Continuous reaction system, manganese iron carbonate precursor and preparation method thereof, lithium manganese iron phosphate and preparation method thereof, positive electrode sheet and battery

Abstract

The application discloses a continuous reaction system, a manganese iron carbonate precursor and a preparation method thereof, a lithium manganese iron phosphate and a preparation method thereof, a positive plate, a battery, and the continuous reaction system comprises a first dissolving kettle, a second dissolving kettle, a kettle type reactor and a tubular reactor, and the kettle type reactor and the tubular reactor are connected in series.

Description

Technical Field

[0001] The present application relates to a continuous reaction system, a manganese iron carbonate precursor and a preparation method thereof, lithium manganese iron phosphate and a preparation method thereof, a positive electrode sheet, and a battery. Background Art

[0002] In recent years, batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. Lithium manganese iron phosphate has become one of the most popular positive electrode active materials due to its advantages such as high capacity and abundant sources of raw materials. As one of the important raw materials for the preparation of lithium manganese iron phosphate, the performance of the manganese iron carbonate precursor is crucial to the performance of lithium manganese iron phosphate and batteries. However, at present, manganese iron carbonate precursors are obtained by intermittent preparation methods, which have problems such as low production efficiency, complicated procedures, difficult to control production processes, large fluctuations in product quality, and poor batch consistency. The above statements are only used to provide background technical information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0003] The present application provides a continuous reaction system, a ferromanganese carbonate precursor and a preparation method thereof, a lithium ferromanganese phosphate and a preparation method thereof, a positive electrode sheet, and a battery, which can improve the production efficiency of the ferromanganese carbonate precursor and obtain a ferromanganese carbonate precursor with small particle size, narrow particle size distribution, high crystallinity, single crystal phase, uniform element distribution, and high batch consistency.

[0004] In a first aspect, the present application provides a continuous reaction system for preparing a manganese ferrocarbonate precursor, wherein the continuous reaction system comprises a first dissolving kettle, a second dissolving kettle, a kettle reactor and a tubular reactor, wherein the kettle reactor and the tubular reactor are connected in series.

[0005] The first dissolving kettle is used to accommodate the metal salt solution required for preparing the manganese ferrocarbonate precursor, and the second dissolving kettle is used to accommodate the precipitant solution required for preparing the manganese ferrocarbonate precursor. The first dissolving kettle has a first discharge port, and the second dissolving kettle has a second discharge port.

[0006] The kettle reactor has a first feed port and a first overflow port. The first feed port of the kettle reactor is connected to the first dissolving kettle and the second dissolving kettle through a first pipe and a second pipe respectively, so that the kettle reactor can accommodate the metal salt solution and the precipitant solution and cause a precipitation reaction to occur after mixing to generate a first reaction liquid. The first pipe is provided with a first stop valve and a first metering pump to adjust the flow rate of the metal salt solution, and the second pipe is provided with a second stop valve and a second metering pump to adjust the flow rate of the precipitant solution. The kettle reactor is also connected to a pH control device to monitor and adjust the pH value of the first reaction liquid.

[0007] The tubular reactor has a second feed port and a third discharge port. The second feed port of the tubular reactor is connected to the first overflow port of the tank reactor through a third pipe, so that the tubular reactor can accommodate the first reaction liquid from the tank reactor and allow it to continue to precipitate to form a second reaction liquid. The third discharge port of the tubular reactor is used to allow the second reaction liquid to flow out. The tubular reactor is also connected to one or more pH control devices to monitor and adjust the pH value of the second reaction liquid.

[0008] In any embodiment, the tubular reactor is a horizontal tubular reactor.

[0009] The second aspect of the present application provides a method for preparing a manganese ferrocarbonate precursor by the continuous reaction system of the first aspect of the present application, comprising at least the following steps: connecting a tank reactor and a tubular reactor in series, wherein the tank reactor has a first feed port and a first overflow port, the first feed port of the tank reactor is connected to the first dissolving tank and the second dissolving tank through a first pipe and a second pipe respectively, the first pipe is provided with a first stop valve and a first metering pump, the second pipe is provided with a second stop valve and a second metering pump, the tank reactor is also connected to a pH control device, the first dissolving tank has a first discharge port, the second dissolving tank has a second discharge port, the tubular reactor has a second feed port and a third discharge port, the second feed port of the tubular reactor is connected to the first overflow port of the tank reactor through a third pipe, and the tubular reactor is also connected to one or more pH control devices. The device is connected; the metal salt solution required for preparing the manganese ferrocarbonate precursor is added to the first dissolving kettle, and the precipitant solution required for preparing the manganese ferrocarbonate precursor is added to the second dissolving kettle; the metal salt solution in the first dissolving kettle and the precipitant solution in the second dissolving kettle are respectively transported to the kettle reactor through the first pipe and the second pipe so that they are mixed and then a precipitation reaction occurs to generate a first reaction liquid; when the liquid level of the first reaction liquid is higher than the first overflow port of the kettle reactor, the first reaction liquid is transported to the tubular reactor, and then the first reaction liquid continues to precipitate in the tubular reactor to form a second reaction liquid, and the second reaction liquid flows out through the third discharge port of the tubular reactor; the second reaction liquid obtained from the third discharge port of the tubular reactor is washed and dried to obtain the manganese ferrocarbonate precursor.

[0010] The preparation method of the ferromanganese carbonate precursor provided in the present application is a continuous preparation method, which has the advantages of high production efficiency, high energy efficiency, simple process, easy operation and low labor cost, and is particularly suitable for large-scale industrial production. The ferromanganese carbonate precursor obtained by the preparation method of the ferromanganese carbonate precursor provided in the present application can have the advantages of small particle size, narrow particle size distribution, high crystallinity, single crystal phase, uniform element distribution, and high batch consistency. The preparation method of the ferromanganese carbonate precursor provided in the present application can also flexibly adjust the particle size and morphology of the ferromanganese carbonate precursor, which is conducive to meeting different production needs so as to prepare lithium manganese iron phosphate with different particle sizes.

[0011] In any embodiment, a complexing agent is further added to the first dissolving kettle. When a complexing agent is further added to the first dissolving kettle, the method for preparing a ferromanganese carbonate precursor provided herein can produce ferromanganese carbonate precursor particles with high purity and uniform element distribution. Furthermore, the molar ratio of each metal element in the obtained ferromanganese carbonate precursor particles is relatively close to that in the raw material, which facilitates further precise control of the metal element content and helps ensure that the ratio of the metal elements reaches a preset value.

[0012] In any embodiment, the complexing agent includes one or more of aminocarboxylates, hydroxycarboxylates and organic phosphonates. Alternatively, the complexing agent includes one or more of sodium ethylenediaminetetramethylenephosphate, sodium ethylenediaminetetraacetate, sodium gluconate and sodium citrate.

[0013] In any embodiment, the reaction temperature in the autoclave reactor is less than or equal to the reaction temperature in the tubular reactor. Adjusting the reaction temperature in the autoclave reactor to be less than or equal to the reaction temperature in the tubular reactor facilitates obtaining ferromanganese carbonate precursor particles having a narrow particle size distribution, uniform element distribution, high crystallinity, and regular morphology.

[0014] In any embodiment, the reaction temperature in the autoclave reactor is 50-80° C. When the reaction temperature in the autoclave reactor is within the above range, it is conducive to the rapid precipitation of metal ions and carbonate ions, forming a large number of crystal nuclei, and is also conducive to reducing the difference in precipitation rates of different metal ions during the precipitation reaction process, thereby facilitating uniform co-precipitation of metal ions.

[0015] In any embodiment, the reaction temperature in the tubular reactor is 50-80° C. When the reaction temperature in the tubular reactor is within the above range, the ferromanganese carbonate grains grown in the autoclave reactor can be further grown and the crystallinity of the ferromanganese carbonate grains can be improved, thereby facilitating the production of a ferromanganese carbonate precursor with high crystallinity and regular morphology.

[0016] In any embodiment, the volume of the autoclave reactor is smaller than that of the tubular reactor. The ferromanganese carbonate precursor particles reside in the tubular reactor for a longer time, thereby helping the obtained ferromanganese carbonate precursor particles to have a narrower particle size distribution, and also helping the obtained ferromanganese carbonate precursor particles to have higher crystallinity and more regular morphology.

[0017] In any embodiment, the volume ratio of the autoclave reactor to the tubular reactor is 1:5-1:7. This helps to ensure that the obtained ferromanganese carbonate precursor particles have a smaller particle size and a narrower particle size distribution, while also helping to ensure that the obtained ferromanganese carbonate precursor particles have a higher crystallinity and a more regular morphology.

[0018] In any embodiment, the residence time of the ferromanganese carbonate precursor in the autoclave reactor during the growth process is 0.5-4 hours.

[0019] In any embodiment, the residence time of the ferromanganese carbonate precursor in the tubular reactor during the growth process is 2.5-28 hours.

[0020] In any embodiment, the concentration of the metal salt solution is 0.5-2 mol / L.

[0021] In any embodiment, the concentration of the precipitant solution is 0.5-2 mol / L.

[0022] In any embodiment, the molar ratio of the metal salt to the precipitant is 1:1-1:2.

[0023] In any embodiment, the flow rate of the metal salt solution is 0.5-4 L / min.

[0024] In any embodiment, the flow rate of the precipitant solution is 0.5-4 L / min.

[0025] In any embodiment, the flow rates of the metal salt solution and the precipitant solution are the same.

[0026] In any embodiment, the method further comprises the steps of: during the reaction, adding a pH regulating liquid into the kettle reactor by a pH control device connected to the kettle reactor, so that the pH of the first reaction solution in the kettle reactor is 6-8, optionally 7-7.5. When the pH in the kettle reactor is within the above range, it is conducive to the rapid precipitation of metal ions and carbonate ions to form a large amount of crystal nuclei, and it is also conducive to reducing the precipitation rate difference of different metal ions during the precipitation reaction, thereby facilitating uniform co-precipitation of metal ions. In addition, when the pH in the kettle reactor is within the above range, it is also conducive to forming a spherical (or spherical) morphology of the ferromanganese carbonate precursor, and then it is also conducive to improving the tap density.

[0027] In any embodiment, the method further comprises the steps of: during the reaction, adding a pH regulating liquid to the tubular reactor by a pH control device connected to the tubular reactor so that the pH of the second reaction liquid in the tubular reactor is 6-8, optionally 7-7.5. When the pH of the second reaction liquid in the tubular reactor is within the above range, it is beneficial to reduce the difference in precipitation rates of different metal ions during the precipitation reaction, thereby facilitating uniform co-precipitation of metal ions. In addition, when the pH in the tubular reactor is within the above range, it is also beneficial to form a spherical (or spherical) morphology of the ferromanganese carbonate precursor, which is further beneficial to improving the tap density.

[0028] In any embodiment, during the reaction process, the first dissolving kettle, the second dissolving kettle, the kettle reactor and the tubular reactor are all placed under a protective gas atmosphere.

[0029] In any embodiment, during the reaction process, the first dissolving kettle, the second dissolving kettle, and the kettle reactor are all kept in a stirring state, thereby reducing the aggregation and growth of the ferromanganese carbonate precursor particles and facilitating the production of a ferromanganese carbonate precursor with a narrow particle size distribution and a high tap density.

