A method for mass production of high-performance selenite lithium-ion battery negative electrode material

Abstract

The application discloses a method for mass production of high-performance selenite lithium ion battery negative electrode material, and belongs to the field of preparation of lithium ion battery negative electrode material. The method solves the problems of long preparation period and low product content of the existing selenite material. The method comprises the following steps: grinding, mixing and uniformly distributing acetate tetrahydrate, selenium dioxide and graphene, placing the mixture in a ball mill tank, adding a dispersion liquid, ball milling to obtain a slurry, drying and collecting the powder to obtain the selenite lithium ion battery negative electrode material. The MSeO3@Graphene negative electrode has super-high specific capacity, and the specific capacity and long cycle performance are also very excellent under a super-high current density. The preparation process is simple, raw materials are easy to obtain, the period is short, the product content is high, and the method is suitable for mass production of selenite lithium ion battery negative electrode material, fills the blank of material limitation in laboratory preparation, and provides a feasible method for industrialization. The method is suitable for mass production of high-performance selenite lithium ion battery negative electrode material.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of preparation of lithium ion battery negative electrode materials, and particularly relates to a method for large-scale preparation of high-performance selenite lithium ion battery negative electrode materials. BACKGROUND

[0002] With the increasing depletion of fossil energy and the continuous pursuit of people for environment-friendly and efficient new energy, more and more researchers focus on the field of lithium ion batteries with high energy density, long cycle life, environmental friendliness and no memory effect.

[0003] In recent years, the negative electrode material, an important component of lithium ion batteries, especially transition metal oxyanion based on conversion reaction, such as stannate, niobate and selenite, has attracted widespread attention due to its excellent redox capacity and high theoretical specific capacity. Studies have shown that metal selenite forms a heterostructure composed of metal oxide and selenium oxide nanocrystals during the first lithium intercalation process. The synergistic mechanism and the coupling of metal oxides and selenium oxides with different band gaps give selenite high electronic conductivity and rich redox reactions, resulting in excellent electrochemical performance of selenite. Metal oxides and selenium dioxide play a major role in this process. The lithium storage mechanism can be described as follows:

[0004] First discharge process:

[0005] Discharge to 0.01V:

[0006] MSeO3+8Li + +8e - ==M+3Li2O+Li2Se (M=Ni, Co, etc.)

[0007] Charge to 3.0V:

[0008] M+Li2O==MO+2Li + +2e -

[0009] Li2Se==Se+2Li + +2e -

[0010] Se+2Li2O==SeO2+4Li++4e -

[0011] Subsequent cycle process:

[0012] MO+2Li + +2e -

[0013] SeO2+6Li++6e​- ←→Li2Se+2Li2O

[0014] Jiang et al. prepared metastable layered CoSeO3·H2O nanosheets using a hydrothermal method; these nanosheets, when used as lithium-ion anode materials, were suitable for applications with current densities of 3 and 10 Ag. -1 Under these conditions, after 1000 cycles, the reversible capacities are 1100 and 515 mAh g, respectively. -1 Park et al. developed a spray pyrolysis strategy to prepare highly porosity anhydrous CoSeO3 microspheres; at a current density of 3Ag... -1 Under these conditions, the reversible capacity after 1400 cycles is 709 mAh g. -1 Furthermore, Park et al. proposed a novel strategy for synthesizing the binary metal selenite material (NiCo)SeO3, utilizing Ni-Co bimetallic Prussian blue analog nanoboxes (Ni3[Co(CN)6]2·12H2O) to synthesize dopamine-derived carbon-coated (NiCo)SeO3. (NiCo)SeO3@C was synthesized at a current density of 5.0 Ag. -1 The discharge capacities at the 7th and 1500th cycles were 583 and 680 mAh g, respectively. -1 Its capacity retention rate was 117%, demonstrating high specific capacity and long-term cycle stability. In summary, selenite materials can be considered as a very promising anode material for lithium-ion batteries. However, the synthesis of the aforementioned selenite materials all require hydrothermal reactions with long reaction cycles, or time-consuming and energy-intensive electrochemical deposition and thermal treatment processes, resulting in a small number of products and severely limiting the large-scale application of selenite. Summary of the Invention

[0015] The purpose of this invention is to solve the problems of long preparation cycle and low product content of existing selenite materials, and to provide a method for large-scale preparation of high-performance selenite lithium-ion battery anode materials.

