CN116979063A - Combined positive electrode active material, preparation method thereof, positive electrode plate, electrode assembly, battery and electric equipment - Google Patents
Combined positive electrode active material, preparation method thereof, positive electrode plate, electrode assembly, battery and electric equipment Download PDFInfo
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- 239000007774 positive electrode material Substances 0.000 title claims abstract description 46
- 238000002360 preparation method Methods 0.000 title abstract description 20
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 98
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 92
- 230000001502 supplementing effect Effects 0.000 claims abstract description 52
- 229910010707 LiFePO 4 Inorganic materials 0.000 claims abstract description 41
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910010710 LiFePO Inorganic materials 0.000 claims abstract description 19
- 238000004519 manufacturing process Methods 0.000 claims abstract description 4
- 239000003795 chemical substances by application Substances 0.000 claims description 75
- 239000000203 mixture Substances 0.000 claims description 13
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 10
- 239000000463 material Substances 0.000 claims description 10
- 229910052698 phosphorus Inorganic materials 0.000 claims description 10
- 239000011574 phosphorus Substances 0.000 claims description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 7
- 229910004283 SiO 4 Inorganic materials 0.000 claims description 6
- 239000011149 active material Substances 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 5
- 239000003792 electrolyte Substances 0.000 claims description 5
- 239000011248 coating agent Substances 0.000 claims description 4
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 3
- 229910018068 Li 2 O Inorganic materials 0.000 claims description 3
- 239000002019 doping agent Substances 0.000 claims description 3
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 14
- 238000009830 intercalation Methods 0.000 description 22
- 230000002687 intercalation Effects 0.000 description 21
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 12
- 239000011267 electrode slurry Substances 0.000 description 11
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 9
- 239000002033 PVDF binder Substances 0.000 description 9
- 239000011230 binding agent Substances 0.000 description 9
- 239000002041 carbon nanotube Substances 0.000 description 9
- 229910021393 carbon nanotube Inorganic materials 0.000 description 9
- 239000002270 dispersing agent Substances 0.000 description 9
- 238000000034 method Methods 0.000 description 9
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 9
- 239000002002 slurry Substances 0.000 description 9
- 239000007787 solid Substances 0.000 description 9
- 239000002904 solvent Substances 0.000 description 9
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 7
- 238000012360 testing method Methods 0.000 description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 5
- 229920003048 styrene butadiene rubber Polymers 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 3
- 238000009770 conventional sintering Methods 0.000 description 3
- 230000002427 irreversible effect Effects 0.000 description 3
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- 239000002699 waste material Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 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 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 239000010406 cathode material Substances 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 239000000839 emulsion Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
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- 230000002441 reversible effect Effects 0.000 description 2
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 2
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- QSNQXZYQEIKDPU-UHFFFAOYSA-N [Li].[Fe] Chemical compound [Li].[Fe] QSNQXZYQEIKDPU-UHFFFAOYSA-N 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/37—Phosphates of heavy metals
- C01B25/375—Phosphates of heavy metals of iron
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/45—Phosphates containing plural metal, or metal and ammonium
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Crystallography & Structural Chemistry (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The application provides a combined positive electrode active material and a preparation method thereof, a positive electrode plate, an electrode assembly, a battery and electric equipment, and belongs to the field of manufacturing of lithium ion secondary batteries. The combined positive electrode active material comprises LiFePO 4 、FePO 4 And lithium supplementing agent, and LiFePO is combined in the positive electrode active material 4 The percentage content X of the FePO is 84 to 99.4 weight percent 4 The content Y of the lithium supplementing agent is 0.2-14.8 wt%, the content Z of the lithium supplementing agent is 0.3-14.8 wt%, the first-time charged delithiation capacity Q of the lithium supplementing agent is more than 300mAh/g, and the combined positive electrode active material can improve the problem of poor cycle performance of the corresponding battery to a certain extent.
Description
Technical Field
The application relates to the field of manufacturing of lithium ion secondary batteries, in particular to a combined positive electrode active material, a preparation method thereof, a positive electrode plate, an electrode assembly, a battery and electric equipment.
Background
In the prior art, conventional lithium iron phosphate batteries (LiFePO 4 ) LiFePO, typically in a single component 4 As a positive electrode active material, there is an irreversible lithium consumption problem, resulting in poor electrical properties of the corresponding battery.
