromanganese phosphate precursor of Example 1;

[0048] Figure 4 This is the XRD result diagram of the ferromanganese phosphate precursor of Example 2;

[0049] Figure 5 This is the SEM result of the ferromanganese phosphate precursor of Example 2;

[0050] Figure 6 This is the XRD result diagram of the ferromanganese phosphate precursor of Example 3;

[0051] Figure 7 This is the SEM result of the ferromanganese phosphate precursor of Example 3;

[0052] Figure 8This is the XRD result diagram of the ferromanganese phosphate precursor of Comparative Example 1;

[0053] Fig. 9 This is the SEM result of the ferromanganese phosphate precursor of Comparative Example 1;

[0054] Fig.10 This is the XRD result diagram of the ferromanganese phosphate precursor of Comparative Example 2;

[0055] Fig.11 This is the SEM result of the ferromanganese phosphate precursor of Comparative Example 2;

[0056] Fig.12 This is the XRD result diagram of the ferromanganese phosphate precursor of Comparative Example 3;

[0057] Fig.13 This is the SEM result of the ferromanganese phosphate precursor of Comparative Example 3. DETAILED DESCRIPTION

[0058] As used herein:

[0059] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0060] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0061] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0062] In these examples, parts and percentages are by mass unless otherwise indicated.

[0063] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0064] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0065] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0066] The present application provides a ferromanganese phosphate precursor, which is a crystalline material. The ferromanganese phosphate precursor includes secondary particles composed of multiple primary particles. The primary particles are nano-dot particles. The average diameter of the primary particles is 20-300nm, and the secondary particles are block structures.

[0067] The primary particles of the ferromanganese phosphate precursor of the present application are in the form of nanodots, the diameter of the primary particles is very small, and the secondary particles are in a block structure. By adjusting the primary particles to have a nanodot morphology, the lithium ion transmission distance is shortened, and the nanostructure has a higher BET value, which can increase the contact area between the material and the electrolyte, thereby improving the electrochemical performance. At the same time, the nano primary particles are highly active and are easy to melt during the positive electrode sintering process to form spherical particles with a high degree of roundness, thereby increasing the compaction density.

[0068] The diameter of the primary particles can be, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm or any value between 20 and 300 nm.

[0069] Optionally, the primary particles have a diameter of 50-150 nm.

[0070] In some embodiments, in the X-ray diffraction pattern of the manganese ferrophosphate precursor, the main peak intensity is 500-4000, for example, it can be 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2200, 2500, 2700, 2900, 3000, 3200, 3500, 3700, 4000 or any value between 500 and 4000. The main peak is the characteristic peak of MnPO4·H2O.

[0071] In some embodiments, the average grain size of the ferromanganese phosphate precursor is For example, it can be or Any value in between.

[0072] The ferromanganese phosphate precursor of the present application has a small average grain size, which can shorten the diffusion distance of lithium ions during the charge and discharge process, promote the lithium ion transmission kinetics, and improve the material rate performance.

[0073] In some embodiments, the crystallinity of the ferromanganese phosphate precursor is 15-80%, for example, it can be 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or any value between 15-80%.

[0074] If the crystallinity of the ferromanganese phosphate precursor is too low, it will affect the stability of the material, and if the crystallinity is too high, it will affect the sintering performance of the positive electrode material.

[0075] In some embodiments, the chemical formula of the manganese ferrophosphate precursor is Mn x Fe 1-x PO4·H2O, wherein 0.2≤x≤0.9; optionally, 0.4≤x≤0.8.

[0076] In some embodiments, the D50 of the ferromanganese phosphate precursor is 1-25 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 16 μm, 18 μm, 20 μm, 21 μm, 22 μm, 25 μm or any value between 1-25 μm.

[0077] In some embodiments, the specific surface area of ​​the ferromanganese phosphate precursor is 5-100 m 2 / g, for example, 5m 2 / g, 10m 2 / g, 15m 2 / g, 20m 2 / g, 25m 2 / g, 30m 2 / g, 35m 2 / g, 40m 2 / g, 45m 2 / g, 50m 2 / g, 55m 2 / g, 60m 2 / g, 65m 2 / g, 70m 2 / g, 75m 2 / g, 80m 2 / g, 85m 2 / g, 90m 2 / g, 95m 2 / g、100m 2 / g or 5-100m 2 Any value between / g.

