CN117996067A - O2 type lithium-rich manganese-based positive electrode material and preparation and application thereof - Google Patents
O2 type lithium-rich manganese-based positive electrode material and preparation and application thereof Download PDFInfo
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- 239000011572 manganese Substances 0.000 title claims abstract description 102
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 93
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 91
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 title claims abstract description 73
- 229910052748 manganese Inorganic materials 0.000 title claims abstract description 73
- 239000007774 positive electrode material Substances 0.000 title claims abstract description 67
- 238000002360 preparation method Methods 0.000 title claims abstract description 26
- 239000011734 sodium Substances 0.000 claims abstract description 60
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 54
- 239000002243 precursor Substances 0.000 claims abstract description 53
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims abstract description 47
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 47
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 37
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 35
- 239000001301 oxygen Substances 0.000 claims abstract description 35
- 239000000463 material Substances 0.000 claims abstract description 30
- 238000005342 ion exchange Methods 0.000 claims abstract description 22
- 229910001415 sodium ion Inorganic materials 0.000 claims abstract description 14
- 239000010405 anode material Substances 0.000 claims abstract description 12
- QTJOIXXDCCFVFV-UHFFFAOYSA-N [Li].[O] Chemical compound [Li].[O] QTJOIXXDCCFVFV-UHFFFAOYSA-N 0.000 claims abstract description 9
- 239000000126 substance Substances 0.000 claims abstract description 9
- 229910018516 Al—O Inorganic materials 0.000 claims abstract description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 47
- 238000000034 method Methods 0.000 claims description 31
- 238000010438 heat treatment Methods 0.000 claims description 25
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 24
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 14
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- 150000003839 salts Chemical class 0.000 claims description 14
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- ZAUUZASCMSWKGX-UHFFFAOYSA-N manganese nickel Chemical compound [Mn].[Ni] ZAUUZASCMSWKGX-UHFFFAOYSA-N 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 8
- 238000000227 grinding Methods 0.000 claims description 8
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- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 7
- 229910052786 argon Inorganic materials 0.000 claims description 7
- 239000012298 atmosphere Substances 0.000 claims description 7
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- 239000003792 electrolyte Substances 0.000 claims description 7
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
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- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 6
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- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 6
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- 239000002904 solvent Substances 0.000 claims description 5
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 4
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 4
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- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 4
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 4
- 239000011888 foil Substances 0.000 claims description 4
- AMXOYNBUYSYVKV-UHFFFAOYSA-M lithium bromide Chemical compound [Li+].[Br-] AMXOYNBUYSYVKV-UHFFFAOYSA-M 0.000 claims description 4
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 4
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 4
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 claims description 4
- HSZCZNFXUDYRKD-UHFFFAOYSA-M lithium iodide Chemical compound [Li+].[I-] HSZCZNFXUDYRKD-UHFFFAOYSA-M 0.000 claims description 4
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims description 4
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- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 4
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- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 claims description 2
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- 229920002125 Sokalan® Polymers 0.000 claims description 2
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 2
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- 238000005119 centrifugation Methods 0.000 claims description 2
- 238000005520 cutting process Methods 0.000 claims description 2
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 claims description 2
- 239000008273 gelatin Substances 0.000 claims description 2
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- 239000003273 ketjen black Substances 0.000 claims description 2
- INHCSSUBVCNVSK-UHFFFAOYSA-L lithium sulfate Inorganic materials [Li+].[Li+].[O-]S([O-])(=O)=O INHCSSUBVCNVSK-UHFFFAOYSA-L 0.000 claims description 2
- GLNWILHOFOBOFD-UHFFFAOYSA-N lithium sulfide Chemical compound [Li+].[Li+].[S-2] GLNWILHOFOBOFD-UHFFFAOYSA-N 0.000 claims description 2
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- 239000004584 polyacrylic acid Substances 0.000 claims description 2
- 239000001632 sodium acetate Substances 0.000 claims description 2
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- 235000010413 sodium alginate Nutrition 0.000 claims description 2
- 239000000661 sodium alginate Substances 0.000 claims description 2
- 229940005550 sodium alginate Drugs 0.000 claims description 2
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims description 2
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- ZNCPFRVNHGOPAG-UHFFFAOYSA-L sodium oxalate Chemical compound [Na+].[Na+].[O-]C(=O)C([O-])=O ZNCPFRVNHGOPAG-UHFFFAOYSA-L 0.000 claims description 2
- 229940039790 sodium oxalate Drugs 0.000 claims description 2
- 238000000967 suction filtration Methods 0.000 claims description 2
- RBTVSNLYYIMMKS-UHFFFAOYSA-N tert-butyl 3-aminoazetidine-1-carboxylate;hydrochloride Chemical compound Cl.CC(C)(C)OC(=O)N1CC(N)C1 RBTVSNLYYIMMKS-UHFFFAOYSA-N 0.000 claims description 2
- 239000002105 nanoparticle Substances 0.000 claims 1
- 150000003624 transition metals Chemical class 0.000 abstract description 10
- 229910052723 transition metal Inorganic materials 0.000 abstract description 9
- 229910008555 Li1.2Mn0.6Ni0.2O2 Inorganic materials 0.000 abstract description 6
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- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 22
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- 230000033116 oxidation-reduction process Effects 0.000 description 15
- 239000010406 cathode material Substances 0.000 description 10
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- 238000002441 X-ray diffraction Methods 0.000 description 5
- 150000001450 anions Chemical class 0.000 description 5
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- 125000000129 anionic group Chemical group 0.000 description 4
- 229910002982 Li2MnO3 phase Inorganic materials 0.000 description 3
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 3
- 229910017052 cobalt Inorganic materials 0.000 description 3
- 239000010941 cobalt Substances 0.000 description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000011065 in-situ storage Methods 0.000 description 3
- 229910003002 lithium salt Inorganic materials 0.000 description 3
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- 229910008090 Li-Mn-O Inorganic materials 0.000 description 2
- 229910006369 Li—Mn—O Inorganic materials 0.000 description 2
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- 229910012851 LiCoO 2 Inorganic materials 0.000 description 1
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 1
- 229910013191 LiMO2 Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 229910018663 Mn O Inorganic materials 0.000 description 1
- 229910003176 Mn-O Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 1
- IVAOQJNBYYIDSI-UHFFFAOYSA-N [O].[Na] Chemical compound [O].[Na] IVAOQJNBYYIDSI-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
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- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
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- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses an O2 type lithium-rich manganese-based positive electrode material and preparation and application thereof, wherein on the basis of traditional O3 type Li 1.2Mn0.6Ni0.2O2, the O2 type lithium-rich manganese-based material is ABCB type oxygen stack to realize reversible transition metal migration, and a P2 sodium positive electrode with low sodium content is used as a precursor, so that a large amount of sodium vacancies are generated, and oxygen vacancies are generated, so that the O2 type lithium-rich manganese-based positive electrode material prepared by Li/Na ion exchange has lithium oxygen double vacancies at the same time, and simultaneously, regulated trace Al element doping is introduced to form Al-O bonds to further inhibit voltage attenuation, and the chemical formula of the final positive electrode material is as follows: li x(Li0.2Mn0.57Ni0.19Al0.04)O2, wherein x is in the range of 0.6.ltoreq.x.ltoreq.1.0. The invention solves the problem that the average working voltage of the existing lithium-rich manganese-based anode material is seriously attenuated.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to an O2 type lithium-rich manganese-based positive electrode material, and preparation and application thereof.