Based on this, a mixed system of lithium iron phosphate and a lithium-supplementing agent is proposed as a positive electrode active material, so that irreversible lithium consumption is supplemented by adding the lithium-supplementing agent, and the addition of the lithium-supplementing agent can effectively improve the problem of irreversible lithium consumption, but the lithium-supplementing agent has a defect of low lithium intercalation capacity, so that the battery corresponding to the mixed system has a problem of poor cycle performance.
Disclosure of Invention
The application aims to provide a combined positive electrode active material, a preparation method thereof, a positive electrode plate, an electrode assembly, a battery and electric equipment, and the problem that the circulation performance of a battery corresponding to a mixed system is poor can be improved to a certain extent.
Embodiments of the present application are implemented as follows:
in a first aspect, embodiments of the present application provide a combined positive electrode active material comprising LiFePO 4 、FePO 4 And lithium supplementing agent, and LiFePO is combined in the positive electrode active material 4 The percentage content X of the FePO is 84 to 99.4 weight percent 4 The percentage content Y is 0.2-14.8 wt%, the percentage content Z of the lithium supplementing agent is 0.3-14.8 wt%, and the first charge delithiation capacity Q of the lithium supplementing agent is more than 300mAh/g.
In the technical scheme, the LiFePO containing specific mass percent 4 、FePO 4 And a lithium-supplementing agent as a positive electrode active material, and limiting the lithium-removing capacity of the lithium-supplementing agent for the first charge to a specific range, can have a high lithium-removing capacity and FePO by means of the lithium-supplementing agent 4 Has the advantage of higher lithium intercalation capacity, realizes lithium deintercalationThe high capacity complementation of the reversible lithium enables the positive plate to have higher capacity exertion, and further enables the corresponding battery to have better cycle performance.
In some alternative embodiments, liFePO 4 The percentage content X of the FePO is 94 to 97 weight percent 4 The percentage content Y is 0.2-1.7 wt%, the percentage content Z of the lithium supplementing agent is 2.8-4.3 wt%, and 176.6 is more than or equal to 160 xX+Q xZ is more than or equal to 162.
In the technical proposal, due to FePO 4 The contribution to the capacity of the lithium can be removed is small, and the capacity of the lithium can be removed is mainly exerted by LiFePO 4 And lithium supplementing agent, by optimizing the mass percentage of the three components, and LiFePO 4 The sum of the lithium-removable capacity of the lithium-supplementing agent and the lithium-removable capacity of the lithium-supplementing agent is limited in a specific range, and the cycle performance of the corresponding battery can be improved while the higher energy density is considered.
In some alternative embodiments, liFePO 4 The percentage content X of the FePO is 96.2 to 97 weight percent 4 The percentage content Y is 0.2-0.8 wt%, the percentage content Z of the lithium supplementing agent is 2.8-3 wt%, and 172.3 is more than or equal to 160 xX+Q xZ is more than or equal to 165.8.
In the technical scheme, the mass percentage of the three materials is further optimized, and LiFePO is prepared 4 The sum of the lithium-removable capacity of the lithium-supplementing agent and the lithium-removable capacity of the battery is limited to a more suitable range, and the energy density of the corresponding battery can be further improved.
In some alternative embodiments, liFePO 4 The percentage content X of the FePO is 93 to 97wt% 4 The percentage content Y is 0.2-3.1 wt%, the percentage content Z of the lithium supplementing agent is 0.9-4.3 wt%,93.9% is more than or equal to 156X (X+Y)/(160X X+Q X Z) is more than or equal to 84.5%.
In the technical scheme, because the lithium intercalation capacity contributed by the lithium supplementing agent is smaller, the lithium intercalation capacity is mainly exerted by LiFePO 4 And FePO 4 Determining by optimizing the mass percentage of the three components and adding LiFePO 4 And FePO 4 Sum of lithium intercalation capacities and LiFePO 4 The ratio of the sum of the lithium-removable capacity of (2) and the lithium-removable capacity of the lithium-supplementing agent is defined within a specific range so that the lithium-removable capacity and the lithium-removable capacityThe cycle performance of the corresponding battery can be further improved by the ratio in a suitable range.
In some alternative embodiments, liFePO 4 The percentage content X of the FePO is 94 to 97 weight percent 4 The percentage content Y is 0.2-3.1 wt%, the percentage content Z of the lithium supplementing agent is 0.9-4.3 wt%,89.6% is more than or equal to 156X (X+Y)/(160X X+Q X Z) is more than or equal to 84.5%.
