Negative electrode material lithium nickel manganate coated silicon as well as preparation method and application thereof
By coating the silicon surface with lithium nickel manganate, the problem of rapid capacity attenuation of silicon anode in lithium-ion batteries is solved, and better cycle performance and rate performance are achieved, which is suitable for sulfide solid-state batteries.
Patent Information
- Application Number
- CN202510201788.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-24
- Publication Date
- 2025-05-06
AI Technical Summary
The silicon anode rapidly attenuates capacity during the circulation of lithium-ion batteries, mainly due to the large volume changes of silicon particles during the lithiation and deliquification process, resulting in poor interface contact, local stress accumulation and lithium loss.
By covering the silicon surface with nickel manganate as a coating material, the interface problem between silicon and sulfide electrolyte is improved, lithium deposition and dendrite generation are reduced, the volume expansion of silicon is suppressed, and the circulation stability and rate performance of the material are improved.
It effectively improves the circulation and rate performance of the silicon anode, reduces capacity attenuation, strengthens contact with sulfide solid electrolyte, and improves the safety of the battery and the realization of high energy density.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of battery materials, and in particular relates to a negative electrode material, nickel lithium manganate coated silicon, and a preparation method and application thereof. Background Art
[0002] The development of long-range electric vehicles and aircraft requires the next generation of lithium batteries with greatly improved energy density, power density and safety. Lithium-ion batteries using graphite anodes can no longer meet the requirements of high energy density, and high-capacity anode materials based on conversion reactions have emerged. Silicon (Si) is an ideal alternative because it can accommodate 3.75 lithium ions per silicon atom, with a theoretical capacity of 3589mAh / g, which is 10 times that of graphite (372mAh / g). In addition, silicon is naturally abundant and low in cost, and has great potential for commercial applications. Although the theoretical capacity of silicon is slightly lower than that of pure lithium metal anodes (3860mAh / g), silicon has a lower tendency to dendrite growth, which is a crucial advantage over lithium metal in terms of battery safety.
[0003] Substantial progress has been made in the practical application of silicon anodes; however, rapid capacity decay upon battery cycling remains a major obstacle. This capacity decay is closely related to the inherently large volume change (>300%) of silicon particles upon (de)lithiation, which results in poor interfacial contact between silicon and other electrode components (e.g., current collectors and carbon additives). Once silicon particles are separated from these components, they are electrically isolated and are therefore no longer electrochemically active. In addition, the large volume change can lead to local stress accumulation, resulting in fracture of silicon particles. This process repeatedly exposes fresh surfaces of lithium-silicon alloy particles during charge and discharge, which react with the liquid electrolyte, resulting in lithium loss (i.e., capacity loss). Although various strategies to suppress the volume expansion of silicon electrodes have been successfully demonstrated to varying degrees, the reversible capacity of silicon anodes remains limited, especially at the high mass loadings required to achieve high energy density.
[0004] Interface problems between silicon and sulfide electrolytes; during the cycle process, lithium ions will be reduced on the low-potential silicon surface to generate lithium metal deposited on the silicon surface, forming lithium dendrites, which can easily lead to capacity decay and short circuit problems.
[0005] Silicon undergoes a large volume expansion during the cycle, and its contact with the sulfide electrolyte continues to deteriorate. As the cycle progresses, silicon undergoes a volume expansion of about 300% during the lithium insertion and delithiation process, resulting in the continuous expansion of the gap between silicon and the sulfide solid electrolyte, and the continuous deterioration of the contact between the two, which makes the electron and ion transmission between the two deteriorate, resulting in a rapid decay of electrical performance.
[0006] Therefore, there is an urgent need to provide a silicon negative electrode material with better electrochemical performance, such as better cycle performance. Summary of the invention
[0007] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a negative electrode material nickel manganese oxide lithium coated silicon and a preparation method and application thereof.
[0008] The present invention uses a specific preparation method to achieve coating materials to improve the interface problem between silicon and sulfide electrolytes and improve the electrical properties of silicon. Lithium nickel manganate has excellent lithium storage performance and lithium conductivity performance. It is used as a coating material to coat the surface of silicon materials, which can improve the interface problem between silicon and sulfide electrolytes, reduce lithium deposition on the negative electrode side, generate lithium dendrites, and improve rate performance. In addition, during the process of lithium insertion and delithiation, lithium nickel manganate has a small volume expansion and a stable structure. Coating it on silicon can inhibit the volume expansion of silicon, reduce the volume change of active materials during the process of lithium insertion and delithiation, and damage the contact between active materials and sulfide solid electrolytes, improve the material cycle stability and rate performance, so that the negative electrode material lithium nickel manganate coated silicon can be better applied to sulfide solid-state batteries.