Background
With the rapid development of the mobile automobile market, high-energy density lithium ion batteries are urgently needed to cope with the requirement of high endurance of electric automobiles. In current lithium ion battery systems, the capacity mismatch between the positive and negative electrode materials (positive electrode capacity is almost an order of magnitude smaller than negative electrode capacity) severely impedes the development of lithium ion batteries. The lithium-rich manganese-based positive electrode material represented by xLi 2MnO3·(1-x)LiMO2 (M is a transition metal) is recognized as one of the most promising candidates for the positive electrode material of the next-generation rechargeable lithium ion battery because of its high specific capacity of 250mah·g -1 and high energy density of 800wh·kg -1.
Compared with the traditional lithium ion battery anode materials such as layered LiCoO 2, olivine LiFePO 4 and ternary NCM, the lithium-rich manganese-based anode material has the advantages of higher specific discharge capacity and specific energy, high pollution, lower cobalt content, even zero cobalt, lower cost, more environmental protection, higher thermal stability and the like, and is rare and expensive. However, the lithium-rich manganese-based material has low initial coulomb efficiency and rapid capacity and average voltage decay due to irreversible transition metal migration and irreversible oxygen release caused by a special anion oxygen oxidation-reduction mechanism under a high voltage platform (more than 4.5V), which severely shortens the service life of the lithium-rich manganese-based material in practical application and greatly limits the large-scale commercial application of the lithium-rich manganese-based material.
The lithium-rich cathode material can be mainly classified into an O3 phase and an O2 phase according to the stacking sequence of oxygen layers, and O3 is more thermodynamically stable than the O2 phase, so that the conventional high-temperature sintering only generates an O3-type lithium-rich manganese-based material. The O2 phase is a metastable state structure which is unstable in thermodynamics, and cannot be prepared by a conventional high-temperature solid-phase sintering method, and can be prepared by a Li/Na ion exchange method by taking a P2 type sodium ion positive electrode material as a precursor, wherein the ion exchange method has certain randomness, and the selection of proper process parameters is very important. The O2 type lithium-rich manganese-based material has been demonstrated to effectively mitigate the sustained decay of the average operating voltage of the lithium-rich manganese-based material by achieving reversible transition metal migration and mitigating the asymmetry of the anionic oxygen redox due to its particular ABCB type oxygen stacking sequence. The conventional O2 type lithium-rich manganese-based positive electrode material generally adopts a P2 sodium-electricity positive electrode with high sodium content as a precursor, such as Na 5/6(Li0.2Mn0.6Ni0.2)O2, wherein the precursor only has a small amount of sodium vacancies, and then the typical O2 type lithium-rich manganese-based positive electrode material prepared by a Li/Na ion exchange method has a chemical formula of Li 1.1Mn0.6Ni0.2O2 and has a certain lithium vacancies, which is similar to the conventional cobalt-free O3 type lithium-rich manganese-based positive electrode material: in contrast to Li 1.2Mn0.6Ni0.2O2, the average operating voltage decay per turn at a current density of 1C (200mA.g -1) at a high cut-off voltage of 2-4.8V can only be raised from 2mv/cycle to 1mv/cycle, and does not reach the desired level. The average operating voltage decay is a key problem limiting the large-scale commercial application of lithium-rich cathode materials, and can directly lead to continuous reduction of the energy density of the battery in the cycling process, and the difficulty of battery management is increased. Therefore, the difficulty of how to further suppress the continuous decay of the average voltage of the lithium-rich manganese-based positive electrode material and control it within a negligible range (< 0.2 mv/cycle) is a major and difficult point of research in the art.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides an O2 type lithium-rich manganese-based positive electrode material, and preparation and application thereof, wherein voltage attenuation before and after circulation of the positive electrode material is negligible, and circulation performance is excellent, so that the problem that the conventional lithium-rich manganese-based positive electrode material has serious average working voltage attenuation is solved, the first-circle energy density of the prepared lithium ion battery is as high as 780 Wh-kg-1, and the current density of normal multiplying power 1C (200 mA-g-1) and low multiplying power 0.3C (60 mA-g-1) is circulated for 200 circles under the high cut-off voltage of 2-4.8V, the average working voltage attenuation before and after circulation is negligible, and the capacity retention rate is greater than 85%.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
On the basis of a cobalt-free O3 type cobalt-free lithium-rich manganese-based positive electrode material Li 1.2Mn0.6Ni0.2O2, the element proportion of manganese/nickel 3:1 is adopted, and the oxygen stacking is different from that of an O3 material BACBAC type, the O2 type lithium-rich manganese-based material is an ABCB type oxygen stacking, reversible transition metal migration is realized, a P2 sodium positive electrode with low sodium content is adopted as a precursor, and oxygen vacancies are generated while a large number of sodium vacancies are generated, so that the O2 type lithium-rich manganese-based positive electrode material prepared by Li/Na ion exchange has lithium oxygen double vacancies, an O1s map of XPS shows that the surface oxygen vacancy content is up to 60%, the oxygen oxidation reduction of anions is effectively inhibited, and simultaneously regulated trace Al element doping is introduced to form stronger Al-O bonds to further stabilize lattice oxygen, and the chemical formula of the positive electrode material is finally obtained as follows: li x(Li0.2Mn0.57Ni0.19Al0.04)O2, wherein x is in the range of 0.6.ltoreq.x.ltoreq.1.0.
