Ferromanganese hydrogen phosphate and preparation method thereof, positive active material, positive pole piece, battery monomer, battery device and power utilization device

Abstract

The invention relates to ferromanganese hydrogen phosphate and a preparation method thereof, a positive active material, a positive pole piece, a battery monomer, a battery device and a power utilization device, the preparation method comprises the following steps: mixing a manganese source and a first acid solution to react until the pH value of the mixed solution is 1.5-5 to obtain a manganese salt solution; an iron source and a second acid solution are mixed and react until the pH value of the mixed solution is 1.5-5, and an iron salt solution is obtained; mixing the manganese salt solution and the ferric salt solution, and carrying out coprecipitation treatment to obtain slurry containing ferromanganese hydrogen phosphate; carrying out post-treatment on the slurry containing the ferromanganese hydrogen phosphate to obtain the ferromanganese hydrogen phosphate; wherein one of the first acidic solution and the second acidic solution comprises organic acid, and the other one comprises phosphoric acid. According to the preparation method disclosed by the invention, the content of impurity ions in the ferromanganese hydrogen phosphate can be reduced, and the purity of the ferromanganese hydrogen phosphate is improved.

Description

Technical Field

[0001] This disclosure relates to the field of batteries, and in particular to a manganese iron hydrogen phosphate and its preparation method, positive electrode active material, positive electrode sheet, battery cell, battery device, and power consumption device. Background Technology

[0002] As the application range of battery cells becomes increasingly wide, the performance requirements of these cells in various environments are becoming more stringent. The positive electrode active material, as a crucial component of the battery cell, is vital to its performance. Positive electrode active materials can be prepared using manganese-iron phosphate precursors, but currently, the purity of manganese-iron phosphate is relatively low. Summary of the Invention

[0003] This disclosure provides a method for preparing ferromanganese hydrogen phosphate, a positive electrode active material, a positive electrode sheet, a battery cell, a battery device, and an electrical device, which can reduce the impurity content in ferromanganese hydrogen phosphate and improve its purity.

[0004] In a first aspect, this disclosure provides a method for preparing ferromanganese hydrogen phosphate, comprising: mixing a manganese source and a first acidic solution and reacting them until the pH of the mixture is 1.5-5 to obtain a manganese salt solution; mixing an iron source and a second acidic solution and reacting them until the pH of the mixture is 1.5-5 to obtain an iron salt solution; mixing the manganese salt solution and the iron salt solution and performing a co-precipitation treatment to obtain a slurry containing ferromanganese hydrogen phosphate; and post-treating the slurry containing ferromanganese hydrogen phosphate to obtain ferromanganese hydrogen phosphate; wherein one of the first acidic solution and the second acidic solution comprises an organic acid and the other comprises phosphoric acid.

[0005] This embodiment of the invention reduces the oxidation and blackening of manganese ions in the manganese salt solution by mixing a manganese source and a first acidic solution until the pH of the mixture is 1.5-5, thus ensuring the stable presence of manganese ions in the manganese salt solution. Similarly, mixing an iron source and a second acidic solution until the pH of the mixture is 1.5-5 reduces the oxidation of ferrous ions, ensuring the stable presence of ferrous ions in the second acidic solution. One of the first and second acidic solutions contains an organic acid, and the other contains phosphoric acid. The organic acid not only promotes the dissolution of the manganese and iron sources but also further lowers the pH of the mixture. The phosphoric acid provides a phosphorus source for ferromanganese hydrogen phosphate while simultaneously dissolving the manganese and iron sources. The preparation process of ferromanganese hydrogen phosphate involves a reaction between liquid-phase ions, resulting in a more uniform distribution of manganese, iron, and phosphorus elements and high crystallinity of the precursor. This makes it a suitable precursor for battery-grade positive electrode active materials, and it can be used as a precursor for lithium manganese iron phosphate positive electrode active materials.

[0006] In some embodiments, in the step of mixing manganese salt solution and iron salt solution for co-precipitation treatment to obtain a slurry containing ferromanganese hydrogen phosphate, the pH value of the slurry containing ferromanganese hydrogen phosphate is 1.5-5. By setting the pH of the slurry containing ferromanganese hydrogen phosphate within the above range, the oxidation degree of ferrous and manganese ions in the solution can be reduced, further improving the yield of ferromanganese hydrogen phosphate.

[0007] In some embodiments, the pH of the manganese salt solution is 1.5-3.5.

[0008] In some embodiments, the pH of the iron salt solution is 1.5-3.5.

[0009] In some embodiments, the pH of the slurry containing ferric manganese hydrogen phosphate is 1.5-3.5.

[0010] By setting the pH of the manganese salt solution, iron salt solution, or slurry containing manganese ferrophosphate within the above range, the oxidation degree of ferrous and manganese ions in the solution can be further reduced, allowing ferrous and manganese ions to exist stably in the solution. The ratio of manganese, iron, and phosphorus in the obtained precursor can also be adjusted to be close to the element ratio required for lithium manganese ferrophosphate cathode active material. The obtained manganese ferrophosphate has good crystallinity, and the yield can meet the needs of industrial production.

[0011] In some embodiments, the organic acid includes one or more of formic acid, acetic acid, benzoic acid, tartaric acid, oxalic acid, and citric acid.

[0012] By selecting organic acids within the aforementioned range, the pH of manganese salt solutions, iron salt solutions, or slurries containing ferromanganese hydrogen phosphate can be further reduced while minimizing the excess of phosphoric acid. This reduces side reactions and further increases the yield of ferromanganese hydrogen phosphate. Simultaneously, the molar ratio of phosphoric acid to total metals in the raw materials can be adjusted to prevent excessive excess, thus reducing waste of phosphoric acid and other raw materials.

[0013] In some embodiments, in the step of mixing a manganese source and a first acidic solution until the pH of the mixture is 1.5-5 to obtain a manganese salt solution, the manganese source includes one or more of elemental manganese, manganese sulfide, manganese trioxide, manganese tetroxide, manganese dioxide, manganese hydroxide, manganese acetate, manganese phosphate, and manganese carbonate.

[0014] In some embodiments, in the step of mixing the iron source and the second acidic solution until the pH of the mixture is 1.5-5 to obtain an iron salt solution, the iron source includes one or more of elemental iron, ferrous oxide, ferric oxide, ferric tetroxide, ferrous hydroxide, ferric hydroxide, ferrous acetate, ferrous phosphate, and ferrous carbonate.

[0015] By using the aforementioned manganese or iron source, the amount of impurity ions introduced can be reduced, further increasing the yield of manganese ferric phosphate. The reaction solution after the reaction can also be reused as a first acidic solution or a second acidic solution, thereby reducing waste liquid discharge and making the reaction process more green and environmentally friendly.

[0016] In some embodiments, the step of mixing the manganese source and the first acidic solution until the pH of the mixture is 1.5-5 to obtain a manganese salt solution further includes filtering the manganese salt solution to obtain a filtered manganese salt solution.

[0017] In some embodiments, the step of mixing the iron source and the second acidic solution until the pH of the mixture is 1.5-5 to obtain an iron salt solution further includes filtering the iron salt solution to obtain a filtered iron salt solution.

[0018] Filtration can remove insoluble impurities from the mixture, further reducing the impurity content in ferromanganese hydrogen phosphate, increasing the purity of the manganese salt solution and iron salt solution, and thus improving the purity of ferromanganese hydrogen phosphate.