[0009] A first aspect of the present invention provides a negative electrode material of lithium nickel manganate coated silicon.
[0010] Specifically, a negative electrode material is lithium nickel manganate coated with silicon, which has a core-shell structure, wherein the core is composed of silicon and the shell is composed of lithium nickel manganate;
[0011] The mass of the core accounts for more than 80% of the total mass of the negative electrode material nickel manganese oxide lithium coated silicon.
[0012] Preferably, the mass of the silicon accounts for 80-95% of the total mass of the negative electrode material nickel lithium manganese oxide coated silicon, and more preferably 90-95%.
[0013] Preferably, the shell has a thickness of 5-100 nm, more preferably 10-80 nm or 20-70 nm.
[0014] Preferably, the particle size of the silicon is 30nm-100μm, more preferably 100nm-1μm or 30nm-50μm. Specifically, it can be 30nm, 50nm, 100nm, 1μm, 50μm, 100μm. A suitable particle size can achieve smaller porosity control.
[0015] A second aspect of the present invention provides a method for preparing a negative electrode material, lithium nickel manganate coated silicon.
[0016] Specifically, a method for preparing a negative electrode material of nickel lithium manganese oxide coated silicon comprises the following steps:
[0017] Mixing silicon, lithium hydroxide, nickel salt, manganese salt, and organic acid to obtain a mixture;
[0018] The mixture is calcined under a protective gas atmosphere to obtain the negative electrode material nickel manganate lithium coated silicon;
[0019] The calcination temperature is not less than 400°C;
[0020] The molar ratio of the lithium hydroxide to the nickel salt is 1:(0.1-0.5).
[0021] Preferably, the calcination temperature is 400-1000°C, more preferably 600-800°C.
[0022] Preferably, the calcination time is 1-24 h, more preferably 6-12 h.
[0023] Preferably, the protective gas is selected from at least one of Ar, He, and N2.
[0024] Preferably, the mixing comprises mixing by ball milling or grinding.
[0025] Preferably, the rotation speed of the ball mill is 100-500 rpm, more preferably 200-400 rpm; the ball milling time is 1-24 h, more preferably 6-12 h.
[0026] Preferably, the molar ratio of the lithium hydroxide to the nickel salt is 1:(0.2-0.3).
[0027] Preferably, the molar ratio of the lithium hydroxide, the nickel salt and the manganese salt is 1:(0.1-0.5):(1.5-1.9), and more preferably 1:(0.2-0.3):(1.7-1.8).
[0028] Preferably, the nickel salt is selected from at least one of nickel nitrate, nickel chloride and nickel sulfate.
[0029] Preferably, the mass ratio of lithium hydroxide to silicon is 1-10:100, more preferably 3-5:100.
[0030] Preferably, the organic acid comprises citric acid.
[0031] Preferably, the mass ratio of the organic acid to silicon is 1-10:100, more preferably 2-5:100.
[0032] Preferably, after the calcination, a washing and drying process is also included.
[0033] Preferably, the washing is performed with deionized water.
[0034] Preferably, the drying is carried out in a vacuum oven, the drying temperature is 60-100°C, preferably 80°C, the vacuum pressure is -0.04 to -0.1 MPa, preferably -0.1 MPa, and the drying time is 1-72 h, preferably 6-24 h.
[0035] A second aspect of the present invention provides a negative electrode material of lithium nickel manganate coated silicon.
[0036] Specifically, a negative electrode material of lithium nickel manganese oxide coated with silicon is prepared by the above preparation method.
[0037] A third aspect of the present invention provides an application of a method for preparing a negative electrode material, nickel lithium manganese oxide coated silicon.
[0038] The application of the preparation method of the above-mentioned negative electrode material nickel manganese oxide lithium coated silicon in the preparation of solid-state batteries.
[0039] Preferably, in the application, the solid-state battery includes a sulfide solid electrolyte.
