WO2024026654A1 - Feuille d'électrode négative, batterie secondaire et dispositif électrique - Google Patents

Feuille d'électrode négative, batterie secondaire et dispositif électrique Download PDF

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WO2024026654A1
WO2024026654A1 PCT/CN2022/109591 CN2022109591W WO2024026654A1 WO 2024026654 A1 WO2024026654 A1 WO 2024026654A1 CN 2022109591 W CN2022109591 W CN 2022109591W WO 2024026654 A1 WO2024026654 A1 WO 2024026654A1
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active material
negative
material layer
negative electrode
negative active
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PCT/CN2022/109591
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English (en)
Chinese (zh)
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田亚西
石春美
唐代春
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/109591 priority Critical patent/WO2024026654A1/fr
Publication of WO2024026654A1 publication Critical patent/WO2024026654A1/fr

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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
    • 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
    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys

Definitions

  • This application belongs to the technical field of secondary batteries, and specifically relates to a negative electrode plate, a secondary battery and an electrical device.
  • Secondary batteries are widely used in various consumer electronics and electric vehicles due to their outstanding characteristics such as light weight, no pollution, and no memory effect. With the continuous development of the new energy industry, customers have put forward higher demand for secondary batteries. Among them, high energy density is the feature that customers are most concerned about, and improving the energy density of secondary batteries is an urgent need for the lithium battery industry.
  • this application provides a negative electrode plate, a secondary battery and a power consumption device, aiming to enable the secondary battery to have higher energy density and capacity retention rate.
  • a negative electrode plate including:
  • a first negative active material layer is located on at least one surface of the negative current collector, and the first negative active material layer includes a first negative active material;
  • a second negative active material layer is located on the surface of the first negative active material layer away from the negative current collector, and the second negative active material layer includes a second negative active material;
  • a third negative active material layer is located on the surface of the second negative active material layer away from the first negative active material layer, and the third negative active material layer includes a third negative active material;
  • the volume expansion rate of the first negative electrode active material and the third negative electrode active material is respectively greater than the volume expansion rate of the second negative electrode active material.
  • this application at least includes the following beneficial effects:
  • the negative electrode sheet of the present application is provided with three negative electrode active material layers, and the volume expansion rate of the first negative electrode active material included in the first negative electrode active material layer is higher than that of the second negative electrode included in the second negative electrode active material layer.
  • the volume expansion rate of the active material, the volume expansion rate of the third negative active material included in the third negative active material layer is higher than the volume expansion rate of the second negative active material included in the second negative active material layer, which occurs after lithium insertion
  • the volume expansion multiple of the first negative active material particles and the third negative active material particles is higher than the volume expansion multiple of the second negative active material particles; compared with only containing the second negative active material layer, by arranging the first negative active material layer
  • the active material layer and the third negative electrode active material layer can form a squeezing effect on the second negative electrode active material layer and reduce the porosity in the second negative electrode active material layer. In this way, the above-mentioned negative electrode sheet is used in secondary batteries, which can effectively reduce the amount of electrolyte and improve the energy
  • the volume expansion rates of the first negative active material layer and the third negative active material layer before and after lithium insertion are respectively greater than the volume expansion of the second negative active material layer before and after lithium insertion. Rate.
  • the volume expansion rate of the first negative electrode active material and the volume expansion rate of the third negative electrode active material are each independently 47% to 220%.
  • the volume expansion rate of the second negative active material is 20% to 25%.
  • the active materials in the second negative electrode active material layer are all the second negative electrode active materials; optionally, the second negative electrode active material is in the second negative electrode active material layer.
  • the quality proportion in the product ranges from 94% to 96.8%.
  • the active material in the first negative active material layer includes the first negative active material and the second negative active material; optionally, the first negative active material is The mass proportion of the first negative active material layer is 15% to 25%, and the mass proportion of the second negative active material in the first negative active material layer is 71.8% to 81.8%;
  • the active material in the third negative electrode active material layer includes the third negative electrode active material and the second negative electrode active material; optionally, the third negative electrode active material is in the third negative electrode active material layer.
