Modified lithium manganese iron phosphate, preparation method thereof, positive electrode material, battery and application

Abstract

The invention relates to the technical field of lithium manganese iron phosphate materials, in particular to modified lithium manganese iron phosphate, a preparation method thereof, a positive electrode material, a battery and application. The modified lithium manganese iron phosphate is prepared from the following raw materials: lithium manganese iron phosphate, C7H7ZnCl and silane; the mass ratio of the lithium manganese iron phosphate to the C7H7ZnCl to the silane is 1: (0.01 to 0.06): (0.01 to 0.08). According to the modified lithium manganese iron phosphate provided by the invention, the raw material contains the silane, and the silicon dioxide obtained by sintering the silane is used as a supporting structure of the LFMP, so that the thermal stability of the LFMP is improved.

Description

Modified lithium manganese iron phosphate, its preparation methods, cathode materials, batteries and applications Technical Field

[0001] This invention relates to the field of lithium manganese iron phosphate materials technology, specifically to a modified lithium manganese iron phosphate, its preparation method, cathode material, battery, and applications. Background Technology

[0002] The preparation of lithium manganese iron phosphate (LFMP) mainly includes high-temperature solid-state method, solvothermal method, sol-gel method and co-precipitation method. It is a cathode material with high safety, high energy density, long cycle life, low preparation cost and environmental friendliness. However, it also has problems such as low rate performance and poor high and low temperature performance. Among them, in the delithiation process of LMFP, Mn 2+ Oxidized to Mn 3+ This leads to severe distortion of the MnO6 octahedron, resulting in low rate performance of the battery.

[0003] Currently, common methods to address the rate performance and high / low temperature performance issues of lithium manganese iron phosphate (LFMP) include metal cation doping and surface coating (graphene, conductive polymers, lithium-ion conductors). Ion doping can alter the cell parameters and electron cloud distribution of LFMP, thereby improving its conductivity and rate performance, which is beneficial for improving the performance of LFMP at high charge and discharge rates. Surface coating can effectively inhibit electrolyte corrosion of active materials, slow down the dissolution of metal ions, and promote lithium-ion transport, which is beneficial for improving the stability and cycle life of LFMP.

[0004] However, current metal cation doping and surface coating methods will reduce the thermal stability of LFMP to some extent, thereby reducing the cycle stability of LFMP and shortening its lifespan. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a modified lithium manganese iron phosphate, its preparation method, cathode material, battery, and applications, thereby resolving at least one aspect of the above-mentioned technical problems.

[0006] The present invention is achieved through the following technical solution: In a first aspect, the present invention provides a modified lithium manganese iron phosphate, the raw materials of which include lithium manganese iron phosphate, C7H7ZnCl and silane; the mass ratio of the lithium manganese iron phosphate, the C7H7ZnCl and the silane is 1:(0.01~0.06):(0.01~0.08).

[0007] In some embodiments, the chemical formula of lithium manganese iron phosphate is: LiFe 1-y Mn y PO4; where 0.5≤y≤0.9.

[0008] In some embodiments, the structural formula of C7H7ZnCl is: .

[0009] Secondly, the present invention provides a method for preparing the above-mentioned modified lithium manganese iron phosphate, comprising the following steps: sintering a mixture to obtain modified lithium manganese iron phosphate; wherein the mixture comprises lithium manganese iron phosphate, C7H7ZnCl and silane.

[0010] In some possible implementations, the preparation of the mixture includes the following steps: hydrolyzing the suspension to obtain a dried precipitate, mixing it with a C7H7ZnCl solution to obtain the mixture; the suspension contains silane and lithium manganese iron phosphate.

[0011] In some possible implementations, the preparation of the mixture further includes the step of surface treatment of the precipitate.

[0012] In some possible implementations, the surface treatment step includes mixing the precipitate with a silane coupling agent.

[0013] In some possible implementations, the sintering step includes: heating to 500°C to 700°C at a heating rate of 2°C / min to 5°C / min and then holding at that temperature.

[0014] Thirdly, the present invention provides a cathode material, including modified lithium manganese iron phosphate prepared by the above preparation method.

[0015] Fourthly, the present invention provides a battery comprising the above-described positive electrode material.

[0016] Fifthly, the present invention provides an application of the modified lithium manganese iron phosphate prepared by the above-mentioned preparation method in the field of battery materials.