In the technical scheme, the mass percentage of the three materials is further optimized, and LiFePO is prepared 4 And FePO 4 Sum of lithium intercalation capacities and LiFePO 4 The ratio of the sum of the lithium-removable capacity of the lithium-supplementing agent and the lithium-removable capacity of the battery is defined in a more suitable range, and the cycle performance of the corresponding battery can be further improved.
In some alternative embodiments, the lithium supplementing agent comprises Li 5 FeO 4 、Li 2 NiO 2 、Li 2 O、Li 3 N、Li 6 CoO 4 、LiF、Li 2 C 2 O 4 、Li 2 C 2 And Li (lithium) 4 SiO 4 At least one of/S.
In the technical scheme, the technical scheme provided by the application is suitable for the lithium supplementing agent with various materials, and more implementable modes can be provided, so that the technical scheme of the application is convenient to popularize and apply.
In a second aspect, an embodiment of the present application provides a method for preparing a combined positive electrode active material as provided in the embodiment of the first aspect, including the steps of:
uniformly mixing a lithium source, a ferrous iron source, a phosphorus source, a coating agent and a doping agent to obtain a mixture; drying and roasting the mixture in turn to obtain a product containing LiFePO 4 And FePO 4 Is an intermediate of the positive electrode material; adding a lithium supplementing agent into the intermediate of the positive electrode material; wherein, in the mixture, the mole ratio of the lithium element, the iron element and the phosphorus element is 1: (2-2.5): (2-2.5).
In the technical proposal, the LiFePO is used for preparing the powder 4 The conventional sintering preparation process can prepare the lithium-iron alloy by controlling the molar ratio of the lithium element, the iron element and the phosphorus element at the raw material endPreparing LiFePO-containing material 4 And FePO 4 The mass percentage of the intermediate of the positive electrode material and the mass percentage of the intermediate of the positive electrode material are in a proper range, and on the basis, the combined positive electrode active material provided by the embodiment of the first aspect can be prepared by adding a proper amount of lithium supplementing agent.
In a third aspect, embodiments of the present application provide a positive electrode sheet, including a positive electrode current collector and an active material layer located on one or both sides of the positive electrode current collector, the active material layer including a combined positive electrode active material as provided in the embodiments of the first aspect.
In a fourth aspect, an embodiment of the present application provides an electrode assembly, including the positive electrode sheet, the negative electrode sheet, and the battery separator provided in the embodiment of the third aspect, where the battery separator is located between the positive electrode sheet and the negative electrode sheet.
In a fifth aspect, embodiments of the present application provide a battery comprising an electrode assembly as provided in the fourth aspect, an electrolyte, and a case, both of which are contained in the case.
In a sixth aspect, an embodiment of the present application provides a powered device, including a battery as provided in the embodiment of the fifth aspect.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
In the description of the present application, unless otherwise indicated, "plural" in "one or more" means two or more; the range of "value a to value b" includes both ends "a" and "b", and "unit of measure" in "value a to value b+ unit of measure" represents "unit of measure" of both "value a" and "value b".
The following specifically describes a combined positive electrode active material, a preparation method thereof, a positive electrode plate, an electrode assembly, a battery and electric equipment.
In a first aspect, embodiments of the present application provide a combined positive electrode active material comprising LiFePO 4 、FePO 4 And lithium supplementing agent, and LiFePO is combined in the positive electrode active material 4 The percentage content X of the FePO is 84 to 99.4 weight percent 4 The percentage content Y is 0.2-14.8 wt%, the percentage content Z of the lithium supplementing agent is 0.3-14.8 wt%, and the first charge delithiation capacity Q of the lithium supplementing agent is more than 300mAh/g.
Of the three components, liFePO 4 Is at maximum and significantly higher than FePO 4 And lithium supplementing agent, because the mixed system needs LiFePO 4 A main body for enabling the corresponding battery to exert the electrical property equivalent to that of the conventional single-system lithium iron phosphate battery, and based on the main body, the corresponding battery has a proper percentage of FePO 4 And lithium supplementing agent as auxiliary component and LiFePO 4 And the electric performance of the corresponding battery is improved through the cooperation of the three components.