  • the mass proportion of the active material layer is 15% to 25%, and the mass proportion of the second negative active material in the third negative active material layer is 71.8% to 81.8%.
  • the first negative active material and the third negative active material each independently include one or more of Ge, Sn, Sb, Bi and SiOx;
  • the second negative active material includes one or more of artificial graphite and hard carbon.
  • the thickness of the first negative electrode active material layer before lithium insertion is denoted as L1
  • the thickness of the second negative electrode active material layer before lithium insertion is denoted as L2
  • the thickness of the third negative electrode active material layer before lithium insertion is denoted as L2.
  • the thickness of the material layer before lithium insertion is recorded as L3, then the first negative electrode active material layer, the second negative electrode active material layer and the third negative electrode active material layer satisfy: 0.1 ⁇ L1/L3 ⁇ 1, 0.08 ⁇ (L1+L3)/L2 ⁇ 0.2.
  • the thickness of the first negative active material layer before lithium insertion satisfies: 1 ⁇ m ⁇ L1 ⁇ 10 ⁇ m; and/or the thickness of the second negative active material layer before lithium insertion satisfies: 100 ⁇ m ⁇ L2 ⁇ 120 ⁇ m; and/or, the thickness of the third negative active material layer before lithium insertion satisfies: 1 ⁇ m ⁇ L3 ⁇ 10 ⁇ m.
  • a second aspect of the application provides a secondary battery, which includes the negative electrode plate of the first aspect of the application;
  • the volume expansion ratios of the first negative active material layer and the third negative active material layer before and after lithium insertion are respectively greater than the volume expansion ratios of the second negative active material layer before and after lithium insertion.
  • a third aspect of the present application provides an electrical device, which includes the secondary battery of the second aspect of the present application.
  • FIG. 1 is a schematic diagram of an embodiment of a secondary battery.
  • FIG. 2 is an exploded view of FIG. 1 .
  • Figure 3 is a schematic diagram of an embodiment of a battery pack.
  • FIG. 4 is a schematic diagram of an electrical device using a secondary battery as a power source according to an embodiment.
  • any lower limit can be combined with any upper limit to form an unexpressed range; and any lower limit can be combined with other lower limits to form an unexpressed range, and likewise any upper limit can be combined with any other upper limit to form an unexpressed range.
  • each individually disclosed point or single value may itself serve as a lower or upper limit in combination with any other point or single value or with other lower or upper limits to form a range not expressly recited.
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be combined in any combination, i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
  • the negative electrode sheet provided by this application includes: a negative electrode current collector; a first negative electrode active material layer, located on at least one surface of the negative electrode current collector; the first negative electrode active material layer includes a first negative electrode active material; a second negative electrode active material layer, located on the surface of the first negative electrode active material layer away from the negative electrode current collector, the second negative electrode active material layer includes a second negative electrode active material; and a third negative electrode active material layer, located on the second negative electrode active material layer away from the first negative electrode On the surface of the active material layer, the third negative active material layer includes a third negative active material; wherein the volume expansion rates of the first negative active material and the third negative active material are respectively greater than the volume expansion rates of the second negative active material.
  • the negative electrode sheet of the present application is provided with three negative electrode active material layers on at least one surface of the negative electrode current collector, and the first negative electrode active material included in the first negative electrode active material layer has a high volume expansion rate
  • the volume expansion rate of the second negative electrode active material included in the second negative electrode active material layer, and the volume expansion rate of the third negative electrode active material included in the third negative electrode active material layer are higher than that of the third negative electrode active material included in the second negative electrode active material layer.
  • the volume expansion rate of the two negative electrode active materials is provided with three negative electrode active material layers on at least one surface of the negative electrode current collector, and the first negative electrode active material included in the first negative electrode active material layer has a high volume expansion rate
  • the volume expansion rate of the second negative electrode active material included in the second negative electrode active material layer, and the volume expansion rate of the third negative electrode active material included in the third negative electrode active material layer are higher than that of the third negative electrode active material included in the second negative electrode active material layer.