[0019] In some embodiments, the step of mixing manganese salt solution and iron salt solution for co-precipitation treatment to obtain a slurry containing ferromanganese hydrogen phosphate includes: stirring the slurry containing ferromanganese hydrogen phosphate; optionally, the stirring temperature is 25-85°C, and the stirring time is 0.5-9.5 h. Stirring the mixture of manganese salt solution and iron salt solution can promote the precipitation of ferromanganese hydrogen phosphate. By controlling the stirring temperature and stirring time within the above ranges, the precipitation of ferromanganese hydrogen phosphate in the slurry can be further promoted, and the particle size of the ferromanganese hydrogen phosphate particles can be further adjusted.

[0020] In some embodiments, in the step of mixing the manganese source and the first acidic solution until the pH of the mixture is 1.5-5 to obtain a manganese salt solution, the molar concentration of manganese ions in the manganese salt solution is 0.1-1 mol / L.

[0021] In some embodiments, in the step of mixing the iron source and the second acidic solution until the pH of the mixture is 1.5-5 to obtain an iron salt solution, the molar concentration of ferrous ions in the iron salt solution is 0.1-1 mol / L.

[0022] By setting the molar concentration of manganese ions or ferrous ions within the above range, the pH value of the metal salt solution obtained from the reaction can be lower, reducing the oxidation of metal ions by air. This ensures that the metal salt ions remain divalent during the subsequent preparation of manganese ferric phosphate, and also allows for adjustment of the particle size of manganese ferric phosphate.

[0023] In some embodiments, the molar ratio of manganese ions to ferrous ions is (0.55-0.85):(0.15-0.45).

[0024] By setting the molar ratio of manganese ions to ferrous ions within the above range, the molar ratio of Mn and Fe in the obtained precursor can be adjusted, thereby adjusting the molar ratio of Mn and Fe in the final lithium manganese iron phosphate cathode active material.

[0025] In some embodiments, the ratio of the sum of the amounts of manganese ions and ferrous ions to the amount of phosphoric acid is 1:(1.00-1.50).

[0026] By setting the ratio of the sum of the amounts of manganese ions and ferrous ions to the amount of phosphoric acid within the above range, the molar ratio of the sum of the amounts of Mn and Fe to P in the obtained precursor can be adjusted, thereby adjusting the molar ratio of the sum of the amounts of Mn and Fe to P in the final obtained lithium manganese iron phosphate cathode active material.

[0027] In some embodiments, the step of post-processing the slurry containing ferromanganese hydrogen phosphate to obtain ferromanganese hydrogen phosphate includes filtering, washing, and drying the slurry; optionally, the drying temperature is 60-180°C, and the drying time is 1-9 hours. Drying can remove moisture from the precursor.

[0028] In some embodiments, the yield of ferromanganese hydrogen phosphate is greater than 90%.

[0029] Secondly, embodiments of this disclosure provide a manganese-iron hydrogen phosphate, which is prepared by the preparation method of the first aspect of this disclosure.

[0030] In some embodiments, the volumetric particle size distribution Dv50 of manganese phosphate is 5-20 μm.

[0031] In some embodiments, the specific surface area of ​​ferromanganese hydrogen phosphate is 3-12 g / m². 2 .

[0032] In some embodiments, the tap density of ferromanganese hydrogen phosphate is 1.8-2.6 g / mL. 3 .

[0033] By setting the volumetric particle size distribution Dv50 and / or specific surface area of ​​ferromanganese hydrogen phosphate within the above-mentioned range, the compaction density of the lithium iron manganese phosphate cathode active material prepared therefrom can be improved, thereby increasing the energy density of the cathode active material.

[0034] In some embodiments, SO4 in manganese ferric hydrogen phosphate 2- The content is less than 500 ppm.

[0035] In some embodiments, Na in manganese ferric hydrogen phosphate + The content is less than 500 ppm.

[0036] When the impurity content in the precursor is within the above range, the adverse effects of impurities on the lithium manganese iron phosphate cathode active material can be reduced, thereby improving the electrochemical performance of the lithium manganese iron phosphate cathode active material.

[0037] Thirdly, this disclosure provides a positive electrode active material prepared by the ferric manganese hydrogen phosphate precursor of the second aspect of this disclosure.

[0038] Fourthly, this disclosure provides a positive electrode sheet, which includes the positive electrode active material of the third aspect of this disclosure.

[0039] Fifthly, this disclosure provides a battery cell, which includes the positive electrode sheet of the fourth aspect of this disclosure.

[0040] In a sixth aspect, this disclosure provides a battery device including a battery cell according to the fifth aspect of this disclosure.

[0041] In a seventh aspect, this disclosure provides an electrical device, including the battery device of the sixth aspect of this disclosure. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are merely some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the drawings without any creative effort.

[0043] Figure 1 This is a schematic diagram of one embodiment of the battery cell disclosed herein.

[0044] Figure 2 This is a schematic diagram of one embodiment of an electrical device that uses a battery as a power source, incorporating the present disclosure.

[0045] Figure 3 This is a scanning electron microscope image of the manganese iron hydrogen phosphate prepared in Example 1 of this disclosure.

[0046] Figure 4 The X-ray diffraction pattern is shown for the manganese iron hydrogen phosphate prepared in Example 1 of this disclosure.

[0047] The attached figures may not be drawn to scale. The reference numerals are explained as follows: 5. Battery cell. Detailed Implementation

[0048] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the present disclosure, including ferromanganese hydrogen phosphate, its preparation method, positive electrode active material, positive electrode sheet, battery cell, battery device, and power consumption device. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for a full understanding of the present disclosure by those skilled in the art and are not intended to limit the subject matter of the claims.

[0049] The "range" disclosed in this disclosure is defined by a lower limit and an upper limit, whereby a given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this disclosure, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0050] Unless otherwise specified, all embodiments and optional embodiments of this disclosure may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the content of this disclosure.

[0051] Unless otherwise specified, all technical features and optional technical features of this disclosure can be combined to form new technical solutions, and such technical solutions should be considered as included in the content of this disclosure.

[0052] Unless otherwise specified, all steps in this disclosure 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 it may include steps (b) and (a) performed sequentially. For example, the method may also 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 it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0053] In this disclosure, the terms "multiple" or "a variety" refer to two or more kinds.

[0054] Unless otherwise stated, the test temperature for all parameters mentioned in this disclosure is 25°C.

[0055] The battery apparatus mentioned in the embodiments of this disclosure may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0056] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells. As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form a single module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0057] In some embodiments, the battery device may be a battery pack, which may include a housing and one or more individual battery cell assemblies housed within the housing. As an example, the individual battery cell assembly may be a battery module, which can be housed within the housing by securing the battery module to the housing. Alternatively, as an example, the individual battery cell assembly may be housed within the housing by directly securing multiple individual battery cells to the housing.

[0058] A single battery cell is the smallest unit that makes up a battery device, and it can independently perform the functions of charging and discharging. A single battery cell can be cylindrical, cuboid, or other shapes, and the embodiments disclosed herein are not limited to this. Figure 1 The example shown is a rectangular battery cell 5.

