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CN119230952A - Electrolyte and lithium ion battery - Google Patents

Electrolyte and lithium ion battery Download PDF

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Publication number
CN119230952A
CN119230952A CN202411643361.8A CN202411643361A CN119230952A CN 119230952 A CN119230952 A CN 119230952A CN 202411643361 A CN202411643361 A CN 202411643361A CN 119230952 A CN119230952 A CN 119230952A
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China
Prior art keywords
electrolyte
lithium
solvent
additive
carbonate
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CN202411643361.8A
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Chinese (zh)
Inventor
冯兵
蔡君瑶
韩鑫琪
王志勇
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Hunan Shinzoom Technology Co ltd
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Hunan Shinzoom Technology Co ltd
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Priority to CN202411643361.8A priority Critical patent/CN119230952A/en
Publication of CN119230952A publication Critical patent/CN119230952A/en
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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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • 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
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Secondary Cells (AREA)

Abstract

The invention relates to an electrolyte and a lithium ion battery, wherein the electrolyte comprises more than or equal to 13 weight percent of additive, less than or equal to 72 weight percent of solvent and the balance of metal salt, and the additive comprises any one or a combination of at least two of fluoroethylene carbonate, 1, 3-propane sulfonate, ethylene carbonate or lithium dioxalate borate, based on the mass percent of the electrolyte being 100 weight percent. The electrolyte provided by the invention improves the ratio of the additive to the metal salt, properly reduces the dosage of the solvent, reduces the contact between solvent molecules and the electrode, and improves the stability of the electrolyte.

Description

Electrolyte and lithium ion battery
Technical Field
The invention belongs to the technical field of batteries, relates to a battery material, and in particular relates to electrolyte and a lithium ion battery.
Background
With the rapid development of modern technology, batteries serve as an important energy storage device and play an irreplaceable role in various fields. In various battery systems, the electrolyte is used as a key component, and the performance quality of the electrolyte directly influences the overall performance and the service life of the battery.
In the charge and discharge process of the battery, a solid electrolyte interface film (SEI film) is formed on the surface of the electrode, and the SEI film with high quality has good stability and ion conductivity, can effectively prevent further reaction between electrolyte and the electrode, and ensures smooth embedding and extraction of ions on the surface of the electrode while protecting the electrode material from corrosion. The composition of the electrolyte affects the growth mechanism and chemical composition of the SEI film, and if the SEI film is not uniform in thickness, not stable in structure, or not good in ion-conducting properties, electrochemical performance of the battery may be reduced.
Therefore, the electrolyte and the lithium ion battery are provided to optimize the composition of the electrolyte and improve the performance of the battery, and have great significance for the development of the battery industry.
Disclosure of Invention
The invention aims to provide an electrolyte and a lithium ion battery, which have good stability, and the battery using the electrolyte not only can improve capacity and first coulombic efficiency, but also can improve survival rate, qualification rate and consistency of the battery, and is beneficial to industrial production.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
In a first aspect, the invention provides an electrolyte, which comprises more than or equal to 13wt% of additive, less than or equal to 72wt% of solvent and the balance of metal salt, wherein the mass percent of the electrolyte is 100 wt%.
The additive comprises any one or a combination of at least two of fluoroethylene carbonate (FEC), 1, 3-Propane Sulfonate (PS), vinylene Carbonate (VC), ethylene carbonate (VEC) or lithium dioxaborate (LiBOB).
Preferably, the electrolyte comprises 13 to 18wt% of the additive, 67 to 70wt% of the solvent, and 12 to 18wt% of the metal salt in mass percent.
Preferably, the solvent comprises Ethyl Methyl Carbonate (EMC) and/or Ethylene Carbonate (EC).
Preferably, the solvent comprises a combination of ethyl methyl carbonate and ethylene carbonate.
Preferably, the mass ratio of the methyl ethyl carbonate to the ethylene carbonate is 1:1 to 4:1.
Preferably, the additive comprises a combination of fluoroethylene carbonate, 1, 3-propane sulfonate lactone and ethylene carbonate.
Preferably, the electrolyte comprises 1 to 5wt% of ethylene carbonate in mass percent.
Preferably, the additive further comprises lithium dioxalate borate (LiBOB).
In terms of mass percent, the components are mixed, the electrolyte comprises 0.5 to 2 weight percent of lithium dioxalate borate.
