CN107611422B - Method for substituting Mn-doped modified lithium nickel manganese oxide with unequal P quantity and application - Google Patents
Method for substituting Mn-doped modified lithium nickel manganese oxide with unequal P quantity and application Download PDFInfo
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Abstract
The invention provides a method for replacing Mn-doped modified lithium nickel manganese oxide with unequal P, which realizes LiNi by replacing a small amount of Mn with unequal P serving as a non-metallic element0.5Mn1.5O4By introducing a small amount of vacancies at the 16d position to adjust the content of oxygen defects in the material, the ratio of ordered and disordered spinel structures in the material is optimized. In the preparation process, dissolving citric acid in a proper amount of deionized water, then sequentially adding a lithium source, a manganese source, a nickel source and a phosphorus source to obtain a mixed solution, heating and stirring until the mixed solution is evaporated to dryness, and then performing pre-decomposition and heat treatment to obtain the P-unequal doped lithium nickel manganese oxide. The P-unequal doped modified lithium nickel manganese oxide prepared by the invention has high tap density, high purity, no impurity phase, and good rate capability and cycle performance. The capacity retention rate is about 93% after 1000 cycles under the multiplying power of 10C, and the capacity retention rate is still as high as 87% after 1600 cycles.
Description
Technical Field
The invention belongs to the field of energy materials, and particularly relates to a preparation method and application of modified lithium nickel manganese oxide.
Background
The positive electrode material with the manganese-based spinel structure is considered to be one of the most attractive positive electrode materials of the lithium ion battery due to the advantages of rich resources, high discharge voltage, environmental friendliness and the like. Due to Mn3+Disproportionation reaction and Jahn-Teller effect, the material has poor cycle performance, especially poor high-temperature cycle performance, and the wide application of the material is severely limited. In addition, the rate capability of the hybrid power system is to be further improved so as to meet the requirement of high power output of the electric vehicle. The positive electrode material with a spinel structure mainly comprises lithium manganate LiMn2O4And lithium nickel manganese LiNi0.5Mn1.5O4And the like. LiNi0.5Mn1.5O4Theoretical capacity of 147mAh g-1The voltage plateau is 4.7-4.75V. With LiMn2O4Compared with the prior art, the voltage plateau is higher by about 15 percent, and the energy density is as high as 690Wh kg-1Higher than LiCoO2、LiFePO4And LiCo1/3Ni1/3Mn1/3O2. The high energy density of the nickel-based lithium manganate spinel structure enables the nickel-based lithium manganate spinel structure to have wide application prospects in the field of electric vehicles or other power batteries.
Spinel-structured LiNi0.5Mn1.5O4There are two kinds of space structures, one isThe disordered spinel structure of the space group and the ordered structure of the P4332 space group are the other. The diffusion path of lithium ions in the disordered structure is from the 8a position of the tetrahedron to the empty 16c position, and lithium ions in the ordered structure diffuse along both paths 8c-4a and 8c-12 d. As can be seen from the comparison of coulomb potential calculation, when lithium ions diffuse in the above three paths, 8c-4a is the easiest, 8a-16c times is the easiest, and 8c-12d is the hardest. Due to the ordered structure, the most diffusive pathways account for only 25%. Therefore, the disordered spinel structure material is more favorable for lithium ion diffusion. The disordered spinel structure material generally has a small amount of oxygen defects, has higher conductivity due to the oxygen defects, and has structural characteristics so that lithium ions are more favorable for diffusion and transportation. Therefore, the rate capability tends to be more excellent than that of the ordered spinel structure. The ordered spinel structure exhibits superior cycle performance due to its general absence of Mn3 +. Therefore, the proportion of ordered and disordered spinel structures in the material can be regulated and controlled by doping and controlling the content of oxygen defects in the material, and the aim of optimizing the comprehensive performance of the material can be achieved.
In the existing method for doping modified lithium nickel manganese oxide, the doped elements are usually metal elements, and few non-metal elements are doped. In the patent of the invention, the improvement of crystal lattice vacancy is based on the fact that the valence state and the bonding energy between the valence state and oxygen are stronger and non-equivalent doping is adoptedConsidering conductivity, the non-equivalent substitution of Mn of 16d crystal site by a non-metal element P realizes LiNi0.5Mn1.5O4The doping modification of the material optimizes the structural proportion of ordered and unordered spinels in the material, and realizes the optimization of the comprehensive performance of the material.