[0030] In any embodiment, the stirring speed of the first dissolving kettle is 300-800 r / min.

[0031] In any embodiment, the stirring speed of the second dissolving kettle is 300-800 r / min.

[0032] In any embodiment, the stirring speed of the tank reactor is 300-800 r / min.

[0033] In any embodiment, the metal salt required for preparing the manganese ferrocarbonate precursor includes a water-soluble divalent iron salt, a water-soluble divalent manganese salt and an optional divalent salt of a water-soluble doping element M, where M represents the doping element at the manganese position and / or iron position of the manganese ferrocarbonate precursor, optionally including one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr.

[0034] In any embodiment, the water-soluble divalent iron salt includes one or more of ferrous chloride, ferrous nitrate, ferrous sulfate, and ferrous acetate.

[0035] In any embodiment, the water-soluble divalent manganese salt includes one or more of manganous chloride, manganous nitrate, manganous sulfate, and manganous acetate.

[0036] In any embodiment, the divalent salt of the water-soluble dopant element M includes one or more of hydrochloride, nitrate, sulfate, and acetate of the dopant element M.

[0037] In any embodiment, the precipitant comprises a carbonate, optionally comprising one or more of ammonium bicarbonate, sodium bicarbonate, ammonium carbonate, and sodium carbonate.

[0038] In any embodiment, the shielding gas includes nitrogen, an inert gas, or a combination thereof.

[0039] The third aspect of the present application provides a ferromanganese carbonate precursor prepared by the method of the second aspect of the present application, which has a chemical formula of Fe x Mn y M 1-x-yCO3, 0<x<1, optionally, 0.199≤x≤0.5; 0<y<1, optionally, 0.499≤y≤0.8; 0≤1-xy<1, optionally, 0<1-xy≤0.05; M represents the doping element of the manganese position and / or iron position of the manganese ferrocarbonate precursor, optionally including one or more of Co, Mg, Zn, Ca, Ti, V, Ni, Cr.

[0040] The ferromanganese carbonate precursor provided in the present application has the advantages of small particle size, narrow particle size distribution, high crystallinity, single crystal phase, uniform element distribution, and high batch consistency.

[0041] In any embodiment, the volume distribution particle sizes Dv90 and Dv50 of the manganese ferrocarbonate precursor satisfy 1<Dv90 / Dv50≤1.4.

[0042] The fourth aspect of the present application provides a method for preparing lithium iron manganese phosphate, which comprises at least the following steps: uniformly mixing the manganese ferrocarbonate precursor prepared by the method of the second aspect of the present application or the manganese ferrocarbonate precursor of the third aspect of the present application with a lithium source, a phosphorus source, an optional source of doping element N, an optional source of doping element Q and an optional source of doping element R to obtain a mixed raw material, wherein N represents the doping element at the lithium site of the lithium iron manganese phosphate, optionally including one or more of Zn, Al, Na, K, Mg, Nb, Mo and W; Q represents the doping element at the phosphorus site of the lithium iron manganese phosphate, optionally including one or more of B, S, Si and N; R represents the doping element at the oxygen site of the lithium iron manganese phosphate, optionally including one or more of S, F, Cl and Br; sintering the obtained mixed raw material to obtain the lithium iron manganese phosphate, wherein the lithium iron manganese phosphate has a chemical formula of Li a N b Fe x Mn y M 1-x-y P 1-m Q m O 4-n R nM represents the doping element of the manganese site and / or iron site of the lithium manganese iron phosphate, optionally including one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr; N represents the doping element of the lithium site of the lithium manganese iron phosphate, optionally including one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W; Q represents the doping element of the phosphorus site of the lithium manganese iron phosphate, optionally including one or more of B, S, Si, and N; R represents the doping element of the oxygen site of the lithium manganese iron phosphate. Miscellaneous elements, optionally including one or more of S, F, Cl and Br; 0.9≤a≤1.1; 0≤b≤0.1, optionally, 0<b≤0.05; 0<x<1, optionally, 0.199≤x≤0.5; 0<y<1, optionally, 0.499≤y≤0.8; 0≤1-xy<1, optionally, 0<1-xy≤0.05; 0≤m≤0.1, optionally, 0<m≤0.05; 0≤n≤0.1, optionally, 0<n≤0.05.

[0043] The lithium manganese iron phosphate obtained by the preparation method provided in this application can achieve a uniform mixing of lithium and multiple metal elements, thereby accelerating the diffusion of lithium ions and making it easier to embed them into the lithium manganese iron phosphate precursor, thereby enabling the prepared lithium manganese iron phosphate to have excellent electrochemical properties. The lithium manganese iron phosphate obtained by the preparation method provided in this application also has the advantages of small particle size, narrow particle size distribution, high crystallinity, single crystal phase, and high batch consistency, which is conducive to improving the capacity and electrochemical performance of the battery.

[0044] In any embodiment, a carbon source is further added to the mixed raw material, thereby preparing carbon-coated lithium manganese iron phosphate.

[0045] In a fifth aspect, the present application provides lithium manganese iron phosphate prepared by the method of the fourth aspect of the present application.

[0046] The lithium manganese iron phosphate provided in this application has the advantages of small particle size, narrow particle size distribution, high crystallinity, single crystal phase, uniform element distribution, and high batch consistency, which is beneficial to improving the capacity and electrochemical performance of the battery.

[0047] The sixth aspect of the present application provides a positive electrode sheet, comprising a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises lithium manganese iron phosphate prepared by the method of the fourth aspect of the present application or the lithium manganese iron phosphate of the fifth aspect of the present application.

[0048] The seventh aspect of the present application provides a battery, comprising the positive electrode sheet according to the sixth aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] To more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on the drawings without inventive effort.

[0050] Figure 1 A continuous reaction system for preparing a manganese ferrocarbonate precursor is shown.

[0051] Figure 2 The scanning electron microscope (SEM) image of the ferromanganese carbonate precursor prepared in Example 1 is shown. Figure 2 The magnification of a is 2000 times. Figure 2 The magnification of b is 5000 times.

[0052] Figure 3 The scanning electron microscope (SEM) image of the ferromanganese carbonate precursor prepared in Comparative Example 1 is shown. Figure 3 The magnification of a is 2000 times. Figure 3 The magnification of b is 5000 times.

[0053] In the accompanying drawings, the drawings are not necessarily drawn to scale.

[0054] The accompanying drawings are described as follows: 1. First dissolving kettle; 2. Second dissolving kettle; 3. Kettle reactor; 4. Tubular reactor; 5. First discharge port; 6. Second discharge port; 7. First stop valve; 8. First metering pump; 9. Second stop valve; 10. Second metering pump; 11. First feed port; 12. First overflow port; 13. Second feed port; 14. pH control device; 15. Third discharge port. DETAILED DESCRIPTION

[0055] Hereinafter, the continuous reaction system, manganese iron carbonate precursor and its preparation method, lithium manganese iron phosphate and its preparation method, positive electrode sheet, and battery implementation methods of the present application will be described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0056] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0057] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0058] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of this application.

[0059] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0060] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0061] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0062] Unless otherwise specified, in this application, the terms "first", "second", "third", etc. are used to distinguish different objects rather than to describe a specific order or a primary-secondary relationship.

[0063] In this application, the terms "plurality" and "multiple" refer to two or more.

[0064] Unless otherwise specified, the terms used in this application have the common meanings that are commonly understood by those skilled in the art.

[0065] Unless otherwise stated, the numerical values ​​of the various parameters mentioned in this application can be measured using various test methods commonly used in the art, for example, they can be measured according to the test methods given in the examples of this application. Unless otherwise stated, the test temperature of each parameter is 25°C.

[0066] The embodiments of the present application provide a continuous reaction system for preparing a ferromanganese carbonate precursor.

[0067] like Figure 1 As shown, the continuous reaction system includes a first dissolving kettle 1, a second dissolving kettle 2, a kettle reactor 3 and a tubular reactor 4, and the kettle reactor 3 and the tubular reactor 4 are connected in series.

[0068] The first dissolving kettle 1 is used to contain the metal salt solution required for preparing the manganese ferrocarbonate precursor, and the second dissolving kettle 2 is used to contain the precipitant solution required for preparing the manganese ferrocarbonate precursor. The first dissolving kettle 1 has a first discharge port 5, and the second dissolving kettle 2 has a second discharge port 6.

[0069] The kettle reactor 3 has a first feed port 11 and a first overflow port 12. The first feed port 11 of the kettle reactor 3 is connected to the first dissolving kettle 1 and the second dissolving kettle 2 through a first pipe and a second pipe respectively, so that the kettle reactor 3 can accommodate the metal salt solution and the precipitant solution and cause a precipitation reaction to occur after mixing to generate a first reaction liquid. A first stop valve 7 and a first metering pump 8 are provided on the first pipe to adjust the flow rate of the metal salt solution. A second stop valve 9 and a second metering pump 10 are provided on the second pipe to adjust the flow rate of the precipitant solution. The kettle reactor 3 is also connected to a pH control device 14 to monitor and adjust the pH value of the first reaction liquid.

[0070] The tubular reactor 4 has a second feed port 13 and a third discharge port 15. The second feed port 13 of the tubular reactor 4 is connected to the first overflow port 12 of the tank reactor 3 through a third pipe, so that the tubular reactor 4 can accommodate the first reaction liquid from the tank reactor 3 and allow it to continue to precipitate to form a second reaction liquid. The third discharge port 15 of the tubular reactor 4 is used to allow the second reaction liquid to flow out. The tubular reactor 4 is also connected to one or more pH control devices 14 to monitor and adjust the pH value of the second reaction liquid.

[0071] The first feed port 11 is located at the bottom of the tank reactor 3 , and the first overflow port 12 is located at the top of the tank reactor 3 .

[0072] When preparing the ferromanganese carbonate precursor, the first stop valve 7 and the second stop valve 9 can both be kept in an open state, thereby ensuring continuous feeding and continuous discharging, and allowing multiple reactors to react simultaneously.

[0073] In some embodiments, the tubular reactor 4 is a horizontal tubular reactor, which can be formed by connecting a plurality of straight tubes and a plurality of U-shaped tubes.

[0074] In some embodiments, the first dissolving kettle 1 , the second dissolving kettle 2 , and the kettle reactor 3 are all provided with stirring devices.

[0075] In some embodiments, a heating device may be further provided in the kettle reactor 3 and the tubular reactor 4 to adjust the reaction temperature in the reactor according to actual needs. The location of the heating device may be adjusted according to actual needs, and the present embodiment is not limited thereto.

[0076] The present embodiment also provides a method for preparing a ferromanganese carbonate precursor using the continuous reaction system provided in the present embodiment.

[0077] The method comprises at least the following steps.

[0078] like Figure 1 As shown, the tank reactor 3 and the tubular reactor 4 are connected in series, the tank reactor 3 has a first feed port 11 and a first overflow port 12, the first feed port 11 of the tank reactor 3 is connected to the first dissolving tank 1 and the second dissolving tank 2 through a first pipe and a second pipe respectively, the first pipe is provided with a first stop valve 7 and a first metering pump 8, the second pipe is provided with a second stop valve 9 and a second metering pump 10, the tank reactor 3 is also connected to a pH control device 14, the first dissolving tank 1 has a first discharge port 5, the second dissolving tank 2 has a second discharge port 6, the tubular reactor 4 has a second feed port 13 and a third discharge port 15, the second feed port 13 of the tubular reactor 4 is connected to the first overflow port 12 of the tank reactor 3 through a third pipe, and the tubular reactor 4 is also connected to one or more pH control devices 14.

