Lithium-poor lithium nickel oxide cation-disordered rock-salt phase positive electrode material and preparation method thereof
Patent Information
- Application Number
- CN202410017106.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-05
- Publication Date
- 2026-09-25
- Estimated Expiration
- 2044-01-05
AI Technical Summary
对于纯镍酸锂阳离子无序岩盐正极材料(体系中仅含有锂、镍、氧三种元素)，目前只有通过溶液烧结法制备得到的报道(Chem.Mater.2003,15,988-993)，然而制得的材料不具有电化学性能
[0020]本发明首次通过溶胶凝胶法成功制备得到一种贫锂镍酸锂阳离子无序岩盐相正极材料。本发明所制备的正极材料具有较好的充放电比容量(171mAh g-1/203mAh g-1)，其放电比容量(203mAh g-1)高于使用相同制备方法和同等测试条件下的层状镍酸锂(139mAhg-1)，并且相比于层状镍酸锂及高镍层状三元正极材料而言，本发明岩盐相镍酸锂对制备及储存环境要求不高，无需干燥间或洁净室，且制备方法工艺简单、易于实施。
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Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of cathode materials for secondary lithium-ion batteries, and relates to a lithium-poor lithium nickelate cation disordered rock salt phase cathode material and its preparation method. Background Technology
[0002] With the rapid development of portable electronic devices, grid energy storage, and new energy electric vehicles, higher demands are being placed on the performance and cost of lithium-ion batteries. For lithium-ion batteries, the cathode material is a key factor determining their performance. Currently commercialized mainstream lithium-ion cathode materials such as LiCoO2, LiMn2O4, and ternary cathodes (NCM, NCA) are mostly ordered, close-packed oxides. Scholars generally believe that an ordered structure is a necessary condition for obtaining high specific capacity and high cycle stability. However, in recent years, a new type of cathode material—cation-disordered rock salt phase—has challenged this established view. This type of material has attracted widespread attention and become a research hotspot because it can provide a discharge specific capacity exceeding 200 mAh / g, and some even exceeding 300 mAh / g, with an energy density reaching 1000 Wh / kg.
[0003] In cationic disordered rock-salt phase cathode materials, cations (lithium ions and transition metal ions) occupy octahedral positions in the cubic anion (oxygen ions and fluoride ions) lattice in a disordered manner, and lithium ions diffuse through octahedral-tetrahedral-octahedral transitions. Currently, research on cationic disordered rock-salt phase cathode materials mainly focuses on manganese-based materials, with less research on nickel-based materials. For pure lithium nickelate cationic disordered rock-salt cathode materials (containing only lithium, nickel, and oxygen elements), there are currently only reports of preparation via solution sintering (Chem. Mater. 2003, 15, 988-993), however, the resulting materials do not exhibit electrochemical properties. Summary of the Invention
[0004] The purpose of this invention is to provide a lithium-poor lithium nickelate cationic disordered rock salt phase cathode material and its preparation method. This method involves uniformly dissolving lithium salt, nickel salt, and organic complexes in water in a specific ratio using a sol-gel method, followed by drying, pre-calcination, and annealing to obtain a lithium-poor lithium nickelate cationic disordered rock salt phase cathode material with good charge-discharge specific capacity.
[0005] The technical solution for achieving the objective of this invention is as follows:
[0006] Lithium-poor lithium nickelate cationic disordered rock salt phase cathode material, composition: Li x Ni 2-x O2 (0 < x < 1), with a cation-disordered rock salt phase crystal structure, is prepared through the following steps:
[0007] (1) Dissolve lithium salt and nickel salt in water at a molar ratio of lithium ion to nickel ion of 0.4 to 1:1, and add organic complex to form a lithium-nickel salt mixed solution;
[0008] (2) The lithium-nickel salt mixed solution was heated and dried at 60-100℃ to form a gel sample;
[0009] (3) After the gel sample is fully pre-fired at 300-500℃, it is then annealed at 600-1200℃ to obtain lithium-poor lithium nickelate cationic disordered rock salt phase cathode material.
[0010] Preferably, in step (1), the lithium salt is lithium nitrate, lithium acetate, lithium hydroxide or lithium sulfate, and the nickel salt is nickel nitrate, nickel acetate, nickel hydroxide or nickel sulfate.
[0011] Preferably, in step (1), the molar ratio of the total cations in the lithium salt and nickel salt to the organic complex is 1:0.6-3.
[0012] Preferably, in step (1), the organic complex is one or more of citric acid, benzoic acid, malic acid, and polyvinylpyrrolidone (PVP). In a specific embodiment of the present invention, citric acid and PVP are taken as examples of organic complexes.