[0017] Compared with the prior art, the modified lithium manganese iron phosphate and its preparation method provided by the present invention have at least the following beneficial technical effects: (1) The modified lithium manganese iron phosphate provided by the present invention contains silane as raw material, and the silicon dioxide obtained by silane sintering serves as the supporting structure of LFMP, which improves the thermal stability of LFMP.

[0018] (2) The modified lithium manganese iron phosphate provided by this invention contains C7H7ZnCl as a raw material. C7H7ZnCl acts as both a zinc dopant source and a pore-forming agent during the preparation process, giving the modified lithium manganese iron phosphate abundant pores. This porous structure shortens the Li... + The diffusion path can be improved to further enhance the rate performance and cycle stability of the material.

[0019] (3) The method for preparing modified lithium manganese iron phosphate provided by the present invention involves mixing lithium manganese iron phosphate, C7H7ZnCl and silane, followed by sintering. C7H7ZnCl serves as both a doping source for carbon and zinc and a pore-forming agent. The resulting modified lithium manganese iron phosphate has abundant pores and a large specific surface area, thereby shortening the Li-24 condensation time. + The diffusion path. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this drawing or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 is a SEM image of the modified lithium manganese iron phosphate in Example 2 of the present invention; Figure 2 is an EDS elemental mapping diagram of the modified lithium manganese iron phosphate in Example 2 of the present invention; Figure 3 is an EDS diagram of zinc in the modified lithium manganese iron phosphate in Example 2 of the present invention.

[0022] The purpose, features, and advantages of this accompanying drawing will be further explained in conjunction with the embodiments and with reference to the accompanying drawing. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described and illustrated below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments provided by this invention without inventive effort are within the scope of protection of this invention.

[0024] Obviously, the following description is merely some examples or embodiments of the present invention. Those skilled in the art can apply the present invention to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this invention, modifications to design, manufacturing, or production based on the technical content disclosed in this invention are merely conventional technical means and should not be construed as insufficient disclosure of the present invention.

[0025] However, there may be instances where unnecessary detailed descriptions are omitted. For example, detailed descriptions of well-known matters or repetitive descriptions of essentially the same structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the following description is provided to enable those skilled in the art to fully understand the invention and is not intended to limit the subject matter of the claims.

[0026] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions, and all technical features and optional technical features of the present invention can be combined with each other to form new technical solutions.

[0027] The first aspect of this invention provides a modified lithium manganese iron phosphate, the raw materials of which include lithium manganese iron phosphate, C7H7ZnCl and silane; the mass ratio of lithium manganese iron phosphate, C7H7ZnCl and silane is 1:(0.01~0.06):(0.01~0.08).

[0028] The modified lithium manganese iron phosphate provided in this invention uses silicon dioxide obtained from silane sintering as the supporting structure for LFMP, improving its thermal stability. C7H7ZnCl acts as both a zinc dopant source and a pore-forming agent during preparation, giving the modified lithium manganese iron phosphate abundant pores. This porous structure shortens the Li-24mm diameter. + The diffusion path can be improved to further enhance the rate performance and cycle stability of the material.

[0029] In some embodiments, the chemical formula of lithium manganese iron phosphate is: LiFe 1-y Mn y PO4; where 0.5≤y≤0.9.

[0030] In some embodiments, the structural formula of C7H7ZnCl is: .

[0031] In some embodiments, the CAS number of C7H7ZnCl is 90252-89-4.

[0032] In some embodiments, the CAS number of the silane is 7803-62-5.

[0033] The second aspect of the present invention provides a method for preparing the above-mentioned modified lithium manganese iron phosphate, comprising the following steps: S10. Sintering the mixture to obtain modified lithium manganese iron phosphate; the mixture includes lithium manganese iron phosphate, C7H7ZnCl and silane.

[0034] The method for preparing modified lithium manganese iron phosphate provided in this invention involves sintering a mixture containing lithium manganese iron phosphate, C7H7ZnCl, and silane. C7H7ZnCl serves as both a carbon and zinc dopant source and utilizes the low-boiling-point properties of ZnCl2, which decomposes from C7H7ZnCl, as a pore-forming agent. The resulting modified lithium manganese iron phosphate exhibits abundant pores and a large specific surface area, thereby shortening the Li-24mm lithium oxide production cycle. + The diffusion path.

[0035] In some embodiments, in step S10 above, the preparation of the mixture includes the following steps: S101. Under stirring conditions, the suspension is hydrolyzed to obtain a dried precipitate, which is then mixed with a C7H7ZnCl solution to obtain a mixture; the suspension contains silane and lithium manganese iron phosphate.