The lithium-supplementing agent can be used better by limiting the first-charge delithiation capacity Q of the lithium-supplementing agent to a range of more than 300mAh/g.
In the application, liFePO with specific mass percent content is contained 4 、FePO 4 And a lithium-supplementing agent as a positive electrode active material, and limiting the lithium-removing capacity of the lithium-supplementing agent for the first charge to a specific range, can have a high lithium-removing capacity and FePO by means of the lithium-supplementing agent 4 The lithium-ion battery has the advantage of higher lithium intercalation capacity, realizes high-capacity complementation of lithium-ion/reversible lithium, enables the positive plate to have higher capacity exertion, and further enables the corresponding battery to have better cycle performance.
As an example, the first charge of the lithium supplement has a delithiation capacity Q of 300-610 mAh/g, such as, but not limited to, Q of 300mAh/g, 400mAh/g, 500mAh/g, and 610mAh/g, or a range of values between any two.
The inventors have found that LiFePO 4 、FePO 4 And lithium supplementing agent in the combined system, liFePO 4 The lithium supplementing agent has better lithium removing capacity but poor lithium intercalation capacity, and FePO 4 The lithium intercalation capacity is excellent, but the lithium intercalation capacity is poor, that is, the contribution degree of the lithium intercalation capacity and the lithium intercalation capacity is different, so that the capacity level of the combined system can be limited from the aspects of the lithium intercalation capacity and the lithium intercalation capacity respectively in order to better promote the relevant electrical performance of the corresponding battery.
As an example, liFePO 4 The percentage content X of the FePO is 94 to 97 weight percent 4 The percentage content Y is 0.2-1.7 wt%, the percentage content Z of the lithium supplementing agent is 2.8-4.3 wt%, and 176.6 is more than or equal to 160 xX+Q xZ is more than or equal to 162.
In the formula 160, liFePO 4 Is a detachable approximation of capacity.
In this embodiment, due to FePO 4 The contribution to the capacity of the lithium can be removed is small, and the capacity of the lithium can be removed is mainly exerted by LiFePO 4 And lithium supplementing agent, by optimizing the mass percentage of the three components, and LiFePO 4 The sum of the lithium-removable capacity of the lithium-supplementing agent and the lithium-removable capacity of the lithium-supplementing agent is limited in a specific range, and the cycle performance of the corresponding battery can be improved while the higher energy density is considered.
As an example, liFePO 4 The percentage content X of the FePO is 96.2 to 97 weight percent 4 The percentage content Y is 0.2-0.8 wt%, the percentage content Z of the lithium supplementing agent is 2.8-3 wt%, and 172.3 is more than or equal to 160 xX+Q xZ is more than or equal to 165.8.
In the embodiment, the mass percentage of the three materials is further optimized, and LiFePO is prepared 4 The sum of the lithium-removable capacity of the lithium-supplementing agent and the lithium-removable capacity of the battery is limited to a more suitable range, and the energy density of the corresponding battery can be further improved.
As an example, liFePO 4 The percentage content X of the FePO is 93 to 97wt% 4 The percentage content Y is 0.2-3.1 wt%, the percentage content Z of the lithium supplementing agent is 0.9-4.3 wt%,93.9% is more than or equal to 156X (X+Y)/(160X X+Q X Z) is more than or equal to 84.5%.
In the formula 156, liFePO is represented 4 And FePO 4 Is a similar value of the lithium intercalation capacity.
In this embodiment, since the lithium intercalation capacity contributed by the lithium-supplementing agent is small, the lithium intercalation capacity is mainly exerted by LiFePO 4 And FePO 4 Determining by optimizing the mass percentage of the three components and adding LiFePO 4 And FePO 4 Sum of lithium intercalation capacities and LiFePO 4 The ratio of the sum of the lithium-removable capacity of the lithium intercalation agent and the lithium-removable capacity of the lithium-replenishing agent is defined within a specific range so that the ratio of the lithium-intercalation capacity to the lithium-removable capacity is within a suitable range, and the cycle performance of the corresponding battery can be further improved.
As an example, liFePO 4 The percentage content X of the FePO is 94 to 97 weight percent 4 The percentage content Y is 0.2-3.1 wt%, the percentage content Z of the lithium supplementing agent is 0.9-4.3 wt%,89.6% is more than or equal to 156X (X+Y)/(160X X+Q X Z) is more than or equal to 84.5%.