Disclosure of Invention
In view of the above problems in the prior art, an object of the present invention is to provide a method for preparing lithium nickel manganese oxide with excellent rate capability and cycle performance, and in particular, to a method for preparing P-unequal substituted Mn-doped modified lithium nickel manganese oxide. The method has the advantages of simple steps, high efficiency, low cost and suitability for large-scale production, the P-doped lithium nickel manganese oxide prepared by the method has high purity and no impurity phase, and the battery prepared by taking the P-doped lithium nickel manganese oxide as the positive electrode has excellent rate performance and cycle performance.
The invention also aims to provide the modified lithium nickel manganese oxide prepared by the method.
The third purpose of the invention is to propose the application of the modified lithium nickel manganese oxide.
The technical scheme for realizing the above purpose of the invention is as follows:
a method for replacing Mn-doped modified lithium nickel manganese oxide with unequal P content adopts a nonmetal element P to replace a small amount of Mn to realize LiNi0.5Mn1.5O4The doping modification is realized by introducing a small amount of vacancies at the 16d position to adjust the content of oxygen defects in the material and optimizing the structural proportion of ordered and disordered spinels in the material, so that the optimization of the comprehensive performance of the material is realized; in the preparation process, dissolving citric acid in a proper amount of deionized water, then sequentially adding a lithium source, a manganese source, a nickel source and a phosphorus source to obtain a mixed solution, heating and stirring until the mixed solution is evaporated to dryness, and then performing pre-decomposition and heat treatment to obtain the P-unequal doped lithium nickel manganese oxide.
The method specifically comprises the following steps:
(1) dissolving citric acid in deionized water to obtain a transparent solution;
(2) adding a lithium source, a manganese source, a nickel source and a phosphorus source into the transparent solution obtained in the step (1), and stirring to obtain a mixed solution;
(3) stirring the mixed solution obtained in the step (2) until the mixed solution is evaporated to dryness to obtain dry gel;
(4) carrying out pre-decomposition on the xerogel obtained in the step (3) to obtain a pre-decomposition product;
(5) and (4) carrying out two-step sintering heat treatment on the pre-decomposed product obtained in the step (4) to obtain the P-unequal doped lithium nickel manganese oxide.
Wherein, the nickel source in the step (2) is one or more of nickel acetate, nickel nitrate or nickel chloride, and is preferably nickel acetate; the manganese source is one or more of simple substance manganese powder, manganese acetate, manganese nitrate or manganese chloride, and is preferably simple substance manganese powder. The lithium source is one or more of lithium acetate, lithium nitrate or lithium chloride, and lithium acetate is preferred. The phosphorus source is one or more of diammonium hydrogen phosphate, ammonium dihydrogen phosphate or ammonium phosphate, and preferably diammonium hydrogen phosphate.
Wherein the molar ratio of the citric acid to the manganese source is (6-12) to 4.5, preferably (6-10) to 4.5;
and/or
According to the mol of the citric acid, the manganese, the nickel, the lithium and the phosphorus, the mol ratio of the citric acid to the manganese source, the nickel source, the lithium source and the phosphorus source is (6-12): (4-4.5): 1-2): 3.15: (0.01-0.21).
The molar ratio of the citric acid to the manganese source, the nickel source, the lithium source and the phosphorus source is (6-10): 4.3125:1.5:3.15: (0.1-0.21), and more preferably (6-10): 4.3125:1.5:3.15: 0.15.