[0079] The metal salt solution required for preparing the ferromanganese carbonate precursor is added to the first dissolving kettle 1 , and the precipitant solution required for preparing the ferromanganese carbonate precursor is added to the second dissolving kettle 2 .

[0080] The metal salt solution in the first dissolving kettle 1 and the precipitant solution in the second dissolving kettle 2 are respectively transported to the kettle reactor 3 through the first pipe and the second pipe so that they are mixed and a precipitation reaction occurs to generate a first reaction liquid. When the liquid level of the first reaction liquid is higher than the first overflow port 12 of the kettle reactor 3, the first reaction liquid is transported to the tubular reactor 4, and then the first reaction liquid continues to precipitate in the tubular reactor 4 to form a second reaction liquid, and the second reaction liquid flows out through the third discharge port 15 of the tubular reactor 4.

[0081] The second reaction liquid obtained from the third discharge port 15 of the tubular reactor 4 is washed and dried to obtain a manganese ferrocarbonate precursor.

[0082] Existing reaction systems for preparing ferromanganese carbonate precursors mostly adopt a single reactor (tank reactor) or a batch production process with multiple reactors in parallel, which has the disadvantage of low production efficiency. In addition, when multiple reactors are used in parallel for production, it is necessary to switch between different reactors at regular intervals, which also has the disadvantages of complicated production process and high labor cost.

[0083] The embodiment of this application adopts Figure 1 The continuous reaction system shown is used to prepare a ferromanganese carbonate precursor. In the continuous reaction system provided in the embodiments of the present application, the kettle reactor and the tubular reactor are connected in series, and the two reactors can react simultaneously, thereby ensuring continuous feeding and continuous discharging. Therefore, the method for preparing a ferromanganese carbonate precursor provided in the embodiments of the present application has the advantages of high production efficiency, high energy efficiency, simple process, easy operation, and low labor cost, and is particularly suitable for large-scale industrial production.

[0084] In the process of intermittent preparation of ferromanganese carbonate precursor, the solubility product constant of ferromanganese carbonate is low and the precipitation rate is fast, which easily leads to problems such as wide particle size distribution of ferromanganese carbonate precursor particles, difficult to control particle size, and uneven element distribution.

[0085] The preparation method of the ferromanganese carbonate precursor that the present application embodiment provides is a continuous preparation method, and in the continuous preparation process, the time of residence in autoclave reactor and tubular reactor during each ferromanganese carbonate precursor particle growth can be kept consistent. In addition, premixing and rapid prenucleation of metal salt solution and precipitant solution mainly occur in autoclave reactor. Tubular reactor and autoclave reactor are connected in series, and the heat transfer area per unit volume of tubular reactor is large, and the reaction speed of material in tubular reactor is fast, flow rate is fast, production capacity is high, and the residence time of material in tubular reactor is more tending to be equal, so the material concentration and chemical reaction speed at any point in tubular reactor do not change with time, only change with tube length. Therefore, compared with making reaction solution flow into another autoclave reactor connected in series from autoclave reactor, after making reaction solution flow into tubular reactor from autoclave reactor, it is possible to reduce crystal nucleus aggregation growth, the ferromanganese carbonate precursor thus obtained can have the advantages such as particle size is small, narrow particle size distribution, high crystallinity, single crystalline phase, uniform element distribution, batch consistency height.

[0086] In the continuous preparation method of the ferromanganese carbonate precursor provided in the embodiment of the present application, the flow rate of the metal salt solution and the precipitant solution, the residence time of the ferromanganese carbonate precursor particles in each reactor during growth, the reaction temperature in each reactor, and the pH and other parameters can all be precisely adjusted. Therefore, the preparation method provided in the embodiment of the present application also has good production flexibility.

[0087] The residence time of the ferromanganese carbonate precursor particles in each reactor (tank reactor and tubular reactor) during growth is negatively correlated with the flow rate of the metal salt solution and the precipitant solution, and positively correlated with the volume of each reactor. When the flow rate of the metal salt solution and the precipitant solution is high, the residence time of the ferromanganese carbonate precursor particles in each reactor is short; when the flow rate of the metal salt solution and the precipitant solution is low, the residence time of the ferromanganese carbonate precursor particles in each reactor is long; when the volume of each reactor is small, the residence time of the ferromanganese carbonate precursor particles in each reactor is short; when the volume of each reactor is large, the residence time of the ferromanganese carbonate precursor particles in each reactor is long. Therefore, the size of the ferromanganese carbonate precursor particles can be adjusted by adjusting the flow rate of the metal salt solution and the precipitant solution and the volume of each reactor.

[0088] The reaction temperature and / or pH of each reactor will also affect the morphology, crystallinity, particle size, particle size distribution and tap density of the obtained manganese ferrocarbonate precursor. Therefore, the morphology, crystallinity, particle size, particle size distribution and tap density of the manganese ferrocarbonate precursor can also be adjusted by adjusting the reaction temperature and / or pH of each reactor.

[0089] Therefore, the preparation method of the ferromanganese carbonate precursor provided in the embodiment of the present application can also flexibly adjust the particle size and morphology of the ferromanganese carbonate precursor, thereby facilitating meeting different production requirements to prepare lithium manganese iron phosphate with different particle sizes.

[0090] The preparation method of the ferromanganese carbonate precursor provided in the embodiment of the present application is a co-precipitation reaction method, and the ferromanganese carbonate precursor obtained by the preparation method provided in the embodiment of the present application can also have a regular spherical (or quasi-spherical) morphology. The spherical (or quasi-spherical) morphology of the ferromanganese carbonate precursor is conducive to the lithium ions passing through the micropores on the surface of the spherical (or quasi-spherical) particles in the subsequent sintering process of the lithium manganese iron phosphate. It is conducive to obtaining a spherical (or quasi-spherical) morphology and a lithium manganese iron phosphate with a uniform distribution of elements. In addition, a complete, uniform and firm carbon coating layer can be formed, thereby improving the conductivity of the obtained lithium manganese iron phosphate.

[0091] In some embodiments, a complexing agent may be added to the first dissolving kettle.

[0092] The complexing agent can complex metal ions to achieve the purpose of controlling free metal ions, thereby improving the precipitation conversion efficiency of metal ions and reducing the difference in precipitation rates of different metal ions in the reaction solution, thereby facilitating uniform co-precipitation. Therefore, when a complexing agent is also added to the first dissolving kettle, the preparation method of the ferromanganese carbonate precursor provided by the present application can obtain ferromanganese carbonate precursor particles with high purity (purity greater than 99.7%) and uniform element distribution, and the molar ratio of each metal element in the obtained ferromanganese carbonate precursor particles is less different from the molar ratio of each metal element in the raw material, which is conducive to further precise control of the metal element content and helps the ratio of the metal elements to better reach the preset value.

[0093] Alternatively, the complexing agent may include one or more of aminocarboxylates, hydroxycarboxylates, and organic phosphonates.

[0094] More optionally, the complexing agent may include one or more of sodium ethylenediaminetetramethylenephosphate, sodium ethylenediaminetetraacetate, sodium gluconate, and sodium citrate. This helps to obtain high-purity ferromanganese carbonate precursor particles with uniform element distribution. The molar ratio of each metal element in the obtained ferromanganese carbonate precursor particles is relatively close to that in the raw materials, which facilitates further precise control of the metal element content and helps the ratio of the metal elements to better reach the preset value.

[0095] Optionally, the mass concentration of the complexing agent may be below 5 wt %, more preferably 1-5 wt %, based on the total mass of the metal salt solution.

[0096] In some embodiments, the reaction temperature in the tank reactor 3 may be less than or equal to the reaction temperature in the tubular reactor 4 .

[0097] In some embodiments, the reaction temperature in the tank reactor 3 may be equal to the reaction temperature in the tubular reactor 4 .

[0098] In some embodiments, the reaction temperature in the tank reactor 3 may be lower than the reaction temperature in the tubular reactor 4. Alternatively, the difference between the reaction temperature in the tubular reactor 4 and the reaction temperature in the tank reactor 3 may be less than or equal to 20°C, more preferably less than or equal to 15°C.

[0099] In the preparation method of the ferromanganese carbonate precursor provided in the embodiment of the present application, the kettle reactor and the tubular reactor are connected in series, and the reaction temperature in the kettle reactor is set to be less than or equal to the reaction temperature in the tubular reactor, thereby enabling different reactors in the continuous reaction system to mainly play different functions. The reaction temperature in the kettle reactor is low, so that in the kettle reactor, premixing and rapid prenucleation of the metal salt solution and the precipitant solution mainly occur; and the lower reaction temperature is also conducive to reducing the crystal nucleus aggregation growth in the first reaction solution, thereby also allowing the metal ions and carbonate ions to coprecipitate to form a large number of crystal nuclei with uniform size and uniform element distribution, thereby facilitating better growth and crystallization of the crystal nuclei in the tubular reactor. The reaction temperature in the tubular reactor is equal to or higher than the reaction temperature in the kettle reactor, so that when the reaction solution flows from the kettle reactor into the tubular reactor, the equal or higher reaction temperature can provide enough energy to promote further growth and crystallization of the crystal nuclei, and is also conducive to improving the crystallinity of the formed ferromanganese carbonate precursor under the premise of reducing the crystal nucleus aggregation growth.

[0100] Therefore, by adjusting the reaction temperature in the autoclave reactor to be less than or equal to the reaction temperature in the tubular reactor, it is helpful to obtain ferromanganese carbonate precursor particles with narrow particle size distribution, uniform element distribution, high crystallinity and regular morphology.

[0101] In some embodiments, the reaction temperature in the autoclave reactor 3 may be 50-80° C. When the reaction temperature in the autoclave reactor is within the above range, it is beneficial for the rapid precipitation of metal ions and carbonate ions, forming a large number of crystal nuclei, and also beneficial for reducing the difference in precipitation rates of different metal ions during the precipitation reaction, thereby facilitating uniform co-precipitation of metal ions.

[0102] In some embodiments, the reaction temperature in the tubular reactor 4 may be 50-80° C. When the reaction temperature in the tubular reactor is within the above range, the ferromanganese carbonate grains grown in the autoclave reactor can be further grown and the crystallinity of the ferromanganese carbonate grains can be improved, thereby facilitating the production of a ferromanganese carbonate precursor with high crystallinity and regular morphology.

[0103] In some embodiments, the concentration of the metal salt solution may be 0.5-2 mol / L, optionally 0.5-1 mol / L.

[0104] In some embodiments, the concentration of the precipitant solution may be 0.5-2 mol / L, optionally 0.5-1 mol / L.

[0105] In some embodiments, the molar ratio of the metal salt to the precipitant may be 1:1 to 1:2.

[0106] In some embodiments, the flow rate of the metal salt solution (or the pumping speed of the first metering pump) may be 0.5-4 L / min, optionally 1-2 L / min.

