Zinc manganate negative electrode material, method for preparing same by adopting coprecipitation method and application of zinc manganate negative electrode material
阅读说明：本技术 一种锰酸锌负极材料、采用共沉淀法制备其的方法及用途 (Zinc manganate negative electrode material, method for preparing same by adopting coprecipitation method and application of zinc manganate negative electrode material ) 是由 张天戈 邓松辉 陈志伟 王理 刘金成 刘建华 于 2020-12-28 设计创作，主要内容包括：本发明提供了一种锰酸锌负极材料、采用共沉淀法制备其的方法及用途,所述的方法包括：以锰源和锌源的混合盐溶液作原料,以氨水作共沉淀剂,采用共沉淀法制备ZnMn-2O-4负极材料。本发明提供了一种共沉淀法制备ZnMn-2O-4负极材料的方法,与常用的共沉淀剂相比,无需严格的物理条件即可得到性能绝佳的具有多孔纳米结构的ZnMn-2O-4颗粒,且该方法能耗和成本较低,对环境友好且适用于大规模产业化制备。(The invention provides a zinc manganate negative electrode material, a method for preparing the same by adopting a coprecipitation method and application thereof, wherein the method comprises the following steps: the mixed salt solution of manganese source and zinc source is used as raw material, ammonia water is used as coprecipitator, and the coprecipitation method is adopted to prepare ZnMn 2 O 4 And (3) a negative electrode material. The invention provides a coprecipitation method for preparing ZnMn 2 O 4 Compared with the common coprecipitator, the method of the cathode material can obtain ZnMn with excellent performance and a porous nano structure without strict physical conditions 2 O 4 The method has low energy consumption and cost, is environment-friendly and is suitable for large-scale industrial preparation.)
1. A method for preparing a zinc manganate negative electrode material by a coprecipitation method is characterized by comprising the following steps:
the mixed salt solution of a manganese source and a zinc source is used as a raw material, ammonia water is used as a coprecipitator, and a coprecipitation method is adopted to prepare the zinc manganate cathode material.
2. The method according to claim 1, wherein the preparation method specifically comprises:
dissolving a zinc source and a manganese source in deionized water to prepare a mixed salt solution, dropwise adding ammonia water serving as a coprecipitator into the mixed salt solution, and stirring to obtain a precipitate;
and (II) sequentially aging, filtering, washing and drying the precipitate to obtain a precursor, and sintering the precursor to obtain the zinc manganate cathode material.
3. The method of claim 2, wherein the zinc source of step (i) comprises any one or a combination of at least two of zinc sulfate, zinc chloride or zinc nitrate;
preferably, the manganese source comprises any one of manganese sulfate, manganese chloride or manganese nitrate or a combination of at least two of the manganese sulfate, the manganese chloride or the manganese nitrate;
preferably, the zinc source and the manganese source are respectively weighed according to the stoichiometric ratio of zinc manganate and are dissolved in deionized water;
preferably, the molar ratio of the zinc element in the zinc source and the manganese element in the manganese source is 1: 2.
4. The method according to claim 2 or 3, wherein the molar concentration of the ammonia water in the step (I) is 0.3-0.4 mol/L, and more preferably 0.32 mol/L;
preferably, the dropping amount of the ammonia water is 15-25 wt% of the total mass of the mixed salt solution;
preferably, the ammonia water is added into a constant pressure burette, and the dropping speed of the ammonia water is controlled by the constant pressure burette;
preferably, the dropping speed of the ammonia water is 2-4 s/drop.
5. The method according to any one of claims 2 to 4, wherein in the step (I), the mixed salt solution is continuously stirred during the dropwise addition of the aqueous ammonia;
preferably, the stirring speed is 300-400 r/min, and more preferably 350 r/min.
6. A process according to any one of claims 2 to 5, wherein the aging time is 10 to 15 hours, more preferably 12 hours;
preferably, the washing medium is distilled water;
preferably, the washing times are 1-5 times, and more preferably 3 times;
preferably, the drying mode is freeze drying;
preferably, the freeze drying temperature is-40 to-50 ℃;
preferably, the drying time is 70-80 h, and further preferably 72 h.
7. A method according to any of claims 2 to 6, wherein the precursor is sintered in a muffle furnace;
preferably, the sintering process comprises: heating the precursor from room temperature to a sintering temperature, and then sintering at the sintering temperature for 1-3 h;
preferably, the sintering temperature is 700-1000 ℃, and further preferably 800 ℃;
preferably, the heating rate from room temperature to the sintering temperature is 2-8 ℃/min, and more preferably 5 ℃/min.