[0078] In some embodiments, the tap density of the ferromanganese phosphate precursor is 0.3-2.0 g / cm 3 , for example, it can be 0.3 g / cm 3 , 0.4g / cm 3 , 0.5g / cm 3 , 0.6g / cm 3 , 0.7g / cm 3 , 0.8g / cm 3 , 0.9g / cm 3 , 1.0g / cm 3 , 1.1g / cm 3 , 1.2g / cm 3 , 1.3g / cm 3 , 1.4g / cm 3 , 1.5g / cm 3 , 1.6g / cm 3, 1.7g / cm 3 , 1.8g / cm 3 , 1.9g / cm 3 , 2.0g / cm 3 or 0.4-2.0g / cm 3 Any value in between.

[0079] In some embodiments, the Mn / Fe ratio of the manganese ferrophosphate precursor is 1.45 to 1.55.

[0080] The present application also provides a method for preparing the above-mentioned ferromanganese phosphate precursor, please refer to Figure 1 ,include:

[0081] S100: using a mixed salt solution including a manganese source and an iron source as a bottom liquid of a reaction kettle;

[0082] S200: adding an oxidant solution, a pH regulator and a phosphorus source solution to the bottom liquid of the reaction kettle in parallel to perform a co-precipitation reaction to obtain a slurry;

[0083] S300: The slurry is subjected to solid-liquid separation, drying, and calcination to obtain a ferromanganese phosphate precursor.

[0084] The preparation method of the ferromanganese phosphate precursor provided in the present application uses a salt solution as the base liquid, and a phosphorus source solution, an oxidant, and a pH adjuster are fed together to achieve uniform precipitation of Mn and Fe; by regulating the reaction temperature, the addition rate of the oxidant and the phosphorus source, and the reaction pH value, the nucleation, growth process, crystallinity, and point-like primary particle size are regulated, and finally the particle uniformity and morphology are regulated.

[0085] In some embodiments, the iron source in step S100 includes at least one of ferrous sulfate, a byproduct of titanium dioxide, industrial grade ferrous sulfate, battery grade ferrous sulfate, ferrous nitrate, ferrous chloride, ferrous oxalate, and ferrous acetate; the manganese source includes at least one of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, and manganese acetate.

[0086] In some embodiments, the total molar concentration of manganese and iron in the mixed salt solution in step S100 is 0.2-2.0 mol / L, for example, it can be 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.2 mol / L, 1.5 mol / L, 1.7 mol / L, 1.9 mol / L, 2.0 mol / L or any value between 0.2 and 2.0 mol / L.

[0087] The molar ratio of manganese to iron in the mixed salt solution is (1-2):1, for example, it can be 1:1, 1.2:1, 1.5:1, 1.7:1, 2:1 or any ratio between (1-2):1.

[0088] In some embodiments, in the oxidant solution in step S200, the ratio of the molar amount of the oxidant to the total molar amount of manganese and iron is (1.1-1.5):1, for example, it can be 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1 or any value between (1.1-1.5):1; the oxidant includes at least one of hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, ozone, nitric acid, ammonium nitrate, potassium nitrate, sodium nitrate, and potassium permanganate.

[0089] In some embodiments, the pH adjuster in step S200 includes at least one of aqueous ammonia, diammonium phosphate, diammonium hydrogen phosphate, and sodium hydroxide solution.

[0090] In some embodiments, in the phosphorus source solution in step S200, the ratio of the molar amount of the phosphorus source to the total molar amount of manganese and iron is (1-1.5):1, for example, it can be 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1 or any value between (1-1.5):1; the phosphorus source includes at least one of phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium phosphate.

[0091] In some embodiments, the temperature of the coprecipitation reaction in step S200 is 70-95°C, for example, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or any value between 70-95°C.

