CN111342008A - Potassium fluoride doped lithium-rich manganese-based material and preparation method and application thereof - Google Patents

Potassium fluoride doped lithium-rich manganese-based material and preparation method and application thereof Download PDF

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CN111342008A
CN111342008A CN202010115495.8A CN202010115495A CN111342008A CN 111342008 A CN111342008 A CN 111342008A CN 202010115495 A CN202010115495 A CN 202010115495A CN 111342008 A CN111342008 A CN 111342008A
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potassium fluoride
lithium
rich manganese
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doped lithium
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张震
王倩
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South China University of Technology SCUT
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Abstract

The invention discloses a potassium fluoride doped lithium-rich manganese-based material and a preparation method and application thereof. The preparation method comprises the following steps: preparing a precipitant solution consisting of sodium carbonate and ammonia water, preparing a transition metal salt solution, preparing a transition metal carbonate precursor by a coprecipitation method, preparing lithium from the precursor, calcining at high temperature, and adding potassium fluoride in the process of preparing lithium to prepare the potassium fluoride-doped lithium-rich manganese-based positive electrode material. The invention uses potassium fluoride in lithium ion batteryThe doping modification of the anode material is carried out, the doping method is simple, the electrochemical performance of the obtained potassium fluoride doped lithium-rich manganese-based material is obviously improved when the potassium fluoride doped lithium-rich manganese-based material is used for the anode material of the lithium ion battery, and the doping modification is carried out at 10C (1C-200 mA g)‑1) At a current density of 131.57mAh g‑1The capacity retention rate reaches 93.37% after 1500 cycles.

Description

Potassium fluoride doped lithium-rich manganese-based material and preparation method and application thereof
Technical Field
The invention belongs to the technical field of lithium ion battery materials, and particularly relates to a potassium fluoride doped lithium-rich manganese-based material, and a preparation method and application thereof.
Background
The lithium ion battery, as the most conventional green high-energy battery, is widely used in mobile phones, notebook computers and other portable devices due to its advantages of high energy density, high specific capacity, no memory effect, environmental friendliness, etc. In recent years, with the widespread use of electric vehicles, there have been high demands for cost in addition to high demands for cycle performance and energy density of lithium ion batteries. The performance, service life and use cost of the lithium ion battery are deeply influenced by the anode material as one of the very important components of the lithium ion battery, so that the design and synthesis of the lithium ion battery anode material with high capacity, good rate performance, long cycle life and low price is one of the important development directions of the lithium ion battery, and the wide attention is paid to how to improve the performance of the lithium ion battery anode material.
The lithium-rich manganese-based positive electrode material is also called a lithium-rich ternary positive electrode material due to its extremely high capacity (over 250mAh g)-1) And energy density (over 900Wh kg)-1) The lithium ion battery has attracted great attention and is one of the most promising positive electrode materials of the lithium ion battery. However, the defects of poor rate capability and cycle stability and the like of the lithium-rich manganese-based cathode material limit the industrial application of the lithium-rich manganese-based cathode material. In order to improve the electrochemical performance of the lithium-rich manganese-based positive electrode material, many modification strategies have been studied, and the common methods mainly include element doping, surface modification, morphological design and the like.
Ion doping is a method for effectively improving the performance of a lithium ion positive electrode material, and in the doping research, anions and cations with physical and chemical properties similar to those of a replaced element are generally selected for doping. Existing ion doping includes both anionic and cationic doping methods. The commonly used cationic dopings are mainly: k+、Na+、Rb+、Mg2+、Al3+、Ti4+And Nb5+Etc., common anion doping is mainly: f-. However, the existing co-doping method is complicated and still has disadvantages, such as Na reported in the literature (Nano Energy 58(2019) 786-+And F-The lithium-rich manganese-based anode material is modified together, and sodium acetate is used as a sodium sourcePolyvinylidene fluoride (PVDF) is used as a fluorine source, the sources of negative and positive doped ions are different, more raw materials are consumed, the manufacturing process is more complicated, and the prepared material is 1C (1C is 200mA g)-1) The discharge capacity is only 202mAh g at current density-1After one hundred cycles, the capacity retention rate is only 93%, and the discharge specific capacity under the large current density of 5C is only 130mAh g-1The disadvantages of poor long-cycle stability and poor rate performance are still not solved.