8. The zinc manganate negative electrode material is characterized in that the zinc manganate negative electrode material is prepared by the preparation method of any one of claims 1 to 7.
9. A lithium ion battery is characterized by comprising a shell and a battery cell positioned in the shell, wherein the battery cell is obtained by sequentially laminating a positive pole piece, a diaphragm and a negative pole piece and then winding or laminating;
the negative pole piece comprises a negative pole current collector and a negative pole slurry coated on the negative pole current collector, wherein the negative pole slurry comprises the zinc manganate negative pole material of claim 8.
10. The lithium ion battery of claim 9, wherein the negative electrode slurry further comprises a conductive agent and a binder.
Technical Field
The invention belongs to the technical field of cathode materials, and relates to a cathode material, a method for preparing the same by adopting a coprecipitation method and application thereof, in particular to a zinc manganate cathode material, a method for preparing the same by adopting the coprecipitation method and application thereof.
Background
The lithium ion battery has the advantages of high energy density, no memory effect, long cycle life, environmental friendliness and the like, and is widely applied to the field of portable electronic equipment. In recent years, lithium ion batteries have attracted more and more attention in the field of high-power long-life batteries such as electric vehicles and hybrid electric vehicles. At present, graphite-based negative electrode materials are widely used for lithium ion batteries. On one hand, the carbon-based negative electrode material has the advantages of low price, electrochemical inertia and low charge and discharge platform; on the other hand, the lithium ion intercalation and deintercalation process provides deposition sites and reduces the formation of lithium dendrites. Welna et al use vertically aligned multi-walled carbon nanotubes as active electrode materials to achieve excellent electrochemical performance of lithium ion batteries. However, the theoretical specific capacity of the graphite negative electrode material is only 372mAh/g, the graphite negative electrode material is poor in compatibility with an electrolyte, and the graphite negative electrode material is easy to pulverize and fall off in the charging and discharging process, so that the energy density of the lithium ion battery is not high, and the requirements of a new generation of high-performance lithium ion battery are difficult to meet.
Transition metal oxides have been widely recognized as promising negative electrode materials for lithium ion batteries due to their high theoretical specific capacity, low cost, and environmental friendliness. Zinc manganate (ZnMn)2O4) The electrode material has the excellent characteristics of high specific capacity, abundant natural resources, environmental friendliness, lower working voltage and the like, and is considered to be a lithium ion battery cathode material with great research value and application prospect. In addition, Zn and Mn are different in electrode potential from each other, so that the material can be used as a mutually buffered body in the charge-discharge cycle process, the volume effect is favorably relieved, and the cycle performance of the material is improved.
Preparation of ZnMn at present2O4The electrode material is prepared by microemulsion method, electrostatic spinning method, and hydrothermal methodMethods, solvothermal methods, and the like.
CN107720829A discloses a preparation method of a lithium ion battery cathode material zinc manganate, wherein oxalic acid is used as a precipitator, and a coprecipitation method is used for preparing the zinc manganate. Specifically, the aqueous solution of manganese salt and zinc salt is slowly dropped into the ethanol solution of oxalic acid, a precursor is obtained through centrifugation, water washing, alcohol washing and vacuum drying, and the zinc manganate is obtained through high-temperature calcination of the precursor.
CN104577110A provides a preparation method of zinc manganate nanofiber negative electrode material for lithium ion battery, the method firstly utilizes electrostatic spinning technology to prepare PAN/PVP/C4H6ZnO4/C4H6MnO4And compounding the nano-fibers, and then calcining at high temperature to obtain the lithium battery cathode material zinc manganate nano-fibers.
CN108400324A discloses a lithium ion battery cathode material zinc manganate nanorod and a preparation method thereof, wherein the method comprises the following steps: calcining MnOOH powder in a tube furnace for 90-120 minutes to obtain a beta-MnO 2 nanorod; dissolving 2-methylimidazole in a methanol solution to obtain a 2-methylimidazole methanol solution, dissolving zinc nitrate hexahydrate in the methanol solution to obtain a zinc nitrate hexahydrate methanol solution, slowly adding the 2-methylimidazole methanol solution into the zinc nitrate hexahydrate methanol solution to obtain a mixed solution, dispersing the prepared beta-MnO 2 nanorod into the mixed solution, and magnetically stirring for 30 minutes to form a suspension; transferring the obtained suspension into a reaction kettle for carrying out hydrothermal reaction for 12-15 hours, and carrying out suction filtration, cleaning and drying on a precipitate obtained after the hydrothermal reaction to obtain a beta-MnO 2/ZIF-8 compound; and calcining the obtained beta-MnO 2/ZIF-8 compound for 2-3 hours to obtain the zinc manganate nanorod.