[0107] In some embodiments, the flow rate of the precipitant solution (or the pumping speed of the second metering pump) may be 0.5-4 L / min, optionally 1-2 L / min.

[0108] In some embodiments, the flow rates of the metal salt solution and the precipitant solution may be the same (ie, the pumping speeds of the first metering pump and the second metering pump may be the same), thereby helping to improve the consistency of the obtained manganese ferrocarbonate precursor particles.

[0109] In some embodiments, the volume of the autoclave reactor 3 may be smaller than that of the tubular reactor 4. The ferromanganese carbonate precursor particles reside in the tubular reactor for a longer time, thereby helping the obtained ferromanganese carbonate precursor particles to have a narrower particle size distribution, and also helping the obtained ferromanganese carbonate precursor particles to have a higher crystallinity and a more regular morphology.

[0110] In some embodiments, the volume ratio of the autoclave reactor 3 to the tubular reactor 4 may be 1:5-1:7. This helps to ensure that the obtained ferromanganese carbonate precursor particles have a smaller particle size and a narrower particle size distribution, while also helping to ensure that the obtained ferromanganese carbonate precursor particles have a higher crystallinity and a more regular morphology.

[0111] In some embodiments, the residence time of the ferromanganese carbonate precursor in the autoclave reactor 3 during the growth process can be 0.5-4 hours. The residence time of the ferromanganese carbonate precursor in the autoclave reactor during the growth process is inversely proportional to the flow rate of the metal salt solution and the flow rate of the precipitant solution, and is directly proportional to the volume of the autoclave reactor.

[0112] In some embodiments, the residence time of the ferromanganese carbonate precursor in the tubular reactor 4 during the growth process can be 2.5-28 hours. The residence time of the ferromanganese carbonate precursor in the tubular reactor during the growth process is inversely proportional to the flow rate of the metal salt solution and the flow rate of the precipitant solution, and is directly proportional to the volume of the tubular reactor.

[0113] In certain embodiments, during the reaction, pH regulating solution can be added into the kettle reactor 3 by the pH control device 14 connected to the kettle reactor 3, so that the pH of the first reaction solution in the kettle reactor 3 is 6-8, optionally 7-7.5. When the pH in the kettle reactor is within the above range, it is conducive to the rapid precipitation of metal ions and carbonate ions to form a large amount of crystal nuclei, and it is also conducive to reducing the precipitation rate difference of different metal ions during the precipitation reaction, thereby being conducive to uniform co-precipitation of metal ions. In addition, when the pH in the kettle reactor is within the above range, it is also conducive to forming a spherical (or spherical) morphology of the ferromanganese carbonate precursor, and then it is also conducive to improving the tap density.

[0114] In some embodiments, during the reaction process, a pH regulating liquid can be added to the tubular reactor 4 by a pH control device 14 connected to the tubular reactor 4 so that the pH of the second reaction liquid in the tubular reactor 4 is 6-8, optionally 7-7.5. When the pH of the second reaction liquid in the tubular reactor is within the above range, it is beneficial to reduce the difference in precipitation rates of different metal ions during the precipitation reaction, thereby facilitating uniform co-precipitation of metal ions. In addition, when the pH in the tubular reactor is within the above range, it is also beneficial to form a spherical (or spherical) morphology of a ferromanganese carbonate precursor, which is further beneficial to improving the tap density.

[0115] The pH adjusting solution may include an acid solution (eg, dilute sulfuric acid) or an alkaline solution (eg, aqueous ammonia).

[0116] During the reaction, the first dissolving kettle 1, the second dissolving kettle 2 and the kettle reactor 3 can all be kept in a stirring state, thereby reducing the aggregation growth of the manganese ferrocarbonate precursor particles and facilitating the acquisition of a manganese ferrocarbonate precursor with a narrow particle size distribution and high tap density.

[0117] In some embodiments, the stirring speed of the first dissolving kettle 1 can be 300-800 r / min. In some embodiments, the stirring speed of the second dissolving kettle 2 can be 300-800 r / min. In some embodiments, the stirring speed of the tank reactor 3 can be 300-800 r / min.

[0118] In some embodiments, no stirring device is provided in the tubular reactor 4. Thus, the reaction solution can flow in the form of plug flow, which is beneficial to the further growth of ferromanganese carbonate grains and the improvement of the crystallinity of ferromanganese carbonate grains, thereby facilitating the production of a ferromanganese carbonate precursor with high crystallinity and regular morphology.

[0119] In some embodiments, during the reaction process, the first dissolving material kettle 1, the second dissolving material kettle 2, the kettle reactor 3 and the tubular reactor 4 can all be under a protective gas atmosphere. In some embodiments, the protective gas can include nitrogen, an inert gas or a combination thereof. Alternatively, the inert gas includes helium, argon or a combination thereof.

[0120] In some embodiments, the metal salts required for preparing the manganese ferrocarbonate precursor may include water-soluble divalent iron salts, water-soluble divalent manganese salts, and optional divalent salts of water-soluble doping elements M, where M represents the doping elements at the manganese position and / or iron position of the manganese ferrocarbonate precursor, optionally including one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr.

[0121] In some embodiments, the water-soluble ferrous salt may include one or more of ferrous chloride, ferrous nitrate, ferrous sulfate, and ferrous acetate.

[0122] In some embodiments, the water-soluble divalent manganese salt may include one or more of manganous chloride, manganous nitrate, manganous sulfate, and manganous acetate.

[0123] In some embodiments, the divalent salt of the water-soluble dopant element M may include one or more of hydrochloride, nitrate, sulfate, and acetate of the dopant element M.

[0124] In some embodiments, the precipitant may include a carbonate, for example, may include one or more of ammonium bicarbonate, sodium bicarbonate, ammonium carbonate, and sodium carbonate.

[0125] In the preparation method of the ferromanganese carbonate precursor provided in the examples of the present application, unless otherwise specified, all raw materials can be directly purchased.

[0126] The present invention also provides a ferromanganese carbonate precursor prepared by the above-mentioned preparation method.

[0127] The ferromanganese carbonate precursor may have the chemical formula Fe x Mn y M 1-x-y CO3, 0<x<1, 0<y<1, 0≤1-xy<1, M represents the doping element at the manganese site and / or iron site of the manganese ferrocarbonate precursor.

[0128] Optionally, M includes one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr.

[0129] Optionally, 0.199≤x≤0.5.

[0130] Optionally, 0.499≤y≤0.8.

[0131] Optionally, 0<1-xy≤0.05.

[0132] The ferromanganese carbonate precursor provided in the embodiments of the present application is prepared by the above method, and therefore has the advantages of small particle size, narrow particle size distribution, high crystallinity, single crystal phase, uniform element distribution, and high batch consistency.

[0133] In some embodiments, the volume distribution particle sizes Dv90 and Dv50 of the manganese ferrocarbonate precursor satisfy 1<Dv90 / Dv50≤1.4.

[0134] The present invention also provides a method for preparing lithium manganese iron phosphate.

[0135] The method comprises at least the following steps: uniformly mixing the ferromanganese carbonate precursor prepared by the above preparation method or the above ferromanganese carbonate precursor with a lithium source, a phosphorus source, an optional source of doping element N, an optional source of doping element Q and an optional source of doping element R to obtain a mixed raw material, wherein N represents the doping element for the lithium site of lithium manganese iron phosphate, optionally including one or more of Zn, Al, Na, K, Mg, Nb, Mo and W; Q represents the doping element for the phosphorus site of lithium manganese iron phosphate, optionally including one or more of B, S, Si and N; R represents the doping element for the oxygen site of lithium manganese iron phosphate, optionally including one or more of S, F, Cl and Br; sintering the obtained mixed raw material to obtain lithium manganese iron phosphate. Lithium manganese iron phosphate has the chemical formula Li a N b Fe x Mn y M 1-x-y P 1-m Q m O 4-n R n , M represents the doping element of the manganese site and / or iron site of the lithium iron manganese phosphate, optionally including one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr; N represents the doping element of the lithium site of the lithium iron manganese phosphate, optionally including one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W; Q represents the doping element of the phosphorus site of the lithium iron manganese phosphate, optionally including one or more of B, S, Si, and N; R represents the doping element of the oxygen site of the lithium iron manganese phosphate, Optionally including one or more of S, F, Cl and Br; 0.9≤a≤1.1; 0≤b≤0.1, optionally, 0<b≤0.05; 0<x<1, optionally, 0.199≤x≤0.5; 0<y<1, optionally, 0.499≤y≤0.8; 0≤1-xy<1, optionally, 0<1-xy≤0.05; 0≤m≤0.1, optionally, 0<m≤0.05; 0≤n≤0.1, optionally, 0<n≤0.05.

[0136] The lithium manganese iron phosphate obtained by the preparation method provided in the embodiment of the present application can achieve a uniform mixing of lithium elements and multiple metal elements, thereby making the lithium ions diffuse faster and more easily embedded in the lithium manganese iron phosphate precursor, thereby enabling the prepared lithium manganese iron phosphate to have excellent electrochemical properties.

[0137] The lithium manganese iron phosphate obtained by the preparation method provided in the embodiments of the present application also has the advantages of small particle size, narrow particle size distribution, high crystallinity, single crystal phase, and high batch consistency, which is beneficial to improving the capacity and electrochemical performance of the battery, such as cycle performance and rate performance.

[0138] In some embodiments, a carbon source is further added to the mixed raw materials, thereby preparing carbon-coated lithium manganese iron phosphate.

[0139] In some embodiments, the carbon source comprises one or more of an organic carbon source and an inorganic carbon source, and optionally comprises a combination of one or more of glucose, sucrose, starch, fructose, polyvinyl alcohol, polyethylene glycol, and citric acid.

[0140] In some embodiments, the lithium source can be a lithium-containing compound known in the art that can be used to prepare phosphate positive active materials. For example, the lithium source can include one or more of lithium hydroxide, lithium carbonate, lithium dihydrogen phosphate, lithium hydrogen phosphate, lithium nitrate, and lithium acetate.

[0141] In some embodiments, the phosphorus source may be a phosphorus-containing compound known in the art for preparing phosphate positive active materials. For example, the phosphorus source may include one or more of phosphoric acid, ammonium monohydrogen phosphate, and ammonium dihydrogen phosphate.

[0142] In some embodiments, the source of the doping element N may include one or more of sulfate, nitrate, hydrochloride, and acetate of the doping element N.

[0143] In some embodiments, the source of the doping element Q may include one or more of sulfates, borates, nitrates, and silicates of the doping element Q.

[0144] In some embodiments, the source of the doping element R may include one or more of a simple substance of the doping element R and an ammonium salt.

[0145] In some embodiments, the sintering process may include a pre-sintering process and a high-temperature sintering process.

[0146] In some embodiments, the temperature of the pre-sintering process may be 350°C-550°C, optionally 400°C-500°C.

[0147] In some embodiments, the pre-sintering treatment time may be 2-12 hours, optionally 3-10 hours.

[0148] In some embodiments, the pre-sintering process can be performed under a protective gas atmosphere. In some embodiments, the protective gas can include nitrogen, an inert gas, or a combination thereof. Alternatively, the inert gas can include helium, argon, or a combination thereof.