[0092] Temperature mainly affects the crystallinity of the ferromanganese phosphate precursor. The higher the temperature, the higher the crystallinity of the final product. When the coprecipitation reaction temperature is lower than 70°C, the precipitation efficiency of Mn will be reduced, and the coprecipitation of Mn and Fe cannot be achieved, affecting the Mn / Fe of the product; when the coprecipitation reaction temperature is higher than 95°C, the product crystallinity will be too high, affecting the positive electrode sintering performance.

[0093] In some embodiments, the pH value of the coprecipitation reaction in step S200 is 1.5-5, for example, it can be 1.5, 1.7, 2, 2.2, 2.5, 2.7, 2.9, 3, 3.2, 3.5, 3.8, 4, 4.3, 4.5, 4.7, 5 or any value between 1.5-5.

[0094] The reaction pH value has an impact on the early nucleation, the later growth process, the final crystallinity of the ferromanganese phosphate precursor, and the point-like primary particle size. Within the scope of this application, the higher the reaction pH value, the stronger the nucleation power of the reaction, the weaker the growth power, the lower the crystallinity of the final product, and the smaller the point-like primary particle size. When the pH of the coprecipitation reaction is lower than 1.5, it will affect the precipitation efficiency of Fe, and ultimately cause the product Mn / Fe to be higher than the designed value; when the pH of the coprecipitation reaction is higher than 5, Mn will be precipitated in a divalent form, resulting in product phase separation.

[0095] In some embodiments, the feed flow rates of the oxidant solution and the phosphorus source solution in step S200 are independently 50-2000 ml / min, for example, 50 ml / min, 100 ml / min, 200 ml / min, 300 ml / min, 400 ml / min, 500 ml / min, 600 ml / min, 700 ml / min, 800 ml / min, 900 ml / min, 1000 ml / min, 1100 ml / min, 1200 ml / min, 1300 ml / min, 1400 ml / min, 1500 ml / min, 1600 ml / min, 1700 ml / min, 1800 ml / min, 1900 ml / min, 2000 ml / min or any value between 50-2000 ml / min.

[0096] The addition rate of the oxidant solution and the phosphorus source solution mainly affects the nucleation rate in the early stage of the reaction, the crystal growth rate in the later stage of the reaction and the point-like primary particle size. When the addition rate of the oxidant solution and the phosphorus source solution is within the above range, the higher the addition rate, the higher the nucleation rate in the early stage of the reaction, the stronger the nucleation motive force, the weaker the growth motive force in the later stage, and the smaller the point-like primary particle size.

[0097] When the feed flow rate of the oxidant solution and the phosphorus source solution is lower than 50 ml / min, the nucleation motive force of the reaction is weak, and the particles are mainly growing, which will cause the primary particle size to be too large; when the feed flow rate of the oxidant solution and the phosphorus source solution is higher than 2000 ml / min, the addition rate of the phosphorus source and the oxidant is greater than the precipitation efficiency of Mn and Fe, resulting in the inability to completely precipitate Mn and Fe in the supernatant after the feeding is completed.

[0098] In some embodiments, the drying temperature in step S300 is 90-150°C, for example, it can be 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C or any value between 90-150°C.

[0099] In some embodiments, the calcination temperature in step S300 is 200-600°C, for example, it can be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 280°C, 300°C, 320°C, 340°C, 350°C, 370°C, 400°C, 420°C, 440°C, 450°C, 480°C, 500°C, 520°C, 540°C, 550°C, 560°C, 570°C, 580°C, 600°C or any value between 200-600°C.

[0100] The present application also provides a lithium manganese iron phosphate positive electrode material, which is prepared from the above-mentioned lithium manganese phosphate precursor.

[0101] The lithium manganese iron phosphate positive electrode material provided in the present application is prepared from the manganese iron phosphate of the present application and has excellent electrochemical performance.

[0102] The present application also provides a method for preparing a lithium iron manganese phosphate positive electrode material, comprising: mixing a lithium source and a carbon source with the ferromanganese phosphate precursor, sand grinding, spray drying, and sintering at 550-750° C. for 3-8 hours to obtain the lithium iron manganese phosphate positive electrode material.