However, these methods have limited ZnMn due to high cost and complicated preparation process2O4Development and application of negative electrode materials. In conclusion, ZnMn with simple process, high yield, low cost and excellent lithium storage performance is sought2O4The preparation method of the lithium ion battery cathode material is particularly important.
Disclosure of Invention
Aiming at the prior artThe invention aims to provide a zinc manganate negative electrode material, a method for preparing the same by adopting a coprecipitation method and application thereof, wherein water is used as a solvent, ammonia water is used as a precipitator, and ZnMn with a porous nano structure and excellent performance can be obtained without strict physical conditions2O4The method has low energy consumption and cost, is environment-friendly and is suitable for large-scale industrial preparation.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a coprecipitation method for preparing ZnMn2O4A method of making a negative electrode material, the method comprising:
the mixed salt solution of manganese source and zinc source is used as raw material, ammonia water is used as coprecipitator, and the coprecipitation method is adopted to prepare ZnMn2O4And (3) a negative electrode material.
The invention provides a coprecipitation method for preparing ZnMn2O4Compared with the common coprecipitator, the method of the cathode material takes the ammonia water as the coprecipitator has the advantages that the coprecipitator can react with a plurality of metal ions to generate insoluble weak base or amphoteric hydroxide, and ZnMn with a porous nano structure and excellent performance can be obtained without strict physical conditions2O4The method has low energy consumption and cost, is environment-friendly and is suitable for large-scale industrial preparation. ZnMn2O4The porous structure of the particles can provide a larger electrode reaction interface and promote Li+And enhances the kinetics of the electrochemical reaction, resulting in a higher reversible capacity of the electrode material. In addition, particles with porous nanostructures can provide buffer space to efficiently accommodate repeated Li+Mechanical stress caused by insertion/extraction.
As a preferred technical scheme of the present invention, the preparation method specifically comprises:
dissolving a zinc source and a manganese source in deionized water to prepare a mixed salt solution, dropwise adding ammonia water serving as a coprecipitator into the mixed salt solution, and stirring to obtain a precipitate;
(II) aging and passing the precipitateFiltering, washing and drying to obtain a precursor, and sintering the precursor to obtain ZnMn2O4And (3) a negative electrode material.
As a preferred technical scheme of the invention, the zinc source in the step (I) comprises any one or a combination of at least two of zinc sulfate, zinc chloride or zinc nitrate;
preferably, the manganese source comprises any one of manganese sulfate, manganese chloride or manganese nitrate or a combination of at least two of the manganese sulfate, the manganese chloride or the manganese nitrate;
preferably, the zinc source and manganese source are based on ZnMn2O4Respectively weighing the stoichiometric ratio and dissolving in deionized water;
preferably, the molar ratio of the zinc element in the zinc source and the manganese element in the manganese source is 1: 2.
In a preferred embodiment of the present invention, the molar concentration of the aqueous ammonia in step (I) is 0.3 to 0.4mol/L, and may be, for example, 0.30mol/L, 0.31mol/L, 0.32mol/L, 0.33mol/L, 0.34mol/L, 0.35mol/L, 0.36mol/L, 0.37mol/L, 0.38mol/L, 0.39mol/L, or 0.40mol/L, but is not limited to the above-mentioned values, and other values not mentioned in the above-mentioned range are also applicable, and more preferably 0.32 mol/L.
The amount of the aqueous ammonia added dropwise is preferably 15 to 25 wt% based on the total mass of the mixed salt solution, but is not limited to the above-mentioned values, and may be 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, for example, and other values not mentioned in this range are also applicable.
Preferably, the ammonia water is added into a constant pressure burette, and the dropping speed of the ammonia water is controlled by the constant pressure burette.
Preferably, the dropping speed of the ammonia water is 2-4 s/drop, for example, 2 drops, 2.5 drops, 3 drops, 3.5 drops or 4 drops, but the dropping speed is not limited to the values listed, and other values not listed in the range of the values are also applicable.