[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0041] The negative electrode material nickel manganese oxide lithium coated silicon prepared by the present invention through specific raw materials and process parameters (such as raw material dosage ratio, calcination temperature) can improve the interface problem between silicon and sulfide electrolyte, reduce lithium deposition on the negative electrode side, generate lithium dendrites, and improve rate performance. In addition, the volume expansion of lithium nickel manganese oxide is small and the structure is stable during the process of lithium insertion and delithiation. Coating it on silicon can inhibit the volume expansion of silicon, reduce the damage to the contact between the active material and the sulfide solid electrolyte caused by the volume change during the lithium insertion and delithiation process of the active material, improve the material cycle stability and rate performance, so that the negative electrode material nickel manganese oxide lithium coated silicon can be better applied to sulfide solid-state batteries.
[0042] The negative electrode material nickel manganese oxide lithium coated silicon (silicon@nickel manganese oxide lithium material) prepared by the present invention for use in sulfide solid-state batteries has nickel manganese oxide lithium uniformly distributed on its surface, which can achieve excellent contact with the sulfide solid-state electrolyte. The excellent lithium storage performance and lithium conductivity performance of nickel manganese oxide lithium can reduce lithium deposition and the formation of lithium dendrites, and improve the cycle performance and safety performance of the sulfide solid-state battery. The low expansion shell of the nickel manganese oxide lithium material can reduce the effect of silicon volume expansion on the electrode structure, inhibit the increase of the porosity in the negative electrode, reduce the contact failure between the negative electrode and the sulfide solid-state electrolyte, improve the problem of accelerated capacity decay of the negative electrode during long-term circulation, and improve the rate performance of the sulfide solid-state battery.
[0043] In summary, the negative electrode material nickel lithium manganese oxide coated silicon prepared by the present invention is of great significance to the high rate performance and safety of sulfide solid-state batteries. BRIEF DESCRIPTION OF THE DRAWINGS
[0044] Figure 1 The SEM (scanning electron microscope) and EDS (energy dispersive spectrometer) test results of sample 1 prepared in Example 1 of the present invention;
[0045] Figure 2 The rate performance test results of the half-cell formed by Sample 1 prepared in Example 1 of the present invention. DETAILED DESCRIPTION
[0046] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.
[0047] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.
[0048] Example 1
[0049] A negative electrode material, lithium nickel manganate coated silicon, has a core-shell structure, the core comprises silicon, and the shell comprises lithium nickel manganate;
[0050] The mass of the core accounts for 95% of the total mass of the negative electrode material nickel manganese oxide lithium coated silicon.
[0051] The particle size of silicon is 100 nm.
[0052] A method for preparing a negative electrode material nickel lithium manganate coated silicon comprises the following steps:
[0053] 1 g of Si with a particle size of 100 nm, 0.05 g of citric acid, 0.05 g of lithium hydroxide, 0.12 g of nickel nitrate, and 0.43 g of manganese carbonate (the molar ratio of lithium hydroxide, nickel nitrate, and manganese carbonate is 1:0.2:1.8) were ball-milled and dispersed at a ball-milling speed of 400 rpm for 6 h to obtain a powdery mixture;
[0054] The dispersed powdered mixture was calcined at high temperature. The specific calcination procedure was as follows: maintaining at 400°C for 1 hour in an argon atmosphere, then heating to 800°C at a heating rate of 5°C / min and maintaining for 6 hours;
[0055] The powder obtained after calcination was washed with deionized water three times, and then dried in a vacuum oven at 80°C and -0.1 MPa for 24 hours to obtain the negative electrode material nickel lithium manganese oxide coated silicon (silicon@nickel lithium manganese oxide material), named Sample 1.
[0056] Example 2
[0057] The nickel nitrate in Example 1 was replaced by nickel chloride, and the other steps remained unchanged. The obtained negative electrode material nickel lithium manganate coated silicon was named Sample 2.
[0058] Example 3
[0059] The particle size of Si in Example 1 was adjusted to 1 μm, and the other steps remained unchanged. The obtained negative electrode material nickel lithium manganese oxide coated silicon was named Sample 3.
[0060] Comparative Example 1
[0061] The amount of nickel nitrate in Example 1 was adjusted to 1.2 g, and the other steps remained unchanged. The obtained product was named Comparative Sample 1.