Preferably, the metal salt is a lithium salt.
Preferably, the lithium salt comprises any one or a combination of at least two of lithium hexafluorophosphate (LiPF 6), lithium tetrafluoroborate (LiBF 4), lithium perchlorate (LiClO 4) or lithium hexafluoroarsenate (LiAsF 6).
In a second aspect, the present invention provides a lithium ion battery comprising the electrolyte of the first aspect.
Preferably, the lithium ion battery comprises a positive electrode, a negative electrode and an electrolyte. The negative electrode includes a negative electrode current collector and a negative electrode active material disposed on the negative electrode current collector.
Preferably, the negative active material of the lithium ion battery includes a graphite negative electrode material.
Compared with the prior art, the invention has the following beneficial effects:
The electrolyte provided by the invention improves the ratio of the additive to the metal salt, properly reduces the dosage of the solvent, reduces the contact between solvent molecules and the electrode, thereby improving the stability of the electrolyte.
Detailed Description
The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
[ Electrolyte ]
The first aspect of the application provides an electrolyte, which comprises more than or equal to 13 weight percent of additive, less than or equal to 72 weight percent of solvent and the balance of metal salt, wherein the mass percent of the electrolyte is 100 weight percent.
The additives include any one or a combination of at least two of fluoroethylene carbonate (FEC), 1, 3-Propane Sulfonate (PS), vinylene Carbonate (VC), ethylene carbonate (VEC), or lithium dioxaborate (LiBOB), and typical but non-limiting combinations include combinations of FEC and PS, PS and VC, VC and VEC, FEC, PS, VC, VC, VEC and LiBOB, or FEC, PS, VC, VEC and LiBOB.
The main function of the electrolyte includes providing a transport medium for ions, and in order to ensure the activity space and migration efficiency of the ions, it is generally necessary to ensure a sufficient amount of solvent in the electrolyte. The electrolyte provided by the invention greatly improves the dosage of the additive, the dosage of the solvent is relatively reduced, the performance of the electrolyte is ensured, the contact between solvent molecules and the electrode is reduced, and the stability of the electrolyte is improved through the cooperative control of the dosage of the additive and the solvent in the electrolyte.
In the electrolyte provided by the invention, the mass percent of the additive is more than or equal to 13wt%, for example, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 20wt% or 22wt%, but the electrolyte is not limited to the recited values, and other non-recited values in the numerical range are applicable.
The use of the additive in the electrolyte can improve the ionic conductivity of the electrolyte, reduce the internal resistance and improve the rate capability. In a certain range, the viscosity of the electrolyte is gradually increased along with the increase of the dosage of the additive in the electrolyte, but the proportion of anions and cations in the corresponding solvent is improved, and the ionic conductivity is also increased, so that the electrolyte is used as a preferable technical scheme for ensuring the performance of the electrolyte and reducing the dosage of the solvent, and the mass percent of the additive in the electrolyte is 13-18 wt%.
The electrolyte provided by the invention has the solvent content less than or equal to 72wt%, such as 65wt%, 66wt%, 68wt%, 70wt%, 71wt% or 72wt%, but is not limited to the recited values, and other non-recited values in the range of values are equally applicable.
The invention reduces the mass percent of the solvent in the electrolyte by less than or equal to 72 percent, reduces the contact between solvent molecules and the electrode, and improves the stability of the electrolyte, but generally needs to ensure enough solvent dosage in the electrolyte in order to ensure the activity space and migration efficiency of ions. As a preferable technical scheme of the invention, the solvent in the electrolyte is used in an amount of 67 to 70wt%.
In certain embodiments, the electrolyte comprises, in mass percent, 13 to 18% of the additive, 67 to 70% of the solvent, and 12 to 18% of the metal salt, wherein the metal salt is present in a mass percent of 12 to 18% and may be, for example, 12, 14, 15, 16, or 18% by weight, although not limited to the recited values, the remaining non-recited values in the range of values are equally applicable.
In certain embodiments, the solvent comprises Ethyl Methyl Carbonate (EMC) and/or Ethylene Carbonate (EC).
In certain embodiments, the solvent is a combination of ethyl methyl carbonate and ethylene carbonate.
In certain embodiments, the mass ratio of ethyl methyl carbonate to ethylene carbonate is 1:1 to 4:1, for example, 1:1, 6:4, 7:3, or 8:2, but is not limited to the recited values, and the remaining non-recited values within the range of values are equally applicable.