As a preferable technical scheme of the invention, in the step (I), the mixed salt solution is continuously stirred in the process of dropwise adding ammonia water.
Preferably, the stirring speed is 300-400 r/min, such as 300r/min, 310r/min, 320r/min, 330r/min, 340r/min, 350r/min, 360r/min, 370r/min, 380r/min, 390r/min or 400r/min, but not limited to the enumerated values, and other non-enumerated values in the numerical range are also applicable, and more preferably 350 r/min.
As a preferred embodiment of the present invention, the aging time is 10 to 15 hours, for example, 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours, 12.5 hours, 13 hours, 13.5 hours, 14 hours, 14.5 hours or 15 hours, and more preferably 12 hours.
Preferably, the washing medium is distilled water.
Preferably, the number of washing is 1 to 5, for example, 1, 2, 3, 4 or 5, but not limited to the recited values, and other values not recited within the range of values are also applicable, and more preferably 3.
Preferably, the drying mode is freeze drying.
Preferably, the freeze-drying temperature is-40 to-50 ℃, and may be, for example, -40 ℃, -41 ℃, -42 ℃, -43 ℃, -44 ℃, -45 ℃, -46 ℃, -47 ℃, -48 ℃, -49 ℃, or-50 ℃, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the drying time is 70 to 80 hours, for example, 70 hours, 71 hours, 72 hours, 73 hours, 74 hours, 75 hours, 76 hours, 77 hours, 78 hours, 79 hours or 80 hours, but is not limited to the recited values, and other values not recited in the range of the values are also applicable, and 72 hours is more preferable.
As a preferable technical scheme of the invention, the precursor is sintered in a muffle furnace.
Preferably, the sintering process comprises: the precursor is heated from room temperature to a sintering temperature, and then sintered at the sintering temperature for 1 to 3 hours, for example, 1.0 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, or 3.0 hours, but not limited to the recited values, and other values in the range of the recited values are also applicable.
Preferably, the sintering temperature is 700 to 1000 ℃, for example 700 ℃, 720 ℃, 740 ℃, 760 ℃, 780 ℃, 800 ℃, 820 ℃, 840 ℃, 860 ℃, 880 ℃, 900 ℃, 920 ℃, 940 ℃, 960 ℃, 980 ℃ or 1000 ℃, but not limited to the recited values, and other values not recited within the range of values are also applicable, and more preferably 800 ℃.
In the invention, the selection of the sintering temperature is crucial, the sintering temperature is particularly limited to 700-1000 ℃, and when the sintering temperature is lower than 700 ℃, an inappropriate precursor compound can be generated; when the sintering temperature is higher than 1000 ℃, the crystal structure is destroyed.
Preferably, the heating rate from room temperature to the sintering temperature is 2 to 8 ℃/min, for example, 2.0 ℃/min, 2.5 ℃/min, 3.0 ℃/min, 3.5 ℃/min, 4.0 ℃/min, 4.5 ℃/min, 5.0 ℃/min, 6.0 ℃/min, 6.5 ℃/min, 7.0 ℃/min, 7.5 ℃/min, or 8.0 ℃/min, but not limited to the values listed, and other values not listed in the range of values are also applicable, and further 5 ℃/min is preferable.
In the invention, the selection of the heating rate is crucial, the heating rate is specially limited to be 2-8 ℃/min, when the heating rate is lower than 2 ℃/min, the prepared material has irregular appearance, and when the heating rate is higher than 8 ℃/min, the material structure is cracked, and the crystal structure is damaged.
In a second aspect, the invention provides a ZnMn2O4Negative electrode material, the ZnMn2O4The negative electrode material is prepared by the preparation method of the first aspect.
In a third aspect, the present invention provides a lithium ion battery, where the lithium ion battery includes a housing and a battery cell located inside the housing, and the battery cell is obtained by sequentially stacking a positive electrode plate, a diaphragm, and a negative electrode plate and then winding or stacking the positive electrode plate, the diaphragm, and the negative electrode plate.
The negative pole piece comprises a negative pole current collector and negative pole slurry coated on the negative pole current collector, and the negative pole slurry comprises ZnMn of the second aspect2O4And (3) a negative electrode material.