  • the volume expansion rate of the two negative electrode active materials are provided
  • the volume expansion multiples of the first negative electrode active material particles and the third negative electrode active material particles are higher than the volume expansion multiples of the second negative electrode active material particles;
  • a squeezing effect can be formed on the second negative electrode active material layer and the porosity in the second negative electrode active material layer can be reduced.
  • the above-mentioned negative electrode sheet is used in secondary batteries, which can effectively reduce the amount of electrolyte and improve the energy density and capacity retention rate of the battery.
  • all the negative active materials in the first negative active material layer may be the first negative active material, or only part of the negative active material may be the first negative active material; preferably, the negative active material in the first negative active material layer may be only the first negative active material. Part of it is the first negative electrode active material.
  • the inventor found that when the negative electrode plate of the present application meets the above design conditions and optionally meets one or more of the following conditions, the energy density of the secondary battery can be further improved. and capacity retention.
  • the volume expansion rates of the first negative active material layer and the third negative active material layer before and after lithium insertion are respectively greater than the volume expansion rates of the second negative active material layer before and after lithium insertion.
  • the first negative electrode active material layer and the second negative electrode active material layer are embedded with lithium, they can form a squeezing effect on the second negative electrode active material layer, reducing the porosity in the second negative electrode active material layer, thereby reducing the amount of electrolyte.
  • Improve battery energy density and capacity retention rate are provided.
  • the first negative active material layer can use both graphite and silicon or other materials with high volume expansion rates as negative active materials
  • the third negative active material layer can use both graphite and silicon or other materials with high volume expansion rates.
  • the second negative active material layer can all use graphite as the negative active material; and the volume expansion rates of the first negative active material layer and the third negative active material layer before and after lithium insertion are respectively higher than that of the second negative active material. The volume expansion rate of the layer before and after lithium insertion.
  • the main change in the thickness direction of the negative active material layer before and after lithium insertion The volume expansion rate of the first negative active material layer and the volume expansion rate of the third negative active material layer mentioned above were measured using the following method: before lithium insertion Perform cross-sectional CP characterization of the negative electrode piece, and measure the thickness L1 of the first negative electrode active material layer and the thickness L3 of the third negative electrode active material layer; continue cross-sectional CP characterization of the negative electrode piece after lithium embedding, and measure the first negative electrode active material layer
  • the thickness L11 of the third negative electrode active material layer and the thickness L31 of the third negative electrode active material layer are calculated based on the formula (L11-L1)/L1*100.
  • the volume expansion rate of the first negative electrode active material layer is calculated based on the formula (L31-L3)/L3*100.
  • the volume expansion rate of the three negative electrode active material layers The volume expansion rate of the three negative electrode active material layers.
  • the volume expansion rate of the first negative active material and the third negative active material are independently 47% to 220%; for example, they can be 47%, 80%, 100%, 130%, 150%, 170%, 200% or 220% etc.
  • Using a negative active material with a high volume expansion rate in the negative active material layer can increase the volume expansion rate of the negative active material layer.
  • the volume expansion rate of the first negative active material is 170% to 220%.
  • the volume expansion rate of the third negative active material is 170% to 220%.
  • the volume expansion rate of the second negative active material is 20% to 25%; for example, it may be 20%, 21%, 22%, 23%, 24% or 25%. Further, the volume expansion rate of the second negative electrode active material is 20% to 23%.
  • the volume expansion rates of the first negative electrode active material, the second negative electrode active material and the third negative electrode active material mentioned above can be obtained by the following method: the first negative electrode active material, the second negative electrode active material and the third negative electrode active material can be obtained by the known method.
  • the expansion multiple N of the negative active material before and after lithium insertion is calculated, and then the corresponding volume expansion rate is obtained based on the formula (N-1)*100%.
  • the expansion ratio N refers to the multiple of the volume of the negative electrode active material after lithium insertion is the volume of the negative electrode active material before lithium insertion.