[0103] The present application also provides a lithium-ion battery, comprising the above-mentioned lithium iron manganese phosphate positive electrode material.

[0104] The present application also provides an electrical device, comprising the above-mentioned lithium-ion battery.

[0105] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0106] Example 1

[0107] This embodiment provides a manganese ferrophosphate precursor, and the preparation method thereof comprises the following steps:

[0108] (1) According to the chemical formula Mn 0.6 Fe 0.4 PO4, add manganese sulfate and ferrous sulfate to a certain amount of pure water, stir until the solution is clear and transparent, add appropriate amount of pure water to make up the volume and filter. Finally, a mixed salt solution with a manganese sulfate concentration of 0.9 mol / L and a ferrous sulfate concentration of 0.6 mol / L is obtained.

[0109] (2) Add an appropriate amount of hydrogen peroxide as an oxidant to pure water in a ratio of oxidant molar amount: total iron + manganese metal ion molar amount = 1.3:1, stir evenly and filter to obtain an oxidant solution with a hydrogen peroxide concentration of 15%.

[0110] (3) Add a certain amount of monoammonium phosphate solid to pure water in a ratio of phosphate molar amount: total metal ion molar amount of iron + manganese = 1.5:1, stir until completely dissolved, then adjust the volume and filter to obtain a phosphorus source solution with a phosphate concentration of 1.5 mol / L.

[0111] (4) The mixed salt solution is used as the base liquid, and the temperature is raised to 90°C with stirring. Then, an oxidant solution, a phosphorus source solution and a pH adjuster, ammonia water, are added in parallel. During the reaction, the pH value of the system is adjusted to 3.0. During the reaction, the feed flow rate of the oxidant solution is 210 ml / min, the feed flow rate of the phosphorus source is 750 ml / min, and the flow rate of ammonia water is controlled to maintain the pH of the system at 3.0. The stirring speed is 500 rpm. After the feeding is completed, a brown-grey slurry is obtained.

[0112] (5) The product obtained in step 4 was centrifuged, dried, and sieved to obtain a powder, wherein the drying temperature was 120° C. and the drying time was 12 h; the powder was calcined and dehydrated at 500° C. for 4 h and then naturally cooled, and the calcination atmosphere was air, to obtain the ferromanganese phosphate precursor material of Example 1, and its XRD result was as follows: Figure 2 As shown in the SEM images Figure 3 shown.

[0113] Example 2

[0114] This embodiment provides a manganese ferrophosphate precursor, and the preparation method thereof comprises the following steps:

[0115] (1) According to the chemical formula Mn 0.6 Fe 0.4 PO4, add manganese sulfate and ferrous sulfate to a certain amount of pure water, stir until the solution is clear and transparent, add appropriate amount of pure water to make up the volume and filter. Finally, a mixed salt solution with a manganese sulfate concentration of 0.9 mol / L and a ferrous sulfate concentration of 0.6 mol / L is obtained.

[0116] (2) Add an appropriate amount of hydrogen peroxide as an oxidant to pure water in a ratio of oxidant molar amount: total iron + manganese metal ion molar amount = 1.3:1, stir evenly and filter to obtain an oxidant solution with a hydrogen peroxide concentration of 15%.

[0117] (3) Add a certain amount of monoammonium phosphate solid to pure water in a ratio of phosphate molar amount: total metal ion molar amount of iron + manganese = 1.2:1, stir until completely dissolved, then adjust the volume and filter to obtain a phosphorus source solution with a phosphate concentration of 1.5 mol / L.

[0118] (4) The mixed salt solution is used as the base liquid, stirred and heated to 95°C, and then the oxidant solution, phosphorus source solution and pH adjuster ammonia water are added in parallel. During the reaction, the pH value of the system is adjusted to 2.5. During the reaction, the oxidant solution feed flow rate is 105 ml / min, the phosphorus source feed flow rate is 375 ml / min, and the ammonia water flow rate is controlled to maintain the system pH = 2.5. The stirring speed is 500 rpm. After the feeding is completed, a brown-grey slurry is obtained.