The O2 type lithium-rich manganese-based positive electrode material has lithium-oxygen double vacancies, and Al and O form an Al-O bond to further inhibit voltage decay.
A preparation method of an O2 type Gao Fuli manganese-based positive electrode material comprises the following steps:
(1) Preparing a P2 sodium-electricity positive electrode precursor: weighing a sodium source, a lithium source, an aluminum oxide and a nickel-manganese coprecipitation precursor according to the proportion of each element in a chemical formula Na 0.6(Li0.2Mn0.57Ni0.19Al0.04)O2, mixing the sodium source, the lithium source, the aluminum oxide and the nickel-manganese coprecipitation precursor, grinding to obtain mixed powder, heating, calcining, and naturally cooling to room temperature to obtain a P2 type sodium-electricity anode precursor;
(2) Preparing an O2-type lithium-rich manganese-based positive electrode material by an ion exchange method: and mixing and grinding the P2 type sodium-electricity positive electrode precursor and a co-crystal molten salt lithium source, performing low-temperature heat treatment, cooling to room temperature, and filtering, washing and drying to obtain the O2 type lithium-rich manganese-based positive electrode material. Wherein the eutectic molten salt lithium source is used for providing the lithium element in the x part of Li x(Li0.2Mn0.57Ni0.19Al0.04)O2, and the filtered washing is used for removing redundant lithium element and sodium element.
Preferably, in the step (1), the elements are mixed according to the proportion of the chemical formula, wherein the sodium source is one or more of sodium oxalate, sodium hydroxide, sodium carbonate, sodium bicarbonate and sodium acetate, the lithium source is one or more of lithium nitrate, lithium chloride, lithium hydroxide, lithium bromide, lithium iodide, lithium sulfide, lithium fluoride, lithium carbonate, lithium sulfate and lithium manganate, the aluminum oxide is nano-grade Al 2O3, and the nickel-manganese precursor is a hydroxide precursor or a carbonate precursor.
Preferably, the method of the temperature-raising calcination treatment in the step (1) comprises the following steps: the temperature rising rate is 1-10 ℃/min, the calcining condition is 600-900 ℃ and the calcining is carried out for 8-15 h, and the sintering atmosphere is air or argon. Different sintering conditions can influence the P2 phase purity of the sodium electric positive electrode precursor, and the sintering conditions are controlled to prepare the pure P2 phase sodium electric positive electrode precursor without impurity phases.
Preferably, the eutectic molten salt lithium source in the step (2) is a mixture of LiNO 3 and LiCl, the molar ratio of LiNO 3/LiCl is y/(1-y), in order to achieve the optimal eutectic molten state and the lowest Li/Na ion exchange barrier, wherein y is in a range of 0.874 < y < 1, and the molar ratio of the content of lithium element in the molten salt lithium source to the content of sodium element in the P2 type sodium electric positive electrode precursor is between 1 and 10.
Preferably, the low-temperature heat treatment method in the step (2) is as follows: the heating rate is 1-10 ℃/min, the heat treatment condition is 255-300 ℃, the heat treatment is 1-10 h, and the heat treatment atmosphere is air or argon. According to the phase diagram of LiNO 3/LiCl, the best eutectic melting effect can be achieved at more than 255 ℃, li/Na ion exchange is more facilitated under the liquid flow state of molten salt, and the metastable state O2 structure can be converted into the thermodynamically more stable O3 structure at more than 300 ℃, so that the temperature is optimal at 255-300 ℃.
Preferably, the method of filtering, washing and drying treatment in the step (2) is as follows: and dissolving the block after ion exchange by using deionized water, washing 3-6 times by using deionized water and ethanol in a suction filtration or centrifugation mode, and drying in an oven at 80-200 ℃ for 24-48 h.
And preparing the lithium ion battery positive electrode plate by using the O2 type lithium-rich manganese-based positive electrode material.
Preferably, the preparation method of the positive electrode plate of the lithium ion battery comprises the following steps: -
Mixing an O2 type lithium-rich manganese-based positive electrode material, a conductive agent and a binder, dissolving in a solvent to obtain slurry, taking an aluminum foil as a current collector, uniformly coating the slurry on the surface of the current collector, and drying to obtain a positive electrode plate of the lithium ion battery;
wherein the binder is selected from one or more of polyvinylidene fluoride, polyacrylic acid, sodium carboxymethylcellulose, sodium alginate and gelatin, the conductive agent is selected from carbon black, super-P or ketjen black, and the solvent is N-methylpyrrolidone; the mass ratio of the O2-type lithium-rich manganese-based anode material to the conductive agent to the binder is 70-90: 5-20: 5 to 20.