[0013] Preferably, in step (1), the molar ratio of lithium ions to nickel ions is 0.8 to 1:1.
[0014] Preferably, in step (1), the water is deionized water.
[0015] Preferably, in step (2), the drying time is 0.5-10h.
[0016] Preferably, in step (3), the heating rate during the pre-firing stage is 1-20℃ / min, and the pre-firing time is 0.5-10h.
[0017] Preferably, in step (3), the atmosphere during annealing is pure oxygen, air, or argon.
[0018] Preferably, in step (3), the heating rate during the annealing stage is 1-20℃ / min, and the holding time is 0.5-16h.
[0019] Compared with the prior art, the present invention has the following advantages:
[0020] This invention marks the first successful preparation of a lithium-poor lithium nickelate cationic disordered rock salt phase cathode material via a sol-gel method. The cathode material prepared by this invention exhibits a good charge-discharge specific capacity (171 mAh g⁻¹). -1 / 203mAh g -1 Its discharge specific capacity (203mAh g)-1 The value is higher than that of layered lithium nickelate (139 mAh g) prepared using the same method and under the same testing conditions. -1 Furthermore, compared to layered lithium nickelate and high-nickel layered ternary cathode materials, the rock salt phase lithium nickelate of this invention has low requirements for preparation and storage environment, does not require a drying room or clean room, and the preparation method is simple and easy to implement. Attached Figure Description
[0021] Figure 1 Li obtained in Example 1 0.63 Ni 1.37 XRD pattern of O2 oxide sample;
[0022] Figure 2 Li obtained in Example 1 0.63 Ni 1.37 SEM image of the O2 oxide sample;
[0023] Figure 3 Li obtained in Example 1 0.63 Ni 1.37 Charge-discharge curves of the O2 oxide sample;
[0024] Figure 4 The Li obtained in Example 5 0.73 Ni 1.27 XRD pattern of O2 oxide sample;
[0025] Figure 5 For the Li obtained in Comparative Example 1 0.95 Ni 1.05 XRD pattern of O2 oxide sample;
[0026] Figure 6 For the Li obtained in Comparative Example 2 0.19 Ni 1.81 Charge-discharge curves of the O2 oxide sample. Detailed Implementation
[0027] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0028] Example 1
[0029] Lithium nitrate (2g by mass), nickel nitrate, and citric acid were placed in a beaker with a lithium ion to nickel ion molar ratio of 0.8:1 and a metal cation to citric acid molar ratio of 1:1. Then, 50mL of deionized water was added, and the mixture was magnetically stirred for 20min. PVP (final concentration 0.3mol / L) was then added, and stirring continued for 2 hours. After stirring, the lithium-nickel salt mixture was dried at 80℃ for 8h to obtain a gel-like sample. The gel-like sample was pre-calcined at 500℃ for 3h under an oxygen atmosphere at a heating rate of 5℃ / min. After pre-calcination, it was held at 700℃ under an argon atmosphere for 14h at a heating rate of 2℃ / min. Finally, ICP analysis yielded Li... 0.63 Ni 1.37 O2 oxide sample.
[0030] Figure 1 and Figure 2 The Li obtained in this embodiment 0.63 Ni 1.37 XRD and SEM images of the O2 oxide sample revealed that, under these conditions, the sample exhibited a highly pure and well-crystallized cationic disordered rock salt phase with a particle size ranging from 0.5 μm to 1 μm. A coin cell was constructed using this material as the positive electrode and a Li sheet as the counter electrode. Constant current charge-discharge tests were conducted at 1.5 V–4.3 V and 100 mA / g. Figure 3 Li obtained in Example 1 0.63 Ni 1.37 The charge-discharge curves of the O2 oxide sample show that its charge specific capacity and discharge specific capacity are 171 mAh g⁻¹. -1 and 203mAh g -1 .
[0031] Example 2
[0032] Lithium nitrate (2g by mass), nickel nitrate, and citric acid were placed in a beaker with a lithium ion to nickel ion molar ratio of 0.8:1 and a metal cation to citric acid molar ratio of 1:1. Then, 50mL of deionized water was added, and the mixture was magnetically stirred for 20min. PVP (final concentration 0.3mol / L) was then added, and stirring continued for 2 hours. After stirring, the lithium-nickel salt mixture was dried at 80℃ for 8h to obtain a gel-like sample. The gel-like sample was pre-calcined at 500℃ for 3h under an oxygen atmosphere at a heating rate of 5℃ / min. After pre-calcination, it was held at 1000℃ in an argon atmosphere for 14h at a heating rate of 2℃ / min. Finally, ICP analysis yielded Li... 0.55 Ni 1.45 O2 cation disordered oxide sample.