[0119] (5) The product obtained in step 4 was centrifuged, dried, and sieved to obtain a powder, wherein the drying temperature was 120° C. and the drying time was 12 h; the powder was calcined and dehydrated at 550° C. for 4 h and then naturally cooled, and the calcination atmosphere was air, to obtain the ferromanganese phosphate precursor material of Example 2, and its XRD result was as follows Figure 4 As shown in the SEM images Figure 5 shown.

[0120] Example 3

[0121] This embodiment provides a manganese ferrophosphate precursor, and the preparation method thereof comprises the following steps:

[0122] (1) According to the chemical formula Mn 0.6 Fe 0.4 PO4, add manganese sulfate and ferrous sulfate to a certain amount of pure water, stir until the solution is clear and transparent, add appropriate amount of pure water to make up the volume and filter. Finally, a mixed salt solution with a manganese sulfate concentration of 1.2 mol / L and a ferrous sulfate concentration of 0.8 mol / L is obtained.

[0123] (2) Add an appropriate amount of sodium persulfate as an oxidant to pure water in a ratio of oxidant molar amount: total iron + manganese metal ion molar amount = 1.2:1, stir evenly and filter to obtain an oxidant solution with a sodium persulfate concentration of 2.0 mol / L.

[0124] (3) Add a certain amount of phosphoric acid solution to pure water in a ratio of phosphate molar amount: total metal ion molar amount of iron + manganese = 1:1, stir until completely dissolved, then adjust the volume and filter to obtain a phosphorus source solution with a phosphate concentration of 1.5 mol / L.

[0125] (4) The mixed salt solution is used as the base liquid, and the temperature is raised to 90°C with stirring, and then the oxidant solution, phosphorus source solution and pH adjuster ammonia water are added in parallel. During the reaction, the pH value of the system is adjusted to 3.5. The feed flow rate of the oxidant solution is 700 ml / min, the feed flow rate of the phosphorus source is 1300 ml / min, and the flow rate of ammonia water is controlled to maintain the pH of the system at 3.5. The stirring speed is 1000 rpm. After the feeding is completed, a brown-grey slurry is obtained.

[0126] (5) The product obtained in step 4 was centrifuged, dried, and sieved to obtain a powder, wherein the drying temperature was 150° C. and the drying time was 12 h. The powder was calcined and dehydrated at 480° C. for 4 h and then naturally cooled. The calcination atmosphere was air, and the ferromanganese phosphate precursor material of Example 3 was obtained. Its XRD result is as follows: Figure 6 As shown in the SEM images Figure 7 shown.

[0127] Comparative Example 1

[0128] This comparative example provides a manganese ferrophosphate precursor, and its preparation method comprises the following steps:

[0129] (1) According to the chemical formula Mn 0.6 Fe 0.4 PO4, add manganese sulfate and ferrous sulfate to a certain amount of pure water, stir until the solution is clear and transparent, add a certain amount of phosphoric acid to the salt solution according to the ratio of phosphoric acid molar amount: total metal ion molar amount of iron + manganese = 1.3:1, add appropriate amount of pure water to make up the volume and filter. Finally, a mixed solution of metal salt + phosphoric acid with a manganese sulfate concentration of 0.9 mol / L, a ferrous sulfate concentration of 0.6 mol / L, and a phosphate concentration of 1.95 mol / L is obtained.

[0130] (2) Add an appropriate amount of hydrogen peroxide as an oxidant to pure water in a ratio of oxidant molar amount: total iron + manganese metal ion molar amount = 1.3:1, stir evenly and filter to obtain an oxidant solution with a hydrogen peroxide concentration of 15%.

[0131] (3) A mixed solution of metal salt and phosphoric acid was used as the base liquid. After stirring and heating to 90°C, an oxidant solution and a pH adjuster, ammonia water, were added in parallel. During the reaction, the pH value of the system was adjusted to 3.0. During the reaction, the feed rate of the oxidant solution was 210 ml / min, and the flow rate of ammonia water was controlled to maintain the pH of the system at 3.0. The stirring speed was 500 rpm. After the feeding was completed, a brown-grey slurry was obtained.