[0036] In the preparation of the above mixture, the suspension is first hydrolyzed to hydrolyze silane in situ into silica sol, which then adsorbs and encapsulates lithium manganese iron phosphate in situ, serving as a supporting structure for the lithium manganese iron phosphate. The resulting precipitate is then mixed with a C7H7ZnCl solution to uniformly disperse C7H7ZnCl in the precipitate. During subsequent sintering, C7H7ZnCl acts as a doping source for both carbon and zinc in the lithium manganese iron phosphate. At high temperatures, C7H7ZnCl decomposes to release ZnCl2, giving the modified lithium manganese iron phosphate abundant pores and a large specific surface area, thereby shortening the Li-24 sintering time. + The diffusion path.

[0037] In some embodiments, in step S101 above, the stirring speed is 10 rpm to 20 rpm.

[0038] In some embodiments, in step S101 above, the preparation of the suspension includes the following steps: S1011. Lithium manganese iron phosphate is mixed with silane under stirring conditions of 2 rpm to 5 rpm.

[0039] In the preparation of the above suspension, low-speed stirring can ensure that lithium manganese iron phosphate and silane are mixed evenly without damaging the silane composition, thus forming a uniform suspension.

[0040] In some embodiments, the step of hydrolyzing the suspension in step S101 above includes: S1012. Under stirring conditions of 10 rpm to 20 rpm, water is added dropwise to the suspension at a speed of 50 d / min to 80 d / min to obtain a dried precipitate.

[0041] In the above-described step of hydrolyzing the suspension, water is added dropwise to the suspension, causing the silane to hydrolyze in situ into silica sol. It should be noted that the amount of water added can be adjusted by those skilled in the art according to the actual preparation process; the endpoint is reached when no precipitation occurs.

[0042] In some embodiments, the step of obtaining the dried precipitate in step S1012 above includes: filtering and drying the hydrolysis product.

[0043] In the above steps of obtaining the dried precipitate, filtration and drying are performed to remove water from the precipitate and prevent subsequent decomposition of C7H7ZnCl due to water.

[0044] In some embodiments, the drying temperature is 100°C to 120°C.

[0045] In some embodiments, in step S101 above, the C7H7ZnCl solution contains C7H7ZnCl and an organic solvent.

[0046] In some specific embodiments, the organic solvent is at least one of tetrahydrofuran, aromatic hydrocarbons, and ethers.

[0047] In some specific embodiments, the aromatic hydrocarbon is toluene.

[0048] In some specific embodiments, the ether is diethyl ether.

[0049] In some embodiments, in step S101 above, the mass fraction of C7H7ZnCl in the C7H7ZnCl solution is 2%~5%.

[0050] In some other embodiments, in step S10 above, the preparation of the mixture includes the following steps: S102. under stirring conditions, the suspension is hydrolyzed to obtain a dry precipitate; the suspension contains silane and lithium manganese iron phosphate.

[0051] S103. After surface treatment of the precipitate, it is mixed with C7H7ZnCl solution to obtain a mixture.

[0052] In the preparation of the above mixture, the precipitate is first surface-treated to activate its surface before being mixed with C7H7ZnCl solution. This improves the compatibility between the precipitate and C7H7ZnCl, ensuring the precipitate is uniformly dispersed in the C7H7ZnCl solution. The resulting modified lithium manganese iron phosphate, obtained through subsequent sintering, exhibits a uniform pore structure, further enhancing its conductivity and cycle stability.

[0053] In some embodiments, in step S103 above, the surface treatment step includes: S1031. Mixing the precipitate with a silane coupling agent.

[0054] In the above surface treatment steps, the precipitate is mixed with a silane coupling agent. The silane coupling agent activates the surface of the precipitate, causing organic groups to be grafted onto the surface of the precipitate. The organic groups can improve the compatibility between the precipitate and C7H7ZnCl and silane, thereby the modified lithium manganese iron phosphate prepared has a more uniform pore structure, higher conductivity and rate performance.

[0055] In some embodiments, in step S1031 above, the mass ratio of the precipitate to the silane coupling agent is 1:(0.2~0.8).

[0056] In some embodiments, in step S1031 above, the silane coupling agent is KH-570.

[0057] In some embodiments, in step S10 above, the sintering step includes: heating to 500°C to 700°C at a heating rate of 2°C / min to 5°C / min and then holding at that temperature.