[0059] In this embodiment of the disclosure, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0060] The battery cells provided in the embodiments of this disclosure include lithium-ion battery cells, lithium metal battery cells, and negative electrode-free lithium metal battery cells, etc., and the embodiments of this disclosure are not limited to these.

[0061] A negative electrode-free lithium metal battery cell typically refers to a battery cell in which a negative electrode film layer is not actively formed on the negative electrode side during the battery cell manufacturing process. For example, a negative electrode film layer of carbonaceous active material is not formed at the negative electrode through processes such as coating or deposition during the battery cell manufacturing process. During the first charge, ions gain electrons on the negative electrode side and deposit on the surface of the negative electrode current collector to form a metallic phase. During discharge, the metal can be converted into metal ions and return to the positive electrode, achieving cyclic charging and discharging. Compared with other battery cells, a negative electrode-free lithium metal battery cell can achieve a higher energy density because it lacks a negative electrode film layer. In some embodiments, to improve the performance of the battery cell, some conventional materials that can be used as negative electrode active materials, such as carbon materials, can also be placed on the negative electrode side of the negative electrode-free lithium metal battery cell. Although these materials have a certain capacity, because their content is small and they are not used as the main negative electrode active material in the battery cell, the battery cell constructed in this way can still be regarded as a negative electrode-free lithium metal battery cell.

[0062] The CB value of a cathodeless lithium metal battery cell is typically very small; for example, in some embodiments, the CB value of a cathodeless lithium metal battery cell can be less than or equal to 0.1. The CB value is the capacity per unit area of ​​the negative electrode divided by the capacity per unit area of ​​the positive electrode in the battery cell. Because a cathodeless lithium metal battery cell contains little or no negative electrode active material, the capacity per unit area of ​​the negative electrode is small, resulting in a very small CB value, typically less than or equal to 0.1.

[0063] Taking a single lithium metal battery cell without a negative electrode as an example, the negative electrode sheet may include a negative current collector but does not include a lithium metal layer. During the charge and discharge cycle of a single lithium metal battery cell without a negative electrode, lithium from the positive electrode will be deposited and stripped off in the form of lithium metal on the negative electrode side.

[0064] A single battery cell includes an electrode assembly and an electrolyte. The electrode assembly can be a wound structure or a stacked structure, and the embodiments disclosed herein are not limited to this.

[0065] In some embodiments, the electrode assembly is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0066] In some embodiments, the electrode assembly has a stacked structure.

[0067] As an example, multiple positive and negative electrode sheets can be set, with multiple positive and multiple negative electrode sheets stacked alternately. As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0068] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0069] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0070] As an example, the separator can be continuously installed between any adjacent positive or negative electrode plates by folding or rolling.

[0071] In some embodiments, the electrode assembly may be cylindrical, flat, or polygonal, etc.

[0072] In some embodiments, the electrode assembly has tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0073] The battery cell also includes an outer packaging, which encapsulates the electrode components and electrolyte. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. It can also be a flexible package, such as a pouch. The material of the flexible package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0074] In some embodiments, the number of electrode components contained in a single battery cell can be one or more, and can be adjusted as needed.

[0075] In some embodiments, individual battery cells can be assembled into a battery module, and the number of individual battery cells contained in the battery module can be multiple, the specific number of which can be adjusted according to the application and capacity of the battery module.

[0076] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0077] The battery device mentioned in the embodiments of this disclosure can be a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery device mentioned in this disclosure can include battery cells, battery modules, or battery packs.

[0078] Lithium manganese iron phosphate (LMP) cathode active materials have become one of the most popular cathode active materials due to their advantages such as high capacity, good safety performance, and abundant raw material sources. The precursors for LMP cathode active materials include phosphate precursors. In related technologies, both the iron and manganese sources are solids in the preparation of ferromanganese hydrogen phosphate, and the reaction product, ferromanganese hydrogen phosphate, is also a solid. This product easily coats the surface of the iron or manganese source, hindering further reaction. Reacting strong metal acid salts with phosphates, such as metal sulfates with sodium dihydrogen phosphate, to prepare ferromanganese hydrogen phosphate results in products with high impurity content. Furthermore, directly reacting the manganese and iron sources with phosphoric acid in a stoichiometric ratio of ferromanganese hydrogen phosphate can lead to insufficient acidity in the later stages of the phosphoric acid reaction, preventing the complete reaction of the manganese and iron sources.

[0079] This disclosure provides a method for preparing ferric manganese hydrogen phosphate, comprising the following steps:

[0080] The manganese source and the first acidic solution are mixed and reacted until the pH of the mixture is 1.5-5 to obtain a manganese salt solution;

[0081] The iron source and the second acidic solution are mixed and reacted until the pH of the mixture is 1.5-5 to obtain an iron salt solution.

[0082] Manganese salt solution and iron salt solution are mixed and co-precipitated to obtain a slurry containing manganese ferric hydrogen phosphate.

[0083] Post-treatment of slurry containing ferromanganese hydrogen phosphate yields ferromanganese hydrogen phosphate.

[0084] One of the first acidic solution and the second acidic solution contains an organic acid, and the other contains phosphoric acid.

[0085] When manganese and iron sources react in the same acidic solution, the acidic solution will preferentially react with the manganese salt. The resulting acidic solution has a high pH value, making it difficult for the iron source to react completely with phosphoric acid, thus leaving some iron source in the solution.

[0086] This embodiment of the invention reduces the oxidation and blackening of manganese ions in the manganese salt solution by mixing a manganese source and a first acidic solution until the pH of the mixture is 1.5-5, thus ensuring the stable presence of manganese ions in the manganese salt solution. Similarly, mixing an iron source and a second acidic solution until the pH of the mixture is 1.5-5 reduces the oxidation of ferrous ions, ensuring the stable presence of ferrous ions in the second acidic solution. One of the first and second acidic solutions contains an organic acid, and the other contains phosphoric acid. The organic acid not only promotes the dissolution of the manganese and iron sources but also further lowers the pH of the mixture. The phosphoric acid provides a phosphorus source for ferromanganese hydrogen phosphate while simultaneously dissolving the manganese and iron sources. The preparation process of ferromanganese hydrogen phosphate involves a reaction between liquid-phase ions, resulting in a more uniform distribution of manganese, iron, and phosphorus elements and high crystallinity of the precursor. This makes it a suitable precursor for battery-grade positive electrode active materials, and it can be used as a precursor for lithium manganese iron phosphate positive electrode active materials.

[0087] The first acidic solution can be used to dissolve the manganese source, and the second acidic solution can be used to dissolve the iron source.

[0088] This embodiment of the invention utilizes the characteristics of iron and manganese sources to neutralize the partial acidity of phosphoric acid and organic acids, thereby reducing the pH value of the mixture of manganese salt solution and iron salt solution, achieving the pH window required for the precipitation of manganese ferrophosphate.

[0089] It should be noted that the pH of the solution after the manganese source and the first acidic solution react in a conventional stoichiometric ratio is usually greater than 5. Therefore, in this embodiment of the invention, the first acidic solution is in excess in the manganese salt solution. Similarly, the pH of the solution after the iron source and the second acidic solution react in a conventional stoichiometric ratio is usually greater than 5. Therefore, in this embodiment of the invention, the second acidic solution is also in excess in the iron salt solution.