[0033] Using this material as the positive electrode and Li sheet as the counter electrode, a coin cell was assembled. Under conditions of 1.5V-4.3V and 100mA / g, the discharge capacity was 151mAh / g.
[0034] Example 3
[0035] Lithium nitrate (2 g by mass), nickel nitrate, and citric acid were placed in a beaker with a lithium ion to nickel ion molar ratio of 0.8:1 and a metal cation to citric acid molar ratio of 1:1. Then, 50 mL of deionized water was added, and the mixture was magnetically stirred for 20 min. PVP (final concentration 0.3 mol / L) was then added, and stirring continued for 2 hours. After stirring, the lithium-nickel salt mixture was dried at 60 °C for 8 h to obtain a gel-like sample. The gel-like sample was pre-calcined at 500 °C for 3 h under an oxygen atmosphere at a heating rate of 5 °C / min. After pre-calcination, it was held at 1200 °C under an argon atmosphere for 14 h at a heating rate of 2 °C / min. Finally, ICP analysis yielded Li... 0.42 Ni 1.58 O2 cation disordered oxide sample.
[0036] Using this material as the positive electrode and Li sheet as the counter electrode, a coin cell was assembled. Under conditions of 1.5V-4.3V and 100mA / g, the discharge capacity was 128mAh / g.
[0037] Example 4
[0038] Lithium nitrate (2g by mass), nickel nitrate, and citric acid were placed in a beaker with a lithium ion to nickel ion molar ratio of 0.8:1 and a metal cation to citric acid molar ratio of 1:1. Then, 50mL of deionized water was added, and the mixture was magnetically stirred for 20min. PVP (final concentration 0.3mol / L) was then added, and stirring continued for 2 hours. After stirring, the lithium-nickel salt mixture was dried at 100℃ for 10h to obtain a gel-like sample. The gel-like sample was pre-calcined at 300℃ for 10h under an oxygen atmosphere at a heating rate of 5℃ / min. After pre-calcination, it was held at 600℃ under an argon atmosphere for 16h at a heating rate of 2℃ / min. Finally, ICP analysis yielded Li... 0.31 Ni 1.69 O2 cation disordered oxide sample.
[0039] Using this material as the positive electrode and Li sheet as the counter electrode, a coin cell was assembled. Under conditions of 1.5V-4.3V and 100mA / g, the discharge specific capacity was 106mAh / g.
[0040] Example 5
[0041] Lithium nitrate (2g by mass), nickel nitrate, and citric acid were placed in a beaker with a lithium ion to nickel ion molar ratio of 1:1 and a metal cation to citric acid molar ratio of 1:1. Then, 50mL of deionized water was added, and the mixture was magnetically stirred for 20min. PVP (final concentration 0.3mol / L) was then added, and stirring was continued for 2 hours.
[0042] After stirring, the lithium-nickel salt mixture was dried at 80℃ for 8 hours to obtain a gel-like sample. The gel-like sample was then pre-calcined at 500℃ for 3 hours under an oxygen atmosphere at a heating rate of 5℃ / min. After pre-calcination, it was held at 700℃ in an argon atmosphere for 14 hours at a heating rate of 2℃ / min. Finally, ICP analysis yielded Li... 0.73 Ni 1.27 O2 oxide sample.
[0043] Figure 4 The Li obtained in this embodiment 0.73 Ni 1.27 The XRD pattern of the O2 oxide sample shows that the crystal structure under these conditions is a cationic disordered rock salt phase, but with certain lithium carbonate impurities. Using this material as the positive electrode and a Li sheet as the counter electrode, a coin cell was assembled. Under conditions of 1.5V-4.3V and 100mA / g, the discharge capacity was 133mAh / g.
[0044] Example 6
[0045] Lithium nitrate (2g by mass), nickel nitrate, and citric acid were placed in a beaker with a lithium ion to nickel ion molar ratio of 0.4:1 and a metal cation to citric acid molar ratio of 1:1. Then, 50mL of deionized water was added, and the mixture was magnetically stirred for 20min. PVP (final concentration 0.3mol / L) was then added, and stirring continued for 2 hours. After stirring, the lithium-nickel salt mixture was dried at 80℃ for 8h to obtain a gel-like sample. The gel-like sample was pre-calcined at 500℃ for 3h under an oxygen atmosphere at a heating rate of 5℃ / min. After pre-calcination, it was held at 700℃ under an argon atmosphere for 14h at a heating rate of 2℃ / min. Finally, ICP analysis yielded Li... 0.29 Ni 1.71 O2 cation disordered rock salt phase oxide sample.