[0132] (5) The product obtained in step 4 was centrifuged, dried, and sieved to obtain a powder, wherein the drying temperature was 120° C. and the drying time was 12 h; the powder was calcined and dehydrated at 500° C. for 4 h and then naturally cooled, and the calcination atmosphere was air, to obtain the ferromanganese phosphate precursor material of comparative example 1, and its XRD result was as follows: Figure 8 As shown in the SEM images Fig. 9 As shown, the product phases are basic iron phosphate and manganese phosphate. Since the base liquid is a salt solution and a phosphorus source, phase separation occurs after adding ammonia water and hydrogen peroxide. At the same time, the system supersaturation is too high, resulting in a large amount of nucleation, so the crystallinity is reduced to a certain extent.

[0133] Comparative Example 2

[0134] This comparative example provides a manganese ferrophosphate precursor, and its preparation method comprises the following steps:

[0135] (1) According to the chemical formula Mn 0.6 Fe 0.4 PO4, add manganese sulfate and ferrous sulfate to a certain amount of pure water, stir until the solution is clear and transparent, add appropriate amount of pure water to make up the volume and filter. Finally, a mixed salt solution with a manganese sulfate concentration of 0.9 mol / L and a ferrous sulfate concentration of 0.6 mol / L is obtained.

[0136] (2) Add an appropriate amount of hydrogen peroxide as an oxidant to pure water in a ratio of oxidant molar amount: total iron + manganese metal ion molar amount = 1.3:1, stir evenly and filter to obtain an oxidant solution with a hydrogen peroxide concentration of 15%.

[0137] (3) Add a certain amount of monoammonium phosphate solid to pure water in a ratio of phosphate molar amount: total metal ion molar amount of iron + manganese = 1.5:1, stir until completely dissolved, then adjust the volume and filter to obtain a phosphorus source solution with a phosphate concentration of 1.5 mol / L.

[0138] (4) The mixed salt solution is used as the base liquid, and the temperature is raised to 90°C with stirring. Then, an oxidant solution, a phosphorus source solution and a pH adjuster, ammonia water, are added in parallel. During the reaction, the pH value of the system is adjusted to 5.5. During the reaction, the feed flow rate of the oxidant solution is 210 ml / min, the feed flow rate of the phosphorus source is 750 ml / min, and the flow rate of ammonia water is controlled to maintain the pH of the system at 5.5. The stirring speed is 500 rpm. After the feeding is completed, a brown-grey slurry is obtained.

[0139] (5) The product obtained in step 4 was centrifuged, dried, and sieved to obtain a powder, wherein the drying temperature was 120° C. and the drying time was 12 h; the powder was calcined and dehydrated at 500° C. for 4 h and then naturally cooled, and the calcination atmosphere was air, to obtain the ferromanganese phosphate precursor material of comparative example 2, and its XRD result was as follows: Fig.10 As shown in the SEM images Fig.11 As shown in the figure, the pure ammonium manganese phosphate is mainly flake-shaped in shape. This is because the reaction pH is too high, and Mn 2+ It is not oxidized and precipitates first, and finally precipitates in the form of ammonium manganese phosphate. At the same time, due to the high crystallinity and high peak intensity of this phase, the amorphous basic iron phosphate peak is basically invisible. However, based on the Mn / Fe of the main component, it can be inferred that Fe has been completely precipitated.

[0140] Comparative Example 3

[0141] This comparative example provides a manganese ferrophosphate precursor, and its preparation method comprises the following steps:

[0142] (1) According to the chemical formula Mn 0.6 Fe 0.4PO4, add manganese sulfate and ferrous sulfate to a certain amount of pure water, stir until the solution is clear and transparent, add appropriate amount of pure water to make up the volume and filter. Finally, a mixed salt solution with a manganese sulfate concentration of 0.9 mol / L and a ferrous sulfate concentration of 0.6 mol / L is obtained.