Disclosure of Invention
In order to improve the performance of the lithium-rich manganese-based positive electrode material and simplify the prior doping technology, the invention mainly aims to provide a potassium fluoride-doped lithium-rich manganese-based material, wherein potassium ions and fluoride ions for doping are derived from the same compound of potassium fluoride.
The invention also aims to provide a preparation method of the potassium fluoride doped lithium-rich manganese-based material.
The invention further aims to provide application of the potassium fluoride doped lithium-rich manganese-based material in preparation of a lithium ion battery anode material.
The invention adopts the co-doping of potassium ions and fluorine ions which are not reported in documents at present, and simultaneously maintains the advantages of cation and anion doping. The potassium ions are doped into the lithium layer of the material, and the potassium ions have larger radius than the lithium ions but have similar properties with the lithium ions, so that the interlayer spacing of the lithium layer is increased, the back-and-forth deintercalation of the lithium ions is facilitated, and the material has good rate performance; f ion doping can replace O-M (M ═ Ni, Co and Mn) bonds through F-M (M ═ Ni, Co and Mn) bonds with stronger bond energy, so that the structure of the material is more stable, and the cycle performance of the material is improved. In order to make up for the defects, the lithium-rich manganese-based positive electrode material adopts potassium fluoride as a source of potassium ions and fluorine ions, is simple and convenient to operate, does not introduce impurities, is energy-saving and environment-friendly, has good cycle performance and rate capability, and has 131.57mAhg between current density of 10C and charging and discharging voltage range of 2.5-4.6V-1The capacity retention rate reaches 93.37 percent after 1500 cycles.
The purpose of the invention is realized by the following technical scheme:
a preparation method of a potassium fluoride doped lithium-rich manganese-based material comprises the following steps:
(1) adding a precipitant and ammonia water into water to prepare a solution, and stirring until the precipitant and the ammonia water are completely dissolved to obtain a precipitant solution;
(2) dissolving nickel salt, cobalt salt and manganese salt in water to prepare a mixed solution, thereby obtaining a transition metal salt solution;
(3) and (3) adding the precipitant solution obtained in the step (1) into the transition metal salt solution obtained in the step (2), stirring while adding, and filtering, washing and drying after complete precipitation reaction to obtain a transition metal carbonate precursor.
(4) Uniformly mixing a transition metal carbonate precursor with a lithium source and potassium fluoride, grinding, pre-calcining and calcining to obtain the potassium fluoride doped lithium-rich manganese-based material, wherein the label of the potassium fluoride doped lithium-rich manganese-based material is Li1.2- xKxNi0.2Co0.08Mn0.52O2-yFy,0.01≤x≤0.06,0.01≤y≤0.06。
Preferably, the concentration of the precipitating agent in the step (1) in water is 0.05-2 mol/L.
Preferably, the volume ratio of the ammonia water to the water in the step (1) is 1: 100-3: 100.
preferably, the concentration of the ammonia water in the step (1) is 10-25%.
Preferably, in the nickel salt, cobalt salt and manganese salt in the step (2), the ratio of Ni: co: the molar ratio of Mn is 0.2: 0.08:0.52.
Preferably, the concentration of the nickel salt in the mixed solution in the step (2) is 0.05-2 mol/L.
Preferably, the volume ratio of the precipitant solution to the transition metal salt solution in step (3) is 3: 1-1: 1.
preferably, the adding in the step (3) is dropwise adding, and the time of the dropwise adding is 1-3 h. The dropwise addition is to make the precipitation reaction more complete, and under the condition that ammonia water is used as a complexing agent, three metal ions can be simultaneously precipitated. Sufficient reaction time is given for precipitation so as to enable particles to grow excellent morphology, and the morphology of the precursor directly influences the electrochemical performance of the material.