In the embodiment, the mass percentage of the three materials is further optimized, and LiFePO is prepared 4 And FePO 4 Sum of lithium intercalation capacities and LiFePO 4 The ratio of the sum of the lithium-removable capacity of the lithium-supplementing agent and the lithium-removable capacity of the battery is defined in a more suitable range, and the cycle performance of the corresponding battery can be further improved.
The material of the lithium supplementing agent is not limited, and may be selected and set according to the conventional method in the art.
As an example, the lithium supplementing agent includes Li 5 FeO 4 、Li 2 NiO 2 、Li 2 O、Li 3 N、Li 6 CoO 4 、LiF、Li 2 C 2 O 4 、Li 2 C 2 And Li (lithium) 4 SiO 4 At least one of/S.
In the embodiment, the technical scheme provided by the application is suitable for the lithium supplementing agent with various materials, and can provide more implementable modes, so that the technical scheme of the application is convenient to popularize and apply.
Li 4 SiO 4 S refers to S-elemental coated Li 4 SiO 4 In general, elemental sulfur and Li 4 SiO 4 And (3) preparing by a high-energy ball milling mode.
It is understood that the combined positive electrode active material is not limited to the above three components, and other components may be added according to actual needs.
In a second aspect, an embodiment of the present application provides a method for preparing a combined positive electrode active material as provided in the embodiment of the first aspect, including the steps of:
uniformly mixing a lithium source, a ferrous iron source, a phosphorus source, a coating agent and a doping agent to obtain a mixture; drying and roasting the mixture in turn to obtain a product containing LiFePO 4 And FePO 4 Is an intermediate of the positive electrode material; adding a lithium supplementing agent into the intermediate of the positive electrode material; wherein, in the mixture, the mole ratio of the lithium element, the iron element and the phosphorus element is 1: (2-2.5): (2-2.5).
In the application, by means of LiFePO 4 The conventional sintering preparation process can prepare the LiFePO by controlling the mole ratio of the lithium element, the iron element and the phosphorus element at the raw material end 4 And FePO 4 The mass percentage of the intermediate of the positive electrode material and the mass percentage of the intermediate of the positive electrode material are in a proper range, and on the basis, the combined positive electrode active material provided by the embodiment of the first aspect can be prepared by adding a proper amount of lithium supplementing agent.
It should be noted that, the preparation process provided by the embodiment of the application is different from the conventional preparation process only in that: the molar ratio of the lithium element to the single iron element or the single phosphorus element is much lower than in conventional production processes (in conventional processes, the molar amount of the lithium element is generally slightly higher than the molar amounts of the single iron element and the single phosphorus element).
It should be noted that, due to LiFePO 4 The conventional sintering preparation process belongs to the technology known in the art, and other parameters are not described in detail and are additionally limited in the embodiment of the application except the differences, so that the related specific process can be selected according to the conventional technology in the art.
In other possible embodiments, the preparation of the combined positive electrode active material may also be performed by preparing three components separately in advance, and then mixing the three components according to mass percentages; or, recovering the waste lithium iron phosphate battery to obtain the lithium iron phosphate battery containing LiFePO 4 And FePO 4 And adding a lithium supplementing agent into the mixture.
In a third aspect, embodiments of the present application provide a positive electrode sheet, including a positive electrode current collector and an active material layer located on one or both sides of the positive electrode current collector, the active material layer including a combined positive electrode active material as provided in the embodiments of the first aspect.
The material of the positive electrode current collector is not limited, and may be, for example, aluminum foil.
In a fourth aspect, an embodiment of the present application provides an electrode assembly, including the positive electrode sheet, the negative electrode sheet, and the battery separator provided in the embodiment of the third aspect, where the battery separator is located between the positive electrode sheet and the negative electrode sheet.
The composition of the negative electrode sheet and the battery separator is not limited, and may be selected and set according to conventional methods in the art.
In a fifth aspect, embodiments of the present application provide a battery comprising an electrode assembly as provided in the fourth aspect, an electrolyte, and a case, both of which are contained in the case.
The composition of the electrolyte and the casing is not limited, and may be selected and set according to the conventional method in the art.
In a sixth aspect, an embodiment of the present application provides a powered device, including a battery as provided in the embodiment of the fifth aspect.