[0046] Using this material as the positive electrode and Li sheet as the counter electrode, a coin cell was assembled. Under conditions of 1.5V-4.3V and 100mA / g, the discharge capacity was 96mAh / g.
[0047] Comparative Example 1
[0048] Lithium nitrate (2g by mass), nickel nitrate, and citric acid were placed in a beaker with a lithium ion to nickel ion molar ratio of 1.1:1 and a metal cation to citric acid molar ratio of 1:1. Then, 50mL of deionized water was added, and the mixture was magnetically stirred for 20min. PVP (final concentration 0.3mol / L) was then added, and stirring continued for 2 hours. After stirring, the lithium-nickel salt mixture was dried at 80℃ for 8h to obtain a gel-like sample. The gel-like sample was pre-calcined at 500℃ for 3h under an oxygen atmosphere at a heating rate of 5℃ / min. After pre-calcination, it was held at 700℃ under an argon atmosphere for 14h at a heating rate of 2℃ / min. Finally, ICP analysis revealed the composition to be Li. 0.95 Ni 1.05 O2 oxide sample.
[0049] Figure 5 The Li obtained in this comparative example 0.95 Ni 1.05 The XRD pattern of the O2 oxide sample shows that the crystal structure of the sample under these conditions is layered lithium nickelate. Using this material as the positive electrode and a Li sheet as the counter electrode, a coin cell was assembled. Under conditions of 1.5V-4.3V and 100mA / g, the discharge specific capacity was 139mAh / g.
[0050] Comparative Example 2
[0051] Lithium nitrate (2g by mass), nickel nitrate, and citric acid were placed in a beaker with a lithium ion to nickel ion molar ratio of 0.3:1 and a metal cation to citric acid molar ratio of 1:1. Then, 50mL of deionized water was added, and the mixture was magnetically stirred for 20min. PVP (final concentration 0.3mol / L) was then added, and stirring continued for 2 hours. After stirring, the lithium-nickel salt mixture was dried at 80℃ for 8h to obtain a gel-like sample. The gel-like sample was pre-calcined at 500℃ for 3h under an oxygen atmosphere at a heating rate of 5℃ / min. After pre-calcination, it was held at 700℃ under an argon atmosphere for 14h at a heating rate of 2℃ / min. Finally, ICP analysis revealed the composition to be Li. 0.19 Ni 1.81 O2 oxide sample.
[0052] Using this material as the positive electrode and a Li sheet as the counter electrode, a coin cell was assembled. Constant current charge-discharge tests were conducted at 1.5V-4.3V and 100mA / g. Figure 6 The Li obtained in this comparative example 0.19 Ni 1.81The charge-discharge curves of the O2 oxide sample reveal a discharge specific capacity of only 32 mAh / g, exhibiting almost no electrochemical performance. This is attributed to the Li prepared under these conditions. 0.19 Ni 1.81 The O2 sample had too high a nickel content and too low a lithium content, resulting in a sample that was mainly composed of NiO.
Claims
1. A method for preparing lithium-poor lithium nickelate cationic disordered rock salt phase cathode material, characterized in that, Includes the following steps: (1) The lithium salt and nickel salt are dissolved in water according to the molar ratio of lithium ion to nickel ion of 0.8~1:1, and an organic complex is added to form a lithium-nickel salt mixed solution. The molar ratio of the total cations in the lithium salt and nickel salt to the organic complex is 1:0.6~3. The organic complex is citric acid and PVP. (2) The lithium-nickel salt mixed solution was heated and dried at 60-100 °C to form a gel-like sample; (3) After the gel sample is fully pre-fired at 300-500 °C, it is then annealed at 600-1200 °C to obtain lithium-poor lithium nickelate cationic disordered rock salt phase cathode material.
2. The preparation method according to claim 1, characterized in that, In step (1), the lithium salt is lithium nitrate, lithium acetate or lithium sulfate, and the nickel salt is nickel nitrate, nickel acetate or nickel sulfate.
3. The preparation method according to claim 1, characterized in that, In step (1), the water is deionized water; in step (2), the drying time is 0.5-10h.
4. The preparation method according to claim 1, characterized in that, In step (3), the heating rate during the pre-firing stage is 1-20 ℃ / min, and the pre-firing time is 0.5-10h.
5. The preparation method according to claim 1, characterized in that, In step (3), the atmosphere during annealing is argon, the heating rate during the annealing stage is 1-20 ℃ / min, and the holding time is 0.5-16h.