[0090] In some embodiments, in the step of mixing manganese salt solution and iron salt solution for co-precipitation treatment to obtain slurry containing manganese ferric phosphate, the pH of the slurry containing manganese ferric phosphate can be 1.5-5, for example, it can be 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or any range of two of the above values.

[0091] By setting the pH of the slurry containing ferromanganese hydrogen phosphate within the above-mentioned range, the oxidation degree of ferrous and manganese ions in the solution can be reduced, thereby further improving the yield of ferromanganese hydrogen phosphate.

[0092] In some embodiments, the pH of the manganese salt solution can be 1.5-3.5.

[0093] In some embodiments, the pH of the iron salt solution can be 1.5-3.5.

[0094] In some embodiments, the pH of the slurry containing ferric manganese hydrogen phosphate can be 1.5-3.5.

[0095] By setting the pH of the manganese salt solution, iron salt solution, or slurry containing manganese ferrophosphate within the above range, the oxidation degree of ferrous and manganese ions in the solution can be further reduced, allowing ferrous and manganese ions to exist stably in the solution. The ratio of manganese, iron, and phosphorus in the obtained precursor can also be adjusted to be close to the element ratio required for lithium manganese ferrophosphate cathode active material. The obtained manganese ferrophosphate has good crystallinity, and the yield can meet the needs of industrial production.

[0096] It should be noted that the solubility of the product, ferromanganese hydrogen phosphate, decreases with increasing pH. Higher pH results in more precipitated ferromanganese hydrogen phosphate, meaning that increasing pH can improve the yield to some extent. However, this can lead to a decrease in the molar ratio of phosphorus in the obtained precursor. This may be because as pH increases, the product ferromanganese hydrogen phosphate gradually converts to orthophosphates, such as Mn3(PO4)2 and Fe3(PO4)2. Orthophosphates have lower solubility and are more easily precipitated. These substances have poor crystallinity and cause the elemental ratio to deviate from the theoretical stoichiometric ratio of ferromanganese hydrogen phosphate, thus deviating from the elemental ratio required for lithium iron manganese phosphate cathode active materials.

[0097] In some embodiments, the purity of the iron source is greater than 99%.

[0098] In some embodiments, the purity of the manganese source is greater than 99%.

[0099] By controlling the purity of the iron source and the manganese source within the above-mentioned range, the impurity content in ferromanganese hydrogen phosphate can be reduced, thereby reducing the influence of the precursor on the performance of lithium ferromanganese hydrogen phosphate and improving the first coulombic efficiency and initial specific capacity of the lithium ferromanganese hydrogen phosphate cathode active material.

[0100] In some embodiments, the organic acid may include one or more of formic acid, acetic acid, benzoic acid, tartaric acid, oxalic acid, and citric acid.

[0101] Lowering the pH of manganese salt solutions, iron salt solutions, or slurries containing ferromanganese hydrogen phosphate by adding excess phosphoric acid alone may lead to side reactions due to the excessive phosphoric acid content. For example, it may generate Mn(H₂PO₄)₂ or Fe(H₂PO₄)₂, which are difficult to precipitate when mixed. By selecting organic acids within the aforementioned range, the pH of manganese salt solutions, iron salt solutions, or slurries containing ferromanganese hydrogen phosphate can be further lowered while reducing the excess phosphoric acid, thus reducing side reactions and further improving the yield of ferromanganese hydrogen phosphate. Simultaneously, the molar ratio of phosphoric acid to total metals in the raw materials can be adjusted to prevent excessive excess, reducing waste of phosphoric acid and other raw materials.

[0102] In some embodiments, in the step of mixing a manganese source and a first acidic solution until the pH of the mixture is 1.5-5 to obtain a manganese salt solution, the manganese source may include one or more of elemental manganese, manganese sulfide, manganese trioxide, manganese tetroxide, manganese dioxide, manganese hydroxide, manganese acetate, manganese phosphate, and manganese carbonate.

[0103] In some embodiments, in the step of mixing the iron source and the second acidic solution until the pH of the mixture is 1.5-5 to obtain an iron salt solution, the iron source may include one or more of elemental iron, ferrous oxide, ferric oxide, ferric tetroxide, ferrous hydroxide, ferric hydroxide, ferrous acetate, ferrous phosphate, and ferrous carbonate.

[0104] By using the aforementioned manganese or iron source, the amount of impurity ions introduced can be reduced, further increasing the yield of manganese ferric phosphate. The reaction solution after the reaction can also be reused as a first acidic solution or a second acidic solution, thereby reducing waste liquid discharge and making the reaction process more green and environmentally friendly.

[0105] It should be noted that when the iron source contains a chemical valence other than +2 ferric iron, for example, the iron source includes ferric oxide or ferric tetroxide; or when the manganese source contains a chemical valence other than +2 manganese, for example, the manganese source includes manganese trioxide, manganese tetroxide, or manganese dioxide, a reducing agent needs to be added to the solution to dissolve the iron or manganese source.

[0106] In some embodiments, elemental iron can be iron powder.

[0107] In some embodiments, elemental manganese can be manganese flakes. Optionally, the manganese flakes can be electrolytic manganese flakes.

[0108] By selecting elemental manganese and elemental iron, the formation of amorphous phosphate precipitates can be reduced, the purity of manganese salt solutions and iron salt solutions can be improved, and the purity of manganese ferric hydrogen phosphate can be further improved. At the same time, elemental manganese and / or elemental iron have higher chemical reactivity and are more likely to react completely with acidic solutions. In addition, elemental manganese and elemental iron are more widely available and cheaper.

[0109] In some embodiments, the step of mixing the iron source and the second acidic solution until the pH of the mixture is 1.5-5 to obtain an iron salt solution may further include heating the iron source and the second acidic solution. This can promote the reaction between the iron source and the second acidic solution.

[0110] In some embodiments, the step of mixing the manganese source and the first acidic solution until the pH of the mixture is 1.5-5 to obtain a manganese salt solution may further include: filtering the manganese salt solution to obtain a filtered manganese salt solution.

[0111] In some embodiments, the step of mixing the iron source and the second acidic solution until the pH of the mixture is 1.5-5 to obtain an iron salt solution may further include: filtering the iron salt solution to obtain a filtered iron salt solution.

[0112] Filtration can remove insoluble impurities from the mixture, further reducing the impurity content in ferromanganese hydrogen phosphate, increasing the purity of the manganese salt solution and iron salt solution, and thus improving the purity of ferromanganese hydrogen phosphate.

[0113] In some embodiments, the step of mixing a manganese salt solution and an iron salt solution for co-precipitation to obtain a slurry containing ferromanganese hydrogen phosphate may include: stirring the slurry containing ferromanganese hydrogen phosphate. Stirring the mixture of manganese salt solution and iron salt solution can promote the precipitation of ferromanganese hydrogen phosphate.

[0114] In some embodiments, the stirring temperature can be 25-85°C, and the stirring time can be 0.5-9.5 h.

[0115] Generally, the higher the stirring temperature, the larger the particle size of the crystallized ferromanganese phosphate particles; the longer the stirring time, the larger the particle size of the crystallized ferromanganese phosphate particles will also be. By controlling the stirring temperature and stirring time within the above ranges, the precipitation of ferromanganese phosphate in the slurry can be further promoted, and the particle size of the ferromanganese phosphate particles can be further adjusted.