[0058] In the above sintering steps, the temperature is increased at a rate of 2℃ / min to 5℃ / min. At low temperatures, zinc is embedded (or further embedded) into the crystal structure of lithium manganese iron phosphate, forming zinc doping. When the temperature is increased to above 500℃, the remaining free C7H7ZnCl decomposes into ZnCl2 and is released from the system. The remaining carbon element is used as carbon dopant in lithium manganese iron phosphate, producing porous carbon-zinc doped modified lithium manganese iron phosphate, thereby shortening the Li content in lithium manganese iron phosphate. + The diffusion path, improving the rate performance and cycle stability of the material.

[0059] In some embodiments, during the sintering step, the holding time at 500°C to 700°C is 2 hours to 6 hours.

[0060] A third aspect of the present invention provides a cathode material, including modified lithium manganese iron phosphate prepared by the preparation method provided in the present invention.

[0061] A fourth aspect of the present invention provides a battery comprising the positive electrode material provided in the embodiments of the present invention.

[0062] The following description, in conjunction with specific embodiments, provides further details.

[0063] The CAS number of the selected C7H7ZnCl is 90252-89-4.

[0064] The CAS number of the selected silane is 7803-62-5.

[0065] Example 1 Example 1 provides a modified lithium manganese iron phosphate, the raw material of which includes LiFe 0.5 Mn 0.5The mass ratio of PO4, C7H7ZnCl and silane is 1:0.01:0.01.

[0066] This embodiment also provides a method for preparing modified lithium manganese iron phosphate, the steps of which are as follows: E11. Under stirring conditions of 5 rpm, lithium manganese iron phosphate is mixed with silane.

[0067] E21. Under stirring conditions of 15 rpm, water is added dropwise to the suspension at a rate of 50 d / min until no precipitate is formed. The solution is then filtered and dried at 100°C to obtain a dried precipitate.

[0068] E31. The precipitate is mixed with C7H7ZnCl solution to obtain a mixture; wherein the solvent of C7H7ZnCl solution is toluene, and the mass fraction of C7H7ZnCl is 3%.

[0069] E41. The mixture was heated to 600℃ at a heating rate of 2℃ / min and then held for 5 hours to obtain modified lithium manganese iron phosphate.

[0070] Example 2 Example 2 provides a modified lithium manganese iron phosphate, the raw material of which includes LiFe 0.4 Mn 0.6 The mass ratio of PO4, C7H7ZnCl and silane is 1:0.04:0.05.

[0071] This embodiment also provides a method for preparing modified lithium manganese iron phosphate, the steps of which are as follows: E12. Under stirring conditions of 3 rpm, lithium manganese iron phosphate is mixed with silane.

[0072] E22. Under stirring conditions of 10 rpm, water is added dropwise to the suspension at a rate of 60 d / min until no precipitate is formed. The solution is then filtered and dried at 110°C to obtain a dried precipitate.

[0073] E32. The precipitate is mixed with KH-570 to obtain a surface-treated precipitate; wherein the mass ratio of the precipitate to KH-570 is 1:0.4.

[0074] E42. The precipitate is mixed with C7H7ZnCl solution to obtain a mixture; wherein the solvent of C7H7ZnCl solution is toluene, and the mass fraction of C7H7ZnCl is 2%.

[0075] E52. The mixture was heated to 700℃ at a heating rate of 4℃ / min and then held for 2 hours to obtain modified lithium manganese iron phosphate.

[0076] Example 3 Example 3 provides a modified lithium manganese iron phosphate, the raw material of which includes LiFe 0.3Mn 0.7 The mass ratio of PO4, C7H7ZnCl and silane is 1:0.06:0.03.

[0077] This embodiment also provides a method for preparing modified lithium manganese iron phosphate, the steps of which are basically the same as those in embodiment 2, except that the rotation speed is 4 rpm in step E12.

[0078] In step E22, the rotation speed is 20 rpm; the drip rate is 70 drops / min; and the drying temperature is 115℃.

[0079] In step E32, the mass ratio of the precipitate to KH-570 is 1:0.6.

[0080] In step E42, the mass fraction of C7H7ZnCl is 4%.

[0081] In step E52, the heating rate is 5℃ / min; the holding temperature is 650℃; and the holding time is 4h.

[0082] Example 4 Example 4 provides a modified lithium manganese iron phosphate, the raw material of which includes LiFe 0.2 Mn 0.8 The mass ratio of PO4, C7H7ZnCl and silane is 1:0.05:0.08.