Optionally, the molar ratio of the citric acid to the manganese source, the nickel source, the lithium source and the phosphorus source in the aqueous solution of the citric acid is (6-12): 4-4.5): 1.5:3.15: (0-0.21), 8:4.3125:1.5:3.15: 0.15. For example, 6:4:1.5:3.15:0.21, 8:4:1.5:3.15:0.21, 10:4:1.5:3.15:0.21, 12:4:1.5:3.15:0.21, 6:4.2375:1.5:3.15:0.15, 8:4.2375:1.5:3.15:0.15, 10:4.2375:1.5:3.15:0.15, 12:4.2375:1.5:3.15:0.15, 6: 4.5: 1.5:3.15:0.15, 8: 4.5: 1.5:3.15:0.15, 10:4.3125:1.5:3.15:0.15, 12:4.3125:1.5:3.15:0.15, 6:4.3875: 1.15: 1.3125: 0.15: 1.15: 3.15: 6: 1.15: 10: 3.15: 6: 10: 6: 1.1.15: 10: 1.15: 6: 1.15: 6: 1.: 4.3125:1.5:3.15:0.15, a large number of experiments show that the battery prepared from the P non-equivalent doped lithium nickel manganese oxide cathode material has better rate multiplying performance and cycle performance when the molar ratio is 8:4.3125:1.5:3.15:0.15, thus a more preferred molar ratio is 8:4.3125:1.5:3.15: 0.15.
The preferable technical scheme of the invention also comprises that the concentration of the citric acid aqueous solution in the step (1) is 0.7-1.3 mol/L. The stirring in the step (1) is magnetic stirring, and the stirring temperature is preferably 10-40 ℃;
the stirring temperature in the step (2) is 10-40 ℃, and the stirring time is 1-10 hours, preferably 5-6 hours;
and (4) stirring in the step (3) is constant-temperature stirring, and the temperature of the constant-temperature stirring is 60-90 ℃.
In the step (4), the pre-decomposition temperature is 180-350 ℃, and the pre-decomposition time is 2-6 h.
Before the thermal treatment of the pre-decomposition product, the pre-decomposition product is ground.
Wherein, in the step (5), the heat treatment is performed in an air atmosphere;
the temperature of the first-step sintering is 550-750 ℃, and 650 ℃ is preferred; the time of the first step of sintering is 5-15 h,
the temperature of the second sintering step is 850-950 ℃, and preferably 900 ℃; the time of the second step of sintering is 1-5 h.
The modified lithium nickel manganese oxide material prepared by the method is provided.
The modified lithium nickel manganese oxide material is used as a positive electrode material of a lithium ion battery.
The invention has the beneficial effects that:
(1) the invention provides a method for doping modified lithium nickel manganese oxide with non-metallic elements, which is simple, high in efficiency, low in cost, low in energy consumption and easy for industrial large-scale production.
(2) The P-unequal doped modified lithium nickel manganese oxide prepared by the method has high tap density, high purity and no impurity phase, and has good rate capability and cycle performance when being used as a lithium ion battery anode material. Under the discharge rate of 1C, the primary capacity reaches 119 mAh/g; under the discharge rate of 40C, the primary capacity reaches 98 mAh/g; the capacity retention rate is about 95% after 1000 cycles under the multiplying power of 1C, and the capacity retention rate is still as high as 80% after 1600 cycles; the capacity retention rate is about 93% after 1000 cycles under the multiplying power of 10C, and the capacity retention rate is still as high as 87% after 1600 cycles.
Drawings
FIG. 1 is an X-ray diffraction pattern of P-unequal doped modified lithium nickel manganese oxide obtained in example 1 of the invention.
FIGS. 2(a), 2(b) and 2(c) are scanning electron micrographs at different magnifications of P unequal doped modified lithium nickel manganese oxide in example 1 of the invention.
Fig. 3(a), fig. 3(b) are rate performance curves of the P unequal amount doping modified lithium nickel manganese obtained in the example 1 of the invention, and fig. 3(a), fig. 3(b) respectively show the cycle performance and the voltage change under different rates.
FIGS. 4(a), (b) are the 1C and 10C cycle performance curves of the P unequal amount doped modified lithium nickel manganese oxide obtained in example 1 of the invention under room temperature conditions.
Detailed Description
The multifunctional nano drug delivery system and the performance thereof are illustrated by specific examples.
The materials in the following examples were prepared directly according to prior art methods or were purchased directly from the market.
Experimental example 1
Adding 0.08mol of citric acid into 100ml of deionized water, and after the citric acid is dissolved, sequentially adding 0.043125mol of simple substance manganese powder, 0.015mol of nickel acetate, 0.0315mol of lithium acetate and 0.0015mol of diammonium hydrogen phosphate; magnetically stirring the transparent solution at room temperature for 5 hours; magnetically stirring the mixed solution at the constant temperature of 80 ℃ and evaporating to dryness to obtain a precursor; pre-decomposing the precursor for 4 hours at 230 ℃, and grinding the obtained pre-decomposed product to obtain a ground product; and carrying out two-step heat treatment on the ground product under the air atmosphere condition, wherein the two-step heat treatment conditions are respectively 650 ℃, 10 hours, 900 ℃ and 2 hours, and then cooling along with the furnace to obtain the high-performance P non-equivalent doped lithium nickel manganese oxide lithium ion battery anode material.