[0016] A method for large-scale preparation of high-performance selenite lithium-ion battery anode materials, comprising the following steps:

[0017] 1. After thoroughly grinding and mixing acetate tetrahydrate, selenium dioxide and graphene to obtain a mixed powder, the powder is placed in a ball mill jar and a dispersion solution is added. After ball milling, a slurry is obtained.

[0018] 2. After the above slurry is dried, the powder is collected, which is the lithium selenite battery anode material, thus completing the preparation method.

[0019] Furthermore, the molar ratio of acetate tetrahydrate to selenium dioxide in step one is 1:1.

[0020] Further, the graphene in step one is added in an amount of 5%-20% of the total mass of the mixed powder.

[0021] Further, the dispersion liquid in step one is a non-polar organic solvent.

[0022] Further, the non-polar organic solvent in step one is cyclohexane.

[0023] Further, the amount of the dispersion liquid in step one is determined according to the amount of the mixed powder.

[0024] Further, the ball milling in step one is performed at a speed of 900-1500r / min for 6-24h.

[0025] Further, the acetate tetrahydrate in step one is nickel acetate tetrahydrate, cobalt acetate tetrahydrate, copper acetate tetrahydrate, zinc acetate tetrahydrate or manganese acetate tetrahydrate.

[0026] Further, the slurry drying in step two is performed by transferring the ball milling tank containing the slurry into an oven and drying at 80-100℃ until the dispersant is completely dried.

[0027] The present application proposes a simple and large-scale method for preparing high-performance selenite lithium ion battery negative electrode materials, which is limited to laboratory preparation methods. As a high electrochemical activity material, selenite provides ultra-high capacity. When used as a half-cell for electrochemical testing, the MSeO3@Graphene negative electrode not only exhibits excellent specific capacity, but also enhances the conductivity of selenite as a stable structural constraint material, which relieves the volume expansion effect of the conversion-type negative electrode material and enhances the cycle stability of the composite material.

[0028] The product in the present application has ultra-high specific capacity performance, and the specific capacity and long cycle performance are also very excellent under ultra-high current density, which has the potential as the next generation of lithium battery negative electrode. For CoSeO3@Graphene, the specific capacity is 1019mAhg -1 after 180 cycles at 0.1C; the specific capacity is 780mAhg -1 after 280 cycles at 0.2C; the specific capacity is 948mAhg -1 after 232 cycles in the rate test; for NiSeO3@Graphene, the specific capacity is 2098mAhg -1 after 320 cycles at 0.2C; the highest specific capacity is 1740mAhg -1 after 0.5C cycles; the highest specific capacity is 710mAhg -1 after 2C cycles for 1000 cycles; the specific capacity is 340mAhg -1;10C cycle 1800 times specific capacity 166 mAhg -1 .

[0029] The raw material is easy to obtain, the process is simple, the period is short, the product content is high, and the application is suitable for large-scale preparation of selenite lithium ion battery negative electrode material, fills the blank of selenite negative electrode material limited to laboratory preparation, and provides a feasible method for industrialization of selenite.

[0030] The application is suitable for large-scale preparation of high-performance selenite lithium ion battery negative electrode material. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is the XRD spectrum of CoSeO3@Graphene in Example 1;

[0032] Figure 2 is the XRD spectrum of NiSeO3@Graphene in Example 2;

[0033] Figure 3 is the scanning electron microscope graph of CoSeO3@Graphene in Example 1, wherein a is a low-magnification scanning electron microscope graph, and b is a high-magnification scanning electron microscope graph;

[0034] Figure 4 is the EDS graph of CoSeO3@Graphene in Example 1;

[0035] Figure 5 is the scanning electron microscope graph of NiSeO3@Graphene in Example 2, wherein a is a low-magnification scanning electron microscope graph, and b is a high-magnification scanning electron microscope graph;