The application of the lithium-rich manganese-based positive electrode plate in the preparation of a lithium ion battery is characterized in that the lithium ion battery is prepared according to the following steps:
Preparing a negative electrode plate: tabletting and cutting lithium metal;
preparation of electrolyte: mixing ethylene carbonate and methyl ethyl carbonate with the volume ratio of 3:7, and preparing carbonate electrolyte with the concentration of 0.1-2 mol/L together;
A diaphragm: commercial polypropylene separator;
Preparation of a lithium ion battery: and sequentially assembling the positive pole piece, the diaphragm, the electrolyte and the negative pole piece of the lithium ion battery in a glove box, and tabletting and standing to prepare the lithium ion battery.
Preferably, the lithium ion battery has a discharge specific capacity of 200-250 mAh.g -1 at the first circle of a voltage interval of 2.0-4.8V, circulates for 200 circles at a current density of normal multiplying power 1C or low multiplying power 0.3C, the average working voltage attenuation before and after the circulation of the lithium ion battery is negligible, and the capacity retention rate is more than 85%.
The invention has the beneficial effects that:
the O2 type lithium-rich manganese-based positive electrode material provided by the invention has an innovative design of a P2 type sodium-electricity positive electrode precursor, and the chemical formula of the P2 sodium precursor is as follows: the property of Na 0.6(Li0.2Mn0.57Ni0.19Al0.04)O2 and P2 sodium precursor can directly influence the performance of the O2 type lithium-rich manganese-based material after Li/Na ion exchange, compared with the traditional P2 sodium precursor Na 5/6(Li0.2Mn0.6Ni0.2)O2, the lower sodium content can lead the P2 sodium precursor to generate a pure P2 phase more easily and generate a large number of sodium vacancies in situ in the high-temperature sintering process, the charge of the sodium vacancies is generally provided with a certain charge compensation by Ni element, but in the designed P2 sodium precursor, the valence of the Ni element is insufficient to compensate the charge of the excessive sodium vacancies, so the designed P2 sodium precursor also has local oxygen defects, namely oxygen vacancies, in addition, trace Al element doping is introduced into the designed P2 sodium precursor, the doping amount of the Al element is 4 percent after the regulation and control, the too small doping amount has no obvious influence on the electrochemical performance and the too much doping amount can lead to the occurrence of impurity phases.
The P2 sodium precursor design of the sodium-oxygen double-vacancy enables the O2 type lithium-rich manganese-based positive electrode material after ion exchange to simultaneously generate lithium vacancies and oxygen vacancies, the lithium-oxygen double-vacancy plays an effective role in inhibiting the anionic oxygen oxidation reduction of a high-pressure area (> 4.5V) of the lithium-rich manganese-based material, the capacity contributed by the first-round irreversible oxygen oxidation reduction reaction is greatly reduced, the loss and oxygen release of lattice oxygen are reduced, and the symmetry of the oxygen oxidation reduction reaction is improved, so that the voltage attenuation of the O2 type lithium-rich manganese-based material is effectively relieved.
Secondly, for trace Al element doping in the P2 sodium precursor, al element doping or substitution is very effective in inhibiting anion oxygen oxidation reduction all the time, such as in a conventional O3 type lithium-rich manganese-based material, proper Al doping can control voltage attenuation to be about 1.5mv/cycle, but does not reach an ideal level, because of instability of an O3 structure, most O3 materials have larger irreversible capacity and irreversible lattice oxygen loss in first-ring charge and discharge, meanwhile, transition metals are irreversibly migrated, the local structure of the O3 materials is irreversibly degenerated into a spinel structure, the ordered superlattice structure of Li-Mn6 honeycomb disappears, redox coupling is important in controlling the oxidation reduction potential of Ni 4+/Ni3+/Ni2+ evolved into Mn 4+/Mn3+/Mn2+ with low redox potential by high redox potential, so that the average voltage of the O3 materials is seriously attenuated, al plays an important role in stabilizing the redox potential of Mn, the doping effect of the Al element is very limited in the matrix, the O2 structure is used as a reversible transition metal, the oxidation-reversible transition metal structure can be realized, the oxidation-reduction coupling effect of Mn element is not limited in the range of the oxidation reduction potential of Mn 2 is controlled in the first-ring, and the oxidation reduction effect of Mn is further controlled in the range of the oxidation reduction potential of Mn 2 is not to be controlled in the positive-to be about 0.2.
2. The preparation method of the O2-type lithium-rich manganese-based battery anode material provided by the invention adopts a novel ion exchange method, is different from a conventional coprecipitation precursor combined high-temperature solid phase sintering method, greatly reduces the synthesis temperature and synthesis time by the ion exchange method, and compared with the conventional high-temperature sintering at 850 ℃ for 20 hours, the ion exchange process only needs 280 ℃ for heat treatment for 1-4 hours, so that the energy cost is obviously reduced, and the problems of serious Li/Ni mixed emission, great volatilization of lithium salt and the like caused by high-temperature sintering can be effectively solved.
There is some randomness in the Li/Na ion exchange process, so it is important to control the process parameters well. Firstly, the molar ratio of Li/Na in the eutectic molten salt lithium source and the P2 sodium precursor is not too high, and the excessive content of the lithium source can cause a large amount of impurity anions to remain in the prepared O2 type lithium-rich manganese-based material, which can seriously obstruct lithium ion transmission and affect the rate performance and coulombic efficiency; the Li/Na ratio is not too low, the content of the lithium source is too low, the Li/Na exchange of the prepared O2 type lithium-rich manganese-based material is incomplete, a large amount of Na element residues exist, and the capacity of the O2 type lithium-rich manganese-based material is reduced.