Referring to fig. 1, X-ray powder diffraction analysis showed that the product was pure-phase lithium nickel manganese oxide having space group Fd3m and high crystallinity.
Referring to fig. 2(a), fig. 2(b) and fig. 2(c), it is known from the analysis of the scanning electron microscope that the primary particles of the product are irregular polyhedrons, the particle size is between 0.5 and 2 μm, and partial agglomeration exists between the primary particles.
The product is used as a positive electrode material and assembled into an experimental button lithium ion battery in an argon protective glove box, and the rate performance and the discharge curves under different rates are respectively shown in fig. 3(a) and fig. 3 (b). Under the discharge rate of 1C, the primary capacity reaches 119 mAh/g; under the discharge rate of 40C, the primary capacity reaches 98 mAh/g; the capacity retention rate after 1000 cycles at a rate of 1C is about 95%, and the capacity retention rate is still as high as 80% after 1600 cycles (fig. 4 (a)); the capacity retention rate is about 93% after 1000 cycles at a rate of 10C (FIG. 4(b)), and the capacity retention rate is still as high as 87% after 1600 cycles. The data show that the synthesized P unequal doped lithium nickel manganese oxide as a positive electrode material is assembled into a battery and has excellent electrochemical performance.
Example 2
Adding 0.06mol of citric acid into 100ml of deionized water, and after the citric acid is dissolved, sequentially adding 0.043125mol of simple substance manganese powder, 0.015mol of nickel acetate, 0.0315mol of lithium acetate and 0.0015mol of diammonium hydrogen phosphate; magnetically stirring the transparent solution at room temperature for 5 hours; magnetically stirring the mixed solution at the constant temperature of 80 ℃ and evaporating to dryness to obtain a precursor; pre-decomposing the precursor for 4 hours at 230 ℃, and grinding the pre-decomposed product to obtain a ground product; and carrying out two-step heat treatment on the ground product under the air atmosphere condition, wherein the treatment conditions are 650 ℃ for 10h and 900 ℃ for 2h, and then cooling along with a furnace to obtain the high-performance lithium nickel manganese oxide lithium ion battery anode material doped with unequal P.
X-ray powder diffraction analysis shows that the product is pure-phase lithium nickel manganese oxide with space group Fd3m and has high crystallinity; the analysis of a scanning electron microscope shows that primary particles of the product are irregular polyhedrons, the particle size is 0.5-2 mu m, and partial agglomeration exists among the primary particles. And (3) assembling the product serving as a positive electrode material into an experimental button type lithium ion battery in an argon protective glove box, and performing charge-discharge circulation between 3.5V and 4.95V at different multiplying powers. Under the discharge rate of 1C, the primary capacity reaches 110 mAh/g; under the discharge rate of 40C, the primary capacity reaches 80 mAh/g; the capacity retention rate is about 80% after 600 cycles under the rate of 10C.
Example 3
Adding 0.10mol of citric acid into 100ml of deionized water, and after the citric acid is dissolved, sequentially adding 0.043125mol of simple substance manganese powder, 0.015mol of nickel acetate, 0.0315mol of lithium acetate and 0.0015mol of diammonium hydrogen phosphate; magnetically stirring the transparent solution at room temperature for 5 hours; magnetically stirring the mixed solution at the constant temperature of 80 ℃ and evaporating to dryness to obtain a precursor; pre-decomposing the precursor for 4 hours at 230 ℃, and grinding the pre-decomposed product to obtain a ground product; and carrying out two-step heat treatment on the ground product under the air atmosphere condition, wherein the treatment conditions are 650 ℃ for 10h and 900 ℃ for 2h, and then cooling along with a furnace to obtain the high-performance lithium nickel manganese oxide lithium ion battery anode material doped with unequal P.