[0062] Comparative Example 2
[0063] The lithium hydroxide in Example 1 was replaced with lithium sulfate, and the other steps remained unchanged. The obtained product was named Comparative Sample 2.
[0064] Comparative Example 3
[0065] The citric acid in Example 1 was omitted, and the other steps remained unchanged. The obtained product was named Comparative Sample 3.
[0066] Comparative Example 4
[0067] The high temperature calcination temperature of 800°C in Example 1 was changed to 300°C, and the other steps remained unchanged. The obtained product was named Comparative Sample 4.
[0068] Product effect testing
[0069] 1. Scanning electron microscope test
[0070] Sample 1 prepared in Example 1 was tested by scanning electron microscopy (SEM). The results are as follows: Figure 1 As shown. Figure 1 It can be seen that sample 1 is composed of a core of silicon and an outer shell of nickel lithium manganese oxide. The small nickel lithium manganese oxide particles are evenly distributed on the silicon surface, firmly coating the silicon, which can effectively reduce the contact between silicon and the sulfide solid electrolyte and improve the lithium conductivity of the material. The thickness of the nickel lithium manganese oxide shell is about 10nm.
[0071] 2. Electrochemical performance test
[0072] Samples 1-3 and comparative samples 1-4 were used as active materials, respectively. The active materials were mixed with LiP6S5Cl and PTFE (polytetrafluoroethylene) in a mass ratio of 60:40:1 to form a composite negative electrode, and the negative electrode sheet was obtained through a roller pressing and slicing process. The negative electrode sheet was placed in a polyetheretherketone tube with a diameter of 10 mm, and then 100 mg of LiP6S5Cl was weighed and added to the polyetheretherketone tube. The tube was pressed and molded at a pressure of 12 MPa and tightly contacted with the negative electrode sheet. Finally, a piece of Li-In alloy was added to the other side of the solid electrolyte, and pressed and molded at a pressure of 360 MPa to prepare a half-cell with a three-layer structure (negative electrode sheet / solid electrolyte / Li-In alloy).
[0073] Test conditions: Charge and discharge tests were performed at 60°C with currents of 0.1C, 0.3C, 0.5C, 0.8C and 1C and cut-off voltages from -0.61 to 0.2V, and half cells were tested at a pressure of 15MPa.
[0074] 2.1 Electrochemical impedance spectroscopy
[0075] The internal resistance of the half-cell was measured by electrochemical impedance spectroscopy (EIS) to determine the contact between the obtained negative electrode sheet and the sulfide solid electrolyte and the lithium conductivity. The internal resistance of the half-cell composed of samples 1-3 and comparative samples 1-4 is shown in Table 1.
[0076] Table 1: Internal resistance of half-cells composed of samples 1-3 and comparative samples 1-4
[0077] sample Sample 1 Sample 2 Sample 3 Comparison sample 1 Comparison sample 2 Comparison sample 3 Comparison sample 4 Internal resistance(Ω) 76 78 83 127 163 112 185
[0078] As can be seen from Table 1, by comparing the internal resistance of the half-cell composed of samples 1-3 and comparative samples 1-4, it can be found that sample 1 has the best contact with the sulfide solid electrolyte, followed by samples 2 and 3; comparative samples 1-4 have high internal resistance and poor contact with the sulfide solid electrolyte. This shows that lithium nickel manganate coated silicon has the lowest internal resistance, which is conducive to the transmission of lithium ions in the negative electrode, thereby achieving higher rate performance.
[0079] In Comparative Sample 1, the excess nickel salt increases the internal resistance; in Comparative Sample 2, the lithium sulfate cannot react well to form lithium nickel manganate; in Comparative Sample 3, after removing the citric acid, the internal resistance of the battery increases because the acidic environment provided by the citric acid is conducive to the formation of lithium nickel manganate particles generated by the reaction and attached to the silicon; and the calcination temperature of 300°C in Comparative Example 4 is not enough to make the reaction occur.
[0080] Sample 1 has achieved good coating of silicon material by lithium nickel manganese oxide, effectively inhibiting the contact between silicon and sulfide solid electrolyte. At the same time, lithium nickel manganese oxide can quickly transfer lithium ions as an intermediate layer.
[0081] 2.2 First Coulombic efficiency test
[0082] The half-cell prepared according to the above method was subjected to the first coulombic efficiency (first efficiency) test, and the results are shown in Table 2.