Secondly, the heat treatment temperature should be about 280 ℃ and the time is not too long, when the mol ratio of the LiNO 3 is more than 87.4% and the temperature is higher than 255 ℃ according to the phase diagram of the eutectic molten salt LiNO 3/LiCl, the LiNO 3/LiCl can reach the eutectic molten state, liCl is added to further reduce the migration barrier of Li/Na ion exchange, and the Li/Na ion exchange can be carried out under the flowable liquid state, so the heat treatment temperature should be more than 255 ℃ but not too high, the temperature rise can lead the Li/Na exchange to become severe, the stability of the generated O2 structure is reduced, the O2 structure is regarded as a thermodynamically unstable metastable structure, the phase change to the thermodynamically more stable O3 structure can occur at about 350 ℃, and the O2 structure can be completed to be converted into the O3 structure at 450 ℃, so the heat treatment temperature range is most suitable between 255 ℃ and 300 ℃.
3. The O2 type lithium-rich manganese-based material disclosed by the invention is contained in the composite anode of the lithium ion battery, and has a novel structural design of O2 with trace Al doping and double lithium oxygen vacancies, the design effectively improves the reversibility and symmetry of the oxidation reduction of the anionic oxygen, inhibits the release of irreversible oxygen and structural degradation, improves the voltage hysteresis, and remarkably improves the voltage stability of the lithium-rich anode material, and the lithium ion battery has excellent cycle and voltage stability under both low multiplying power and normal multiplying power: the specific capacity of the first-cycle discharge in the voltage interval of 2.0-4.8V reaches 200-250 mAh g -1, the lithium ion battery circulates for 200 cycles with the current density of low multiplying power 0.3C (60 mA g -1) and normal multiplying power 1C (200 mA g -1), the capacity retention rate of the lithium ion battery is more than 85%, and the average working voltage attenuation before and after the circulation is negligible.
In conclusion, the preparation method is novel and unique, the energy consumption is greatly reduced, a brand-new O2 type lithium-rich structure design is adopted, and in-situ construction of lithium oxygen double vacancies effectively inhibits irreversible oxygen release, improves the symmetry of anion redox and stabilizes lattice oxygen; the oxidation-reduction potential of Mn is further stabilized by doping trace Al elements, so that voltage attenuation is effectively inhibited and voltage hysteresis is relieved in a long-cycle process; the element of the invention is zero cobalt and high manganese, the raw materials are easy to obtain, the cost is low, the invention is safe and environment-friendly, and the invention has wide prospect in application as the next generation high specific energy lithium ion battery.
Drawings
FIG. 1 is a schematic flow chart of the preparation method of the invention.
FIG. 2 is a phase diagram of eutectic molten salt LiNO 3/LiCl.
Fig. 3 is an XRD pattern of the target sodium-electric positive electrode precursor obtained in example 1.
Fig. 4 is an XRD pattern of the target positive electrode material obtained in example 1.
Fig. 5 is an XRD pattern of the target sodium-electric positive electrode precursor obtained in comparative example 1.
Fig. 6 is an XRD pattern of the target positive electrode material obtained in comparative example 1.
Fig. 7 is an XRD pattern of the target positive electrode material obtained in comparative example 2.
FIG. 8 is an O1s spectrum of XPS spectrum of the target positive electrode material obtained in example 1.
FIG. 9 is an O1s spectrum of XPS spectrum of the target positive electrode material obtained in comparative example 1.
Fig. 10 is a first charge-discharge curve of the target cathode material obtained in example 1 at a current density of 0.1C.
Fig. 11 is a first charge-discharge curve of the target cathode material obtained in comparative example 1 at a current density of 0.1C.
Fig. 12 is a first charge-discharge curve of the target cathode material obtained in comparative example 2 at a current density of 0.1C.
Fig. 13 is a graph showing the rate performance of the target positive electrode material obtained in example 1.
Fig. 14 is a graph of the rate performance of the target positive electrode material obtained in comparative example 1.
Fig. 15 is a graph showing the rate performance of the target positive electrode material obtained in comparative example 2.
Fig. 16 is a graph showing the cycle performance of the target cathode material obtained in example 1 at a current density of 1C.
Fig. 17 is a graph showing the cycle performance of the target cathode material obtained in comparative example 1 at a current density of 1C.
Fig. 18 is a graph showing the cycle performance of the target cathode material obtained in comparative example 2 at a current density of 1C.
Fig. 19 is a graph showing the cycle performance of the target positive electrode material obtained in example 1 at a current density of 0.3C.
Fig. 20 is a graph showing the cycle performance of the target positive electrode material obtained in comparative example 1 at a current density of 0.3C.
Fig. 21 is a graph showing the cycle performance of the target positive electrode material obtained in comparative example 2 at a current density of 0.3C.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings.