As a preferable technical solution of the present invention, the negative electrode slurry further includes a conductive agent and a binder.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a coprecipitation method for preparing ZnMn2O4Compared with the common coprecipitator, the method of the cathode material takes the ammonia water as the coprecipitator has the advantages that the coprecipitator can react with a plurality of metal ions to generate insoluble weak base or amphoteric hydroxide, and ZnMn with a porous nano structure and excellent performance can be obtained without strict physical conditions2O4The method has low energy consumption and cost, is environment-friendly and is suitable for large-scale industrial preparation. ZnMn2O4The porous structure of the particles can provide a larger electrode reaction interface and promote Li+And enhances the kinetics of the electrochemical reaction, resulting in a higher reversible capacity of the electrode material. In addition, particles with porous nanostructures can provide buffer space to efficiently accommodate repeated Li+Mechanical stress caused by insertion/extraction.
Drawings
FIG. 1 shows ZnMn prepared in example 3 of the present invention2O4XRD pattern of the negative electrode material.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
Example 1
This example provides a coprecipitation process for preparing ZnMn2O4The method for preparing the anode material specifically comprises the following steps:
(1) zinc sulfate and manganese sulfate according to ZnMn2O4Respectively weighing stoichiometric ratio, dissolving in deionized water to prepare a mixed salt solution, wherein the molar ratio of zinc element in a zinc source to manganese element in a manganese source is 1: 2; adding 0.3mol/L coprecipitator ammonia water into a constant pressure burette, dropwise adding the ammonia water into the mixed salt solution, and controlling ammonia through the constant pressure buretteThe dropping speed of water is 2 s/drop, the mixed salt solution is continuously stirred to obtain a precipitate in the process of dropping ammonia water, the stirring speed is 300r/min, and the total dropping amount of the ammonia water is 15 wt% of the total mass of the mixed salt solution;
(2) aging the precipitate for 10h, filtering, washing with distilled water for 1 time, freeze-drying at-40 deg.C for 70h to obtain a precursor, heating the precursor in a muffle furnace at a temperature rise rate of 2 deg.C/min from room temperature to 700 deg.C, and sintering at 700 deg.C for 1h to obtain ZnMn2O4And (3) a negative electrode material.
Example 2
This example provides a coprecipitation process for preparing ZnMn2O4The method for preparing the anode material specifically comprises the following steps:
(1) zinc chloride and manganese chloride in accordance with ZnMn2O4Respectively weighing stoichiometric ratio, dissolving in deionized water to prepare a mixed salt solution, wherein the molar ratio of zinc element in a zinc source to manganese element in a manganese source is 1: 2; adding 0.32mol/L coprecipitator ammonia water into a constant pressure burette, dropwise adding the ammonia water into the mixed salt solution, controlling the dropwise adding speed of the ammonia water to be 2 s/drop through the constant pressure burette, continuously stirring the mixed salt solution to obtain a precipitate in the process of dropwise adding the ammonia water, wherein the stirring speed is 320r/min, and the total dropwise adding amount of the ammonia water is 16 wt% of the total mass of the mixed salt solution;
(2) aging the precipitate for 11h, filtering, washing with distilled water for 2 times, freeze-drying at-42 deg.C for 72h to obtain precursor, heating the precursor in a muffle furnace at a temperature rise rate of 3 deg.C/min from room temperature to 760 deg.C, and sintering at 760 deg.C for 1.4h to obtain ZnMn2O4And (3) a negative electrode material.
Example 3
This example provides a coprecipitation process for preparing ZnMn2O4The method for preparing the anode material specifically comprises the following steps:
(1) zinc nitrate and manganese nitrate in accordance with ZnMn2O4The stoichiometric ratio is respectively weighed and dissolved in deionized water to prepare a mixed salt solution,the molar ratio of the zinc element in the zinc source to the manganese element in the manganese source is 1: 2; adding 0.34mol/L coprecipitator ammonia water into a constant pressure burette, dropwise adding the ammonia water into the mixed salt solution, controlling the dropwise adding speed of the ammonia water to be 3 s/drop through the constant pressure burette, continuously stirring the mixed salt solution to obtain a precipitate in the process of dropwise adding the ammonia water, wherein the stirring speed is 340r/min, and the total dropwise adding amount of the ammonia water is 20 wt% of the total mass of the mixed salt solution;
(2) aging the precipitate for 12h, filtering, washing with distilled water for 3 times, freeze-drying at-44 deg.C for 74h to obtain a precursor, placing the precursor in a muffle furnace, heating from room temperature to 820 deg.C at a heating rate of 4 deg.C/min, and sintering at 820 deg.C for 1.8h to obtain ZnMn2O4And (3) a negative electrode material.