[0036] Figure 6 is the EDS graph of NiSeO3@Graphene in Example 2;

[0037] Figure 7 is the cycle performance graph of CoSeO3@Graphene in Example 1 under a current density of 0.1C;

[0038] Figure 8 is the cycle performance graph of CoSeO3@Graphene in Example 1 under a current density of 0.2C;

[0039] Figure 9 is the rate performance ladder graph of CoSeO3@Graphene in Example 1 under a current density of 0.1-10C;

[0040] Figure 10 is the cycle performance graph of NiSeO3@Graphene in Example 2 under a current density of 0.2C;

[0041] Figure 11 is the cycle performance graph of NiSeO3@Graphene in Example 2 at a current density of 0.5C;

[0042] Figure 12 is the cycle performance graph of NiSeO3@Graphene in Example 2 at a current density of 1C;

[0043] Figure 13 is the cycle performance graph of NiSeO3@Graphene in Example 2 at a current density of 2C;

[0044] Figure 14 is the cycle performance graph of NiSeO3@Graphene in Example 2 at a current density of 5C;

[0045] Figure 15 is the cycle performance graph of NiSeO3@Graphene in Example 2 at a current density of 10C;

[0046] Figure 16 is the rate performance ladder graph of NiSeO3@Graphene in Example 2 at a current density of 0.2-15C. DETAILED DESCRIPTION

[0047] The technical solution of the present application is not limited to the following specific embodiments, but also includes any combination of the specific embodiments.

[0048] Specific embodiment one: the method for large-scale preparation of high-performance selenite lithium ion battery negative electrode material in this embodiment is realized according to the following steps:

[0049] I. After the acetate tetrahydrate, selenium dioxide and graphene are fully ground and mixed, a mixed powder is obtained, which is then placed in a ball mill tank and a dispersion liquid is added. After ball milling, a slurry is obtained;

[0050] II. After the above slurry is dried, the powder is collected, which is the selenite lithium ion battery negative electrode material, and the preparation method is completed.

[0051] The slurry obtained by ball milling in step one of this embodiment is black.

[0052] Specific embodiment two: the difference between this embodiment and specific embodiment one is that the molar ratio of the acetate tetrahydrate to selenium dioxide in step one is 1:1. The other steps and parameters are the same as those in specific embodiment one.

[0053] Specific embodiment three: the difference between this embodiment and specific embodiment one is that the addition amount of graphene in step one is 5%-20% of the total mass of the mixed powder. The other steps and parameters are the same as those in specific embodiment one.

[0054] Specific embodiment four: the difference between this embodiment and specific embodiment one is that the dispersion liquid in step one is a non-polar organic solvent. The other steps and parameters are the same as specific embodiment one.

[0055] Specific embodiment five: the difference between this embodiment and specific embodiment four is that the non-polar organic solvent in step one is cyclohexane. The other steps and parameters are the same as specific embodiment four.

[0056] Specific embodiment six: the difference between this embodiment and specific embodiment one is that the amount of the dispersion liquid in step one is based on the amount of the mixed powder. The other steps and parameters are the same as specific embodiment one.

[0057] Specific embodiment seven: the difference between this embodiment and specific embodiment one is that the ball milling in step one is at a speed of 900-1500 r / min for 6-24 h. The other steps and parameters are the same as specific embodiment one.

[0058] Specific embodiment eight: the difference between this embodiment and specific embodiment one is that the acetate tetrahydrate in step one is nickel acetate tetrahydrate, cobalt acetate tetrahydrate, copper acetate tetrahydrate, zinc acetate tetrahydrate, or manganese acetate tetrahydrate. The other steps and parameters are the same as specific embodiment one.

[0059] Specific embodiment nine: the difference between this embodiment and specific embodiment one is that the slurry drying in step two is by transferring the ball mill tank containing the slurry to an oven and drying at 80-100℃ until the dispersant is completely dried. The other steps and parameters are the same as specific embodiment one.