Preferably, the stirring speed in the step (3) is 200-600 rpm, and more preferably 400 rpm; the reaction time of the precipitation reaction is 12-15 h.
Preferably, the ratio of the molar amount of Ni in the transition metal carbonate precursor in step (4) to the molar amount of Li in the lithium source is 0.2:1.14 to 1.19.
Preferably, the ratio of the molar amount of Ni in the transition metal carbonate precursor in step (4) to the molar amount of K in the potassium fluoride is 0.2:0.01 to 0.06.
Preferably, the precalcination and the calcination in step (4) are carried out in the following manner: heating to 400-600 ℃ at a heating rate of 3-5 ℃/min, and pre-sintering for 4-6 h; then heating to 800-950 ℃ at a heating rate of 3-5 ℃/min, and calcining at high temperature for 10-20 h; more preferably: heating to 450 ℃ at the heating rate of 5 ℃/min, keeping the temperature for presintering for 5h, then heating to 900 ℃ at the heating rate of 5 ℃/min, and calcining for 15 h.
Preferably, the ratio of the molar amount of Ni in the transition metal carbonate precursor in step (4) to the molar amount of Li in the lithium source is 0.2:1.17 to 1.19.
Preferably, the ratio of the molar amount of Ni in the transition metal carbonate precursor in the step (4) to the molar amount of K in the potassium fluoride is 0.2:0.01 to 0.03.
Preferably, the precipitant in step (1) is one or more of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide, and more preferably sodium carbonate.
Preferably, the nickel salt in step (2) is one or more of nickel sulfate, nickel acetate and nickel nitrate, and more preferably nickel acetate.
Preferably, the cobalt salt in step (2) is one or more of cobalt sulfate, cobalt acetate, cobalt nitrate and cobalt chloride, and more preferably cobalt acetate.
Preferably, the manganese salt in the step (2) is one or more than two of manganese sulfate, manganese acetate and manganese nitrate.
Preferably, the lithium source in step (4) is one or both of lithium carbonate and lithium hydroxide, and more preferably lithium carbonate.
The potassium fluoride-doped lithium-rich manganese-based material prepared by the preparation method of the potassium fluoride-doped lithium-rich manganese-based material.
The potassium fluoride-doped lithium-rich manganese-based material is applied to the preparation of the lithium ion battery anode material.
Preferably, the application of the potassium fluoride doped lithium-rich manganese-based material in the preparation of the lithium ion battery anode material comprises the following steps: and mixing the potassium fluoride-doped lithium-rich manganese-based material, acetylene black and PVDF for pulping, and then coating the obtained product on an aluminum foil to obtain the lithium ion battery anode.
More preferably, the method comprises the following steps: mixing the potassium fluoride-doped lithium-rich manganese-based positive electrode material, acetylene black and PVDF according to the mass ratio of 80:10:10 to prepare slurry, and coating the slurry on an aluminum foil to obtain the lithium ion battery positive electrode.
Further preferably, the application comprises the following steps: weighing 0.2g of potassium fluoride-doped lithium-rich manganese-based positive electrode material, 0.025g of PVDF and 0.025g of acetylene black, uniformly mixing and grinding the materials, transferring the materials into a small glass bottle, adding 1mLNMP, magnetically stirring the materials for 1 hour, coating the materials on an aluminum foil to prepare an electrode, and assembling the electrode in a glove box by taking metal lithium as a counter electrode to form the CR2016 type button cell.
Compared with the prior doping technology, the invention has the following advantages and beneficial effects:
(1) the invention adopts a simple coprecipitation method to prepare the carbonate precursor, adopts potassium fluoride to co-dope potassium ions and fluorine ions in one step in the process of preparing lithium, has simple and feasible preparation process, shares one source for doping two ions, does not introduce other impurities, and successfully synthesizes the potassium fluoride-doped lithium-rich manganese-based anode material Li1.2-xKxNi0.2Co0.08Mn0.52O2-yFy(x is more than or equal to 0.01 and less than or equal to 0.06, and y is more than or equal to 0.01 and less than or equal to 0.06) and is applied to the anode of the lithium ion battery.