Preparation of the obtained ZnMn2O4The XRD pattern of the cathode material is shown in figure 1, and as can be seen from figure 1, the diffraction peaks of the material prepared by the method are equal to those of ZnMn2O4The standard card JCPDS 77-0470 corresponds to each other one by one, which shows that the prepared sample is ZnMn2O4。
Example 4
This example provides a coprecipitation process for preparing ZnMn2O4The method for preparing the anode material specifically comprises the following steps:
(1) zinc sulfate and manganese chloride according to ZnMn2O4Respectively weighing stoichiometric ratio, dissolving in deionized water to prepare a mixed salt solution, wherein the molar ratio of zinc element in a zinc source to manganese element in a manganese source is 1: 2; adding 0.36mol/L coprecipitator ammonia water into a constant pressure burette, dropwise adding the ammonia water into the mixed salt solution, controlling the dropwise adding speed of the ammonia water to be 3 s/drop through the constant pressure burette, continuously stirring the mixed salt solution to obtain a precipitate in the process of dropwise adding the ammonia water, wherein the stirring speed is 360r/min, and the total dropwise adding amount of the ammonia water is 21 wt% of the total mass of the mixed salt solution;
(2) aging the precipitate for 13h, filtering, washing with distilled water for 3 times, freeze-drying at-46 deg.C for 76h to obtain precursor, placing the precursor in muffle furnace at 5 deg.C/mHeating the in to 880 ℃ from room temperature at the heating rate, and then sintering the in at 880 ℃ for 2.2h to obtain ZnMn2O4And (3) a negative electrode material.
Example 5
This example provides a coprecipitation process for preparing ZnMn2O4The method for preparing the anode material specifically comprises the following steps:
(1) zinc chloride and manganese nitrate in accordance with ZnMn2O4Respectively weighing stoichiometric ratio, dissolving in deionized water to prepare a mixed salt solution, wherein the molar ratio of zinc element in a zinc source to manganese element in a manganese source is 1: 2; adding 0.38mol/L coprecipitator ammonia water into a constant-pressure burette, dropwise adding the ammonia water into the mixed salt solution, controlling the dropwise adding speed of the ammonia water to be 4 s/drop through the constant-pressure burette, continuously stirring the mixed salt solution to obtain a precipitate in the process of dropwise adding the ammonia water, wherein the stirring speed is 380r/min, and the total dropwise adding amount of the ammonia water is 23 wt% of the total mass of the mixed salt solution;
(2) aging the precipitate for 14h, filtering, washing with distilled water for 4 times, freeze-drying at-48 ℃ for 78h to obtain a precursor, putting the precursor into a muffle furnace, heating from room temperature to 940 ℃ at the heating rate of 6 ℃/min, and sintering at 940 ℃ for 2.6h to obtain ZnMn2O4And (3) a negative electrode material.
Example 6
This example provides a coprecipitation process for preparing ZnMn2O4The method for preparing the anode material specifically comprises the following steps:
(1) zinc nitrate and manganese sulphate in the form of ZnMn2O4Respectively weighing stoichiometric ratio, dissolving in deionized water to prepare a mixed salt solution, wherein the molar ratio of zinc element in a zinc source to manganese element in a manganese source is 1: 2; adding 0.4mol/L coprecipitator ammonia water into a constant pressure burette, dropwise adding the ammonia water into a mixed salt solution, controlling the dropwise adding speed of the ammonia water to be 4 s/drop through the constant pressure burette, continuously stirring the mixed salt solution to obtain a precipitate in the process of dropwise adding the ammonia water, wherein the stirring speed is 400r/min, and the total dropwise adding amount of the ammonia water is the mixed salt solution25 wt% of the total mass;
(2) aging the precipitate for 15h, filtering, washing with distilled water for 5 times, freeze-drying at-50 deg.C for 80h to obtain precursor, heating the precursor in a muffle furnace at a temperature rise rate of 8 deg.C/min from room temperature to 1000 deg.C, and sintering at 1000 deg.C for 3h to obtain ZnMn2O4And (3) a negative electrode material.
Example 7
The difference between this example and example 3 is that in step (1), the molar concentration is 0.25mol/L, and other process parameters and operation steps are exactly the same as those in example 1.
Example 8
The difference between this example and example 3 is that in step (1), the molar concentration is 0.45mol/L, and other process parameters and operation steps are exactly the same as those in example 1.