[0060] The beneficial effects of the present application are verified by the following examples:

[0061] Example 1:

[0062] A method for large-scale preparation of high-performance selenite lithium ion battery negative electrode material, which is realized according to the following steps:

[0063] I. After the cobalt acetate tetrahydrate, selenium dioxide and graphene are thoroughly ground and mixed, a mixed powder is obtained, which is then placed in a ball mill tank and a dispersion liquid is added. After ball milling, a slurry is obtained;

[0064] II. After the above slurry is dried, the powder is collected, which is a selenite lithium ion battery negative electrode material, and the preparation method is completed.

[0065] The slurry obtained by ball milling in step one of this example is black.

[0066] The molar ratio of the four water acetic acid cobalt and selenium dioxide in step one of the embodiment is 1:1, which is 2.49g and 1.11g respectively.

[0067] The adding amount of the graphene in step one of the embodiment is 10% of the total mass of the mixed powder, that is, 0.4g.

[0068] The dispersant in step one of the embodiment is cyclohexane, and the amount is based on the immersion of the mixed powder.

[0069] The ball milling in step one of the embodiment is at a speed of 1350r / min for 12h.

[0070] The slurry drying in step two of the embodiment is to transfer the ball milling tank containing the slurry to the oven and dry at 100℃ until the dispersant is completely dried.

[0071] The prepared selenite lithium ion battery negative electrode material in the embodiment is specifically a cobalt selenite / graphene composite lithium ion battery negative electrode material (CoSeO3@Graphene).

[0072] Embodiment 2:

[0073] A method for large-scale preparation of high-performance selenite lithium ion battery negative electrode material, which is realized by the following steps:

[0074] I. After the four water acetic acid nickel, selenium dioxide and graphene are fully ground and mixed, the mixed powder is obtained, then placed in a ball milling tank, and a dispersant is added, and the slurry is obtained after ball milling;

[0075] II. After the above slurry is dried, the powder is collected, which is the selenite lithium ion battery negative electrode material, and the preparation method is completed.

[0076] The slurry obtained by ball milling in step one of the embodiment is black.

[0077] The molar ratio of the four water acetic acid nickel and selenium dioxide in step one of the embodiment is 1:1, which is 2.49g and 1.11g respectively.

[0078] The adding amount of the graphene in step one of the embodiment is 10% of the total mass of the mixed powder, that is, 0.4g.

[0079] The dispersant in step one of the embodiment is cyclohexane, and the amount is based on the immersion of the mixed powder.

[0080] The ball milling in step one of the embodiment is at a speed of 1350r / min for 12h.

[0081] The slurry in step two of the present example is dried by transferring the slurry-containing ball mill jar into an oven and drying at 100°C until the dispersant is completely dried.

[0082] The selenite lithium ion battery anode material prepared in the present example is specifically a selenite nickel / graphene composite lithium ion battery anode material (NiSeO3@Graphene).

[0083] The XRD patterns of the CoSeO3@Graphene and NiSeO3@Graphene prepared in Example 1 and Example 2 are shown in Figure 1 and Figure 2 It can be seen that the crystal peaks of the selenite / graphene (MSeO3@Graphene) composite lithium ion battery anode material are in good agreement with the standard card, and no impurity peaks exist. The CoSeO3@Graphene and NiSeO3@Graphene composite electrode materials are in complete agreement with the standard PDF cards of CoSeO32H2O (JCPDS no. 80-1391) and NiSeO32H2O (JCPDS no. 80-1392), respectively. This indicates that the selenite anode material is successfully prepared by a simple and efficient ball milling method, filling the gap of the selenite anode material which is limited to laboratory preparation.