[0116] In some embodiments, in the step of mixing the manganese source and the first acidic solution until the pH of the mixture is 1.5-5 to obtain a manganese salt solution, the molar concentration of manganese ions in the manganese salt solution can be 0.1-1 mol / L.

[0117] In some embodiments, in the step of mixing the iron source and the second acidic solution until the pH of the mixture is 1.5-5 to obtain an iron salt solution, the molar concentration of ferrous ions in the iron salt solution can be 0.1-1 mol / L.

[0118] It should be noted that although manganese and iron salts in the solution may be completely or incompletely ionized—for example, manganese acetate in acetic acid is incompletely ionized, while ferrous phosphate in phosphoric acid is completely ionized—the molar concentrations of ions in the embodiments of this disclosure all represent the total content of iron or manganese in the solution.

[0119] By setting the molar concentration of manganese ions or ferrous ions within the above range, the pH value of the metal salt solution obtained from the reaction can be lower, reducing the oxidation of metal ions by air. This ensures that the metal salt ions remain divalent during the subsequent preparation of manganese ferric phosphate, and also allows for adjustment of the particle size of manganese ferric phosphate.

[0120] In some embodiments, the molar ratio of manganese ions to ferrous ions is (0.55-0.85):(0.15-0.45).

[0121] By setting the molar ratio of manganese ions to ferrous ions within the above range, the molar ratio of Mn and Fe in the obtained precursor can be adjusted, thereby adjusting the molar ratio of Mn and Fe in the final lithium manganese iron phosphate cathode active material.

[0122] In some embodiments, the ratio of the sum of the amounts of manganese ions and ferrous ions to the amount of phosphoric acid is 1:(1.00-1.50).

[0123] By setting the ratio of the sum of the amounts of manganese ions and ferrous ions to the amount of phosphoric acid within the above range, the molar ratio of the sum of the amounts of Mn and Fe to P in the obtained precursor can be adjusted, thereby adjusting the molar ratio of the sum of the amounts of Mn and Fe to P in the final obtained lithium manganese iron phosphate cathode active material.

[0124] In some embodiments, the step of post-processing the slurry containing ferromanganese hydrogen phosphate to obtain ferromanganese hydrogen phosphate may include filtering, washing, and drying the slurry containing ferromanganese hydrogen phosphate.

[0125] In some embodiments, the drying temperature can be 60-180°C, and the drying time can be 1-9 hours.

[0126] Drying can remove moisture from the precursor.

[0127] In some embodiments, the free water content in the precursor after drying can be 0.1%-2.0%.

[0128] The preparation method of this disclosure can improve the yield of ferromanganese hydrogen phosphate.

[0129] In some embodiments, the yield of ferromanganese hydrogen phosphate is greater than 90%, and optionally, the yield of ferromanganese hydrogen phosphate is greater than 92%.

[0130] [Ferric manganese hydrogen phosphate]

[0131] Ferric manganese phosphate is prepared by the method disclosed herein.

[0132] In some embodiments, the volumetric particle size distribution Dv50 of manganese phosphate can be 5-20 μm.

[0133] In some embodiments, the specific surface area of ​​manganese phosphate can be 3-12 g / m². 2 .

[0134] In some embodiments, the tap density of ferromanganese hydrogen phosphate can be 1.8-2.6 g / mL. 3 .

[0135] By setting the volumetric particle size distribution Dv50 and / or specific surface area of ​​ferromanganese hydrogen phosphate within the above-mentioned range, the compaction density of the lithium iron manganese phosphate cathode active material prepared therefrom can be improved, thereby increasing the energy density of the cathode active material.

[0136] The volumetric particle size distribution (Dv50) of ferromanganese hydrogen phosphate is a well-known concept in the art and can be determined using instruments and methods known in the field. For example, it can be conveniently determined using a laser particle size analyzer (such as the Malvern Mastersizer 3000) according to GB / T 19077-2016. The physical definition of Dv50 is the particle size corresponding to a cumulative volumetric distribution percentage of 50% for the material.

[0137] In some embodiments, SO4 in manganese ferric hydrogen phosphate 2- The content is less than 500 ppm. Options include less than 400 ppm, less than 300 ppm, less than 200 ppm, less than 100 ppm, or less than 50 ppm.

[0138] In some embodiments, Na in manganese ferric hydrogen phosphate + The content is less than 500 ppm. Options include less than 400 ppm, less than 300 ppm, less than 200 ppm, less than 100 ppm, or less than 50 ppm.

[0139] When the impurity content in the precursor is within the above range, the adverse effects of impurities on the lithium manganese iron phosphate cathode active material can be reduced, thereby improving the electrochemical performance of the lithium manganese iron phosphate cathode active material.

[0140] [Positive electrode active material]

[0141] The positive electrode active material is prepared using the manganese iron hydrogen phosphate precursor disclosed herein.

[0142] When using one or more of the manganese iron hydrogen phosphate precursors from the embodiments, lithium manganese iron hydrogen phosphate cathode active materials can be obtained.

[0143] [Positive electrode plate]

[0144] The positive electrode sheet includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The positive electrode film layer includes the positive electrode active material described in the embodiments of the present disclosure or the positive electrode active material prepared by the preparation method described in the embodiments of the present disclosure.

[0145] In some embodiments, the content of positive electrode active material in the positive electrode film layer is 80%-99%, optionally 90%-95%, based on the total mass of the positive electrode film layer as 100%.

[0146] The positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0147] The positive electrode active material may include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their respective modified compounds. In some embodiments, to further improve the energy density of the secondary battery, the positive electrode active material may include materials of the general formula Li. a Ni b Co c M d O e A f One or more of lithium transition metal oxides and their modified compounds. 0.8% gold oxide, 0.5% gold oxide < 1%, 0 < c < 1%, 0 < d < 1%, 1.5% gold oxide, 0.5% gold oxide, M including but not limited to one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, A including but not limited to one or more of N, F, S and Cl.

[0148] As an example, other positive electrode active materials may include LiCoO2, LiNiO2, LiMnO2, and LiNi 1 / 2 Mn 1 / 2 O2, LiMn2O4, Li 4 / 3 Ti 5 / 3 O4, LiNi 1 / 2 Mn 1 / 2 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.80 Co 0.15 Al 0.05 O2, LiFePO4, LiMnPO4, Li 1.13 Ti 0.57 Fe 0.3 One or more of S2.

[0149] During the charging and discharging process, lithium (Li) is deintercalated and consumed in a single battery cell, resulting in different molar contents of Li at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar contents of Li refer to the initial state of the material, i.e., the state before feeding. When the positive electrode active material is applied to the battery cell system, the molar contents of Li will change after charge-discharge cycles.

[0150] In the examples of positive electrode active materials disclosed in this disclosure, the molar content of O is only a theoretical value. The release of oxygen from the crystal lattice will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0151] In some embodiments, the positive electrode film layer may further include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0152] In some embodiments, the positive electrode film layer may further include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resins, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0153] In some embodiments, the positive current collector may be a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as a metal foil, pure metals, alloys, or surface-treated metals may be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer substrate and a metal material layer formed on at least one surface of the polymer substrate. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymer substrate may include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE). The composite current collector may be formed by forming a metal material on a polymer substrate.

[0154] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing positive electrode active materials, positive electrode conductive agents, positive electrode binders, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to this.