The proper additive component is favorable for obtaining a high-quality SEI film, so that further reaction between electrolyte and an electrode can be effectively prevented, electrode materials are protected from corrosion, and smooth embedding and extraction of ions on the surface of the electrode are ensured.
In certain embodiments, the additive comprises a combination of fluoroethylene carbonate, 1, 3-propane sulfonate lactone, and ethylene carbonate.
In certain embodiments, the electrolyte comprises, in mass percent, from 1wt% to 5wt% ethylene carbonate, such as may be 1wt%, 2wt%, 3wt%, 4wt%, or 5wt%, but is not limited to the recited values, with the remaining unrecited values in the range of values being equally applicable.
In certain embodiments, the additive comprises a combination of fluoroethylene carbonate, 1, 3-propane sulfonate, ethylene carbonate, and lithium dioxalate borate.
In certain embodiments, the electrolyte includes from 0.5wt% to 2wt% of lithium dioxaborate, such as may be 0.5wt%, 1wt%, 1.5wt% or 2wt%, in mass percent, but is not limited to the recited values, with the remaining unrecited values in the range of values being equally applicable.
In certain embodiments, the metal salt is a lithium salt.
In certain embodiments, the lithium salt comprises any one or a combination of at least two of lithium hexafluorophosphate (LiPF 6), lithium tetrafluoroborate (LiBF 4), lithium perchlorate (LiClO 4), or lithium hexafluoroarsenate (LiAsF 6), typical single non-limiting combinations include a combination of LiPF 6 and LiBF 4, a combination of LiBF 4 and LiClO 4, a combination of LiClO 4 and LiAsF 6, a combination of LiPF 6、LiBF4 and LiClO 4, or a combination of LiPF 6、LiBF4、LiClO4 and LiAsF 6.
In certain embodiments, the method of preparing the electrolyte of the present invention includes the step of uniformly mixing the additive, solvent, and metal salt in the amounts formulated.
In some embodiments, the electrolyte is prepared by mixing a solvent with a metal salt, dissolving, and then mixing additives. The electrolyte includes 13 to 18wt% of the additive, 67 to 70wt% of the solvent, and 12 to 18wt% of the metal salt, based on 100wt% of the total mass of the solvent, the metal salt, and the additive.
[ Lithium ion Battery ]
Typically, lithium ion batteries include a positive electrode, a negative electrode, a separator, and an electrolyte. In the charge and discharge process of the lithium ion battery, lithium ions are inserted and extracted back and forth between the positive electrode and the negative electrode. The diaphragm is arranged between the anode and the cathode, can play a role in preventing the anode from being short-circuited, and can enable active ions to pass through. The electrolyte plays a role in conducting active ions between the positive pole piece and the negative pole piece.
An embodiment of the application provides a lithium ion battery comprising the electrolyte of the first aspect of the application.
In certain embodiments, a positive electrode of a lithium ion battery includes a positive electrode current collector and a positive electrode film layer on at least one side of the positive electrode current collector, the positive electrode film layer including a positive electrode active material. The positive electrode active material may include a lithium sheet or a lithium-containing transition metal oxide.
Alternatively, the lithium-containing transition metal oxide comprises a lithium iron phosphate or nickel cobalt manganese ternary material, which may comprise one or more of lithium nickel cobalt manganese oxide and modified compounds thereof. The modifying compound of the lithium nickel cobalt manganese oxide may comprise materials well known in the art, for example may comprise doped modified or surface modified lithium nickel cobalt manganese oxide.
In certain embodiments, the positive electrode film layer may have a compacted density of 3.0g/cm 3 to 3.8g/cm 3, optionally 2.9g/cm 3 to 3.6g/cm 3.
The compacted density of the positive electrode film layer has a meaning well known in the art and can be tested using equipment and methods known in the art. Compacted density of positive electrode film = areal density of positive electrode film/thickness of single sided positive electrode film. The surface density of the positive electrode film layer is the known meaning in the art, and can be tested by adopting equipment and a method known in the art, for example, a positive electrode sheet which is coated on one side and subjected to cold pressing (in the case of a positive electrode sheet coated on two sides, the positive electrode film layer on one side can be wiped off firstly), a small wafer is punched and weighed, then the positive electrode film layer of the weighed positive electrode sheet is wiped off, and the weight of the current collector is weighed. Area density of the positive electrode film layer= (weight of small wafer-weight of current collector)/area of small wafer.