[0143] (2) Add an appropriate amount of hydrogen peroxide as an oxidant to pure water in a ratio of oxidant molar amount: total iron + manganese metal ion molar amount = 1.3:1, stir evenly and filter to obtain an oxidant solution with a hydrogen peroxide concentration of 15%.

[0144] (3) Add a certain amount of monoammonium phosphate solid to pure water in a ratio of phosphate molar amount: total metal ion molar amount of iron + manganese = 1.5:1, stir until completely dissolved, then adjust the volume and filter to obtain a phosphorus source solution with a phosphate concentration of 1.5 mol / L.

[0145] (4) The mixed salt solution is used as the base liquid, and the temperature is raised to 65°C with stirring. Then, an oxidant solution, a phosphorus source solution and a pH adjuster, ammonia water, are added in parallel. During the reaction, the pH value of the system is adjusted to 3.0. During the reaction, the feed flow rate of the oxidant solution is 210 ml / min, the feed flow rate of the phosphorus source is 750 ml / min, and the flow rate of ammonia water is controlled to maintain the pH of the system at 3.0. The stirring speed is 500 rpm. After the feeding is completed, a brown-grey slurry is obtained.

[0146] (5) The product obtained in step 4 was centrifuged, dried, and sieved to obtain a powder, wherein the drying temperature was 120° C. and the drying time was 12 h; the powder was calcined and dehydrated at 500° C. for 4 h and then naturally cooled, and the calcination atmosphere was air, to obtain the ferromanganese phosphate precursor material of comparative example 3, and its XRD result was as follows: Fig.12 As shown in the SEM images Fig.13 As shown, the physical phase is basic iron phosphate. Due to insufficient crystallization kinetics at low temperatures, it has an amorphous morphology. At the same time, the morphology is also a nano-dot morphology, but the Mn / Fe is only 0.45. This is because the reaction temperature is too low, resulting in the inability to completely precipitate Mn, and the basic iron phosphate crystallization kinetics is insufficient, resulting in the product being precipitated in the form of amorphous basic iron phosphate.

[0147] The physical parameters of the ferromanganese phosphate precursors obtained in the examples and comparative examples were tested using the following methods:

[0148] Particle size: Malvern 3000 particle size analyzer.

[0149] BET: Specific surface area tester, model BSD-BET400, manufacturer: Best Instrument Technology (Beijing) Co., Ltd.

[0150] Tap density: Tap density meter, model BT-313, manufacturer is Dandong Better Instrument Co., Ltd.

[0151] Mn, Fe, P element testing method: ICP.

[0152] Diameter of primary particles: measured using NanoMeasurer software.

[0153] The physical parameters of the ferromanganese phosphate precursors obtained in the examples and comparative examples are shown in Table 1.

[0154] Table 1 Physical parameters of ferromanganese phosphate precursors obtained in various embodiments and comparative examples

[0155]

[0156]

[0157] The lithium source and the carbon source were mixed with the ferromanganese phosphate precursor obtained in each embodiment and comparative example, sand-milled and spray-dried, and then sintered at 550-750°C for 3-8h to prepare a lithium ferromanganese phosphate positive electrode material. The lithium ferromanganese phosphate positive electrode materials obtained in each embodiment and comparative example were mixed in a mass ratio of active material: binder: conductive agent = 8:1:1, and NMP was added and stirred to prepare a positive electrode slurry, which was assembled into a button battery after coating, drying, and cutting, and the 0.1C and 1C charge and discharge electrochemical performance tests were carried out in a voltage window of 2.0-4.5V.

[0158] The electrochemical properties of the lithium-ion batteries obtained in the embodiments and comparative examples are shown in Table 2.

[0159] Table 2 Electrochemical performance of lithium ion batteries obtained in various embodiments and comparative examples

[0160]

[0161] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0162] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A ferromanganese phosphate precursor, characterized in that: The ferromanganese phosphate precursor is a crystalline material, and includes secondary particles composed of a plurality of primary particles. The primary particles are nano-dot particles, and the average diameter of the primary particles is 20-300 nm. The secondary particles are block structures.