[0083] This embodiment also provides a method for preparing modified lithium manganese iron phosphate, the steps of which are basically the same as those in embodiment 2, except that the rotation speed is 2 rpm in step E12.

[0084] In step E22, the rotation speed is 18 rpm; the drip rate is 55 drops / min; and the drying temperature is 112℃.

[0085] In step E32, the mass ratio of the precipitate to KH-570 is 1:0.7.

[0086] In step E42, the mass fraction of C7H7ZnCl is 5%.

[0087] In step E52, the heating rate is 5℃ / min; the holding temperature is 655℃; and the holding time is 3h.

[0088] Example 5 Example 5 provides a modified lithium manganese iron phosphate, the raw material of which includes LiFe 0.1 Mn 0.9 The mass ratio of PO4, C7H7ZnCl and silane is 1:0.03:0.04.

[0089] This embodiment also provides a method for preparing modified lithium manganese iron phosphate, the steps of which are basically the same as those in Embodiment 2, except that the rotation speed is 3 rpm in step E12.

[0090] In step E22, the rotation speed is 12 rpm; the drip rate is 65 drops / min; and the drying temperature is 105℃.

[0091] In step E32, the mass ratio of the precipitate to KH-570 is 1:0.2.

[0092] In step E42, the mass fraction of C7H7ZnCl is 3%.

[0093] In step E52, the heating rate is 4℃ / min; the holding temperature is 500℃; and the holding time is 6h.

[0094] Example 6 Example 6 provides a modified lithium manganese iron phosphate, the raw material of which includes LiFe 0.5 Mn 0.5 The mass ratio of PO4, C7H7ZnCl and silane is 1:0.06:0.08.

[0095] This embodiment also provides a method for preparing modified lithium manganese iron phosphate, the steps of which are basically the same as those in embodiment 2, except that the rotation speed is 2 rpm in step E12.

[0096] In step E22, the rotation speed is 20 rpm; the drip rate is 80 drops / min; and the drying temperature is 120℃.

[0097] In step E32, the mass ratio of the precipitate to KH-570 is 1:0.8.

[0098] In step E42, the mass fraction of C7H7ZnCl is 4%.

[0099] In step E52, the heating rate is 5℃ / min; the holding temperature is 700℃; and the holding time is 3h.

[0100] Comparative Example 1 provides a method for preparing modified lithium manganese iron phosphate. The steps are basically the same as those in Example 2, except that in step E22, when the suspension is hydrolyzed, the same amount of water as that in Example 2 is directly added.

[0101] Comparative Example 2 provides a method for preparing modified lithium manganese iron phosphate. The steps are basically the same as those in Example 2, except that in step E52, the mixture is directly placed in 700°C for sintering for 2 hours.

[0102] To verify the advancement of the modified lithium manganese iron phosphate and its preparation method provided in this embodiment of the invention, taking Example 2 as an example, the modified lithium manganese iron phosphate prepared in Example 2 was scanned using a scanning electron microscope, and the corresponding SEM image is shown in Figure 1. EDS elemental analysis was then performed, resulting in the elemental analysis diagrams shown in Figures 2 and 3. Figure 2 is the overall EDS elemental mapping diagram of the modified lithium manganese iron phosphate provided in Example 2, and Figure 3 is the EDS elemental mapping diagram of zinc in the modified lithium manganese iron phosphate provided in Example 2. The content of each element is shown in Table 1 below.

[0103] Table 1

[0104] The modified lithium manganese iron phosphate or lithium manganese iron phosphate provided in the examples and comparative examples were then made into coin cells and tested. Among them, 1. The assembly steps of the coin cell are as follows: (1) Positive electrode: Modified lithium manganese iron phosphate, conductive carbon black and polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 90:5:5, and N-methylpyrrolidone (NMP) is used as solvent to make a slurry. The slurry is uniformly coated on aluminum foil, dried, compacted, and vacuum dried at 120°C for 12h to obtain the positive electrode. The active material of the positive electrode is 12mg.

[0105] (2) Negative electrode: The negative electrode is a lithium metal sheet.

[0106] (3) The diaphragm is a polypropylene porous membrane, and the electrolyte is 1 mol / L LiPF6 / EC+DEC+DMC (EC:DEC:DMC=1:1:1 volume ratio).

[0107] EC: Ethylene Carbonate; DEC: Diethyl Carbonate; DMC: Dimethyl Carbonate.