In certain embodiments, the positive electrode film layer further optionally includes a positive electrode conductive agent. The present application is not particularly limited in the kind of the positive electrode conductive agent, and the positive electrode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, as an example.
In certain embodiments, the positive electrode film layer further optionally includes a positive electrode binder. The kind of the positive electrode binder is not particularly limited in the present application, and the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluoroacrylate-based resin, as an example.
In some embodiments, the positive current collector may be a metal foil or a composite current collector. As an example of the metal foil, aluminum foil may be used. The composite current collector may include a polymeric material base layer and a metal material layer formed on at least one surface of the polymeric material base layer. As an example, the metal material may include at least one of aluminum, aluminum alloy, nickel alloy, titanium alloy, silver, and silver alloy. As an example, the polymeric material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and Polyethylene (PE).
The positive electrode film layer is usually formed by coating positive electrode slurry on a positive electrode current collector, drying and cold pressing. The positive electrode slurry is generally formed by dispersing a positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring uniformly. The solvent may be N-methylpyrrolidone (NMP), but is not limited thereto.
In certain embodiments, lithium metal may be substituted for the positive electrode of a lithium ion battery.
In some embodiments, in the lithium ion battery of the embodiments of the present application, the anode may include an anode current collector and an anode film layer disposed on at least one surface of the anode current collector and including an anode active material. For example, the anode current collector has two surfaces opposing in the own thickness direction, and the anode film layer is provided on either or both of the two opposing surfaces of the anode current collector.
The negative electrode active material may employ a negative electrode active material for a secondary battery, which is well known in the art. As an example, the anode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate. The silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material.
In certain embodiments, the negative electrode active material is a graphite negative electrode material that is not coated with amorphous carbon.
In certain embodiments, the negative electrode film layer further optionally includes a negative electrode conductive agent. The present application is not particularly limited in the kind of the anode conductive agent, and the anode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, as an example.
In certain embodiments, the negative electrode film layer further optionally includes a negative electrode binder. The present application is not particularly limited in kind of the anode binder, and the anode binder may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), and carboxymethyl chitosan (CMCS), as an example.
In certain embodiments, the negative electrode film layer may also optionally include other adjuvants. As an example, other adjuvants may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, and the like.
In some embodiments, the negative electrode current collector may employ a metal foil or a composite current collector. As an example of the metal foil, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal material layer formed on at least one surface of the polymeric material base layer. As an example, the metallic material may include at least one of copper, copper alloy, nickel alloy, titanium alloy, silver, and silver alloy. As an example, the polymeric material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and Polyethylene (PE).
The negative electrode film layer is usually formed by coating a negative electrode slurry on a negative electrode current collector, drying and cold pressing. The negative electrode slurry is generally formed by dispersing a negative electrode active material, an optional conductive agent, an optional binder, and other optional auxiliaries in a solvent and stirring uniformly. The solvent may be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.
The negative electrode tab does not exclude other additional functional layers than the negative electrode film layer. For example, in some embodiments, the negative electrode tab further includes a conductive primer layer (e.g., composed of a conductive agent and a binder) disposed on a surface of the negative electrode current collector sandwiched between the negative electrode current collector and the negative electrode film layer. In some embodiments, the negative electrode tab of the present application further comprises a protective layer covering the surface of the negative electrode film layer.
In the embodiment of the application, the type of the isolating membrane used for the electrode assembly in the battery monomer is not particularly limited, and any known porous isolating membrane with good chemical stability and mechanical stability can be selected.
In some embodiments, the material of the isolating film may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolating film may be a single-layer film or a multi-layer composite film. When the isolating film is a multi-layer composite film, the materials of the layers are the same or different.
In certain embodiments, the positive electrode sheet, the separator, the negative electrode sheet, and the electrolyte may be made into a lithium ion battery.
In certain embodiments, the lithium ion battery outer package may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. The outer package of the battery cell may also be a pouch, such as a pouch-type pouch. The soft bag can be made of plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT) and polybutylene succinate (PBS).
Examples
Example 1
Preparation of negative electrode plate
Mixing graphite anode material (artificial graphite), conductive agent Super P and binder PVDF with NMP according to the mass ratio of 91.6:6.6:1.8 to prepare uniform slurry with solid content of 50%, coating the uniform slurry on a current collector copper foil, drying and rolling to enable the surface density to be 1.3mg/cm 2, cutting the uniform slurry into round pole pieces with the diameter of 14mm, and vacuum drying for 6 hours at the temperature of 80 ℃ to prepare the anode pole pieces.