X-ray powder diffraction analysis shows that the product is pure-phase lithium nickel manganese oxide with space group Fd3m and has high crystallinity; the analysis of a scanning electron microscope shows that primary particles of the product are irregular polyhedrons, the particle size is 0.5-2 mu m, and partial agglomeration exists among the primary particles. And (3) assembling the product serving as a positive electrode material into an experimental button type lithium ion battery in an argon protective glove box, and performing charge-discharge circulation between 3.5V and 4.95V at different multiplying powers. Under the discharge rate of 1C, the primary capacity reaches 105 mAh/g; under the discharge rate of 40C, the primary capacity reaches 75 mAh/g; the capacity retention rate is about 79% after 600 cycles under the magnification of 10C.
Example 4
Adding 0.08mol of citric acid into 100ml of deionized water, and after the citric acid is dissolved, sequentially adding 0.042375mol of simple substance manganese powder, 0.015mol of nickel acetate, 0.0315mol of lithium acetate and 0.0015mol of diammonium hydrogen phosphate; magnetically stirring the transparent solution at room temperature for 5 hours; magnetically stirring the mixed solution at the constant temperature of 80 ℃ and evaporating to dryness to obtain a precursor; pre-decomposing the precursor for 4 hours at 230 ℃, and grinding the pre-decomposed product to obtain a ground product; and carrying out two-step heat treatment on the ground product under the air atmosphere condition, wherein the two-step heat treatment conditions are respectively 650 ℃ for 10h and 900 ℃ for 2h, and then cooling along with a furnace to obtain the high-performance P-unequal doped lithium nickel manganese oxide lithium ion battery positive electrode material.
X-ray powder diffraction analysis shows that the product is pure-phase lithium nickel manganese oxide with space group Fd3m and has high crystallinity; the analysis of a scanning electron microscope shows that primary particles of the product are irregular polyhedrons, the particle size is 0.5-2 mu m, and partial agglomeration exists among the primary particles. And (3) assembling the product serving as a positive electrode material into an experimental button type lithium ion battery in an argon protective glove box, and performing charge-discharge circulation between 3.5V and 4.95V at different multiplying powers. Under the discharge rate of 1C, the primary capacity reaches 114 mAh/g; under the discharge rate of 40C, the primary capacity reaches 75 mAh/g; the capacity retention rate is about 76% after 1000 cycles under the multiplying power of 1C; the capacity retention rate is about 91% after 1000 cycles under the multiplying power of 10 ℃.
Example 5
Adding 0.10mol of citric acid into 100ml of deionized water, and after the citric acid is dissolved, sequentially adding 0.042375mol of simple substance manganese powder, 0.015mol of nickel acetate, 0.0315mol of lithium acetate and 0.0015mol of diammonium hydrogen phosphate; magnetically stirring the transparent solution at room temperature for 5 hours; magnetically stirring the mixed solution at the constant temperature of 80 ℃ and evaporating to dryness to obtain a precursor; pre-decomposing the precursor for 4 hours at 230 ℃, and grinding the obtained pre-decomposed product to obtain a ground product; and carrying out two-step heat treatment on the ground product under the air atmosphere condition, wherein the treatment conditions are respectively 650 ℃, 10 hours and 900 ℃ for 2 hours, and then cooling along with the furnace to obtain the high-performance P non-equivalent doped lithium nickel manganese oxide lithium ion battery anode material.
X-ray powder diffraction analysis shows that the product is pure-phase lithium nickel manganese oxide with space group Fd3m and has high crystallinity; the analysis of a scanning electron microscope shows that primary particles of the product are irregular polyhedrons, the particle size is 0.5-2 mu m, and partial agglomeration exists among the primary particles. And (3) assembling the product serving as a positive electrode material into an experimental button type lithium ion battery in an argon protective glove box, and performing charge-discharge circulation between 3.5V and 4.95V at different multiplying powers. Under the discharge rate of 1C, the primary capacity reaches 110 mAh/g; under the discharge rate of 40C, the primary capacity reaches 73 mAh/g; the capacity retention rate is about 85% after 600 cycles under the multiplying power of 10 ℃.