[0149] In some embodiments, the temperature of the high-temperature sintering process may be 600°C-800°C, optionally 650°C-750°C.

[0150] In some embodiments, the high temperature sintering treatment time may be 5-24 hours, optionally 8-12 hours.

[0151] In some embodiments, the high temperature sintering process can be carried out under a protective gas atmosphere. In some embodiments, the protective gas can include nitrogen, an inert gas, or a combination thereof. Alternatively, the inert gas can include helium, argon, or a combination thereof.

[0152] In some embodiments, the pre-sintering process and the high temperature sintering process may be performed in a tube furnace.

[0153] The amount of each raw material added can conform to the stoichiometric ratio of the target product. In some embodiments, the amount of lithium source added can be slightly excessive, for example, 100%-110% of the theoretical mass of the lithium source, where the theoretical mass of the lithium source refers to the mass of the lithium source calculated based on the stoichiometric ratio of lithium iron manganese phosphate.

[0154] In the preparation method of lithium manganese iron phosphate provided in the embodiments of the present application, unless otherwise specified, all raw materials and instruments used can be directly purchased. Each raw material may contain or not contain water of crystallization.

[0155] The present application also provides a lithium manganese iron phosphate prepared by the above method.

[0156] The lithium manganese iron phosphate provided in the embodiments of the present application has the advantages of small particle size, narrow particle size distribution, high crystallinity, single crystal phase, uniform element distribution, and high batch consistency, which is beneficial to improving the capacity and electrochemical performance of the battery, such as cycle performance and rate performance.

[0157] In some embodiments, the surface of the lithium manganese iron phosphate is further coated with carbon, thereby improving the conductivity of the lithium manganese iron phosphate.

[0158] The embodiment of the present application also provides a positive electrode sheet.

[0159] The positive electrode sheet includes a positive electrode current collector and a positive electrode film disposed on at least one surface of the positive electrode current collector. For example, the positive electrode current collector has two surfaces that face each other in the thickness direction, and the positive electrode film is disposed on either or both of the two opposing surfaces of the positive electrode current collector.

[0160] The positive electrode film layer includes the above-mentioned lithium manganese iron phosphate or the lithium manganese iron phosphate prepared by the above-mentioned preparation method. Of course, the positive electrode film layer may also include other positive electrode active materials, for example, it may also include lithium transition metal oxides and the like. Examples of lithium transition metal oxides may include one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. The modified compound may be a doping modification and / or surface coating modification of the positive electrode active material.

[0161] In some embodiments, the positive electrode film layer may further optionally include a positive electrode conductive agent. The present application does not particularly limit the type of the positive electrode conductive agent. As examples, the positive electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0162] In some embodiments, the positive electrode film layer may further optionally include a positive electrode binder. This application does not particularly limit the type of positive electrode binder. As an example, the positive electrode binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic resin.

[0163] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, aluminum foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0164] The positive electrode film layer is typically formed by coating a positive electrode slurry onto a positive electrode current collector, drying it, and cold pressing it. The positive electrode slurry is typically formed by dispersing the positive electrode active material, an optional positive electrode conductive agent, an optional positive electrode binder, and any other components in a solvent and stirring them uniformly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP).

[0165] An embodiment of the present application also provides a battery.

[0166] The battery mentioned in the embodiments of the present application may be a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a battery cell, a battery module, or a battery pack.

[0167] A battery cell is the smallest unit of a battery that can independently realize the functions of charging and discharging. A battery cell can be cylindrical, rectangular, or in other shapes, and the embodiments of the present application are not limited thereto.

[0168] When there are multiple battery cells, the multiple battery cells are connected in series, in parallel, or in mixed series via a busbar. In some embodiments, the battery may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module. In some embodiments, the battery may be a battery pack, which includes a housing and battery cells, with the battery cells or battery modules housed in the housing. In some embodiments, the housing may serve as part of the vehicle's chassis structure. For example, a portion of the housing may form at least a portion of the vehicle's floor, or a portion of the housing may form at least a portion of the vehicle's crossbeam or longitudinal beam.

[0169] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0170] The battery cells mentioned in the embodiments of the present application include lithium-ion battery cells, lithium metal battery cells, negative electrode-free lithium metal battery cells, etc., which are not limited in the embodiments of the present application.

[0171] The battery cell includes an electrode assembly and an electrolyte. The electrode assembly can be a wound structure or a laminated structure, which is not limited in the present embodiment.

[0172] The battery cell also includes an outer packaging, which can be used to encapsulate the electrode assembly and electrolyte. The outer packaging can be a hard shell, such as a hard plastic shell, aluminum shell, steel shell, etc. The outer packaging can also be a soft package, such as a bag-type soft package. The soft package can be made of plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0173] The battery cell includes the above-mentioned positive electrode sheet. The battery cell also includes a negative electrode sheet. The structure and composition of the negative electrode sheet can be selected according to the type of battery cell, and the embodiments of the present application are not limited thereto.

[0174] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and comprising a negative electrode active material. For example, the negative electrode current collector may have two opposing surfaces in its thickness direction, and the negative electrode film layer may be disposed on either or both of the two opposing surfaces of the negative electrode current collector.

[0175] The negative electrode active material may be a material known in the art. As an example, the negative electrode active material may include, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloy materials. Tin-based materials may include one or more of elemental tin, tin oxide, and tin alloy materials. The present application is not limited to these materials, and other conventionally known materials that can be used as negative electrode active materials may also be used.

[0176] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. The present application does not particularly limit the type of the negative electrode conductive agent. For example, the negative electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0177] In some embodiments, the negative electrode film layer may further optionally include a negative electrode binder. The present application does not particularly limit the type of the negative electrode binder. As examples, the negative electrode binder may include one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0178] In some embodiments, the negative electrode film layer may further include other additives. For example, the other additives may include a thickener, such as sodium carboxymethyl cellulose (CMC), a PTC thermistor material, and the like.

[0179] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. As an example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).

[0180] The negative electrode film layer is typically formed by coating the negative electrode slurry onto the negative electrode current collector, drying it, and cold pressing it. The negative electrode slurry is typically formed by dispersing the negative electrode active material, optional negative electrode conductive agent, optional negative electrode binder, and other optional additives in a solvent and stirring them uniformly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0181] The negative electrode sheet does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode sheet may further include a conductive primer layer (e.g., composed of a conductive agent and a binder) disposed on the surface of the negative electrode current collector and sandwiched between the negative electrode current collector and the negative electrode film layer; in some embodiments, the negative electrode sheet may further include a protective layer covering the surface of the negative electrode film layer.

[0182] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a metal layer disposed on at least one surface of the negative electrode current collector. The metal layer may include one or more of lithium element and lithium alloy.

[0183] A lithium alloy may be an alloy of metallic lithium and other metallic elements or non-metallic elements. For example, the other metallic elements in the lithium alloy may include one or more of tin, zinc, aluminum, magnesium, silver, gold, gallium, indium, and platinum, and the non-metallic elements in the lithium alloy may include one or more of boron, carbon, and silicon.

[0184] In some embodiments, the negative electrode sheet may further include a negative electrode current collector but not a metal layer, thereby forming a negative electrode metal-free battery cell.

[0185] In some embodiments, the negative electrode sheet may also be directly made of a sheet (or foil) of lithium or a lithium alloy.

[0186] Battery cells include an electrolyte. The electrolyte conducts active ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte; it can be selected based on needs. For example, the electrolyte can include one or more of a solid electrolyte and a liquid electrolyte (i.e., an electrolyte solution).

[0187] In some embodiments, the electrolyte is an electrolyte solution including an electrolyte salt and a solvent.

[0188] As an example, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobisoxalatophosphate (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0189] The type of solvent is not specifically limited and can be selected according to actual needs. In some embodiments, as an example, the solvent can include ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and diethyl sulfone (ESE) One or more.

[0190] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, or additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature power performance.

[0191] Battery cells using liquid electrolytes, as well as some using solid electrolytes, also include a separator. This separator is placed between the positive and negative electrodes, primarily preventing short circuits between the positive and negative electrodes while allowing active ions to pass through. This application does not specifically limit the type of separator; any known porous separator with good chemical and mechanical stability can be used.

[0192] In some embodiments, the material of the isolation membrane can include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different.

[0193] The preparation method of battery cells is well known. In some embodiments, the positive electrode sheet, separator, negative electrode sheet and electrolyte can be assembled to form a battery cell. As an example, the positive electrode sheet, separator, and negative electrode sheet can be formed into an electrode assembly through a winding process and / or a lamination process. The electrode assembly is placed in an outer package, dried, and then injected with the above-mentioned electrolyte. After vacuum packaging, standing, formation, shaping and other processes, a battery cell is obtained. Multiple battery cells can also be further connected in series, in parallel or in mixed connection to form a battery module. Multiple battery modules can also be connected in series, in parallel or in mixed connection to form a battery pack. In some embodiments, multiple battery cells can also directly form a battery pack.

[0194] The present application also provides an electrical device, which includes the battery of the present application. The battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device can be, but is not limited to, a mobile device (such as a mobile phone, a tablet computer, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0195] The electrical device can select a specific type of battery, such as a battery cell, a battery module, or a battery pack, according to its usage requirements.

[0196] As an example, the electric device may be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements of the electric device for high power and high energy density, a battery pack or a battery module may be used as a power source.

[0197] As another example, an electric device may be a mobile phone, a tablet computer, a laptop computer, etc. Such an electric device is usually required to be lightweight and thin, and may use a battery cell as a power source.

[0198] Example

[0199] The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used directly without further processing, and all instruments used in the examples are commercially available.

[0200] Example 1

[0201] use Figure 1 The continuous reaction system shown is used to prepare the manganese ferrocarbonate precursor.

[0202] A 2 mol / L aqueous solution of manganous sulfate / ferrous sulfate (a molar ratio of manganese to iron of 6:4) was prepared in the first dissolving kettle, along with 3% of the complexing agent sodium ethylenediaminetetramethylenephosphate. A 2 mol / L aqueous solution of sodium carbonate was prepared in the second dissolving kettle. The aqueous solution of the metal salt and the aqueous solution of sodium carbonate were continuously fed concurrently from the first and second dissolving kettles into the reactor through two inlet pipes, each at a flow rate of 1 L / min. Both the first and second dissolving kettles were maintained under nitrogen flow and stirred at a speed of 400 rpm.

[0203] The kettle reactor is kept in a nitrogen-filled and stirred state with a stirring speed of 400 r / min. The reaction temperature in the kettle reactor is 55°C and the pH value is 7.5 (ammonia or dilute sulfuric acid can be added during the reaction to adjust the pH). In the kettle reactor, manganese-iron metal ions and carbonate ions quickly form manganese-iron carbonate precipitation and form a large number of crystals. After 2 hours of reaction, the liquid level of the kettle reactor is higher than the first overflow port, and the reaction liquid flows out of the first overflow port and enters the horizontal tubular reactor to continue the precipitation reaction. During the precipitation reaction, nitrogen is kept in the horizontal tubular reactor, and the reaction temperature in the horizontal tubular reactor is maintained at 55°C by controlling the external heat exchanger. The pH value of the reaction liquid is monitored by the pH control device of each pipeline area, and the pH value in the kettle reactor is kept at 7.5.