[0083] Table 2: First coulombic efficiency of half-cells composed of samples 1-3 and comparative samples 1-4
[0084] sample Sample 1 Sample 2 Sample 3 Comparison sample 1 Comparison sample 2 Comparison sample 3 Comparison sample 4 First effect (%) 92 91.8 91.5 79.5 71.6 83.4 65.8
[0085] As can be seen from Table 2, by comparing the first efficiencies of the half-cells composed of sample 1-3 and comparison sample 1-4, it can be seen that the first efficiency of sample 1-3 is higher, while the first efficiency of comparison sample 1-4 is lower, indicating that the nickel lithium manganese oxide-coated silicon effectively reduces the contact between silicon and the sulfide solid electrolyte, so the side reaction of silicon and the sulfide solid electrolyte is correspondingly reduced, and the first efficiency is improved.
[0086] The first effect of sample 1 is the highest, indicating that the surface nickel lithium manganate coating is the most uniform. In comparative sample 1, the excess nickel salt increases the internal resistance and reduces the first effect; in comparative sample 2, lithium sulfate cannot react to produce nickel lithium manganate coating the silicon surface, and the side reaction cannot be reduced; in comparative sample 3, after removing citric acid, the nickel lithium manganate cannot be better attached to silicon in a non-acidic environment; and in comparative example 4, the calcination temperature of 300°C cannot react to produce nickel lithium manganate coating the silicon surface, and the side reaction cannot be reduced.
[0087] 2.3x performance test
[0088] The half-cell composed of sample 1 was tested for rate performance, and the results are as follows: Figure 2 As shown. Figure 2 It can be seen that sample 1 exhibits excellent rate performance, and can even maintain a specific capacity of 2736 mAh / g at a rate of 1 C. This fully proves that the negative electrode material nickel manganese oxide lithium coated silicon prepared by the present invention has excellent performance and commercial potential.
Claims
1. A negative electrode material nickel lithium manganate coated silicon, characterized in that: It has a core-shell structure, the core is composed of silicon, and the shell is composed of lithium nickel manganate; The mass of the core accounts for more than 80% of the total mass of the negative electrode material nickel manganese oxide lithium coated silicon.
2. The negative electrode material nickel lithium manganate coated silicon according to claim 1, characterized in that: The mass of the silicon accounts for 80-95% of the total mass of the negative electrode material, the lithium nickel manganate coated silicon.
3. The negative electrode material nickel lithium manganate coated silicon according to claim 1, characterized in that: The shell has a thickness of 5-100 nm.
4. The negative electrode material nickel lithium manganate coated silicon according to claim 1, characterized in that: The particle size of the silicon is 30nm-100μm.
5. The method for preparing the negative electrode material nickel lithium manganate coated silicon according to any one of claims 1 to 4, characterized in that: The following steps are involved: Mixing silicon, lithium hydroxide, nickel salt, manganese salt, and organic acid to obtain a mixture; The mixture is calcined under a protective gas atmosphere to obtain the negative electrode material nickel manganate lithium coated silicon; The calcination temperature is not less than 400°C; The molar ratio of the lithium hydroxide to the nickel salt is 1:(0.1-0.5).
6. The preparation method according to claim 5, characterized in that: The calcination temperature is 400-1000° C.; and / or the calcination time is 1-24 hours.
7. The preparation method according to claim 5, characterized in that: The molar ratio of the lithium hydroxide to the nickel salt is 1:(0.2-0.3).
8. The preparation method according to claim 5, characterized in that: The molar ratio of the lithium hydroxide, the nickel salt and the manganese salt is 1:(0.1-0.5):(1.5-1.9); and / or the nickel salt is selected from at least one of nickel nitrate, nickel chloride and nickel sulfate; and / or the mass ratio of the lithium hydroxide to silicon is 1-10:
100.
9. The preparation method according to claim 5, characterized in that: The organic acid includes citric acid; and / or, the mass ratio of the organic acid to silicon is 1-10:100; and / or, after the calcination is completed, a washing and drying process is also included.
10. Use of the negative electrode material nickel lithium manganate coated silicon according to any one of claims 1 to 4 or the preparation method according to any one of claims 5 to 9 in the preparation of solid-state batteries.