Example 6
Adding 0.08mol of citric acid into 100ml of deionized water, and after the citric acid is dissolved, sequentially adding 0.043875mol of simple substance manganese powder, 0.015mol of nickel acetate, 0.0315mol of lithium acetate and 0.0015mol of diammonium hydrogen phosphate; magnetically stirring the transparent solution at room temperature for 5 hours; magnetically stirring the mixed solution at the constant temperature of 80 ℃ and evaporating to dryness to obtain a precursor; pre-decomposing the precursor for 4 hours at 230 ℃, and grinding the obtained pre-decomposed product to obtain a ground product; and carrying out two-step heat treatment on the ground product under the air atmosphere condition, wherein the two-step heat treatment conditions are respectively 650 ℃ multiplied by 10h and 900 ℃ multiplied by 2h, and then cooling along with a furnace to obtain the high-performance P non-equivalent doped lithium nickel manganese oxide lithium ion battery anode material.
X-ray powder diffraction analysis shows that the product is pure-phase lithium nickel manganese oxide with space group Fd3m and has high crystallinity; the analysis of a scanning electron microscope shows that primary particles of the product are irregular polyhedrons, the particle size is 0.5-2 mu m, and partial agglomeration exists among the primary particles. And (3) assembling the product serving as a positive electrode material into an experimental button type lithium ion battery in an argon protective glove box, and performing charge-discharge circulation between 3.5V and 4.95V at different multiplying powers. Under the discharge rate of 1C, the primary capacity reaches 100 mAh/g; under the discharge rate of 40C, the primary capacity reaches 67 mAh/g; the capacity retention rate is about 68% after 1000 cycles under the multiplying power of 1C; the capacity retention rate is about 87% after 1000 cycles under the multiplying power of 10 ℃.
Example 7
Adding 0.06mol of citric acid into 100ml of deionized water, and after the citric acid is dissolved, sequentially adding 0.043875mol of simple substance manganese powder, 0.015mol of nickel acetate, 0.0315mol of lithium acetate and 0.0015mol of diammonium hydrogen phosphate; magnetically stirring the transparent solution at room temperature for 5 hours; magnetically stirring the mixed solution at the constant temperature of 80 ℃ and evaporating to dryness to obtain a precursor; pre-decomposing the precursor for 4 hours at 230 ℃, and grinding the pre-decomposed product to obtain a ground product; and carrying out two-step heat treatment on the ground product under the air atmosphere condition, wherein the treatment conditions are 650 ℃ multiplied by 10h and 900 ℃ multiplied by 2h, and then cooling along with a furnace to obtain the high-performance P-unequal doped lithium nickel manganese oxide lithium ion battery positive electrode material.
X-ray powder diffraction analysis shows that the product is pure-phase lithium nickel manganese oxide with space group Fd3m and has high crystallinity; the analysis of a scanning electron microscope shows that primary particles of the product are irregular polyhedrons, the particle size is 0.5-2 mu m, and partial agglomeration exists among the primary particles. And (3) assembling the product serving as a positive electrode material into an experimental button type lithium ion battery in an argon protective glove box, and performing charge-discharge circulation between 3.5V and 4.95V at different multiplying powers. Under the discharge rate of 1C, the primary capacity reaches 102 mAh/g; under the discharge rate of 40C, the primary capacity reaches 65 mAh/g; the capacity retention rate is about 65% after 1000 cycles under the multiplying power of 1C; the capacity retention rate is about 80% after 1000 cycles under the magnification of 10C.
Comparative example 1
Adding 0.08mol of citric acid into 100ml of deionized water, and after the citric acid is dissolved, sequentially adding 0.045mol of simple substance manganese powder, 0.015mol of nickel acetate and 0.0315mol of lithium acetate, wherein other preparation methods and conditions are the same as those in example 1.
The lithium nickel manganese LiNi prepared by the comparative example0.5Mn1.5O4The product is used as an anode material, an experimental button type lithium ion battery is assembled in a glove box protected by argon, charge and discharge cycles are carried out between 3.5V and 4.95V at different multiplying factors, the 1C initial discharge capacity is 118mAh/g, and the 40C initial discharge capacity is 67 mAh/g; under the condition of room temperature, the capacity retention rate of 1C after 1000 times of circulation is 42%; the capacity retention rate is about 51% after 1000 cycles under the magnification of 10C.