Example 1
As shown in fig. 1: the preparation method of the O2 type lithium-rich manganese-based material prepares the O2 type lithium-rich manganese-based material into a lithium ion battery, and comprises the following steps:
(1) Preparation of Li x(Li0.2Mn0.57Ni0.19Al0.04)O2 cathode material:
The accurate weighing mole ratio is 3.1:1:7.6:0.2 of sodium carbonate (3% excess), lithium carbonate, manganese nickel (3:1) carbonate precursor and nano alumina are ground in an agate mortar for 30 minutes until the mixture is uniform, the obtained powder is transferred to a crucible, the crucible is put into a muffle furnace, the crucible is preheated and kept at 500 ℃ at a heating rate of 5 ℃/min for 8 hours in air atmosphere, the crucible is heated to 800 ℃ at 5 ℃/min for 8 hours in high-temperature calcination and kept at room temperature, and the P2 sodium electric anode precursor is obtained after the crucible is cooled to room temperature: na 0.6(Li0.2Mn0.57Ni0.19Al0.04)O2;
Grinding the obtained P2 sodium electropositive precursor material and LiNO 3/LiCl eutectic molten salt with the molar ratio of 88/12 uniformly in an argon glove box according to the molar ratio of Li/Na of 6.2:1 (shown in figure 2), transferring the obtained mixture into a porcelain boat, putting into a tubular furnace, heating to 300 ℃ at the heating rate of 5 ℃/min under the argon atmosphere for 4 hours, cooling the obtained block to room temperature along with the furnace, washing and filtering the obtained block with deionized water for 5 times to remove redundant lithium salt, drying at 80 ℃ in a blast drying box for 24 hours to remove redundant moisture, and taking out the obtained powder to obtain the target positive electrode material;
x-ray powder diffraction test is carried out on the obtained P2 sodium electric positive electrode precursor and the target positive electrode material obtained after Li/Na ion exchange to determine phases, the test results are respectively shown in fig. 3 and 4, each diffraction peak of the P2 sodium precursor obtained in fig. 3 is completely matched with the peak of the P2 phase of the P6 3/mmc space group in the PDF card, and no redundant peak except that about 21 degrees of small protruding peaks represent the Li-Mn-O ordered honeycomb superlattice structure indicates that the pure P2 sodium precursor is obtained: na 0.6(Li0.2Mn0.57Ni0.19Al0.04)O2. The diffraction peaks of the positive electrode material obtained in fig. 4 are completely matched with the peaks of the O2 phase of the P6 3 mc space group in the PDF card, and since lithium enrichment is a typical two-phase solid solution, a small peak of about 21 ° is a characteristic peak of the Li 2MnO3 phase, which indicates that the O2-type lithium-rich manganese-based positive electrode material is successfully synthesized: li x(Li0.2Mn0.57Ni0.19Al0.04)O2;
(2) Preparing an O2-Li x(Li0.2Mn0.57Ni0.19Al0.04)O2 positive electrode plate:
Mixing the positive electrode material prepared in the step (1) with a conductive additive (Super P) and a binder (polyvinylidene fluoride) according to a mass ratio of 80:10:10, adding a proper amount of solvent N-methyl pyrrolidone (NMP), uniformly stirring, coating the mixture on an aluminum foil, putting the aluminum foil into a vacuum oven at 80 ℃ for drying for 12 hours, and punching into a positive electrode plate with the diameter of 10 mm;
(3) Assembling a lithium ion battery:
Assembling the positive electrode plate prepared in the step (2) and the negative electrode of the metal lithium plate into a lithium ion battery, wherein electrolyte consists of 1.2mol/L LiPF 6 and Ethylene Carbonate (EC)/ethylmethyl carbonate (EMC) with the volume ratio of 3:7, and the separator adopts a commercial polypropylene (PP) separator, and the CR2025 button cell is assembled in a glove box which is filled with argon and has water oxygen values of lower than 0.1 ppm;
(4) Cell performance test:
the prepared lithium ion battery is subjected to constant current charge-discharge curve performance test within a test voltage range of 2.0-4.8V, a first-circle charge-discharge curve at 0.1C (1C=200mA g -1) is shown in figure 10, and the first-circle coulomb efficiency is 124.1%; the rate performance curve of the material is shown in fig. 11, the capacities of 0.1C, 0.2C, 0.5C, 1C, 2C and 5C under different rates are respectively 233.6mAh·g-1、223.1mAh·g-1、209.9mAh·g-1、195.5mAh·g-1、173.3mAh·g-1、138.8mAh·g-1;, the cycle performance under the current density of 1C is shown in fig. 16, the capacity retention rate is as high as 87.5% after the battery is cycled for 200 circles, and the average voltage before and after the cycle is minus attenuated by-2 mv; the cycle performance at low current density of 0.3C is as shown in fig. 19, the capacity retention rate is as high as 87.7% after 200 cycles of the battery, and the average voltage is only attenuated by 18mv before and after the cycle.
Comparative example 1
The preparation method of the O2 type lithium-rich manganese-based positive electrode material and the preparation of the O2 type lithium-rich manganese-based positive electrode material into a lithium ion battery are the same as those in the preparation steps (2) and (3) of the embodiment 1, and the only difference is that:
(1) Preparing an O2-Li x(Li0.2Mn0.6Ni0.2)O2 anode material:
The accurate weighing mole ratio is 3.1:1:8 (3% of excess sodium carbonate), lithium carbonate and manganese nickel (3:1) carbonate precursor, grinding for 30 minutes until the mixture is uniform, transferring the obtained powder into a crucible, putting the crucible into a muffle furnace, pre-calcining at a temperature rising rate of 5 ℃/min to 500 ℃ for 8 hours under air atmosphere, calcining at a high temperature of 5 ℃/min to 800 ℃ for 8 hours, and cooling to room temperature along with the furnace to obtain the P2 sodium electric anode precursor: na 0.6(Li0.2Mn0.6Ni0.2)O2;
Grinding the obtained P2 sodium precursor material and LiNO 3/LiCl eutectic molten salt with the molar ratio of 88/12 uniformly in an argon glove box according to the molar ratio of Li/Na of 6.2:1, transferring the obtained mixture into a porcelain boat, placing the porcelain boat into a tubular furnace, heating to 300 ℃ at the heating rate of 5 ℃/min under the argon atmosphere, carrying out heat treatment for 4 hours, cooling the furnace to room temperature, removing the obtained block, washing and filtering the obtained block by deionized water for 5 times to remove redundant lithium salt, and then drying the obtained block in a blast drying box at 80 ℃ for 24 hours to remove redundant moisture, and taking out the obtained powder to obtain the target anode material;
The obtained P2 sodium precursor and the target positive electrode material obtained after Li/Na ion exchange are subjected to X-ray powder diffraction test to determine phases, the test results are respectively shown in fig. 5 and 6, each diffraction peak of the obtained P2 sodium precursor in fig. 5 is completely matched with the peak of the P2 phase of the P6 3/mmc space group in the PDF card, and no redundant peak is left except that about 21 degrees of small-protrusion peaks represent the Li-Mn-O ordered honeycomb superlattice structure, so that the pure P2 sodium precursor is obtained: na 0.6(Li0.2Mn0.6Ni0.2)O2. The diffraction peaks of the positive electrode material obtained in fig. 6 are completely matched with the peaks of the O2 phase of the P6 3 mc space group in the PDF card, and since lithium enrichment is a typical two-phase solid solution, a small peak of about 21 ° is a characteristic peak of the Li 2MnO3 phase, which indicates that the O2-type lithium-rich manganese-based positive electrode material is successfully synthesized: li x(Li0.2Mn0.6Ni0.2)O2;
(4) Cell performance test:
The prepared lithium ion battery is subjected to constant current charge-discharge curve performance test within a test voltage range of 2.0-4.8V, a first-circle charge-discharge curve at 0.1C (1C=200mA g -1) is shown in FIG. 11, and the first-circle coulomb efficiency is 127.2%; the rate performance curves of the materials are shown in fig. 14, the capacities of 0.1C, 0.2C, 0.5C, 1C, 2C and 5C at different rates are respectively 240.5mAh·g-1、236.7mAh·g-1、219.8mAh·g-1、206.5mAh·g-1、183.1mAh·g-1、144.5mAh·g-1;, the cycle performance at the current density of 1C is shown in fig. 17, the capacity retention rate after 200 cycles of the battery is only 73.3%, and the average voltage decay before and after the cycle is 99mv; the cycle performance at a low current density of 0.3C is shown in fig. 20, the capacity retention after 200 cycles of the battery is 72.4%, and the average voltage decays by 123mv before and after the cycle.