It should be noted that the type of the electric equipment is not limited, and is, for example, a mobile phone, a portable device, a notebook computer, a battery car, an electric automobile, a ship, a spacecraft, an electric toy, an energy storage device, an electric tool, and the like.
The features and capabilities of the present application are described in further detail below in connection with the examples.
Example 1
The embodiment of the application provides a preparation method of a lithium ion battery, which comprises the following steps:
1) Preparation of positive electrode plate
50kg of LiFePO 4 、0.103kg FePO 4 、1.443kg Li 5 FeO 4 (Q is 610 mAh/g), 0.641kg of conductive carbon black, 4.969kg of carbon nano tube (4.3% slurry), 0.961kg of polyvinylidene fluoride, 0.053kg of dispersing agent and 35.61kg of N-methylpyrrolidone (binder solvent) are stirred and mixed by a vacuum stirrer (the solid content is 60%) to obtain a positive electrode slurry. Then, the positive electrode slurry was coated on both sides of an aluminum foil (positive electrode current collector, thickness 13 μm) containing a carbon-coated layer, and subjected to drying, cold pressing and die cutting to obtain a compact density of 2.55g/cm with a thickness of 162 μm 3 Is a positive electrode sheet of the battery.
2) Preparation of negative electrode plate
Stirring and mixing graphite, conductive carbon black, sodium carboxymethyl cellulose, styrene-butadiene rubber emulsion (containing 42% of styrene-butadiene rubber) and deionized water by a vacuum stirrer to obtain negative electrode slurry; then, coating the negative electrode slurry on two sides of a copper foil (negative electrode current collector, thickness is 6 mu m), and drying, cold pressing and die cutting to obtain a negative electrode plate; wherein, graphite, conductive carbon black, sodium carboxymethyl cellulose, styrene-butadiene rubber emulsion (containing 45% of styrene-butadiene rubber) and deionized water have a mass ratio of 1:0.022:0.013:0.045:1.
3) Battery assembly
And placing an isolating film with the thickness of 12 mu m between the positive pole piece and the negative pole piece, preparing a bare cell by a lamination mode, welding a pole lug on a top cover pole post by a connecting sheet, filling a square aluminum shell, welding the top cover and the aluminum shell to obtain a dry cell, baking and dehydrating to ensure that the water content is lower than 250ppm, injecting electrolyte with the injection coefficient of 3.2g/Ah, and sealing, standing, forming, degassing, packaging, capacity-dividing and other procedures to obtain the square aluminum shell battery.
Example 2
The embodiment of the application provides a preparation method of a lithium ion battery, which is different from embodiment 1 only in that:
50kg of LiFePO 4 、0.416kg FePO 4 、1.559kg Li 5 FeO 4 (Q is 610 mAh/g), 0.646kg of conductive carbon black, 5.01kg of carbon nano tube (4.3% slurry), 0.969kg of polyvinylidene fluoride, 0.054kg of dispersing agent and 35.61kg of N-methylpyrrolidone (binder solvent) are stirred and mixed by a vacuum stirrer (the solid content is 60%) to obtain a positive electrode slurry.
Example 3
The embodiment of the application provides a preparation method of a lithium ion battery, which is different from embodiment 1 only in that:
51.615kg of waste lithium iron phosphate cathode material (equivalent to 50kg of LiFePO 4 、1.615kg FePO 4 )、1.989kg Li 5 FeO 4 (Q is 610 mAh/g), 0.668kg of conductive carbon black, 5.183kg of carbon nano tube (4.3% slurry), 1.003kg of polyvinylidene fluoride, 0.056kg of dispersing agent and 35.61kg of N-methyl pyrrolidone (binder solvent) are stirred and mixed by a vacuum stirrer (the solid content is 60%) to obtain a positive electrode slurry.
Example 4
The embodiment of the application provides a preparation method of a lithium ion battery, which is different from embodiment 1 only in that:
50kg of LiFePO 4 、0.904kg FePO 4 、2.287kg Li 5 FeO 4 (Q is 610 mAh/g), 0.661kg of conductive carbon black, 5.128kg of carbon nano tube (4.3% slurry), 0.992kg of polyvinylidene fluoride, 0.055kg of dispersing agent and 35.61kg of N-methyl pyrrolidone (binder solvent) are stirred and mixed by a vacuum stirrer (the solid content is 60%) to obtain a positive electrode slurry.