Example 9
The difference between this example and example 3 is that in step (1), the dropping amount of ammonia water is 15 wt% of the total mass of the mixed salt solution, and other process parameters and operation steps are exactly the same as those in example 1.
Example 10
The difference between this example and example 3 is that in step (1), the dropping amount of ammonia water is 25 wt% of the total mass of the mixed salt solution, and other process parameters and operation steps are completely the same as those in example 1.
Example 11
The difference between this example and example 3 is that in step (2), the sintering temperature is 600 ℃, and other process parameters and operation steps are exactly the same as those in example 1.
Example 12
The difference between this example and example 3 is that in step (2), the sintering temperature is 1100 ℃, and other process parameters and operation steps are exactly the same as those in example 1.
Example 13
The difference between this example and example 3 is that in step (2), the temperature rise rate is 1.5 ℃/min, and other process parameters and operation steps are exactly the same as those in example 1.
Example 14
The difference between this example and example 3 is that in step (2), the temperature rise rate is 9 ℃/min, and other process parameters and operation steps are exactly the same as those in example 1.
Comparative example 1
The comparative example provides a coprecipitation method for preparing ZnMn2O4The method for preparing the anode material specifically comprises the following steps:
(1) zinc sulfate, zinc chloride or nitrate and manganese sulfate, manganese chloride or nitrate according to ZnMn2O4Respectively weighing stoichiometric ratio, dissolving in deionized water to prepare a mixed salt solution, wherein the molar ratio of zinc element in a zinc source to manganese element in a manganese source is 1: 2; dissolving 0.15mol of oxalic acid in 100mL of absolute ethyl alcohol, stirring until the oxalic acid is completely dissolved to obtain an alcoholic solution of the oxalic acid as a coprecipitator, dropwise adding the alcoholic solution of the oxalic acid into the mixed salt solution, controlling the dropwise adding speed of ammonia water to be 3 s/drop through a constant-pressure burette, continuously stirring the mixed salt solution to obtain a precipitate in the process of dropwise adding the ammonia water, wherein the stirring speed is 340r/min, and the total dropwise adding amount of the ammonia water is 20 wt% of the total mass of the mixed salt solution;
(2) aging the precipitate for 12h, filtering, washing with distilled water for 3 times, freeze-drying at the temperature of 74h to obtain a precursor, putting the precursor into a muffle furnace, heating from room temperature to 820 ℃ at the heating rate of 4 ℃/min, and sintering at 820 ℃ for 1.8h to obtain ZnMn2O4And (3) a negative electrode material.
The lithium ion battery is prepared by the following method:
(1) preparing a positive pole piece: the method comprises the steps of fully and uniformly stirring a nickel cobalt lithium manganate positive electrode material, a conductive agent carbon nano tube and a binder polyvinylidene fluoride (PVDF) in an N-methyl pyrrolidone solvent according to a mass ratio of 96:2:2, coating the mixture on an aluminum foil, and drying and cold pressing the aluminum foil to obtain a positive electrode piece.
(2) Negative pole pieceThe preparation of (1): ZnMn obtained by comparing examples 1-12 and comparative example 12O4The negative pole piece is prepared by the steps of fully stirring and uniformly mixing a negative pole material, a conductive agent acetylene black, a binder Styrene Butadiene Rubber (SBR) and a thickening agent sodium carboxymethyl cellulose (CMC) in deionized water according to a mass ratio of 96:2:1:1, coating the mixture on a copper foil, and drying and cold pressing the mixture.
(3) And (3) isolation film: polyethylene (PE) porous polymeric films were used as separators.
(4) Preparing an electrolyte: 1.2mol/L LiPF6Adding the mixture into a solvent of dimethyl carbonate, diethyl carbonate and ethylene carbonate in a mass ratio of 1:1: 1. And simultaneously adding 2.1 wt% of 1, 3, 6-hexanetrinitrile, succinonitrile and adiponitrile in a mass ratio of 1:1:1 as a high-voltage protection additive.
And stacking the positive pole piece, the isolating film and the negative pole piece in sequence, wherein the diaphragm is positioned between the positive pole and the negative pole to play a role in isolating, and winding or laminating. And (4) placing the battery core in an outer package, injecting electrolyte and packaging.