Comparative example 2
The preparation method of the O3 type lithium-rich manganese-based positive electrode material and the preparation of the O3 type lithium-rich manganese-based positive electrode material into a lithium ion battery are the same as those in the preparation steps (2) and (3) of the embodiment 1, and the only difference is that:
(1) Preparing an O3-Li 1.2Mn0.6Ni0.2O2 anode material:
The accurate weighing mole ratio is 6.3:8 (5% excess) and manganese nickel (3:1) carbonate precursor, grinding for 30 minutes until the mixture is uniform, transferring the obtained powder into a crucible, placing the crucible into a muffle furnace, pre-calcining at a temperature rising rate of 5 ℃/min to 500 ℃ for heat preservation for 5 hours under an air atmosphere, calcining at a high temperature of 5 ℃/min to 850 ℃ for heat preservation for 12 hours, and cooling to a room temperature along with the furnace to obtain the target cathode material: li 1.2Mn0.6Ni0.2O2;
The positive electrode material obtained by the method is subjected to X-ray powder diffraction test to determine a phase, and the test result is shown in fig. 7, wherein the obtained positive electrode material is of a typical O3 structure of an R-3m space group, a small peak at about 21 degrees is a Li 2MnO3 phase of a C2/m space group, and no redundant peak exists, so that the O3 type lithium-rich manganese-based positive electrode material is successfully synthesized: li 1.2Mn0.6Ni0.2O2;
(4) Cell performance test:
The prepared lithium ion battery is subjected to constant current charge-discharge curve performance test within a test voltage range of 2.0-4.8V, a first-circle charge-discharge curve at 0.1C (1C=200mA g -1) is shown in FIG. 12, and the first-circle coulomb efficiency is 72.1%; the rate performance curves of the materials are shown in fig. 13, the capacities of 0.1C, 0.2C, 0.5C, 1C, 2C and 5C at different rates are respectively 239.9mAh·g-1、221.8mAh·g-1、199.7mAh·g-1、179.5mAh·g-1、157.8mAh·g-1、132.2mAh·g-1;, the cycle performance at the current density of 1C is shown in fig. 18, the capacity retention rate after 200 cycles of the battery is only 73.8%, and the average voltage decay before and after the cycle is 360mv; the cycle performance at a low current density of 0.3C is shown in fig. 21, the capacity retention rate after 200 cycles of the battery is 65.3%, and the average voltage decay before and after the cycle is 463mv. As shown in fig. 15.
TABLE 1
Fig. 8 and 9 are O1s spectra of X-ray photoelectron spectroscopy (XPS) tests of example 1 and comparative example 1, respectively, in which the oxygen vacancies each correspond to a fitted peak at 531.9eV, and the results show that the surface oxygen vacancy contents of example 1 and comparative example 1 are both up to 60%, which indicates that the low sodium content of 0.6 in the P2 sodium electrical positive precursor successfully constructs a large number of oxygen vacancies. By comparing the electrochemical performances of the comparative example 1 and the comparative example 2, the conventional O3 type lithium-rich manganese-based material, namely the comparative example 2, has extremely serious average voltage attenuation after long circulation, particularly at low multiplying power of 0.3C, the comparative example 1 is an O2 type lithium-rich manganese-based material without Al doping, and the voltage stability is greatly improved compared with the comparative example 2, so that the special O2 structure and the lithium-oxygen double-vacancy design effectively reduce irreversible oxygen oxidation reduction, and the oxygen oxidation reduction and transition metal migration reversibility are enhanced, so that the voltage attenuation is remarkably relieved relative to the conventional O3 structure. Compared with comparative example 1, the preparation method can obtain the preparation method of the lithium-rich manganese-based anode material, wherein the introduction of the Al element forms stronger Al-O bond so as to weaken the covalent nature of Mn-O bond, further weaken the oxidation reduction of anionic oxygen, stabilize the oxidation reduction potential of Mn, inhibit the dissolution of transition metal Mn, obtain excellent cycle stability and negligible voltage attenuation, and the voltage stability is obviously superior to that of most of O3 and O2-type lithium-rich manganese-based anode materials.