[0204] After reacting in the horizontal tubular reactor for 12 hours (i.e., the time from the time the reaction liquid enters the horizontal tubular reactor to the time it exits the horizontal tubular reactor), the reaction liquid flows out of the third discharge port. The resulting reaction liquid is filtered and washed multiple times through a filter press. The washed material is then transferred to a dryer and dried at 120°C for 6 hours to obtain a ferromanganese carbonate precursor.

[0205] Example 2

[0206] use Figure 1 The continuous reaction system shown is used to prepare the manganese ferrocarbonate precursor.

[0207] A 1 mol / L aqueous solution of manganous sulfate / ferrous sulfate (a molar ratio of manganese to iron of 6:4) was prepared in the first dissolving kettle, along with 3% sodium ethylenediaminetetraacetic acid (EDTA) as a chelating agent. A 1 mol / L aqueous solution of sodium bicarbonate was prepared in the second dissolving kettle. The aqueous solution of the metal salt and the aqueous solution of sodium carbonate were continuously fed concurrently from the first and second dissolving kettles into the reactor via two inlet pipes, each at a flow rate of 2 L / min. Both the first and second dissolving kettles were maintained under nitrogen flow and stirred at a speed of 600 rpm.

[0208] The kettle reactor is kept in a nitrogen-filled and stirred state with a stirring speed of 600 r / min. The reaction temperature in the kettle reactor is 60°C and the pH value is 7.5 (ammonia or dilute sulfuric acid can be added during the reaction to adjust the pH). In the kettle reactor, manganese-iron metal ions and carbonate ions quickly form manganese-iron carbonate precipitates and form a large number of crystals. After 1 hour of reaction, the liquid level of the kettle reactor is higher than the first overflow port, and the reaction liquid flows out of the first overflow port and enters the horizontal tubular reactor to continue the precipitation reaction. During the precipitation reaction, nitrogen is kept in the horizontal tubular reactor, and the reaction temperature in the horizontal tubular reactor is maintained at 60°C by controlling the external heat exchanger. The pH value of the reaction liquid is monitored by the pH controller in each pipeline area, and the pH value in the kettle reactor is kept at 7.5.

[0209] After reacting in the horizontal tubular reactor for 6 hours (i.e., the time from the time the reaction liquid enters the horizontal tubular reactor to the time it exits the horizontal tubular reactor), the reaction liquid flows out of the third discharge port. The resulting reaction liquid is filtered and washed multiple times through a filter press, and the washed material is then transferred to a dryer and dried at 120°C for 6 hours to obtain a ferromanganese carbonate precursor.

[0210] Example 3

[0211] use Figure 1 The continuous reaction system shown is used to prepare the manganese ferrocarbonate precursor.

[0212] A 1 mol / L manganese sulfate / ferrous sulfate mixed metal salt solution (with a molar ratio of manganese to iron of 7:3) was prepared in the first dissolving kettle, and 3 wt% of the complexing agent sodium gluconate was added. A 1 mol / L ammonium bicarbonate aqueous solution was prepared in the second dissolving kettle. The metal salt aqueous solution and sodium carbonate aqueous solution were continuously injected into the reactor from the first and second dissolving kettles in parallel through two liquid inlet pipes, with a flow rate of 1 L / min for each liquid inlet pipe. Both the first and second dissolving kettles were kept purged with nitrogen and stirred at a speed of 600 rpm.

[0213] The kettle reactor is kept in a nitrogen-filled and stirred state with a stirring speed of 600 r / min. The reaction temperature in the kettle reactor is 70°C and the pH value is 7.5 (ammonia or dilute sulfuric acid can be added during the reaction to adjust the pH). In the kettle reactor, manganese-iron metal ions and carbonate ions quickly form manganese-iron carbonate precipitates and form a large number of crystals. After 2 hours of reaction, the liquid level of the kettle reactor is higher than the first overflow port, and the reaction liquid flows out of the first overflow port and enters the horizontal tubular reactor to continue the precipitation reaction. During the precipitation reaction, nitrogen is kept in the horizontal tubular reactor, and the reaction temperature in the horizontal tubular reactor is maintained at 70°C by controlling the external heat exchanger. The pH value of the reaction liquid is monitored by the pH controller in each pipeline area, and the pH value in the kettle reactor is kept at 7.5.

[0214] After reacting in the horizontal tubular reactor for 12 hours (i.e., the time from the time the reaction liquid enters the horizontal tubular reactor to the time it exits the horizontal tubular reactor), the reaction liquid flows out of the third discharge port. The resulting reaction liquid is filtered and washed multiple times through a filter press. The washed material is then transferred to a dryer and dried at 120°C for 6 hours to obtain a ferromanganese carbonate precursor.

[0215] Example 4

[0216] use Figure 1 The continuous reaction system shown is used to prepare the manganese ferrocarbonate precursor.

[0217] A 0.5 mol / L manganese sulfate / ferrous sulfate mixed metal salt solution (with a molar ratio of manganese:iron:cobalt of 7:2.9:0.1) was prepared in a first dissolving kettle, and 3% wt of sodium citrate, a complexing agent, was added. A 0.5 mol / L ammonium bicarbonate aqueous solution was prepared in a second dissolving kettle. The metal salt aqueous solution and sodium carbonate aqueous solution were continuously injected into the reactor reactor from the first dissolving kettle and the second dissolving kettle in parallel through two liquid inlet pipes, with the flow rate of both liquid inlet pipes being 1 L / min. Both the first and second dissolving kettles were kept purged with nitrogen and stirred at a stirring speed of 700 r / min.

[0218] The kettle reactor is kept in a nitrogen-filled and stirred state with a stirring speed of 700 r / min. The reaction temperature in the kettle reactor is 70°C and the pH value is 7.5 (ammonia or dilute sulfuric acid can be added during the reaction to adjust the pH). In the kettle reactor, manganese-iron metal ions and carbonate ions quickly form manganese-iron carbonate precipitation and form a large number of crystals. After 2 hours of reaction, the liquid level of the kettle reactor is higher than the first overflow port, and the reaction liquid flows out of the first overflow port and enters the horizontal tubular reactor to continue the precipitation reaction. During the precipitation reaction, nitrogen is kept in the horizontal tubular reactor, and the reaction temperature in the horizontal tubular reactor is maintained at 70°C by controlling the external heat exchanger. The pH value of the reaction liquid is monitored by the pH controller in each pipeline area, and the pH value in the kettle reactor is kept at 7.5.

[0219] After reacting in the horizontal tubular reactor for 12 hours (i.e., the time from the time the reaction liquid enters the horizontal tubular reactor to the time it exits the horizontal tubular reactor), the reaction liquid flows out of the third discharge port. The resulting reaction liquid is filtered and washed multiple times through a filter press. The washed material is then transferred to a dryer and dried at 120°C for 6 hours to obtain a ferromanganese carbonate precursor.

[0220] Example 5

[0221] use Figure 1 The continuous reaction system shown is used to prepare the manganese ferrocarbonate precursor.

[0222] A 1 mol / L manganese sulfate / ferrous sulfate mixed metal salt solution (with a molar ratio of manganese to iron of 6:4) was prepared in a first dissolving kettle, and 3 wt% of a complexing agent, sodium ethylenediaminetetraacetate, was added. A 1.2 mol / L sodium bicarbonate aqueous solution was prepared in a second dissolving kettle. The metal salt aqueous solution and sodium carbonate aqueous solution were continuously injected into the reactor from the first dissolving kettle and the second dissolving kettle in parallel through two liquid inlet pipes, each with a flow rate of 2 L / min. Both the first and second dissolving kettles were kept purged with nitrogen and stirred at a speed of 600 r / min.

[0223] The kettle reactor is kept in a nitrogen-filled and stirred state with a stirring speed of 600 r / min. The reaction temperature in the kettle reactor is 60°C and the pH value is 7.5 (ammonia or dilute sulfuric acid can be added during the reaction to adjust the pH). In the kettle reactor, manganese-iron metal ions and carbonate ions quickly form manganese-iron carbonate precipitates and form a large number of crystals. After 1 hour of reaction, the liquid level of the kettle reactor is higher than the first overflow port, and the reaction liquid flows out of the first overflow port and enters the horizontal tubular reactor to continue the precipitation reaction. During the precipitation reaction, nitrogen is kept in the horizontal tubular reactor, and the reaction temperature in the horizontal tubular reactor is maintained at 60°C by controlling the external heat exchanger. The pH value of the reaction liquid is monitored by the pH controller in each pipeline area, and the pH value in the kettle reactor is kept at 7.5.

[0224] After reacting in the horizontal tubular reactor for 6 hours (i.e., the time from the time the reaction liquid enters the horizontal tubular reactor to the time it exits the horizontal tubular reactor), the reaction liquid flows out of the third discharge port. The resulting reaction liquid is filtered and washed multiple times through a filter press, and the washed material is then transferred to a dryer and dried at 120°C for 6 hours to obtain a ferromanganese carbonate precursor.

[0225] Example 6

[0226] use Figure 1 The continuous reaction system shown is used to prepare the manganese ferrocarbonate precursor.

[0227] A 2 mol / L aqueous solution of a mixed metal salt of manganous sulfate and ferrous sulfate (with a molar ratio of manganese to iron of 6:4) was prepared in the first dissolving kettle; a 2 mol / L aqueous solution of sodium carbonate was prepared in the second dissolving kettle. The aqueous solution of the metal salt and the aqueous solution of sodium carbonate were continuously injected into the reactor from the first dissolving kettle and the second dissolving kettle in parallel through two liquid inlet pipes, with a flow rate of 1 L / min for each liquid inlet pipe. Both the first and second dissolving kettles were kept purged with nitrogen and stirred at a speed of 400 r / min.

[0228] The kettle reactor is kept in a nitrogen-filled and stirred state with a stirring speed of 400 r / min. The reaction temperature in the kettle reactor is 55°C and the pH value is 7.5 (ammonia or dilute sulfuric acid can be added during the reaction to adjust the pH). In the kettle reactor, manganese-iron metal ions and carbonate ions quickly form manganese-iron carbonate precipitation and form a large number of crystals. After 2 hours of reaction, the liquid level of the kettle reactor is higher than the first overflow port, and the reaction liquid flows out of the first overflow port and enters the horizontal tubular reactor to continue the precipitation reaction. During the precipitation reaction, nitrogen is kept in the horizontal tubular reactor, and the reaction temperature in the horizontal tubular reactor is maintained at 55°C by controlling the external heat exchanger. The pH value of the reaction liquid is monitored by the pH control device of each pipeline area, and the pH value in the kettle reactor is kept at 7.5.

[0229] After reacting in the horizontal tubular reactor for 12 hours (i.e., the time from the time the reaction liquid enters the horizontal tubular reactor to the time it exits the horizontal tubular reactor), the reaction liquid flows out of the third discharge port. The resulting reaction liquid is filtered and washed multiple times through a filter press. The washed material is then transferred to a dryer and dried at 120°C for 6 hours to obtain a ferromanganese carbonate precursor.

[0230] Example 7

[0231] use Figure 1 The continuous reaction system shown is used to prepare the manganese ferrocarbonate precursor.