  • the active materials in the second negative electrode active material layer are all second negative electrode active materials; optionally, the mass proportion of the second negative electrode active material in the second negative electrode active material layer is 94%. ⁇ 96.8%; for example, it can be 94%, 94.5%, 95%, 95.5%, 96%, 96.5% or 96.8%, etc. Further, the mass proportion of the second negative electrode active material in the second negative electrode active material layer is 95% to 96.8%.
  • the active material in the first negative active material layer includes a first negative active material and a second negative active material; optionally, the mass of the first negative active material in the first negative active material layer The proportion is 15% to 25%, and the mass proportion of the second negative active material in the first negative active material layer is 71.8% to 81.8%; the volume expansion rate of the first negative active material is greater than the volume of the second negative active material The expansion rate.
  • adding part of the first negative active material to replace the second negative active material can increase the volume expansion rate of the first negative active material layer, which is more effective for the second negative electrode.
  • the active material layer forms an effective squeeze.
  • the active material in the third negative active material layer includes a third negative active material and a second negative active material; optionally, the mass of the third negative active material in the third negative active material layer The proportion is 15% to 25%, and the mass proportion of the second negative active material in the third negative active material layer is 71.8% to 81.8%; the volume expansion rate of the third negative active material is greater than the volume of the second negative active material The expansion rate.
  • adding part of the third negative active material to replace the second negative active material can increase the volume expansion rate of the third negative active material layer, which is more effective for the second negative electrode.
  • the active material layer forms an effective squeeze.
  • the first negative active material and the third negative active material each independently include one or more of Ge, Sn, Sb, Bi and SiOx; where 0 ⁇ x ⁇ 2.
  • the volume expansion multiples N of Ge, Sn, Sb, Bi and SiOx before and after lithium insertion can be measured by known methods and are respectively around 2.72, 2.90, 1.47, 2.15 and 3.20. According to the formula (N-1)*100% The volume expansion ratios of Ge, Sn, Sb, Bi and SiOx before and after lithium insertion were obtained to be around 172%, 190%, 47%, 115% and 220% respectively.
  • the second negative active material includes one or more of artificial graphite and hard carbon.
  • the thickness of the first negative active material layer before lithium insertion is marked as L1
  • the thickness of the second negative active material layer before lithium insertion is marked as L2
  • the thickness of the third negative active material layer before lithium insertion is recorded as L2.
  • the thickness is recorded as L3, then the first negative active material layer, the second negative active material layer and the third negative active material layer satisfy: 0.1 ⁇ L1/L3 ⁇ 1, 0.08 ⁇ (L1+L3)/L2 ⁇ 0.2.
  • the thickness ratio of the negative active material layer meets the above range, it can not only squeeze the second negative active material layer, but also prevent the first negative active material and the third negative active material from being pulverized during the subsequent long cycle. , exposing more fresh surfaces, resulting in increased electrolyte consumption.
  • the thickness of the first negative active material layer before lithium insertion satisfies: 1 ⁇ m ⁇ L1 ⁇ 10 ⁇ m; for example, it can be 1 ⁇ m, 2 ⁇ m, 4 ⁇ m, 6 ⁇ m, 8 ⁇ m or 10 ⁇ m, etc. Further, the thickness of the first negative active material layer before lithium insertion satisfies: 4 ⁇ m ⁇ L1 ⁇ 6 ⁇ m.
  • the thickness of the second negative active material layer before lithium insertion satisfies: 100 ⁇ m ⁇ L2 ⁇ 120 ⁇ m; for example, it may be 100 ⁇ m, 105 ⁇ m, 110 ⁇ m, 115 ⁇ m or 120 ⁇ m. Further, the thickness of the second negative active material layer before lithium insertion satisfies: 110 ⁇ m ⁇ L2 ⁇ 120 ⁇ m.