(2) The invention adopts potassium fluoride as raw material to realize the codoping of potassium ions and fluorine ions, and the potassium ions are doped into the lithium layer of the material, so that the lithium layer is formed byThe radius of potassium ions is larger than that of lithium ions, so that the interlayer spacing of a lithium layer is increased, the lithium ions can be more favorably deintercalated back and forth, and the material has good rate performance. F ion doping can replace O-M (M ═ Ni, Co and Mn) bonds by F-M (M ═ Ni, Co and Mn) bonds with stronger bond energy, so that the structure of the material is more stable, the cycling stability of the material is improved, on the other hand, F is univalent negative, oxygen is bivalent negative, and in order to keep the electrical neutrality of the material, part of metal ions are reduced (generally Ni is adopted)3+Reduction to Ni2 +). Due to Ni2+Specific ratio of Ni to Ni3+The material has larger ionic radius, so that the interlayer distance can be increased, the transmission resistance of lithium ions can be reduced, and the rate capability of the material can be improved. Therefore, the cycle performance and rate performance of the potassium fluoride doped lithium-rich manganese-based positive electrode material are superior to those of the lithium-rich manganese-based positive electrode material synthesized by doping potassium ions or fluorine ions.
(3) The raw materials used in the invention are low in price and easy to obtain. The preparation method has simple process and no pollution, and is suitable for large-scale industrial production.
(4) When the potassium fluoride doped lithium-rich manganese-based material prepared by the invention is used for the anode of a lithium ion battery, the material has higher specific capacity and excellent cycle performance and rate capability. Li1.2-xKxNi0.2Co0.08Mn0.52O2-yFyWhen x and y are 0.01, the current density is 10C and the charging and discharging voltage is 2.5-4.6V, the voltage has 131.57mAh g-1The capacity retention rate reaches 93.37 percent after 1500 cycles. Such excellent electrochemical performance is not achieved by simple anion and cation doping (K, F is not co-doped with the same substance). Meanwhile, compared with the prior art, the potassium fluoride doped lithium-rich manganese-based anode material prepared by the invention has higher specific capacity and rate performance, excellent cycle performance under high current density and long service life of the battery.
Drawings
Fig. 1 is a scanning electron microscope image of the potassium fluoride-doped lithium-rich manganese-based material prepared in example 1 of the present invention.
Fig. 2 is an element distribution test chart of the potassium fluoride-doped lithium-rich manganese-based material prepared in example 1 of the present invention.
Fig. 3 is an X-ray diffraction pattern of the potassium fluoride-doped lithium-rich manganese-based material prepared in example 1 of the present invention.
FIG. 4 shows that the potassium fluoride doped lithium-rich manganese-based material prepared in examples 1, 2 and 3 of the present invention is used as a lithium ion cathode material at 1000mA g-1Current density of (a).
FIG. 5 shows that the amount of the potassium fluoride-doped lithium-rich manganese-based material prepared in example 1 of the present invention as a lithium ion positive electrode material is 2000mA g-1Long cycle cycling performance plot at current density.
Fig. 6 is a graph of rate performance measured by taking the potassium fluoride-doped lithium-rich manganese-based material prepared in example 1 of the present invention as a lithium ion cathode material under different current densities.
Detailed Description
The following describes the technical solutions of the present invention in further detail with reference to the embodiments of the present invention and the accompanying drawings, but the embodiments of the present invention are not limited thereto.
Example 1
A preparation method of a potassium fluoride doped lithium-rich manganese-based material takes a lithium-rich manganese-based positive electrode material as a matrix, a potassium element replaces a lithium element, a fluorine element replaces an oxygen element, and the replacement proportion of the potassium element and the oxygen element is 1%.