[0084] The scanning electron microscope images of the selenite cobalt / graphene (CoSeO3@Graphene) composite lithium ion battery anode material prepared in Example 1 at different magnifications are shown in Figure 3 From the low magnification scanning electron microscope image (see Figure 3 part a), the micron-sized selenite cobalt particles formed after ball milling are uniformly dispersed on the surface of graphene. In the high magnification scanning electron microscope image (see Figure 3 part b), it can be clearly seen that the graphene sheets have a certain overlap, forming slightly thicker graphene sheets. The smaller size selenite particles formed after ball milling will provide a larger specific surface area, thereby significantly improving the electrochemical performance, and the graphene coating structure improves the overall electrical conductivity of the material while alleviating the problem of poor material stability caused by repeated volume changes of the conversion-type anode. Figure 4 The energy spectrum analysis of the element types in the sample is shown in

[0085] The scanning electron microscope images of the selenite nickel / graphene (NiSeO3@Graphene) composite lithium ion battery anode prepared in Example 2 are shown in Figure 5 The low magnification scanning electron microscope image is shown in Figure 5 part a, Figure 5Part b is a high-magnification scanning electron microscope image. The morphology is not significantly different from that of CoSeO3@Graphene in Example 1; both exhibit selenite particles uniformly dispersed around the graphene. Similarly, energy dispersive spectroscopy analysis of the elements in the sample shows... Figure 6 As shown, the ratio of Ni, Se, and O detected by EDS is close to 1:1:3, indicating that nickel selenite was successfully prepared.

[0086] The cycling performance and rate performance of the CoSeO3@Graphene prepared in Example 1 were evaluated using constant current charge-discharge tests, such as... Figure 7 As shown. Figure 7 The cycling performance of CoSeO3@Graphene at a current density of 0.1C (1C = 1000 mAg) is shown in the graph. -1 ).from Figure 7 From this, we can obtain that the initial discharge capacity of CoSeO3@Graphene is 1369 mAh g. -1 During the next 50 cycles, the specific capacity decreased slightly, but after continuing cycling up to 180 cycles, the specific capacity gradually recovered to 1019 mAh g. -1 Cyclic performance at 0.2C current density is as follows: Figure 8 As shown, after the first five activation cycles, the specific capacity continuously increases during the 280 cycles, reaching a maximum of 780 mAh g. -1 It exhibits excellent discharge specific capacity, demonstrating superior cycle stability and capacity performance. Figure 9 The rate performance gradient of the CoSeO3@Graphene composite electrode material at current densities ranging from 0.1 to 10C is shown. The discharge specific capacities at the end of each current density test are 797, 557, 420, 372, 304, 186, and 94 mAh g, respectively. -1 Furthermore, as the current density recovers to 0.1C, the specific capacity continues to increase to a maximum of 1024 mAh g. -1 However, the specific capacity decreased towards the end of the test, ultimately achieving 948mAh g at 232 laps. -1 The discharge specific capacity is significantly improved by the addition of graphene, which significantly reduces the volume expansion of the conversion-type anode material and enhances cycle stability. Even after a 10C ultra-high current density test, it can still recover to its original state and maintain the trend of increasing specific capacity.

[0087] Figure 10The electrochemical performance of the NiSeO3 / Graphene composite prepared in Example 2 at a current density of 0.2C was demonstrated. Although there was some fluctuation in specific capacity throughout the charge-discharge test, the overall trend was increasing, and even after 320 cycles, the specific capacity did not show a significant capacity loss, and the highest charge specific capacity could reach 2098 mAh g -1 , which was much higher than the same type of cobalt selenite; at the same time, the current density was continuously increased to 0.5C, as shown in Figure 11 , the first discharge specific capacity was 1332 mAh g -1 , similar to the former, there was a certain degree of fluctuation in specific capacity during the cycle, but it still maintained a sustained increase in the first 240 cycles, and the highest charge specific capacity reached 1740 mAh g -1 , but in the following 160 cycles, there was a capacity decay phenomenon, and finally, when the cycle reached 400 cycles, the discharge specific capacity still maintained at 1151 mAh g -1 such a high value. With the continuous increase of current density to 1C, as shown in Figure 12 , similarly, the capacity increased consistently in the first 300 cycles or so, and the highest discharge specific capacity was 1059 mAh g -1 , and in the following 100 cycles, it maintained a decay trend, and finally reached 787 mAh g -1 , but was still higher than the first discharge specific capacity of 735 mAh g -1 . When the current density reached 2C, as shown in Figure 13 , similarly, the specific capacity continued to increase to 710 mAh g -1 , and continuously decreased to 397 mAh g -1 until the cycle reached 1000 cycles. The capacity performance of nickel selenite was significantly higher than that of cobalt selenite, which made our preparation method have great potential to replace the currently used lower capacity graphite negative electrode.