[0155] [Negative electrode plate]

[0156] The structure and composition of the negative electrode can be selected according to the type of battery cell, and the embodiments disclosed herein are not limited in this regard.

[0157] In some embodiments, the negative electrode sheet may include a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector and comprising a negative electrode active material. For example, the negative current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0158] The negative electrode active material can be any negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, mesophase microcarbon spheres, silicon-based materials, and tin-based materials. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, this disclosure is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0159] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0160] In some embodiments, the negative electrode film layer may further include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0161] In some embodiments, the negative electrode film layer may also include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0162] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, negative electrode conductive agent, negative electrode binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0163] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet may also include a conductive undercoat layer (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector; in some embodiments, the negative electrode sheet may also include a protective layer covering the surface of the negative electrode film layer.

[0164] In some embodiments, the negative electrode sheet may include a negative current collector and a metal layer disposed on at least one surface of the negative current collector, wherein the metal material in the metal layer may include one or more of elemental lithium and lithium alloy.

[0165] Lithium alloys can be alloys formed from metallic lithium with other metallic or non-metallic elements. For example, other metallic elements in lithium alloys may include one or more of tin, zinc, aluminum, magnesium, silver, gold, gallium, indium, and platinum, while non-metallic elements may include one or more of boron, carbon, and silicon.

[0166] In some embodiments, the negative electrode may be a lithium sheet (foil) or a lithium alloy sheet (foil).

[0167] In some embodiments, the negative electrode may include a negative current collector and does not include a metal layer, thereby assembling to form a negative electrode-free lithium metal battery cell.

[0168] In some embodiments, the negative electrode current collector may include a metal foil, a conductive polymer material, a carbon material, or a composite current collector. Examples of metal foils include pure metals, alloys, and surface-treated metals, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer substrate and a metal material layer formed on at least one surface of the polymer substrate. Examples of metal materials include, but are not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, aluminum, aluminum alloys, silver, and silver alloys. Examples of polymer materials include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE). The composite current collector can be formed by forming a metal material on a polymer substrate.

[0169] In some embodiments, the negative electrode can be made of foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. When foamed metal is used as the negative electrode sheet, the surface of the foamed metal may or may not contain a negative electrode active material.

[0170] As an example, negative electrode active materials can be filled or / and deposited within the negative electrode current collector.

[0171] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0172] [Electrolytes]

[0173] Each battery cell includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This disclosure does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte may include one or more selected from solid electrolytes, gel electrolytes, and liquid electrolytes (i.e., electrolyte solutions).

[0174] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0175] The type of electrolyte salt is not specifically limited and can be selected according to actual needs. In some embodiments, as an example, the electrolyte salt may include, but is not limited to, one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0176] There are no specific restrictions on the type of solvent; it can be selected according to actual needs.

[0177] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate (PPC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl 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), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE). Ether solvents may also be selected. Ether solvents may include one or more of the following: ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, and crown ether.

[0178] 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, and additives that can improve certain battery performance, such as additives that improve the overcharge / fast charge performance of individual battery cells, additives that improve the high-temperature performance of individual battery cells, additives that improve the low-temperature performance of individual battery cells, etc.

[0179] The gel electrolyte includes a polymer as a backbone network and can be used in conjunction with an ionic liquid-lithium salt.

[0180] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0181] As an example, the polymers of polymeric solid electrolytes may include polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids, cellulose, etc.

[0182] As an example, inorganic solid electrolytes can be one or more of the following: oxide solid electrolytes (crystalline perovskite, lithium superconducting ion conductors, garnet, amorphous LiPON thin films), sulfide solid electrolytes (crystalline lithium superconducting ion conductors, amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0183] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0184] [Isolation membrane]

[0185] In some embodiments, the electrode assembly further includes a separator disposed between the positive and negative electrodes. This disclosure does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0186] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a single component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be applied to the surface of the separator.

[0187] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0188] Methods for preparing battery cells are well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with the electrolyte. After vacuum sealing, settling, and formation processes, a battery cell is obtained.

[0189] [Electrical appliances]

[0190] This disclosure also provides an electrical device, which includes the battery device provided in this disclosure. The battery device can be used as the power source for the electrical device or as the energy storage unit of the electrical device. The electrical device can be, but is not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and spacecraft (e.g., airplanes, rockets, space shuttles, and spacecraft), energy storage systems, etc.

[0191] Electrical devices can choose the type of battery device according to their usage needs, such as individual battery cells, battery modules, or battery packs. Figure 2 This is a schematic diagram illustrating an example of an electrical device. This device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used as the power source.

[0192] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0193] Example

[0194] The following examples describe the contents of this disclosure in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0195] Test section

[0196] (1) Morphological test

[0197] The microstructure of the precursor material in Example 1 was observed using a scanning electron microscope (SEM, instrument brand: ZEISS Sigma 300).

[0198] (2) Crystal structure characterization

[0199] The crystal structure of the material was analyzed using X-ray diffraction (XRD). A D / MAX-Ultima X-ray diffractometer (Rigaku Corporation, Japan) was used for structural characterization. Radiation source: Co-Ka, wavelength: Tube voltage: 40KV, tube current: 40mA, scanning speed: 8° / min, scanning range: 10-90°.

[0200] (3) Determination of elemental composition and impurity content

[0201] For each example and comparative example, weigh 0.2 g of the sample into a 100 mL beaker, add 10 mL of 10% nitric acid solution, heat and digest at 120 °C for 0.5 h, and dilute to volume with a 100 mL volumetric flask. Then, pipette 1 mL into a 100 mL volumetric flask and dilute to volume to obtain the test solution. Use an inductively coupled plasma optical emission spectrometer (ICP-OES, Agilent 5800) to determine the contents of manganese, iron, and phosphorus in the test solution, calculate the elemental ratio in the precursor, and determine the contents of sulfate and sodium ions in the sample using the same method.

[0202] (4) Initial Cycle Performance Test of Button Cells

[0203] The prepared ferric manganese hydrogen phosphate monohydrate (100 mmol), Li₂CO₃ (50 mmol), and sucrose (15 mmol) were placed in a ball mill jar, with a small amount of ethanol and water added as solvents. The mixture was ball-milled at 500 r / min for 8 h to obtain a slurry. The obtained slurry was transferred to a spray dryer for spray drying and granulation to obtain powder. The inlet air temperature was set to 210 °C and the outlet air temperature to 100 °C. The obtained powder was placed in an atmosphere furnace and sintered at 750 °C under a nitrogen atmosphere for 12 h. After naturally cooling to room temperature, the powder was pulverized by air jet milling to obtain lithium iron manganese phosphate cathode active material.

[0204] The prepared lithium manganese iron phosphate positive electrode active material, along with the binder polyvinylidene fluoride (PVDF) and the conductive agent acetylene black, were added to N-methylpyrrolidone (NMP) at a weight ratio of 90:5:5. The mixture was stirred in a drying chamber to form a slurry. The slurry was then coated onto aluminum foil, dried, and cold-pressed to form a positive electrode sheet.

[0205] A coin cell was assembled in a coin cell box using a lithium sheet as the negative electrode and a 1 mol / L LiPF6 solution in a 1:1:1 volume ratio of ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) as the electrolyte.