A preparation method of a potassium fluoride doped lithium-rich manganese-based material comprises the following steps:
10.1750g of sodium carbonate and 3mL of 25 wt% concentrated ammonia water are weighed and added into 100mL of deionized water to prepare a solution, and the solution is stirred until the solution is completely dissolved to obtain a precipitant solution; 4.9772g of nickel acetate, 1.9928g of cobalt acetate and 12.7447g of manganese acetate are sequentially weighed and dissolved in 100mL of deionized water to form a transition metal salt solution, a precipitator solution is dropwise added into the continuously stirred transition metal salt solution, the dropwise addition is completed within 3h, the stirring speed is 400rpm, the reaction is carried out for 15h, the obtained solution is filtered, washed and dried to obtain a transition metal carbonate precursor, 2g of the transition metal carbonate precursor, 0.9924g of lithium carbonate and 0.0101g of potassium fluoride are weighed, mixed and ground together, then presintered at 450 ℃ for 5h at the heating rate of 5 ℃/min, then heated to 900 ℃ at the heating rate of 5 ℃/min, and calcined for 15h, and the potassium fluoride-doped lithium-rich manganese-based material is obtained.
Assembling the battery: 0.2g of the potassium fluoride-doped lithium-rich manganese-based material prepared in the embodiment, 0.025g of PVDF and 0.025g of acetylene black are weighed, put into a mortar, uniformly mixed and ground, transferred into a small glass bottle, added with 1mL of NMP, magnetically stirred for 1h, coated on an aluminum foil to prepare an electrode, and assembled into a CR2016 type button cell in a glove box by using metal lithium as a counter electrode, and subjected to electrochemical performance test.
Example 2
A preparation method of a potassium fluoride doped lithium-rich manganese-based material takes a lithium-rich manganese-based positive electrode material as a matrix, a potassium element replaces a lithium element, a fluorine element replaces an oxygen element, and the replacement proportion of the potassium element and the oxygen element is 2%.
A preparation method of a potassium fluoride doped lithium-rich manganese-based material comprises the following steps:
10.1750g of sodium carbonate and 3mL of 25 wt% concentrated ammonia water are weighed and added into 100mL of deionized water to prepare a solution, and the solution is stirred until the solution is completely dissolved to obtain a precipitant solution; 4.9772g of nickel acetate, 1.9928g of cobalt acetate and 12.7447g of manganese acetate are sequentially weighed and dissolved in 100mL of deionized water to form a transition metal salt solution, a precipitator solution is dropwise added into the continuously stirred transition metal salt solution, the dropwise addition is completed within 3h, the stirring speed is 400rpm, the reaction is carried out for 15h, the obtained solution is filtered, washed and dried to obtain a transition metal carbonate precursor, 2g of the transition metal carbonate precursor, 0.9841g of lithium carbonate and 0.0202g of potassium fluoride are weighed, mixed and ground, then, the mixture is presintered at the temperature of 450 ℃ for 5h at the temperature rising speed of 5 ℃/min, then the mixture is heated to 900 ℃ at the temperature rising speed of 5 ℃/min, and the calcination is carried out for 15h, so that the potassium fluoride doped lithium-rich manganese-based material is.
Assembling the battery: 0.2g of the potassium fluoride-doped lithium-rich manganese-based material prepared in the embodiment, 0.025g of PVDF and 0.025g of acetylene black are weighed, put into a mortar, uniformly mixed and ground, transferred into a small glass bottle, added with 1mL of NMP, magnetically stirred for 1h, coated on an aluminum foil to prepare an electrode, and assembled into a CR2016 type button cell in a glove box by using metal lithium as a counter electrode, and subjected to electrochemical performance test.
Example 3
A preparation method of a potassium fluoride doped lithium-rich manganese-based material takes a lithium-rich manganese-based positive electrode material as a matrix, a potassium element replaces a lithium element, a fluorine element replaces an oxygen element, and the replacement proportion of the potassium element and the oxygen element is 3%.