[0232] A 2 mol / L aqueous solution of manganous sulfate / ferrous sulfate (a molar ratio of manganese to iron of 6:4) was prepared in the first dissolving kettle, along with 3% of the complexing agent sodium ethylenediaminetetramethylenephosphate. A 2 mol / L aqueous solution of sodium carbonate was prepared in the second dissolving kettle. The aqueous solution of the metal salt and the aqueous solution of sodium carbonate were continuously fed concurrently from the first and second dissolving kettles into the reactor through two inlet pipes, each at a flow rate of 1 L / min. Both the first and second dissolving kettles were maintained under nitrogen flow and stirred at a speed of 400 rpm.

[0233] The kettle reactor is kept in a nitrogen-filled and stirred state with a stirring speed of 400 r / min. The reaction temperature in the kettle reactor is 55°C and the pH value is 7.5 (ammonia or dilute sulfuric acid can be added during the reaction to adjust the pH). In the kettle reactor, manganese-iron metal ions and carbonate ions quickly form manganese-iron carbonate precipitation and form a large number of crystals. After 2 hours of reaction, the liquid level of the kettle reactor is higher than the first overflow port, and the reaction liquid flows out of the first overflow port and enters the horizontal tubular reactor to continue the precipitation reaction. During the precipitation reaction, nitrogen is kept in the horizontal tubular reactor, and the reaction temperature in the horizontal tubular reactor is maintained at 55°C by controlling the external heat exchanger. The pH value of the reaction liquid is monitored by the pH control device of each pipeline area, and the pH value in the kettle reactor is kept at 7.5.

[0234] After reacting in the horizontal tubular reactor for 10 hours (i.e., the time from the time the reaction liquid enters the horizontal tubular reactor to the time it exits the horizontal tubular reactor), the reaction liquid flows out of the third discharge port. The resulting reaction liquid is filtered and washed multiple times through a filter press, and the washed material is then transferred to a dryer and dried at 120°C for 6 hours to obtain a ferromanganese carbonate precursor.

[0235] Example 8

[0236] use Figure 1 The continuous reaction system shown is used to prepare the manganese ferrocarbonate precursor.

[0237] A 2 mol / L aqueous solution of manganous sulfate / ferrous sulfate (a molar ratio of manganese to iron of 6:4) was prepared in the first dissolving kettle, along with 3% of the complexing agent sodium ethylenediaminetetramethylenephosphate. A 2 mol / L aqueous solution of sodium carbonate was prepared in the second dissolving kettle. The aqueous solution of the metal salt and the aqueous solution of sodium carbonate were continuously fed concurrently from the first and second dissolving kettles into the reactor through two inlet pipes, each at a flow rate of 1 L / min. Both the first and second dissolving kettles were maintained under nitrogen flow and stirred at a speed of 400 rpm.

[0238] The kettle reactor is kept in a nitrogen-filled and stirred state with a stirring speed of 400 r / min. The reaction temperature in the kettle reactor is 55°C and the pH value is 7.5 (ammonia or dilute sulfuric acid can be added during the reaction to adjust the pH). In the kettle reactor, manganese-iron metal ions and carbonate ions quickly form manganese-iron carbonate precipitation and form a large number of crystals. After 2 hours of reaction, the liquid level of the kettle reactor is higher than the first overflow port, and the reaction liquid flows out of the first overflow port and enters the horizontal tubular reactor to continue the precipitation reaction. During the precipitation reaction, nitrogen is kept in the horizontal tubular reactor, and the reaction temperature in the horizontal tubular reactor is maintained at 55°C by controlling the external heat exchanger. The pH value of the reaction liquid is monitored by the pH control device of each pipeline area, and the pH value in the kettle reactor is kept at 7.5.

[0239] After 14 hours of reaction in the horizontal tubular reactor (i.e., the time from the time the reaction liquid enters the horizontal tubular reactor to the time it exits the horizontal tubular reactor), the reaction liquid flows out of the third discharge port. The resulting reaction liquid is filtered and washed multiple times through a filter press. The washed material is then transferred to a dryer and dried at 120°C for 6 hours to obtain a ferromanganese carbonate precursor.

[0240] Example 9

[0241] use Figure 1 The continuous reaction system shown is used to prepare the manganese ferrocarbonate precursor.

[0242] A 2 mol / L aqueous solution of manganous sulfate / ferrous sulfate (a molar ratio of manganese to iron of 6:4) was prepared in the first dissolving kettle, along with 3% of the complexing agent sodium ethylenediaminetetramethylenephosphate. A 2 mol / L aqueous solution of sodium carbonate was prepared in the second dissolving kettle. The aqueous solution of the metal salt and the aqueous solution of sodium carbonate were continuously fed concurrently from the first and second dissolving kettles into the reactor through two inlet pipes, each at a flow rate of 1 L / min. Both the first and second dissolving kettles were maintained under nitrogen flow and stirred at a speed of 400 rpm.

[0243] The kettle reactor is kept in a nitrogen-filled and stirred state with a stirring speed of 400 r / min. The reaction temperature in the kettle reactor is 55°C and the pH value is 7.5 (ammonia or dilute sulfuric acid can be added during the reaction to adjust the pH). In the kettle reactor, manganese-iron metal ions and carbonate ions quickly form manganese-iron carbonate precipitation and form a large number of crystals. After 2 hours of reaction, the liquid level of the kettle reactor is higher than the first overflow port, and the reaction liquid flows out of the first overflow port and enters the horizontal tubular reactor to continue the precipitation reaction. During the precipitation reaction, nitrogen is kept in the horizontal tubular reactor, and the reaction temperature in the horizontal tubular reactor is maintained at 55°C by controlling the external heat exchanger. The pH value of the reaction liquid is monitored by the pH control device of each pipeline area, and the pH value in the kettle reactor is kept at 7.5.

[0244] After 16 hours of reaction in the horizontal tubular reactor (i.e., the time from the time the reaction liquid enters the horizontal tubular reactor to the time it exits the horizontal tubular reactor), the reaction liquid flows out of the third discharge port. The resulting reaction liquid is filtered and washed multiple times through a filter press. The washed material is then transferred to a dryer and dried at 120°C for 6 hours to obtain a ferromanganese carbonate precursor.

[0245] Example 10

[0246] use Figure 1 The continuous reaction system shown is used to prepare the manganese ferrocarbonate precursor.

[0247] A 2 mol / L aqueous solution of manganous sulfate / ferrous sulfate (a molar ratio of manganese to iron of 6:4) was prepared in the first dissolving kettle, along with 3% of the complexing agent sodium ethylenediaminetetramethylenephosphate. A 2 mol / L aqueous solution of sodium carbonate was prepared in the second dissolving kettle. The aqueous solution of the metal salt and the aqueous solution of sodium carbonate were continuously fed concurrently from the first and second dissolving kettles into the reactor through two inlet pipes, each at a flow rate of 1 L / min. Both the first and second dissolving kettles were maintained under nitrogen flow and stirred at a speed of 400 rpm.

[0248] The kettle reactor is kept in a nitrogen-filled and stirred state with a stirring speed of 400 r / min. The reaction temperature in the kettle reactor is 55°C and the pH value is 7.5 (ammonia or dilute sulfuric acid can be added during the reaction to adjust the pH). In the kettle reactor, manganese-iron metal ions and carbonate ions quickly form manganese-iron carbonate precipitation and form a large number of crystals. After 2 hours of reaction, the liquid level of the kettle reactor is higher than the first overflow port, and the reaction liquid flows out of the first overflow port and enters the horizontal tubular reactor to continue the precipitation reaction. During the precipitation reaction, nitrogen is kept in the horizontal tubular reactor, and the reaction temperature in the horizontal tubular reactor is maintained at 55°C by controlling the external heat exchanger. The pH value of the reaction liquid is monitored by the pH control device of each pipeline area, and the pH value in the kettle reactor is kept at 7.5.

[0249] After reacting in the horizontal tubular reactor for 8 hours (i.e., the time from the time the reaction liquid enters the horizontal tubular reactor to the time it exits the horizontal tubular reactor), the reaction liquid flows out of the third discharge port. The resulting reaction liquid is filtered and washed multiple times through a filter press. The washed material is then transferred to a dryer and dried at 120°C for 6 hours to obtain a ferromanganese carbonate precursor.

[0250] Comparative Example 1

[0251] A 2 mol / L solution of manganese sulfate / ferrous sulfate mixed metal salt (the molar ratio of manganese to iron is 6:4) and a 2 mol / L solution of sodium carbonate were prepared separately. The metal salt solution and the sodium carbonate solution were injected into the reactor simultaneously, and rapid stirring was started at 400 r / min. The reaction temperature in the reactor was 55°C and the reaction time was 14 hours. After the reaction, the slurry was discharged from the discharge port of the reactor, filtered and washed multiple times by a filter press, and then the washed material was transferred to a dryer and dried at 120°C for 6 hours to obtain a manganese ferrocarbonate precursor.

[0252] Test section

[0253] (1) Volume distribution particle size Dv50 and Dv90 test

[0254] The volume distribution particle size of the prepared ferromanganese carbonate precursor was measured using a Malvern Master Size 3000 laser particle size analyzer. Dv50 and Dv90 refer to the particle sizes corresponding to the 50% and 90% cumulative volume distribution percentages. The testing criteria can be found in GB / T 19077-2016.

[0255] (2) Mn / Fe molar ratio test

[0256] The contents of manganese and iron in the prepared ferromanganese carbonate precursor were measured using a Plasma 3000 inductively coupled plasma optical emission spectrometer (ICP-OES) and their molar ratios were calculated.

[0257] The contents of manganese and iron in the ferromanganese carbonate precursor are measured by ICP-OES using an inductively coupled plasma optical emission spectrometer, such as Plasma 3000, and their molar ratios are calculated.

[0258] (3) Tap density test

[0259] The tap density test method and steps can be referred to GB / T5162-2006. The test instrument can be Dandong Better BT-311 tap density tester.

[0260] Table 1

[0261]

[0262] Figure 2 The scanning electron microscope (SEM) image of the ferromanganese carbonate precursor prepared in Example 1 is shown. Figure 2 The magnification of a is 2000 times. Figure 2 The magnification of b is 5000 times.

[0263] Figure 3 The scanning electron microscope (SEM) image of the ferromanganese carbonate precursor prepared in Comparative Example 1 is shown. Figure 3 The magnification of a is 2000 times. Figure 3 The magnification of b is 5000 times.

[0264] Comprehensive test results in Table 1 and Figure 2 It can be seen that the ferromanganese carbonate precursor prepared by the continuous preparation method provided in the examples of the present application has the advantages of small particle size, narrow particle size distribution, regular morphology, etc.

[0265] Comprehensive test results in Table 1 and Figure 3 It can be seen that the ferromanganese carbonate precursor prepared by the existing intermittent preparation method has a large particle size and a wide particle size distribution.

[0266] Based on the test results of Example 1, Example 6, and Comparative Example 1, it can be seen that the Mn / Fe molar ratio in the ferromanganese carbonate precursor particles prepared by the continuous preparation method provided in the examples of the present application is less different from the Mn / Fe molar ratio in the metal salt solution, which is conducive to achieving precise control of the manganese and iron content. Based on the test results of Example 1, Example 6, and Comparative Example 1, it can also be seen that when a complexing agent is added to the first dissolving kettle, it is helpful to further accurately control the manganese and iron content in the prepared ferromanganese carbonate precursor particles.