  • the thickness of the third negative active material layer before lithium insertion satisfies: 1 ⁇ m ⁇ L3 ⁇ 10 ⁇ m; for example, it can be 1 ⁇ m, 2 ⁇ m, 4 ⁇ m, 6 ⁇ m, 8 ⁇ m or 10 ⁇ m, etc. Further, the thickness of the third negative active material layer before lithium insertion satisfies: 4 ⁇ m ⁇ L3 ⁇ 10 ⁇ m.
  • the thickness L1 of the first negative active material layer before lithium insertion mentioned above, the thickness L2 of the second negative active material layer before lithium insertion, and the thickness L3 of the third negative active material layer before lithium insertion were measured using the following method. : Perform cross-sectional CP characterization of the negative electrode sheet before lithium insertion, and measure the thickness L1 of the first negative active material layer, the thickness L2 of the second negative active material layer, and the thickness L3 of the third negative active material layer.
  • Embodiments of the present application also provide a method for preparing a negative electrode sheet, including the following steps:
  • the negative electrode current collector can use conventional metal foil or composite current collector.
  • the metal foil may be copper foil.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material layer usually also includes conductive agents and other optional auxiliaries.
  • the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • PTC thermistor materials may be PTC thermistor materials, etc.
  • Secondary batteries refer to batteries that can be recharged to activate active materials and continue to be used after the battery is discharged.
  • a secondary battery includes a positive electrode sheet, the negative electrode sheet provided above in this application, a separator and an electrolyte.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the isolation film is arranged between the positive electrode piece and the negative electrode piece to play the role of isolation.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • a positive electrode sheet usually includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode film layer includes a positive electrode active material.
  • the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may use a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the cathode active material may be a cathode active material known in the art for lithium ion batteries.
  • the cathode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (can also be abbreviated to NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (can also be abbreviated to NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (can also be abbreviated to NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as Li Li
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon. At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • composites of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon.
  • At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • the cathode active material may be a cathode active material known in the art for sodium-ion batteries.
  • the cathode active material may be a cathode active material known in the art for sodium-ion batteries.
  • only one type of positive electrode active material may be used alone, or two or more types may be combined.
  • the positive active material can be selected from sodium iron composite oxide (NaFeO 2 ), sodium cobalt composite oxide (NaCoO 2 ), sodium chromium composite oxide (NaCrO 2 ), sodium manganese composite oxide (NaMnO 2 ), sodium nickel Composite oxide (NaNiO 2 ), sodium nickel titanium composite oxide (NaNi 1/2 Ti 1/2 O 2 ), sodium nickel manganese composite oxide (NaNi 1/2 Mn 1/2 O 2 ), sodium iron manganese composite Oxide (Na 2/3 Fe 1/3 Mn 2/3 O 2 ), sodium nickel cobalt manganese composite oxide (NaNi 1/3 Co 1/3 Mn 1/3 O 2 ), sodium iron phosphate compound (NaFePO 4 ), sodium manganese phosphate compound (NaMn P O 4 ), sodium cobalt phosphate compound (NaCoPO 4 ), Prussian blue materials, polyanionic materials (phosphates, fluorophosphates, pyrophosphates, sulfates), etc.,
  • the positive electrode film layer also optionally includes binders, conductive agents and other optional auxiliaries.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • VDF polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • VDF polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • VDF polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the above-mentioned components for preparing the positive electrode sheet, such as the positive active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methyl pyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode piece can be obtained.
  • a solvent such as N-methyl pyrrolidone
  • the secondary battery further includes a separator film.
  • a separator film There is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an electrolyte that serves to conduct ions between a positive electrode and a negative electrode.
  • the electrolyte solution may include electrolyte salts and solvents.
  • the electrolyte salt may be selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bisfluorosulfonyl imide ( LiFSI), lithium bistrifluoromethanesulfonimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoromethanesulfonate borate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), one or more of lithium difluorodioxalate phosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP).
  • LiFSI lithium bisfluorosulfonyl imide
  • LiTFSI lithium bis
  • the solvent may be selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), carbonic acid Dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), One or more of ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl sulf
  • additives are also included in the electrolyte.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature performance of the battery, and additives that improve the low-temperature performance of the battery. Additives etc.