The prepared lithium ion battery is subjected to the following performance tests:
(1) and (3) capacity testing: ZnMn obtained in 10 each of examples and comparative examples2O4The negative electrode material is made into a lithium ion battery, and the lithium ion battery is charged to 4.4V at room temperature by constant current of 0.1C multiplying power, and then is charged to the current of less than 0.02C under the condition of 4.4V constant voltage, so that the lithium ion battery is in a 4.4V full charge state. Then constant current discharge is carried out to 2.5V under the multiplying power of 0.1C, the discharge capacity is obtained, and the discharge gram capacity is calculated by adopting the following formula:
discharge capacity-discharge capacity/ZnMn2O4Mass of the negative electrode material.
(2) Cycle capacity retention rate test: ZnMn obtained in 10 each of examples and comparative examples2O4The negative electrode material is made into a lithium ion battery, and the lithium ion battery is subjected to charge-discharge cycle through the following test steps:
charging and discharging at room temperature, and performing constant-current and constant-voltage charging at a charging current of 0.5C until the upper limit voltage is 4.4V and the cutoff current is 0.02C; then standing for 20 minutes; then, constant current discharge was performed at a discharge current of 0.5C until 2.5V.
The discharge capacity retention rate of the lithium ion battery is calculated by adopting the following formula:
the cycle capacity retention rate test ═ (discharge capacity at the n-th cycle/discharge capacity at the first cycle) × 100%.
The results of 0.1C gram capacity, first charge and discharge efficiency, and capacity retention after 100 cycles are shown in table 1.
TABLE 1
As can be seen from the data in table 1:
(1) the test results of examples 1-6 and comparative example 1 show that the gram discharge capacity, the first charge-discharge efficiency and the capacity retention rate of the lithium ion batteries obtained in examples 1-6 are all kept at higher levels, even slightly better than that of comparative example 1. The invention replaces the alcoholic solution of oxalic acid adopted in the comparative example 1 with ammonia water as the coprecipitator, which has the advantages that the ammonia water can react with a plurality of metal ions to generate insoluble weak base or amphoteric hydroxide, and ZnMn with porous nano structure and excellent performance can be obtained without strict physical conditions2O4The method has low energy consumption and cost, is environment-friendly and is suitable for large-scale industrial preparation.
(2) It is obvious from the test results of the embodiment 3, the embodiment 7 and the embodiment 8 that the gram-discharge capacity, the first charge-discharge efficiency and the capacity retention rate of the lithium ion battery obtained in the embodiment 3 are all higher than those of the embodiment 7 and the embodiment 8, because the molar concentration of the ammonia water in the embodiment 7 is too low, and the molar concentration of the ammonia water in the embodiment 8 is too high, the test results show that the molar concentration of the ammonia water is too high or too low, which affects the performances of the lithium ion battery.
(3) It is obvious from the test results of the examples 3, 9 and 10 that the gram-discharge capacity, the first charge-discharge efficiency and the capacity retention rate of the lithium ion battery obtained in the example 3 are all higher than those of the examples 9 and 10, because the dropwise addition amount of the ammonia water in the example 9 is too small, and the dropwise addition amount of the ammonia water in the example 10 is too large, the test results show that the excessive or too small dropwise addition amount of the ammonia water can affect various performances of the lithium ion battery, because when the dropwise addition amount of the ammonia water is too small, the ammonia water cannot generate hydroxide precipitates with metal ions; when the dropping amount of the ammonia water is too much, resource waste is caused.
(4) As is apparent from the test results of the examples 3, 11 and 12, the gram discharge capacity, the first charge-discharge efficiency and the capacity retention rate of the lithium ion battery obtained in the example 3 are all higher than those of the examples 11 and 12, because the sintering temperature in the example 11 is too low, and the sintering temperature in the example 12 is too high, the test results show that the sintering temperature is too low or too high, which affects the performances of the lithium ion battery, because when the sintering temperature is too low, the precursor material cannot be generated; when the sintering temperature is too high, the crystal structure of the material is destroyed.
(5) As is apparent from the test results of the embodiments 3, 13, and 14, the gram-discharge capacity, the first charge-discharge efficiency, and the capacity retention rate of the lithium ion battery obtained in the embodiment 3 are all higher than those of the embodiments 13 and 14, because the temperature rising rate in the embodiment 11 is too slow, and the temperature rising rate in the embodiment 12 is too fast, the test results show that the too fast or too slow temperature rising rate affects various performances of the lithium ion battery, because the material morphology is irregular when the temperature rising rate is too slow; when the temperature rise rate is too fast, the crystal structure on the surface of the material is damaged.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.