A preparation method of a potassium fluoride doped lithium-rich manganese-based material comprises the following steps:
10.1750g of sodium carbonate and 3mL of 25 wt% concentrated ammonia water are weighed and added into 100mL of deionized water to prepare a solution, and the solution is stirred until the solution is completely dissolved to obtain a precipitant solution; 4.9772g of nickel acetate, 1.9928g of cobalt acetate and 12.7447g of manganese acetate are sequentially weighed and dissolved in 100mL of deionized water to form a transition metal salt solution, a precipitator solution is dropwise added into the continuously stirred transition metal salt solution, the dropwise addition is completed within 3h, the stirring speed is 400rpm, the reaction is carried out for 15h, the obtained solution is filtered, washed and dried to obtain a transition metal carbonate precursor, 2g of the transition metal carbonate precursor, 0.9758g of lithium carbonate and 0.0303g of potassium fluoride are weighed, mixed and ground together, the mixture is presintered at the temperature rising speed of 5 ℃/min for 5h at 450 ℃ and then is calcined at the temperature rising speed of 5 ℃/min to 900 ℃ for 15h, and the potassium fluoride doped lithium-rich manganese-based material is obtained.
Assembling the battery: 0.2g of the potassium fluoride-doped lithium-rich manganese-based material prepared in the embodiment, 0.025g of PVDF and 0.025g of acetylene black are weighed, put into a mortar, uniformly mixed and ground, transferred into a small glass bottle, added with 1mL of NMP, magnetically stirred for 1h, coated on an aluminum foil to prepare an electrode, and assembled into a CR2016 type button cell in a glove box by using metal lithium as a counter electrode, and subjected to electrochemical performance test.
And (3) performance testing:
testing on potassium fluoride doped lithium rich manganese based material prepared in example 1:
firstly, Scanning Electron Microscope (SEM) tests were performed on the potassium fluoride-doped lithium-rich manganese-based material prepared in example 1, and the results are shown in fig. 1; scanning element distribution test is performed on the potassium fluoride-doped lithium-rich manganese-based material prepared in example 1, and the result is shown in fig. 2; XRD test was performed on the potassium fluoride-doped lithium-rich manganese-based material prepared in example 1, and the result is shown in FIG. 3.
As shown in FIG. 1, the material particles prepared in example 1 are polyhedral in shape, the crystal form of the material is perfect, and the size distribution range of the particles is 0.3-1 μm. It can be seen from fig. 2 that K and F are uniformly distributed in the material, and the doping of potassium fluoride in the lithium-rich manganese-based material is successfully realized. As shown in FIG. 3, the main peak of the sample belongs to a typical alpha-NaFeO2The structure is characterized in that some weak peaks between 20 and 23 degrees belong to a C2/m space group and are Li2MnO3Characteristic peaks of the components, these characteristic peaks originating from Li in the material+And Mn4+Ordered arrangement in the transition metal layer. Two groups of peaks located in the range of 37.5-39.5 degrees and the range of 63-67 degrees are split obviously, which indicates that the sample has good alpha-NaFeO2A layered structure.
And secondly, carrying out rate performance and cycle performance tests on the potassium fluoride doped lithium-rich manganese-based material prepared in the embodiment 1. After the battery prepared in the embodiment 1 is placed for 12 hours, the battery tester (Shenzhen Xinwei) is adopted to carry out battery charge and discharge, cycle performance and rate performance tests, the test temperature is room temperature, and the current density is 100mA g-1~2000mA g-1Under the condition, the voltage interval of constant current charging and discharging is 2.5-4.6V. The test results of example 1 are shown in FIGS. 4 to 6.