[0108] 2. Testing: At 0.1C, the charge and discharge specific capacity was tested within a voltage range of 2.0V~4.3V. The calculation method for 0.1C efficiency is: 0.1C efficiency (%) = 0.1C discharge specific capacity (mAh / g) / 0.1C charge specific capacity (mAh / g) × 100%. The results are shown in Table 2 below.

[0109]

[0110] From Tables 1-2 and Figures 1-3 of the specification, at least the following conclusions can be drawn: (1) In Table 2, it can be seen from the comparison between Examples 1-6 and Comparative Example 1 that the modified lithium manganese iron phosphate provided in the embodiments of the present invention uses C7H7ZnCl as both a source of carbon and zinc doping and a pore-forming agent to form pores. The modified lithium manganese iron phosphate obtained has excellent conductivity, cycle stability and rate performance.

[0111] (2) In Table 2, it can be seen from the comparison between Example 2 and Comparative Example 1 that the silica sol obtained by the stepwise hydrolysis of silane can adsorb and encapsulate lithium manganese iron phosphate in situ and uniformly, so that lithium manganese iron phosphate is uniformly dispersed in the silica sol. Finally, the modified lithium manganese iron phosphate has high cycle stability.

[0112] (3) As can be seen from the comparison between Example 2 and Comparative Example 2 in Table 2, the preparation method of modified lithium manganese iron phosphate provided in this invention involves gradually raising the temperature and then holding it at a low temperature during sintering. This allows zinc to be embedded into the lithium manganese iron phosphate crystal structure at low temperatures, forming zinc doping. When the temperature is raised to 500℃~700℃ and held at that temperature, the remaining free C7H7ZnCl decomposes to release ZnCl2 and is released from the system, thus producing porous carbon-doped modified lithium manganese iron phosphate. This can shorten the Li + The diffusion path, improving the rate performance and cycle stability of the material.

[0113] (4) In Table 2, it can be seen from the comparison between Example 1 and Examples 2 to 6 that surface treatment of the precipitate can further improve the conductivity, cycle stability and rate performance of modified lithium manganese iron phosphate.

[0114] (5) As can be seen from Figures 1-3 and Table 1 in the specification, the modified lithium manganese iron phosphate provided in the embodiments of the present invention has a rich porous structure and is doped with zinc.

[0115] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A modified lithium manganese iron phosphate, characterized in that, The raw materials include lithium manganese iron phosphate, C7H7ZnCl and silane; the mass ratio of the lithium manganese iron phosphate, the C7H7ZnCl and the silane is 1:(0.01~0.06):(0.01~0.08).

2. The modified lithium manganese iron phosphate according to claim 1, characterized in that, The raw material satisfies at least one of the following characteristics (1) to (2): (1) The chemical formula of lithium manganese iron phosphate is: LiFe 1-y Mn y PO4; where 0.5≤y≤0.9; (2) The structural formula of C7H7ZnCl is: 。 3. A method for preparing modified lithium manganese iron phosphate, characterized in that, The preparation of the modified lithium manganese iron phosphate according to any one of claims 1 to 2 comprises the following steps: sintering the mixture to obtain the modified lithium manganese iron phosphate; the mixture comprises lithium manganese iron phosphate, C7H7ZnCl and silane.

4. The method for preparing modified lithium manganese iron phosphate according to claim 3, characterized in that, The preparation of the mixture includes the following steps: hydrolyzing the suspension to obtain a dried precipitate, mixing it with a C7H7ZnCl solution to obtain the mixture; the suspension contains silane and lithium manganese iron phosphate.

5. The method for preparing modified lithium manganese iron phosphate according to claim 4, characterized in that, The preparation of the mixture also includes the following step: surface treatment of the precipitate.

6. The method for preparing modified lithium manganese iron phosphate according to claim 5, characterized in that, The surface treatment step includes: mixing the precipitate with a silane coupling agent.

7. The method for preparing modified lithium manganese iron phosphate according to any one of claims 3 to 6, characterized in that, The sintering step includes: heating to 500℃~700℃ at a heating rate of 2℃ / min~5℃ / min and then holding at that temperature.

8. A positive electrode material, characterized in that, This includes modified lithium manganese iron phosphate prepared by the preparation method according to any one of claims 3 to 7.

9. A battery comprising the positive electrode material of claim 8.

10. An application of a modified lithium manganese iron phosphate, characterized in that, Application of modified lithium manganese iron phosphate prepared by any one of claims 3 to 7 in the field of battery materials.

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