[0088] To further illustrate the excellent cycle performance of the NiSeO3 / Graphene composite prepared in Example 2, we continued to perform cycle tests at current densities of 5C and 10C, and tested its rate performance at 0.2-15C. The cycle performance curve at a current density of 5C is shown in Figure 14 , the first discharge specific capacity could reach 731 mAh g -1 , but there was some fluctuation during the initial cycle process, and when the cycle was stable, the specific capacity was 200 mAh g -1 , after 1500 cycles of super-long cycle, the specific capacity showed a trend of first increasing and then decreasing, among which, the highest discharge specific capacity could reach 406 mAh g -1Even though the specific capacity slightly decreased in the second half, it was still maintained at 340 mAh g -1 at 1500 cycles, which was significantly higher than the initial state, with a capacity retention of up to 170%, and the average coulombic efficiency was higher than 99% throughout the whole process, showing excellent high-rate, long cycle, and high specific capacity characteristics. Even if the current density was increased to 10C, as shown in Figure 15 , although the specific capacity rapidly decreased in the first 150 cycles, it remained stable and even slightly increased in the subsequent 1650 cycles, reaching a maximum of 185 mAh g -1 , and 166 mAh g -1 at the end of 1800 cycles. The above results show that the NiSeO3 / Graphene composite material has ultra-high specific capacity performance at low current density, and the specific capacity and long cycle performance are also very excellent at ultra-high current density, which has the potential to be used as the next generation of lithium battery anodes. We further increased the current density to 15C and tested the rate performance at 0.2-15C current density. The results, as shown in Figure 16 , show that the discharge specific capacity after cycling at different current densities was 735, 636, 587, 514, 317, 153, and 86 mAh g -1 , respectively, even at such a high current density of 15C, the capacity retention still reached 11.7%; showing an amazing large current charging and discharging ability. It is worth noting that, as in the previous cycle test, when the current density returned to the initial value of 0.2C, the discharge specific capacity still maintained a continuous increasing trend, and continuously increased to 1887 mAh g -1 in the subsequent 220 cycles, showing excellent cycle stability and high specific capacity characteristics.

[0089] The product of the present application proposes a method for large-scale preparation of high-performance selenite lithium ion battery anode material, which successfully obtains high specific capacity and long cycle stable selenite lithium ion battery anode material from cheap and easily available experimental raw materials through a simple and efficient experimental scheme. At the same time, the special protection formed by graphene improves the poor conductivity of the conversion type oxygen-containing acid salt anode material, and also relieves the overall volume expansion effect, improving the rate performance and cycle stability of the material. The present application provides the possibility for large-scale industrial production of selenite anode materials.

Claims

1. A method for large-scale preparation of high-performance selenite lithium-ion battery anode materials, characterized in that... It is implemented in the following steps:

1. After thoroughly grinding and mixing acetate tetrahydrate, selenium dioxide and graphene to obtain a mixed powder, the powder is placed in a ball mill jar and a dispersion solution is added. After ball milling, a slurry is obtained.

2. After the above slurry is dried, the powder is collected, which is the lithium selenite battery anode material, thus completing the preparation method described above; In step one, the molar ratio of acetate tetrahydrate to selenium dioxide is 1:

1. The amount of graphene added in step one is 5%-20% of the total mass of the mixed powder; The dispersion mentioned in step one is a non-polar organic solvent; The nonpolar organic solvent mentioned in step one is cyclohexane; The amount of dispersion liquid used in step one is based on immersing the mixed powder; The ball milling process described in step one involves a rotation speed of 900-1500 r / min and a milling time of 6-24 h. The acetate tetrahydrate mentioned in step one is nickel acetate tetrahydrate, cobalt acetate tetrahydrate, copper acetate tetrahydrate, zinc acetate tetrahydrate, or manganese acetate tetrahydrate. The slurry drying in step two involves transferring the ball mill jar containing the slurry to an oven and drying it at 80-100°C until the dispersant is completely dried.

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