As can be seen from FIG. 4, when the potassium fluoride-doped lithium-rich manganese-based material prepared in example 1 is used in a lithium ion battery, the amount of the potassium fluoride-doped lithium-rich manganese-based material is 1000mA g-1(5C) The first discharge specific capacity is 136.1mAh g at the current density of-1With a maximum of 154.2mAh g-1The specific capacity is still 130.3mAh g after 200 cycles-1The capacity retention rate reaches 95.8 percent. As can be seen from FIG. 5, the potassium fluoride-doped lithium-rich manganese-based material prepared in example 1 has a high specific capacity and excellent cycle performance in a lithium ion battery at 2000mA g-1(10C) The first discharge specific capacity is 100.57mAh g-1With a maximum of 131.57mAhg-1The specific capacity is still 93.9mAh g after 1500 cycles-1The capacity retention rate reaches 93.37%. Drawing (A)6 is 0.1C (1C ═ 200mA g) at different magnifications-1) And the multiplying power performance tested under 0.5C, 1C, 2C, 5C and 10C shows that the multiplying power performance is very good.
Testing on potassium fluoride doped lithium rich manganese based material prepared in example 2:
the potassium fluoride-doped lithium-rich manganese-based material prepared in example 2 was subjected to cycle performance testing. The current density is 1000mA g-1In the case of (2), the operation or test method was the same as in example 1. The test results of example 2 are shown in fig. 4.
As can be seen from FIG. 4, when the potassium fluoride-doped lithium-rich manganese-based material prepared in example 2 is used in a lithium ion battery, the amount of the potassium fluoride-doped lithium-rich manganese-based material is 1000mA g-1(5C) The first discharge specific capacity is 128.1mAh g at the current density of-1The highest of which is 135.9mAh g-1The specific capacity is still 117.8mAh g after 200 cycles-1The capacity retention rate reaches 91.9 percent.
Testing on potassium fluoride doped lithium rich manganese based material prepared in example 3:
the potassium fluoride-doped lithium-rich manganese-based material prepared in example 3 was subjected to cycle performance testing. The current density is 1000mA g-1In the case of (2), the operation or test method was the same as in example 1. The test results of example 3 are shown in fig. 4.
As can be seen from FIG. 4, when the potassium fluoride-doped lithium-rich manganese-based material prepared in example 3 is used in a lithium ion battery, the amount of the potassium fluoride-doped lithium-rich manganese-based material is 1000mA g-1(5C) The first discharge specific capacity is 124.4mAh g at the current density of-1Has a maximum of 128.9mAh g-1The specific capacity is still 96.1mAh g after 200 cycles-1The capacity retention rate reaches 77.3 percent.
Table 1 shows the results of comparing the specific capacity and the cycle performance of the lithium ion battery when the potassium fluoride-doped lithium-rich manganese-based material prepared in example 1 of the present invention and the materials reported in the literature are used as the positive electrode material of the lithium ion battery. From table 1, it can be derived: compared with the prior art, the potassium fluoride doped lithium-rich manganese-based cathode material prepared by the invention has higher specific capacity and rate capability, excellent cycle performance under high current density and long service life of the battery.
Table 1 comparison of specific capacity and cycling performance of the invention with those reported in the literature (1C ═ 200mA g)-1)
Figure BDA0002391371020000091
Note: reference to the literature
[1]Nano Energy 58(2019)786–796。
[2][2]Solid State Ionics 332(2019)47–54。
[3]J.Phys.Chem.C 2018,122,27836-27842。
The present invention is not limited to the above-described embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (10)

1. A preparation method of a potassium fluoride doped lithium-rich manganese-based material is characterized by comprising the following steps:
(1) adding a precipitant and ammonia water into water to prepare a solution, and stirring until the precipitant and the ammonia water are completely dissolved to obtain a precipitant solution;
(2) dissolving nickel salt, cobalt salt and manganese salt in water to prepare a mixed solution, thereby obtaining a transition metal salt solution;
(3) adding the precipitant solution obtained in the step (1) into the transition metal salt solution obtained in the step (2), stirring while adding, and filtering, washing and drying after complete precipitation reaction to obtain a transition metal carbonate precursor;
(4) uniformly mixing a transition metal carbonate precursor with a lithium source and potassium fluoride, grinding, pre-calcining and calcining to obtain the potassium fluoride doped lithium-rich manganese-based material, wherein the label of the potassium fluoride doped lithium-rich manganese-based material is Li1.2- xKxNi0.2Co0.08Mn0.52O2-yFy,0.01≤x≤0.06,0.01≤y≤0.06。
2. The method for preparing the potassium fluoride-doped lithium-rich manganese-based material according to claim 1, wherein the ratio of the molar amount of Ni in the transition metal carbonate precursor in the step (4) to the molar amount of Li in the lithium source is 0.2: 1.14-1.19; the molar weight ratio of Ni in the transition metal carbonate precursor to K in the potassium fluoride in the step (4) is 0.2: 0.01-0.06.