2. The ferromanganese phosphate precursor according to claim 1, characterized in that At least one of the following conditions is met: A. In the X-ray diffraction spectrum of the ferromanganese phosphate precursor, the main peak intensity is 500-4000; B. The average grain size of the ferromanganese phosphate precursor is C. The crystallinity of the ferromanganese phosphate precursor is 15-80%.

3. The ferromanganese phosphate precursor according to claim 1, characterized in that At least one of the following conditions is met: A. The chemical formula of the manganese ferrophosphate precursor is Mn x Fe 1-x PO4·H2O, where 0.2≤x≤0.9; Optional, 0.4≤x≤0.8; B. The D50 of the ferromanganese phosphate precursor is 1-25 μm; C. The specific surface area of ​​the ferromanganese phosphate precursor is 5-100m 2 / g; D. The tap density of the ferromanganese phosphate precursor is 0.3-2.0 g / cm 3 ; E. The diameter of the primary particles is 50-150 nm; F. The Mn / Fe ratio of the ferromanganese phosphate precursor is 1.45 to 1.

55.

4. A method for preparing the ferromanganese phosphate precursor according to any one of claims 1 to 3, characterized in that: include: A mixed salt solution including a manganese source and an iron source is used as a bottom liquid of a reaction kettle; Adding an oxidant solution, a pH regulator and a phosphorus source solution to the bottom liquid of the reaction kettle in parallel to perform a co-precipitation reaction to obtain a slurry; The slurry is subjected to solid-liquid separation, drying and calcination to obtain the ferromanganese phosphate precursor.

5. The method for preparing the ferromanganese phosphate precursor according to claim 4, characterized in that: At least one of the following conditions is met: A. The iron source includes at least one of ferrous sulfate, a byproduct of titanium dioxide, industrial-grade ferrous sulfate, battery-grade ferrous sulfate, ferrous nitrate, ferrous chloride, ferrous oxalate, and ferrous acetate; B. the manganese source comprises at least one of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate and manganese acetate; C. The total molar concentration of manganese and iron in the mixed salt solution is 0.2 to 2.0 mol / L; D. The molar ratio of manganese to iron in the mixed salt solution is (1-2):1; E. In the oxidant solution, the ratio of the molar amount of the oxidant to the total molar amount of manganese and iron is (1.1-1.5):1; the oxidant includes at least one of hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, ozone, nitric acid, ammonium nitrate, potassium nitrate, sodium nitrate, and potassium permanganate; F. The pH regulator includes at least one of aqueous ammonia, diammonium phosphate, diammonium hydrogen phosphate, and sodium hydroxide solution; G. In the phosphorus source solution, the ratio of the molar amount of the phosphorus source to the total molar amount of manganese and iron is (1-1.5):1; the phosphorus source includes at least one of phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium phosphate.

6. The method for preparing the ferromanganese phosphate precursor according to claim 4, characterized in that: At least one of the following conditions is met: A. The temperature of the coprecipitation reaction is 70-95°C; B. the pH value of the coprecipitation reaction is 1.5-5; C. The feed flow rates of the oxidant solution and the phosphorus source solution are independently 50-2000 ml / min; D. The drying temperature is 90-150°C; E. The calcination temperature is 200-600°C.

7. A lithium manganese iron phosphate positive electrode material, characterized in that: Prepared from the ferromanganese phosphate precursor according to any one of claims 1 to 3.

8. A method for preparing the lithium iron manganese phosphate positive electrode material as claimed in claim 7, characterized in that: include: The lithium source and the carbon source are mixed with the manganese iron phosphate precursor, and after sand grinding and spray drying, sintering is carried out at 550-750° C. for 3-8 hours to obtain the manganese iron phosphate lithium positive electrode material.

9. A lithium ion battery, characterized in that: Including the lithium manganese iron phosphate positive electrode material as described in claim 7.

10. An electrical equipment, characterized in that: Includes the lithium ion battery as claimed in claim 9.

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