  • the secondary battery of the present application is a lithium-ion secondary battery.
  • the secondary battery can be prepared according to conventional methods in the art, for example, the positive electrode sheet, the separator film, and the negative electrode sheet are wound (or stacked) in order, so that the separator film is between the positive electrode sheet and the negative electrode sheet for isolation. function to obtain the battery core, place the battery core in the outer package, inject the electrolyte and seal it to obtain a secondary battery.
  • FIG. 1 shows an example of a square-structured secondary battery 4 .
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • the outer package may include a housing 41 and a cover 43 .
  • the housing 41 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 41 has an opening communicating with the accommodation cavity, and the cover plate 43 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 42 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 42 .
  • the number of electrode assemblies 42 contained in the secondary battery 4 can be one or more, and can be adjusted according to requirements.
  • the above-mentioned secondary batteries can also be assembled into a battery pack, and the number of secondary batteries contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • FIG. 3 is a battery pack 1 as an example.
  • the battery pack 1 may include a battery box and a plurality of secondary batteries 4 provided in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the secondary battery 4 .
  • the plurality of secondary batteries 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device, which includes at least one of the secondary battery or battery pack.
  • the secondary battery or battery pack may be used as a power source for the device or as an energy storage unit for the device.
  • the device may be, but is not limited to, a mobile device (such as a mobile phone, a laptop, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, or an electric golf ball). vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • the device can select secondary batteries or battery packs according to its usage requirements.
  • FIG. 4 shows an electrical device 5 as an example.
  • the electric device 5 is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like.
  • a battery pack can be used.
  • the device may be a mobile phone, a tablet, a laptop, etc.
  • the device is usually required to be thin and light, and a secondary battery can be used as a power source.
  • the thickness of the first negative active material layer is marked as L1
  • the thickness of the second negative active material layer is marked as L2
  • the thickness of the third negative active material layer is marked as L3.
  • the volume expansion rate of the negative electrode active material SiOx used is 220%
  • the volume expansion rate of the negative electrode active material Sb used is 47%
  • the volume expansion rate of the negative electrode active material Bi used The volume expansion rate of the used negative electrode active material Sn is 190%
  • the volume expansion rate of the used negative electrode active material Ge is 172%
  • the volume expansion rate of the used negative electrode active material artificial graphite is 23%.
  • the first negative active material layer has a thickness of 4 ⁇ m;
  • the weight ratio of artificial graphite (as the second negative active material), conductive agent carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethylcellulose (CMC) is 96.8:0.7:1.3:1.2 Dissolve in solvent deionized water, mix evenly and prepare a second negative electrode slurry; apply the second negative electrode slurry on the surface of the first negative electrode active material layer to form a second negative electrode active material layer with a thickness of 120 ⁇ m;
  • the preparation method of the negative electrode sheet in Examples 2-20 is basically similar to the preparation method of the negative electrode sheet in Example 1. The difference lies in: when preparing the negative electrode sheet, the type and/or amount of the first negative electrode active material used, and the amount of the first negative electrode active material. At least one of the types and/or amounts of the three negative active materials, the thickness of the first negative active material layer, the thickness of the second negative active material layer, and the thickness of the third negative active material layer are different. See Table 1 for details.
  • the preparation method of the negative electrode sheet in Comparative Example 1 is basically similar to the preparation method of the negative electrode sheet in Example 1, except that it only includes the first negative electrode active material layer and the second negative electrode active material layer (that is, it does not contain the third negative electrode active material layer). material layer), and the thickness of the first negative active material layer is different. See Table 1 for details.
  • the preparation method of the negative electrode sheet in Comparative Example 2 is basically similar to the preparation method of the negative electrode sheet in Example 1, except that it only includes the second negative electrode active material layer and the third negative electrode active material layer (that is, it does not contain the first negative electrode active material layer). material layer), see Table 1 for details.