[0206] In a constant temperature environment of 25℃, the coin cell is charged at a constant current of 0.1C to 4.3V, and then charged at a constant voltage of 4.3V until the current is less than or equal to 0.05mA. The charging capacity at this point is the initial charging capacity, denoted as C0. After the coin cell is left to stand for 2 minutes, it is discharged at a constant current of 0.1C to 2.0V. The discharge capacity at this point is the initial discharge capacity, denoted as D0. The initial coulombic efficiency (%) of the coin cell is (D0 / C0) × 100%. The initial specific capacity (mAh / g) of the coin cell is D0 / m, where m represents the mass of the lithium manganese iron phosphate cathode active material.

[0207] Example 1

[0208] (1) Preparation of manganese salt solution: Weigh 0.6 mol of electrolytic manganese flakes (manganese content 99%) and 1.26 mol of glacial acetic acid (acetic acid content 99%) according to the molar ratio of 1:2.1. First, mix the glacial acetic acid with 500 g of water evenly, then add the electrolytic manganese flakes and stir until the reaction is complete. After filtering with 5 μm filter paper, add water to the clear liquid to make up to 600 mL, mix evenly, and obtain a 1.00 mol / L manganese salt solution for later use. The pH value of the manganese salt solution is 2.

[0209] (2) Preparation of iron salt solution: According to the molar ratio of reduced iron powder (iron mass fraction of 99%) to phosphoric acid of 0.4:1.05, weigh out 0.4 mol of reduced iron powder and 1.05 mol of 75% phosphoric acid. First, mix the phosphoric acid with 200g of water evenly, put it in a water bath and heat it to 70℃ and keep it warm. Then add the reduced iron powder and stir until the reaction is complete. After filtering with 5μm filter paper, add water to the clear liquid to make up to 400mL and mix evenly to obtain an iron-phosphorus mixed solution with iron ion concentration of 1.00mol / L and phosphoric acid concentration of 2.63mol / L for later use. The pH value of the iron salt solution is 2.

[0210] (3) Coprecipitation reaction: The manganese salt solution obtained in step (1) and the iron salt solution obtained in step (2) are mixed and stirred for 1.0 h at a reaction temperature of 40 °C to obtain a manganese ferric phosphate slurry. The above manganese ferric phosphate slurry is filtered, washed with water, and dried at 105 °C for 2.0 h to obtain the manganese ferric phosphate precursor Mn. 0.6 Fe 0.4 HPO4·H2O. The scanning electron microscope image of the manganese-iron hydrogen phosphate prepared in Example 1 is shown below. Figure 3 As shown, the X-ray diffraction pattern of manganese iron hydrogen phosphate is as follows. Figure 4 As shown.

[0211] Example 2

[0212] (1) Preparation of manganese salt solution: According to the molar ratio of electrolytic manganese flakes (manganese content of 99%) to glacial acetic acid (acetic acid content of 99%), weigh 0.7 mol of electrolytic manganese flakes and 1.47 mol of glacial acetic acid respectively. First, mix the glacial acetic acid with 1200 g of water evenly, then add the electrolytic manganese flakes and stir until the reaction is complete. After filtering with 5 μm filter paper, add water to the clear liquid to make up to 1400 mL, mix evenly, and obtain a 1.00 mol / L manganese salt solution for later use. The pH value of the manganese salt solution is 2.

[0213] (2) Preparation of iron salt solution: According to the molar ratio of reduced iron powder (iron mass fraction of 99%) to phosphoric acid of 0.3:1.01, weigh out 0.3 mol of reduced iron powder and 1.01 mol of 75% phosphoric acid. First, mix the phosphoric acid with 400g of water evenly, put it in a water bath and heat it to 80℃ and keep it warm. Then add the reduced iron powder and stir until the reaction is complete. After filtering with 5μm filter paper, add water to the clear liquid to make up to 600mL and mix evenly to obtain an iron-phosphorus mixed solution with iron ion concentration of 0.5mol / L and phosphoric acid concentration of 1.68mol / L for later use. The pH value of the iron salt solution is 2.

[0214] (3) Coprecipitation reaction: The manganese salt solution obtained in step (1) and the iron salt solution obtained in step (2) are mixed and stirred for 1.5 h at a reaction temperature of 40 °C to obtain a manganese ferrophosphate slurry. The above manganese ferrophosphate slurry is filtered, washed with water, and dried at 95 °C for 3 h to obtain the manganese ferrophosphate precursor Mn. 0.7 Fe 0.3 HPO4·H2O.

[0215] Example 3

[0216] Except for adjusting the amount of acetic acid added to make the pH of the manganese salt solution 5, and adjusting the amount of phosphoric acid added to make the pH of the iron salt solution 5, the rest of the preparation process is the same as in Example 1.

[0217] Example 4

[0218] Except for adjusting the amount of acetic acid added to make the pH of the manganese salt solution 4, and adjusting the amount of phosphoric acid added to make the pH of the iron salt solution 4, the rest of the preparation process is the same as in Example 1.

[0219] Example 5

[0220] Except for adjusting the amount of acetic acid added to make the pH of the manganese salt solution 3, and adjusting the amount of phosphoric acid added to make the pH of the iron salt solution 3, the rest of the preparation process is the same as in Example 1.

[0221] Example 6

[0222] Except for adjusting the amount of acetic acid added to make the pH of the manganese salt solution 1.5 and adjusting the amount of phosphoric acid added to make the pH of the iron salt solution 1.5, the rest of the preparation process is the same as in Example 1.

[0223] Example 7

[0224] Except that the first acidic solution is a mixed aqueous solution of acetic acid and phosphoric acid, the pH of the manganese salt solution is adjusted to 1.7, the second acidic solution is acetic acid, the pH of the iron salt solution is adjusted to 2, and the pH of the mixed slurry is 1.9, the rest of the preparation process is the same as in Example 1.

[0225] Example 8

[0226] Except for the manganese source being manganese acetate and the iron source being ferrous acetate, the preparation process is the same as in Example 1.

[0227] Example 9

[0228] Except for the manganese source being manganese carbonate and the iron source being ferrous phosphate, the preparation process is the same as in Example 1.

[0229] Example 10

[0230] Except for the manganese source being manganese oxide, the preparation process is the same as in Example 1.

[0231] Comparative Example 1

[0232] Except for adjusting the amount of acetic acid added to make the pH of the manganese salt solution 6, adjusting the amount of phosphoric acid added to make the pH of the iron salt solution 6, and the pH of the mixed slurry 6, the rest of the preparation process is the same as in Example 1.

[0233] Comparative Example 2

[0234] According to the molar ratio of Mn to Fe of 0.6:0.4, 3 mol of manganese sulfate and 2 mol of ferrous sulfate were weighed out respectively, and pure water was added according to the total metal ion molar concentration of 1 mol / L. The mixture was heated to 40℃ and kept at the temperature until the powder was completely dissolved, and 5000 mL of metal salt solution was obtained for later use.

[0235] Based on the above total metal ion to phosphorus molar ratio of 1:1.05, 5.25 mol of disodium hydrogen phosphate was added to a stirred tank, and pure water was added according to the molar concentration of disodium hydrogen phosphate solution of 1.05 mol / L. The mixture was stirred, and the water bath heating function was turned on to heat to 40℃ and kept at that temperature to prepare 5000 mL of phosphate salt solution for later use.