Example 5
The embodiment of the application provides a preparation method of a lithium ion battery, which is different from embodiment 1 only in that:
50kg of LiFePO 4 、0.904kg FePO 4 、2.287kg Li 2 NiO 2 (Q is 400 mAh/g), 0.661kg of conductive carbon black, 5.128kg of carbon nano tube (4.3% slurry), 0.992kg of polyvinylidene fluoride, 0.055kg of dispersing agent and 35.61kg of N-methyl pyrrolidone (binder solvent) are stirred and mixed by a vacuum stirrer (the solid content is 60%) to obtain a positive electrode slurry.
Example 6
The embodiment of the application provides a preparation method of a lithium ion battery, which is different from embodiment 1 only in that:
50kg of LiFePO 4 、1.075kg FePO 4 、2.151kg Li 2 NiO 2 (Q is 400 mAh/g), 0.6622kg of conductive carbon black, 5.131kg of carbon nano tube (4.3% slurry), 0.993kg of polyvinylidene fluoride, 0.055kg of dispersing agent and 35.61kg of N-methylpyrrolidone (binder solvent) are stirred and mixed by a vacuum stirrer (the solid content is 60%) to obtain a positive electrode slurry.
Comparative example 1
The comparative example of the present application provides a method for preparing a lithium ion battery, which is different from example 1 only in that:
51.546kg of waste lithium iron phosphate cathode material (equivalent to 50kg of LiFePO 4 、1.546kg FePO 4 ) 0.641kg of conductive carbon black, 4.969kg of carbon nano tube (4.3% slurry), 0.961kg of polyvinylidene fluoride, 0.053kg of dispersing agent and 35.61kg of N-methylpyrrolidone (binder solvent) were stirred and mixed by a vacuum stirrer (solid content: 60%) to obtain a positive electrode slurry.
Comparative example 2
The comparative example of the present application provides a method for preparing a lithium ion battery, which is different from example 1 only in that:
50kg of LiFePO 4 、1.546kg Li 2 NiO 2 (Q is 400 mAh/g), 0.641kg of conductive carbon black, 4.969kg of carbon nano tube (4.3% slurry), 0.961kg of polyvinylidene fluoride, 0.053kg of dispersing agent and 35.61kg of N-methylpyrrolidone (binder solvent) are stirred and mixed by a vacuum stirrer (the solid content is 60%) to obtain a positive electrode slurry.
Comparative example 3
The comparative example of the present application provides a method for preparing a lithium ion battery, which is different from example 1 only in that:
50kg of LiFePO 4 Mixing 0.622kg of conductive carbon black, 4.82kg of carbon nano tube (4.3% slurry), 0.933kg of polyvinylidene fluoride, 0.052kg of dispersing agent and 35.61kg of N-methyl pyrrolidone (binder solvent) by stirring by a vacuum stirrer (solid content is 60%) to obtain positive electrodeAnd (5) pole sizing agent.
In order to better understand the differences between the respective examples and comparative examples, summary explanation is made below in the form of tables.
Table 1 parameter summary tables for each example and comparative example
Test example 1
Battery performance test
The testing method comprises the following steps:
lithium ion batteries were prepared according to the methods of examples 1 to 6 and comparative examples 1 to 3, respectively, and then, the prepared batteries were numbered, respectively, and then, batteries corresponding to the different numbers were clamped using symmetrical steel plate clamps, and the cycle numbers were recorded as cycle lives of the corresponding batteries while recording gram capacity exertion of the composition, by testing the cycle numbers at 25 ℃ and a current density of 1C, where the battery capacity was attenuated to 80% of the original.
Table 2 statistical table of battery performance test results
Referring to Table 2, it is understood from the test results of examples 1 to 6 and comparative examples 1 to 3 that LiFePO was prepared 4 、FePO 4 And lithium supplementing agent as positive electrode active material, compared with LiFePO only 4 Or LiFePO 4 The combination with one of them is used as a positive electrode active material, and the battery corresponding to the former has more excellent cycle performance.
From the test results of examples 1 to 2 and examples 3 to 6, it is understood that LiFePO was further optimized 4 、FePO 4 And lithium supplementing agent, and LiFePO is prepared 4 The sum of the lithium-removable capacity of the lithium-supplementing agent and the lithium-removable capacity of the battery is limited to a more suitable range, and the energy density of the corresponding battery can be further improved.