  • the difference between the preparation method of the negative electrode sheet in Comparative Example 3 and the negative electrode sheet in Example 1 is that it only contains a second negative electrode active material layer, and the thickness of the second negative electrode active material layer is different. See Table 1 for details.
  • the difference between the preparation method of the negative electrode sheet in Comparative Example 4 and the negative electrode sheet in Example 15 is that it only contains a second negative electrode active material layer, and the thickness of the second negative electrode active material layer is different. See Table 1 for details.
  • the difference between the preparation method of the negative electrode sheet in Comparative Example 5 and the negative electrode sheet in Example 16 is that it only contains a second negative electrode active material layer, and the thickness of the second negative electrode active material layer is different. See Table 1 for details.
  • Preparation of the positive electrode piece Stir and mix the nickel cobalt manganese (NCM) ternary material, the conductive agent carbon black, and the binder polyvinylidene fluoride (PVDF) in a weight ratio of 96.7:1.7:1.6 to obtain the positive electrode. slurry; then, the positive electrode slurry is evenly coated on the positive electrode current collector, and then dried, cold pressed, and cut to obtain the positive electrode piece.
  • NCM nickel cobalt manganese
  • PVDF binder polyvinylidene fluoride
  • Isolation film Polyethylene film (PE) with a thickness of 12 ⁇ m is used as the isolation film.
  • the electrolyte is mainly used to fill the pores of the electrode assembly and outer packaging as well as the pores in the second negative active material layer; when the thickness error of the second negative active material layer is within ⁇ 3 ⁇ m or When the total thickness error of the three negative active material layers is within ⁇ 6 ⁇ m, the difference in the amount of electrolyte caused can be ignored.
  • the prepared secondary battery was charged to 3.8V at 1C in a constant temperature environment of 25°C, then charged to 4.2V at 0.87C, and finally charged to 4.4V at 0.33C, left for 10 minutes, and then discharged to 2.5V at 1C. . Repeat the above steps and record the battery capacity after 800 cycles.
  • Each prepared secondary battery was charged to 4.4V at 0.33C standard at room temperature, and charged to 0.05C at 4.4V constant voltage. After standing for 10 minutes, it was discharged to 2.5V at 0.33C. The discharge capacity was recorded, and the discharge time was then calculated. energy density.
  • the formula is as follows:
  • the negative electrode sheet is provided with three layers of negative active material, and the volume expansion rate of the first negative active material is higher than that of the second negative active material.
  • the volume expansion rate is higher than the volume expansion rate of the second negative active material.
  • Example 4 the mass proportion of the first negative active material is the smallest, and in Example 5, the mass proportion of the first negative active material is the smallest.
  • One negative electrode active material accounts for the largest mass proportion.
  • the amount of electrolyte used in the secondary battery in Example 4 and Example 5 is higher than that in Example 1-3, and its 800cls capacity retention rate and battery energy density are respectively lower than those in Example 1- 3.
  • the second negative active material layer has more porosity, resulting in electrolyte consumption.
  • the mass proportion of the first negative active material in the first negative active material layer is 15% to 25%.
  • Embodiment 1 and Embodiments 6-9 The main difference between Embodiment 1 and Embodiments 6-9 is that the mass proportion of the third negative active material in the third negative active material layer is different.
  • the mass proportion of the first negative active material is the smallest.
  • Example 9 the mass proportion of the first negative active material is the largest.
  • the electrolyte consumption of the secondary battery in Example 8 and Example 9 is higher than that in Example 1 and Examples 7-8, and its 800cls capacity retention rate and battery energy The density is lower than Example 1 and Examples 7-8 respectively.
  • the second negative active material layer has more porosity, resulting in electrolyte consumption.
  • the mass proportion of the third negative active material in the third negative electrode active material layer is 15% to 25%.