The above examples are only for describing the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims (12)
1. A method for substituting Mn with unequal P to dope modified lithium nickel manganese oxide is characterized in that a small amount of Mn is replaced with unequal P to realize LiNi0.5Mn1.5O4The doping modification is realized by introducing a small amount of vacancies at the 16d position to adjust the content of oxygen defects in the material and optimizing the structural proportion of ordered and disordered spinels in the material, so that the optimization of the comprehensive performance of the material is realized; in the preparation process, the method comprises the following steps:
(1) dissolving citric acid in deionized water to obtain a transparent solution;
(2) adding a lithium source, a manganese source, a nickel source and a phosphorus source into the transparent solution obtained in the step (1), and stirring to obtain a mixed solution;
(3) stirring the mixed solution obtained in the step (2) until the mixed solution is evaporated to dryness to obtain dry gel;
(4) carrying out pre-decomposition on the xerogel obtained in the step (3) to obtain a pre-decomposition product;
(5) and (4) carrying out two-step sintering heat treatment on the pre-decomposed product obtained in the step (4) to obtain the P-unequal doped lithium nickel manganese oxide.
2. The method of claim 1, wherein the nickel source in step (2) is one or more of nickel acetate, nickel nitrate, or nickel chloride; the manganese source is one or more of simple substance manganese powder, manganese acetate, manganese nitrate or manganese chloride, and the lithium source is one or more of lithium acetate, lithium nitrate or lithium chloride; the phosphorus source is one or more of diammonium hydrogen phosphate, ammonium dihydrogen phosphate or ammonium phosphate.
3. The method according to claim 1 or 2, wherein the molar ratio of citric acid to manganese source is (6-12): 4.5.
4. The method according to claim 3, wherein the molar ratio of citric acid to manganese source is (6-10): 4.5.
5. The method according to claim 1 or 2, wherein the molar ratio of the citric acid to the manganese source, the nickel source, the lithium source and the phosphorus source is (6-12): 4-4.5): 1-2): 3.15 (0.01-0.21) based on the moles of the citric acid, the manganese, the nickel, the lithium and the phosphorus.
6. The method according to claim 5, wherein the molar ratio of the citric acid to the manganese source, the nickel source, the lithium source and the phosphorus source is (6-10): 4.3125:1.5:3.15 (0.1-0.21).
7. The method according to claim 6, wherein the molar ratio of the citric acid to the manganese source, the nickel source, the lithium source and the phosphorus source is (6-10): 4.3125:1.5:3.15: 0.15.
8. The method according to claim 1, wherein the concentration of the aqueous solution of citric acid in the step (1) is 0.7-1.3 mol/L;
the stirring temperature in the step (2) is 10-40 ℃, the stirring time is 1-10 h,
and (4) stirring in the step (3) is constant-temperature stirring, and the temperature of the constant-temperature stirring is 60-90 ℃.
9. The method according to claim 1, wherein in the step (4), the temperature of the pre-decomposition is 180-350 ℃, the time of the pre-decomposition is 2-6 h,
before the thermal treatment of the pre-decomposition product, the pre-decomposition product is ground.
10. The method according to claim 1, wherein in step (5), the heat treatment is performed under an air atmosphere;
the temperature of the first sintering step is 550-750 ℃, the time of the first sintering step is 5-15 h,
the temperature of the second sintering step is 850-950 ℃, and the time of the second sintering step is 1-5 h.
11. The modified lithium nickel manganese oxide material prepared by the method of any one of claims 1 to 10.
12. Use of the modified lithium nickel manganese oxide material of claim 11 as a positive electrode material for a lithium ion battery.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201710591258.7A CN107611422B (en) | 2017-07-19 | 2017-07-19 | Method for substituting Mn-doped modified lithium nickel manganese oxide with unequal P quantity and application |
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| CN101150190A (en) * | 2007-10-30 | 2008-03-26 | 天津巴莫科技股份有限公司 | Anode material zirconium and phosphor adulterated lithium cobaltate of lithium ion secondary battery and its making method |
| CN105753072A (en) * | 2016-02-03 | 2016-07-13 | 国家纳米科学中心 | Lithium nickel manganese oxide as well as preparation method and application thereof |
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| CN101150190A (en) * | 2007-10-30 | 2008-03-26 | 天津巴莫科技股份有限公司 | Anode material zirconium and phosphor adulterated lithium cobaltate of lithium ion secondary battery and its making method |
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