From the test results of examples 2 and 6 and examples 1 and 3 to 5, it is understood that LiFePO was further optimized 4 、FePO 4 And lithium supplementing agent, and LiFePO is prepared 4 And FePO 4 Sum of lithium intercalation capacities and LiFePO 4 The ratio of the sum of the lithium-removable capacity of the lithium-supplementing agent and the lithium-removable capacity of the battery is defined in a more suitable range, and the cycle performance of the corresponding battery can be further improved.
The embodiments described above are some, but not all embodiments of the application. The detailed description of the embodiments of the application is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Claims (11)
1. A combined positive electrode active material is characterized by comprising LiFePO 4 、FePO 4 And a lithium supplementing agent, wherein in the combined positive electrode active material, the LiFePO 4 The percentage content X of the FePO is 84 to 99.4 weight percent 4 The percentage content Y of the lithium supplementing agent is 0.2-14.8 wt%, the percentage content Z of the lithium supplementing agent is 0.3-14.8 wt%, and the first-time charged lithium removing capacity Q of the lithium supplementing agent is more than 300mAh/g.
2. The combined positive electrode active material according to claim 1, wherein the LiFePO 4 The percentage content X of the FePO is 94 to 97wt% 4 The percentage content Y of the lithium supplementing agent is 0.2 to 1.7 weight percent, the percentage content Z of the lithium supplementing agent is 2.8 to 4.3 weight percent, and 176.6 is more than or equal to 160 xX+QxZ is more than or equal to 162.
3. The combined positive electrode active material according to claim 2, wherein the LiFePO 4 The percentage content X of the FePO is 96.2 to 97 weight percent 4 The percentage content Y of the lithium supplementing agent is 0.2 to 0.8 weight percent, the percentage content Z of the lithium supplementing agent is 2.8 to 3 weight percent, and 172.3 is more than or equal to 160 xX+Q xZ is more than or equal to 165.8.
4. The combined positive electrode active material according to claim 1, wherein the LiFePO 4 The percentage content X of the FePO is 93 to 97wt% 4 The percentage content Y of the lithium supplementing agent is 0.2 to 3.1 weight percent, the percentage content Z of the lithium supplementing agent is 0.9 to 4.3 weight percent, and 93.9 percent is more than or equal to 156 percent (X+Y)/(160 X+Q+Z) is more than or equal to 84.5 percent.
5. The combined positive electrode active material according to claim 4, wherein the LiFePO 4 The percentage content X of the FePO is 94 to 97wt% 4 The percentage content Y of the lithium supplementing agent is 0.2 to 3.1 weight percent, the percentage content Z of the lithium supplementing agent is 0.9 to 4.3 weight percent, and 89.6 percent is more than or equal to 156 percent (X+Y)/(160 X+Q+Z) is more than or equal to 84.5 percent.
6. The combined positive electrode active material according to any one of claims 1 to 5, wherein the lithium supplementing agent comprises Li 5 FeO 4 、Li 2 NiO 2 、Li 2 O、Li 3 N、Li 6 CoO 4 、LiF、Li 2 C 2 O 4 、Li 2 C 2 And Li (lithium) 4 SiO 4 At least one of/S.
7. A method for producing the combined positive electrode active material according to any one of claims 1 to 6, comprising the steps of:
uniformly mixing a lithium source, a ferrous iron source, a phosphorus source, a coating agent and a doping agent to obtain a mixture;
drying and roasting the mixture in sequence to obtain the LiFePO-containing material 4 And the FePO 4 Is an intermediate of the positive electrode material; and
adding the lithium supplementing agent into the positive electrode material intermediate;
wherein, in the mixture, the molar ratio of the lithium element to the iron element to the phosphorus element is 1: (2-2.5): (2-2.5).
8. A positive electrode sheet comprising a positive electrode current collector and an active material layer on one or both sides of the positive electrode current collector, the active material layer comprising the combined positive electrode active material according to any one of claims 1 to 6.
9. An electrode assembly comprising the positive electrode sheet, the negative electrode sheet, and the battery separator of claim 8, the battery separator being positioned between the positive electrode sheet and the negative electrode sheet.
10. A battery comprising the electrode assembly of claim 9, an electrolyte, and a housing, both of which are contained within the housing.
11. A powered device comprising the battery of claim 10.
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