Preparation of electrolyte
Methyl ethyl carbonate (EMC) and Ethylene Carbonate (EC) were uniformly mixed in a volume ratio of 8:2, and then, lithium hexafluorophosphate (LiPF 6) solid as a lithium salt was added thereto to dissolve. At this time, the content of lithium hexafluorophosphate was 1.2mol/L.
The electrolyte of example 1 was prepared by adding fluoroethylene carbonate (FEC), 1, 3-Propane Sulfonate (PS), ethylene carbonate (VEC) respectively, and the mass ratio of FEC, PS, VEC was 10:3:5 (18.0 wt% of additive, 69.4wt% of solvent, and 12.6wt% of lithium hexafluorophosphate were included in the electrolyte).
Preparation of button cell for test
Lithium sheets 1mm thick and 16mm in diameter were used as a counter electrode of a half cell, a lithium source was provided, and the negative electrode sheet obtained by the above method was opposed to the lithium sheet via a separator (polyethylene film), and after the electrolyte obtained by the above method was injected, a lithium ion secondary cell (2430 button cell) for experiment was prepared.
Gram Capacity and first Coulomb efficiency determination
The prepared button cell was tested using a constant current charge and discharge mode, the discharge rate was set to 0.05C, the charge rate was set to 0.1C, the discharge cutoff voltage was set to 5mV, and the charge cutoff voltage was set to 2V, to obtain reversible gram capacity and first coulomb efficiency. First coulombic efficiency = first charge gram capacity/first discharge gram capacity x 100%.
Determination of Battery survival, yield and consistency
After the first charge and discharge of 10 button cells were performed with a discharge rate of 0.05C, a charge rate of 0.1C, a discharge cutoff voltage of 5mV, and a charge cutoff voltage of 2V, survival rate, yield, and uniformity were measured.
The survival rate is the percentage of the total number of button cells that exclude significant shorts and overcharging and overdischarging button cells. Overcharging and overdischarging means that either the actual charge data or the discharge data exceeds 20% of the nominal gram capacity.
The percent pass is the percentage of the total number of button cells that has a STD (relative standard deviation) of charge gram capacity less than 0.4%, a STD (relative standard deviation) of first coulombic efficiency less than 0.4% and a first coulombic efficiency very poor less than 1%.
Consistency is judged by the gram capacity obtained by first charge and discharge of the power buckling and STD (relative standard deviation) of first coulombic efficiency data, and the smaller the STD is, the better the consistency of the batch of batteries is, and the better the consistency is regarded as STD <0.9, and the worse the contrary is regarded as STD.
Example 2
This example an electrolyte was prepared in the same manner as in example 1, except that the composition of the additive was different from example 1, and the rest was the same as in example 1. Further, a lithium ion battery of example 2 was fabricated in the same manner as example 1. With respect to the obtained battery, evaluation of battery characteristics was performed in the same manner as in example 1.
In this example, fluoroethylene carbonate (FEC), 3-Propane Sulfonate (PS), ethylene carbonate (VEC) and lithium dioxaborate (LiBOB) were added as additives in a mass ratio of FEC, PS, VEC, liBOB of 10:3:1:1, respectively, to prepare an electrolyte of example 2 (the electrolyte includes 15.0wt% of the additive, 69.8wt% of the solvent and 15.2wt% of lithium hexafluorophosphate).
Example 3
This example an electrolyte was prepared in the same manner as in example 1, except that the composition of the additive was different from example 1, and the rest was the same as in example 1. Further, a lithium ion battery of example 3 was fabricated in the same manner as example 1. With respect to the obtained battery, evaluation of battery characteristics was performed in the same manner as in example 1.
In this example, fluoroethylene carbonate (FEC), 3-Propane Sulfonate (PS), vinylene Carbonate (VC) and lithium dioxaborate (LiBOB) were added as additives in a mass ratio of FEC, PS, VC, liBOB to 3 to 1, respectively, to prepare an electrolyte of example 3 (the electrolyte includes 15.0wt% of the additive, 69.8wt% of the solvent and 15.2wt% of lithium hexafluorophosphate).