[0236] Maintaining the water bath temperature of the phosphorus source solution at 40°C, the above-mentioned metal salt solution was added to the phosphate salt solution under stirring and mixed for 1.0 h to obtain a manganese-iron phosphate slurry for later use. The above manganese-iron phosphate slurry was filtered, washed with water, and dried at 105°C for 2 h to obtain the manganese-iron phosphate precursor Mn. 0.6 Fe 0.4 HPO4·H2O.

[0237] The test results of Examples 1-10 and Comparative Examples 1-2 are shown in Table 1.

[0238] Table 1

[0239]

[0240] As can be seen from Examples 1-10 and Comparative Example 2, the content of impurity ions in the ferromanganese hydrogen phosphate prepared in the embodiments of this disclosure is low, the yield of ferromanganese hydrogen phosphate is high, and the first coulombic efficiency and initial specific capacity of the positive electrode active material are improved.

[0241] As shown in Examples 1-6 and Comparative Example 1, the yield of ferromanganese hydrogen phosphate gradually increases with increasing pH value, but the elemental ratios of the generated ferromanganese hydrogen phosphate deviate from the elemental ratios required for lithium iron manganese hydrogen phosphate cathode active materials. By setting the pH value in the range of 1.5-3, the ratio of manganese, iron, and phosphorus in the obtained precursor can be adjusted to be close to the elemental ratios required for lithium iron manganese phosphate cathode materials, and the yield can meet the needs of industrial production.

[0242] As can be seen from Examples 1 and 8-10, when the iron source is elemental iron and the manganese source is elemental manganese, the content of impurity ions in ferromanganese hydrogen phosphate can be further reduced, the purity of ferromanganese hydrogen phosphate can be improved, and thus the initial coulombic efficiency and initial specific capacity of the positive electrode active material can be further improved.

[0243] Although this disclosure has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this disclosure. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This disclosure is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing ferric manganese hydrogen phosphate, characterized in that, include: The manganese source and the first acidic solution are mixed and reacted until the pH of the mixture is 1.5-5 to obtain a manganese salt solution; The iron source and the second acidic solution are mixed and reacted until the pH of the mixture is 1.5-5 to obtain an iron salt solution. The manganese salt solution and the iron salt solution are mixed and co-precipitated to obtain a slurry containing manganese ferric hydrogen phosphate. The slurry containing ferromanganese hydrogen phosphate is post-treated to obtain ferromanganese hydrogen phosphate; The first acidic solution and the second acidic solution each contain an organic acid and phosphoric acid, respectively.

2. The preparation method according to claim 1, characterized in that, In the step of mixing the manganese salt solution and the iron salt solution for co-precipitation treatment to obtain a slurry containing manganese ferric hydrogen phosphate, the pH value of the slurry containing manganese ferric hydrogen phosphate is 1.5-5.

3. The preparation method according to claim 1 or 2, characterized in that, The pH value of the manganese salt solution is 1.5-3.5; and / or, The pH value of the iron salt solution is 1.5-3.5; and / or, The pH value of the slurry containing manganese phosphate is 1.5-3.

5.

4. The preparation method according to any one of claims 1-3, characterized in that, The organic acids include one or more of formic acid, acetic acid, benzoic acid, tartaric acid, oxalic acid, and citric acid.

5. The preparation method according to any one of claims 1-4, characterized in that, In the step of mixing a manganese source and a first acidic solution until the pH of the mixture is 1.5-5 to obtain a manganese salt solution, the manganese source includes one or more of elemental manganese, manganese sulfide, manganese trioxide, manganese tetroxide, manganese dioxide, manganese hydroxide, manganese acetate, manganese phosphate, and manganese carbonate; and / or, In the step of mixing the iron source and the second acidic solution until the pH of the mixture is 1.5-5 to obtain an iron salt solution, the iron source includes one or more of elemental iron, ferrous oxide, ferric oxide, ferric tetroxide, ferrous hydroxide, ferric hydroxide, ferrous acetate, ferrous phosphate, and ferrous carbonate.

6. The preparation method according to any one of claims 1-5, characterized in that, The step of mixing the manganese source and the first acidic solution until the pH of the mixture is 1.5-5 to obtain a manganese salt solution further includes: filtering the manganese salt solution to obtain a filtered manganese salt solution; and / or, The step of mixing the iron source and the second acidic solution until the pH of the mixture is 1.5-5 to obtain an iron salt solution further includes filtering the iron salt solution to obtain a filtered iron salt solution.

7. The preparation method according to any one of claims 1-6, characterized in that, The step of mixing the manganese salt solution and the iron salt solution and performing co-precipitation treatment to obtain a slurry containing manganese ferric hydrogen phosphate includes: stirring the slurry containing manganese ferric hydrogen phosphate; Optionally, the stirring temperature is 25-85℃, and the stirring time is 0.5-9.5h.

8. The preparation method according to any one of claims 1-7, characterized in that, In the step of mixing a manganese source and a first acidic solution until the pH of the mixture is 1.5-5 to obtain a manganese salt solution, the molar concentration of manganese ions in the manganese salt solution is 0.1-1 mol / L; and / or, In the step of mixing the iron source and the second acidic solution until the pH of the mixture is 1.5-5 to obtain an iron salt solution, the molar concentration of ferrous ions in the iron salt solution is 0.1-1 mol / L; and / or, The molar ratio of manganese ions to ferrous ions is (0.55-0.85):(0.15-0.45); the molar ratio of the sum of the manganese ions and ferrous ions to the molar ratio of phosphoric acid is 1:(1.00-1.50).

9. The preparation method according to any one of claims 1-8, characterized in that, In the step of post-processing the slurry containing ferromanganese hydrogen phosphate to obtain ferromanganese hydrogen phosphate, the post-processing includes filtering, washing and drying the slurry containing ferromanganese hydrogen phosphate. Optionally, the drying temperature is 60-180℃, and the drying time is 1-9 hours.

10. The preparation method according to any one of claims 1-9, characterized in that, The yield of the ferromanganese hydrogen phosphate is greater than 90%.

11. A type of manganese-iron phosphate, characterized in that, It is prepared by any one of the preparation methods of claims 1-10.

12. The ferromanganese hydrogen phosphate according to claim 11, characterized in that, The ferromanganese hydrogen phosphate satisfies one or more of the following conditions (1)-(5): (1) The volumetric particle size distribution Dv50 of the ferromanganese hydrogen phosphate is 5-20 μm; (2) The specific surface area of ​​the ferromanganese hydrogen phosphate is 3-12 g / m². 2 ; (3) The tap density of the ferromanganese hydrogen phosphate is 1.8-2.6 g / mL. 3 ; (4) SO4 in the aforementioned manganese ferric phosphate 2- The content is less than 500 ppm; (5) Na in the aforementioned manganese ferric hydrogen phosphate + The content is less than 500 ppm.

13. A positive electrode active material, characterized in that, It is prepared using the manganese-iron hydrogen phosphate precursor as described in claim 11 or 12.

14. A positive electrode plate, characterized in that, The positive electrode sheet comprises the positive electrode active material as described in claim 13.

15. A single battery cell, characterized in that, The battery cell includes the positive electrode sheet as described in claim 14.

16. A battery device, characterized in that, Includes the battery cell as described in claim 15.

17. An electrical device, characterized in that, Includes the battery device as described in claim 16.

Images