  • Embodiment 1 and Embodiments 10-16 The main difference between Embodiment 1 and Embodiments 10-16 is that: the thickness of the first negative active material layer, the second negative active material layer and/or the third negative active material layer is different, wherein the ratio of L1/L3 in Embodiment 13 The maximum, the ratio of (L1+L3)/L2 in Example 14 is the smallest, and the electrolyte consumption of the secondary battery in Example 8 and Example 9 is higher than that in Example 1, Examples 10-12 and Examples 15-16, And its 800cls capacity retention rate and battery energy density are lower than those in Example 1, Examples 10-12 and Examples 15-16 respectively.
  • 0.1 ⁇ L1/L3 ⁇ 1, 0.08 ⁇ (L1+L3)/L2 ⁇ 0.2 which can further reduce the amount of electrolyte and improve the 800cls capacity retention rate and energy density of the battery.
  • Embodiment 1 mainly lies in: the types of the first negative active material and/or the second negative active material are different. Compared with Embodiments 17-20, Embodiment 1 has lower electrolyte dosage and Higher 800cls capacity rate and energy density.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

La présente demande concerne une feuille d'électrode négative, une batterie secondaire et un appareil électrique. La feuille d'électrode négative comprend : un collecteur de courant d'électrode négative ; une première couche de matériau actif d'électrode négative située sur au moins une surface du collecteur de courant d'électrode négative, la première couche de matériau actif d'électrode négative comprenant un premier matériau actif d'électrode négative ; une deuxième couche de matériau actif d'électrode négative située sur la surface de la première couche de matériau actif d'électrode négative à l'opposé du collecteur de courant d'électrode négative, la deuxième couche de matériau actif d'électrode négative comprenant un deuxième matériau actif d'électrode négative ; et une troisième couche de matériau actif d'électrode négative située sur la surface de la deuxième couche de matériau actif d'électrode négative à l'opposé de la première couche de matériau actif d'électrode négative, la troisième couche de matériau actif d'électrode négative comprenant un troisième matériau actif d'électrode négative, et les taux d'expansion de volume du premier matériau actif d'électrode négative et du troisième matériau actif d'électrode négative étant respectivement supérieurs à ceux du deuxième matériau actif d'électrode négative.
PCT/CN2022/109591 2022-08-02 2022-08-02 Feuille d'électrode négative, batterie secondaire et dispositif électrique WO2024026654A1 (fr)

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CN104218213A (zh) * 2014-08-15 2014-12-17 中山大学 一种多层膜电极及其制备方法和应用
CN105789556A (zh) * 2016-04-26 2016-07-20 中国科学院长春应用化学研究所 一种电极片和锂离子电池
KR20160087121A (ko) * 2015-01-13 2016-07-21 주식회사 엘지화학 규소계 물질을 포함하는 다층 구조의 음극 및 이를 포함하는 이차전지
CN112542573A (zh) * 2020-12-03 2021-03-23 陕西煤业化工技术研究院有限责任公司 一种锂电池硅基薄膜负极片及其制备方法
CN114050233A (zh) * 2021-11-25 2022-02-15 珠海冠宇电池股份有限公司 一种负极极片及电池
CN114079048A (zh) * 2020-08-18 2022-02-22 比亚迪股份有限公司 一种负极极片以及锂离子电池

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104218213A (zh) * 2014-08-15 2014-12-17 中山大学 一种多层膜电极及其制备方法和应用
KR20160087121A (ko) * 2015-01-13 2016-07-21 주식회사 엘지화학 규소계 물질을 포함하는 다층 구조의 음극 및 이를 포함하는 이차전지
CN105789556A (zh) * 2016-04-26 2016-07-20 中国科学院长春应用化学研究所 一种电极片和锂离子电池
CN114079048A (zh) * 2020-08-18 2022-02-22 比亚迪股份有限公司 一种负极极片以及锂离子电池
CN112542573A (zh) * 2020-12-03 2021-03-23 陕西煤业化工技术研究院有限责任公司 一种锂电池硅基薄膜负极片及其制备方法
CN114050233A (zh) * 2021-11-25 2022-02-15 珠海冠宇电池股份有限公司 一种负极极片及电池

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