[0267] Based on the test results of Example 1 and Examples 7-10, it can be seen that the particle size and particle size distribution of the obtained manganese ferrocarbonate precursor particles can be adjusted by adjusting the volume ratio of the autoclave reactor and the tubular reactor (ie, the reaction time ratio).

[0268] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A continuous reaction system for preparing a ferromanganese carbonate precursor, wherein: The continuous reaction system comprises a first dissolving kettle, a second dissolving kettle, a kettle reactor and a tubular reactor, wherein the kettle reactor and the tubular reactor are connected in series; The first dissolving kettle is used to contain the metal salt solution required for preparing the ferromanganese carbonate precursor, and the second dissolving kettle is used to contain the precipitant solution required for preparing the ferromanganese carbonate precursor. The first dissolving kettle has a first discharge port, and the second dissolving kettle has a second discharge port. The tank reactor has a first feed port and a first overflow port. The first feed port of the tank reactor is connected to the first dissolving tank and the second dissolving tank through a first pipe and a second pipe, respectively, so that the tank reactor can accommodate the metal salt solution and the precipitant solution and mix them to produce a precipitation reaction to generate a first reaction liquid. The first pipe is provided with a first stop valve and a first metering pump to adjust the flow rate of the metal salt solution. The second pipe is provided with a second stop valve and a second metering pump to adjust the flow rate of the precipitant solution. The tank reactor is also connected to a pH control device to monitor and adjust the pH value of the first reaction liquid. The tubular reactor has a second feed port and a third discharge port. The second feed port of the tubular reactor is connected to the first overflow port of the tank reactor through a third pipe, so that the tubular reactor can accommodate the first reaction liquid from the tank reactor and allow it to continue to precipitate to form a second reaction liquid. The third discharge port of the tubular reactor is used to allow the second reaction liquid to flow out. The tubular reactor is also connected to one or more pH control devices to monitor and adjust the pH value of the second reaction liquid.

2. The continuous reaction system according to claim 1, wherein The tubular reactor is a horizontal tubular reactor.

3. A method for preparing a ferromanganese carbonate precursor by the continuous reaction system according to claim 1 or 2, comprising at least the following steps: A tank reactor and a tubular reactor are connected in series, wherein the tank reactor has a first feed port and a first overflow port, the first feed port of the tank reactor is communicated with the first dissolving kettle and the second dissolving kettle through a first pipeline and a second pipeline respectively, the first pipeline is provided with a first stop valve and a first metering pump, the second pipeline is provided with a second stop valve and a second metering pump, the tank reactor is also connected to a pH control device, the first dissolving kettle has a first discharge port, the second dissolving kettle has a second discharge port, the tubular reactor has a second feed port and a third discharge port, the second feed port of the tubular reactor is communicated with the first overflow port of the tank reactor through a third pipeline, and the tubular reactor is also connected to one or more pH control devices; Adding the metal salt solution required for preparing the ferromanganese carbonate precursor to the first dissolving kettle, and adding the precipitant solution required for preparing the ferromanganese carbonate precursor to the second dissolving kettle; The metal salt solution in the first dissolving kettle and the precipitant solution in the second dissolving kettle are respectively transported to the kettle reactor through the first pipe and the second pipe so that they are mixed and a precipitation reaction occurs to generate a first reaction liquid; when the liquid level of the first reaction liquid is higher than the first overflow port of the kettle reactor, the first reaction liquid is transported to the tubular reactor, and then the first reaction liquid continues to precipitate in the tubular reactor to form a second reaction liquid, and the second reaction liquid flows out through the third discharge port of the tubular reactor; The second reaction liquid obtained from the third discharge port of the tubular reactor is washed and dried to obtain a manganese ferrocarbonate precursor.

4. The method according to claim 3, wherein: A complexing agent is also added into the first dissolving kettle.

5. The method according to claim 4, wherein The complexing agent includes one or more of aminocarboxylates, hydroxycarboxylates and organic phosphonates.

6. The method according to claim 5, wherein: The complexing agent includes one or more of sodium ethylenediaminetetramethylenephosphate, sodium ethylenediaminetetraacetate, sodium gluconate, and sodium citrate.

7. The method according to claim 3, wherein: The reaction temperature in the tank reactor is less than or equal to the reaction temperature in the tubular reactor.

8. The method according to claim 7, wherein: The reaction temperature in the tank reactor is 50-80°C; and / or, The reaction temperature in the tubular reactor is 50-80°C.

9. The method according to claim 3, wherein: The volume of the tank reactor is smaller than that of the tubular reactor.

10. The method according to claim 9, wherein: The volume ratio of the tank reactor to the tubular reactor is 1:5-1:

7.

11. The method according to claim 3, wherein: The residence time of the ferromanganese carbonate precursor in the autoclave reactor during the growth process is 0.5-4h; and / or, The residence time of the ferromanganese carbonate precursor in the tubular reactor during the growth process is 2.5-28 hours.

12. The method according to claim 3, wherein: The concentration of the metal salt solution is 0.5-2 mol / L; and / or, The concentration of the precipitant solution is 0.5-2 mol / L; and / or, The molar ratio of the metal salt to the precipitant is 1:1-1:2; and / or, The flow rate of the metal salt solution is 0.5-4 L / min; and / or, The flow rate of the precipitant solution is 0.5-4 L / min; and / or, The flow rates of the metal salt solution and the precipitant solution are the same.

13. The method according to any one of claims 3 to 12, wherein: The method further comprises the steps of: During the reaction, a pH regulating liquid is added to the tank reactor through a pH control device connected to the tank reactor to adjust the pH of the first reaction liquid in the tank reactor to 6-8; and / or, During the reaction, a pH regulating liquid is added into the tubular reactor through a pH control device connected to the tubular reactor, so that the pH of the second reaction liquid in the tubular reactor is 6-8.

14. The method according to claim 13, wherein The method further comprises the steps of: During the reaction, a pH regulating liquid is added to the tank reactor through a pH control device connected to the tank reactor to adjust the pH of the first reaction liquid in the tank reactor to 7-7.5; and / or, During the reaction, a pH regulating liquid is added into the tubular reactor through a pH control device connected to the tubular reactor, so that the pH of the second reaction liquid in the tubular reactor is 7-7.

5.

15. The method according to claim 3, wherein During the reaction, the first dissolving kettle, the second dissolving kettle, the kettle reactor and the tubular reactor are all placed under a protective gas atmosphere; and / or, During the reaction process, the first dissolving kettle, the second dissolving kettle and the tank reactor are all kept in a stirring state.

16. The method according to claim 15, wherein The stirring speed of the first dissolving kettle is 300-800 r / min; and / or, The stirring speed of the second dissolving kettle is 300-800 r / min; and / or, The stirring speed of the tank reactor is 300-800 r / min.

17. The method according to claim 3, wherein: The metal salts required for preparing the ferromanganese carbonate precursor include water-soluble divalent iron salts, water-soluble divalent manganese salts and optional divalent salts of water-soluble doping elements M, where M represents the doping elements at the manganese and / or iron sites of the ferromanganese carbonate precursor.

18. The method according to claim 17, wherein M includes one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr.

19. The method according to claim 17, wherein The water-soluble divalent iron salt includes one or more of ferrous chloride, ferrous nitrate, ferrous sulfate, and ferrous acetate; and / or, The water-soluble divalent manganese salt includes one or more of manganous chloride, manganous nitrate, manganous sulfate, and manganous acetate; and / or, The divalent salt of the water-soluble doping element M includes one or more of hydrochloride, nitrate, sulfate, and acetate of the doping element M.

20. The method according to claim 3, wherein The precipitating agent includes a carbonate.

21. The method according to claim 20, wherein The precipitant includes one or more of ammonium bicarbonate, sodium bicarbonate, ammonium carbonate and sodium carbonate.

22. The method according to claim 15, wherein The protective gas includes nitrogen, an inert gas or a combination thereof.

23. A ferromanganese carbonate precursor prepared by the method according to any one of claims 3 to 22, having a chemical formula of Fe x Mn y M 1-x-y CO3, 0＜x＜1； 0＜y＜1； 0≤1-xy<1; M represents a doping element at the manganese site and / or iron site of the ferromanganese carbonate precursor.

24. The ferromanganese carbonate precursor according to claim 23, wherein 0.199≤x≤0.5。 25. The ferromanganese carbonate precursor according to claim 23, wherein 0.499≤y≤0.8。 26. The ferromanganese carbonate precursor according to claim 23, wherein 0<1-xy≤0.

05.

27. The ferromanganese carbonate precursor according to claim 23, wherein M includes one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr.

28. The ferromanganese carbonate precursor according to any one of claims 23 to 27, wherein: The volume distribution particle sizes Dv90 and Dv50 of the manganese ferrocarbonate precursor satisfy 1<Dv90 / Dv50≤1.

4.

29. A method for preparing lithium manganese iron phosphate, comprising at least the following steps: The ferromanganese carbonate precursor prepared by the method according to any one of claims 3 to 22 or the ferromanganese carbonate precursor according to any one of claims 23 to 28 is uniformly mixed with a lithium source, a phosphorus source, an optional source of a doping element N, an optional source of a doping element Q, and an optional source of a doping element R to obtain a mixed raw material. The obtained mixed raw materials are sintered to obtain the lithium manganese iron phosphate. in, The lithium manganese iron phosphate has the chemical formula Li a N b Fe x Mn y M 1-x-y P 1-m Q m O 4-n R n , M represents a doping element at the manganese site and / or iron site of the lithium manganese iron phosphate; N represents a doping element for the lithium site of the lithium iron manganese phosphate; Q represents the doping element at the phosphorus position of the lithium manganese iron phosphate; R represents the doping element of the oxygen site of the lithium manganese iron phosphate; 0.9≤a≤1.1； 0≤b≤0.1； 0＜x＜1； 0＜y＜1； 0≤1-xy<1; 0≤m≤0.1； 0≤n≤0.1。 30. The method according to claim 29, wherein N includes one or more of Zn, Al, Na, K, Mg, Nb, Mo and W; Q includes one or more of B, S, Si and N; R includes one or more of S, F, Cl and Br; M includes one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr.

31. The method according to claim 29, wherein 0＜b≤0.05。 32. The method of claim 29, wherein: 0.199≤x≤0.5。 33. The method of claim 29, wherein: 0.499≤y≤0.8。 34. The method of claim 29, wherein: 0<1-xy≤0.

05.

35. The method of claim 29, wherein: 0＜m≤0.05。 36. The method of claim 29, wherein: 0＜n≤0.05。 37. The method of claim 29, wherein: A carbon source is also added to the mixed raw material.

38. Lithium manganese iron phosphate prepared by the method according to any one of claims 29 to 37.

39. A positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein: The positive electrode film layer includes lithium manganese iron phosphate prepared by the method according to any one of claims 29 to 37 or the lithium manganese iron phosphate according to claim 38.

40. A battery comprising the positive electrode sheet according to claim 39.

Images