3. The method for preparing the potassium fluoride-doped lithium-rich manganese-based material according to claim 2, wherein the ratio of the molar amount of Ni in the transition metal carbonate precursor in the step (4) to the molar amount of Li in the lithium source is 0.2: 1.17-1.19; the molar weight ratio of Ni in the transition metal carbonate precursor to K in the potassium fluoride in the step (4) is 0.2: 0.01-0.03.
4. The method for preparing the potassium fluoride-doped lithium-rich manganese-based material according to any one of claims 1 to 3, wherein in the nickel salt, the cobalt salt and the manganese salt in the step (2), the ratio of Ni: co: the molar ratio of Mn is 0.2: 0.08: 0.52; and (4) dropwise adding, wherein the dropwise adding time is 1-3 h.
5. The method for preparing the potassium fluoride-doped lithium-rich manganese-based material according to claim 4, wherein the concentration of the precipitating agent in the step (1) in water is 0.05-2 mol/L; the volume ratio of the ammonia water to the water in the step (1) is 1: 100-3: 100, respectively; the concentration of the ammonia water in the step (1) is 10-25%.
6. The method for preparing the potassium fluoride-doped lithium-rich manganese-based material according to any one of claims 1 to 3, wherein the concentration of the nickel salt in the mixed solution in the step (2) is 0.05 to 2 mol/L;
the volume ratio of the precipitant solution to the transition metal salt solution in the step (3) is 3: 1-1: 1.
7. the method for preparing the potassium fluoride-doped lithium-rich manganese-based material according to any one of claims 1 to 3, wherein the stirring speed in the step (3) is 200 to 600 rpm; the reaction time of the precipitation reaction in the step (3) is 12-15 h; the precalcination and the calcination mode in the step (4) are as follows: heating to 400-600 ℃ at a heating rate of 3-5 ℃/min, and pre-sintering for 4-6 h; then, the temperature is raised to 800-950 ℃ at the heating rate of 3-5 ℃/min, and the high-temperature calcination is carried out for 10-20 h.
8. The method for preparing the potassium fluoride-doped lithium-rich manganese-based material according to any one of claims 1 to 3, wherein the precipitating agent in the step (1) is one or more of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide;
the nickel salt in the step (2) is one or more than two of nickel sulfate, nickel acetate and nickel nitrate;
the cobalt salt in the step (2) is one or more than two of cobalt sulfate, cobalt acetate, cobalt nitrate and cobalt chloride, and is more preferably cobalt acetate;
the manganese salt in the step (2) is one or more than two of manganese sulfate, manganese acetate and manganese nitrate;
and (4) the lithium source is one or two of lithium carbonate and lithium hydroxide.
9. The potassium fluoride-doped lithium-rich manganese-based material prepared by the preparation method of the potassium fluoride-doped lithium-rich manganese-based material according to any one of claims 1 to 8.
10. The use of the potassium fluoride-doped lithium-rich manganese-based material of claim 9 in the preparation of a positive electrode material for a lithium ion battery.
CN202010115495.8A 2020-02-25 2020-02-25 Potassium fluoride doped lithium-rich manganese-based material and preparation method and application thereof Pending CN111342008A (en)

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