In summary, according to the O2 type lithium-rich manganese-based positive electrode material and the lithium ion battery, the O2 type lithium-rich manganese-based positive electrode material with remarkably improved initial efficiency, excellent cycle stability and negligible voltage attenuation is obtained by in-situ construction of the lithium-oxygen double vacancies in the stable O2 type structure and introduction of the trace Al doping. Meanwhile, the process is novel and unique, the energy consumption is effectively reduced, the raw materials of the components are easy to obtain, the cost is low, the process is safe and environment-friendly, and the process has wide prospect in application as a next-generation high-specific-energy lithium ion battery.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. An O2 type lithium-rich manganese-based positive electrode material is characterized by comprising the following chemical formula: li x(Li0.2Mn0.57Ni0.19Al0.04)O2, wherein x is in the range of 0.6.ltoreq.x.ltoreq.1.0;
The O2 type lithium-rich manganese-based positive electrode material has lithium oxygen double vacancies, and Al and O form an Al-O bond to stabilize lattice oxygen.
2. The method for preparing the O2 type Gao Fuli manganese-based positive electrode material according to claim 1, which is characterized by comprising the following steps:
(1) Preparing a P2 sodium-electricity positive electrode precursor: weighing a sodium source, a lithium source, an aluminum oxide and a nickel-manganese coprecipitation precursor according to the proportion of each element in a chemical formula Na 0.6(Li0.2Mn0.57Ni0.19Al0.04)O2, mixing the sodium source, the lithium source, the aluminum oxide and the nickel-manganese coprecipitation precursor, grinding to obtain mixed powder, heating, calcining, and naturally cooling to room temperature to obtain a P2 type sodium-electricity anode precursor;
(2) Preparing an O2-type lithium-rich manganese-based positive electrode material by an ion exchange method: and mixing and grinding the P2 type sodium-electricity positive electrode precursor and a eutectic molten salt lithium source, performing low-temperature heat treatment, cooling to room temperature, filtering, washing and drying to obtain the O2 type lithium-rich manganese-based positive electrode material, wherein the eutectic molten salt lithium source is used for providing the lithium element of the x part in Li x(Li0.2Mn0.57Ni0.19Al0.04)O2, and filtering and washing are used for removing redundant lithium element and sodium element.
3. The method for preparing the O2 type Gao Fuli manganese-based positive electrode material according to claim 2, wherein in the step (1), the elements are mixed according to the chemical formula, wherein the sodium source is one or more of sodium oxalate, sodium hydroxide, sodium carbonate, sodium bicarbonate and sodium acetate, the lithium source is one or more of lithium nitrate, lithium chloride, lithium hydroxide, lithium bromide, lithium iodide, lithium sulfide, lithium fluoride, lithium carbonate, lithium sulfate and lithium manganate, the aluminum oxide is nano-sized Al 2O3, and the nickel-manganese precursor is a hydroxide precursor or a carbonate precursor.
4. The method for preparing the O2 type Gao Fuli manganese-based positive electrode material according to claim 1, wherein the method for heating and calcining treatment in the step (1) is as follows: the temperature rising rate is 1-10 ℃/min, the calcining condition is 600-900 ℃ and the calcining is carried out for 8-15 h, and the sintering atmosphere is air or argon.
5. The method for preparing an O2-type Gao Fuli manganese-based positive electrode material according to claim 1, wherein in the step (2), the eutectic molten salt lithium source is a mixture of LiNO 3 and LiCl and the molar ratio LiNO 3/LiCl is y/(1-y), in order to achieve the best eutectic molten state and the lowest Li/Na ion exchange barrier, where y ranges from 0.874 < y < 1, and the molar ratio Li/Na of the lithium element content in the molten salt lithium source to the sodium element content in the P2-type sodium-electric positive electrode precursor ranges from 1 to 10.
6. The method for preparing an O2 type Gao Fuli manganese-based positive electrode material according to claim 1, wherein the method for low-temperature heat treatment in the step (2) is as follows: the heating rate is 1-10 ℃/min, the heat treatment condition is 255-300 ℃, the heat treatment is 1-10 h, and the heat treatment atmosphere is air or argon.
7. The method for preparing the O2 type Gao Fuli manganese-based positive electrode material according to claim 1, wherein the method for filtering, washing and drying in the step (2) is as follows: and dissolving the block after ion exchange by using deionized water, washing 3-6 times by using deionized water and ethanol in a suction filtration or centrifugation mode, and drying in an oven at 80-200 ℃ for 24-48 h.
8. The positive plate of the lithium ion battery is characterized by being prepared from the O2-type lithium-rich manganese-based positive plate material in claim 1.
9. The method for preparing the positive electrode plate of the lithium ion battery according to claim 8, comprising the steps of: -
Mixing an O2 type lithium-rich manganese-based positive electrode material, a conductive agent and a binder, dissolving in a solvent to obtain slurry, taking an aluminum foil as a current collector, uniformly coating the slurry on the surface of the current collector, and drying to obtain a positive electrode plate of the lithium ion battery;
wherein the binder is selected from one or more of polyvinylidene fluoride, polyacrylic acid, sodium carboxymethylcellulose, sodium alginate and gelatin, the conductive agent is selected from carbon black, super-P or ketjen black, and the solvent is N-methylpyrrolidone; the mass ratio of the O2-type lithium-rich manganese-based anode material to the conductive agent to the binder is 70-90: 5-20: 5 to 20.
10. The use of the lithium-rich manganese-based positive electrode sheet according to claim 8 in the preparation of a lithium ion battery, wherein the lithium ion battery is prepared according to the following steps:
Preparing a negative electrode plate: tabletting and cutting lithium metal;
preparation of electrolyte: mixing ethylene carbonate and methyl ethyl carbonate with the volume ratio of 3:7, and preparing carbonate electrolyte with the concentration of 0.1-2 mol/L together;
A diaphragm: commercial polypropylene separator;
Preparation of a lithium ion battery: and sequentially assembling the positive pole piece, the diaphragm, the electrolyte and the negative pole piece of the lithium ion battery in a glove box, and tabletting and standing to prepare the lithium ion battery.
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