Example 4
This example an electrolyte was prepared in the same manner as in example 1, except that the composition of the additive and the solvent of the electrolyte were different from example 1, and the rest was the same as in example 1. Further, a lithium ion battery of example 4 was fabricated in the same manner as example 1. With respect to the obtained battery, evaluation of battery characteristics was performed in the same manner as in example 1.
In this example, fluoroethylene carbonate (FEC) and 3-Propane Sulfonate (PS) were added as additives in a mass ratio of 10:3, respectively, to prepare an electrolyte of example 4 (the electrolyte contains 13.0wt% of the additive, 69.0wt% of the solvent and 18.0wt% of lithium hexafluorophosphate).
Example 5
This example an electrolyte was prepared in the same manner as in example 1, except that the composition of the additive and the solvent of the electrolyte were different from example 1, and the rest was the same as in example 1. Further, a lithium ion battery of example 5 was fabricated in the same manner as example 1. With respect to the obtained battery, evaluation of battery characteristics was performed in the same manner as in example 1.
In this example, fluoroethylene carbonate (FEC), 3-Propane Sulfonate (PS) and ethylene carbonate (VEC) were added as additives, respectively, and the electrolyte of example 6 was prepared (18.0 wt% of the additive, 69.4wt% of the solvent and 12.6wt% of lithium hexafluorophosphate were contained in the electrolyte, and the solvent was methyl ethyl carbonate and ethylene carbonate in a mass ratio of 1:1) at a mass ratio of FEC, PS, VEC to 10:3:5.
Comparative example 1
This comparative example an electrolyte was prepared in the same manner as in example 1, with the percentages of additives, solvents and lithium salts in the electrolyte adjusted, and the remainder was the same as in example 1. Further, a lithium ion battery of comparative example 1 was fabricated in the same manner as in example 1. With respect to the obtained battery, evaluation of battery characteristics was performed in the same manner as in example 1.
In this comparative example, methyl ethyl carbonate (EMC) and Ethylene Carbonate (EC) were uniformly mixed in a volume ratio of 1:1, and then, lithium hexafluorophosphate (LiPF 6) solid as a lithium salt was added thereto to dissolve. At this time, the content of lithium hexafluorophosphate was 0.8mol/L.
In this comparative example, fluoroethylene carbonate (FEC), 3-Propane Sulfonate (PS) and ethylene carbonate (VEC) were added as additives in a mass ratio of 7:3:1, respectively, to prepare an electrolyte of comparative example 1 (the electrolyte includes 11.0wt% of the additive, 79.0wt% of the solvent and 10.0wt% of lithium hexafluorophosphate).
Comparative example 2
This comparative example an electrolyte was prepared in the same manner as in example 1, with the percentages of additives, solvents and lithium salts in the electrolyte adjusted, and the remainder was the same as in example 1. Further, a lithium ion battery of comparative example 2 was fabricated in the same manner as in example 1. With respect to the obtained battery, evaluation of battery characteristics was performed in the same manner as in example 1.
In this comparative example, methyl ethyl carbonate (EMC) and Ethylene Carbonate (EC) were uniformly mixed in a volume ratio of 8:2, and then, lithium hexafluorophosphate (LiPF 6) solid as a lithium salt was added thereto to dissolve. At this time, the content of lithium hexafluorophosphate was 0.6mol/L.
In this comparative example, fluoroethylene carbonate (FEC), 3-Propane Sulfonate (PS) and ethylene carbonate (VC) were added as additives in a mass ratio of FEC, PS, VC to 3:1, respectively, to prepare an electrolyte of comparative example 3 (the electrolyte includes 14.0wt% of the additive, 78.0wt% of the solvent and 8.0wt% of lithium hexafluorophosphate).
Comparative example 3
This comparative example an electrolyte was prepared in the same manner as in example 1, with the percentages of additives, solvents and lithium salts in the electrolyte adjusted, and the remainder was the same as in example 1. Further, a lithium ion battery of comparative example 3 was fabricated in the same manner as in example 1. With respect to the obtained battery, evaluation of battery characteristics was performed in the same manner as in example 1.
In this comparative example, methyl ethyl carbonate (EMC) and Ethylene Carbonate (EC) were uniformly mixed in a volume ratio of 8:2, and then, lithium hexafluorophosphate (LiPF 6) solid as a lithium salt was added thereto to dissolve. At this time, the content of lithium hexafluorophosphate was 0.6mol/L.
In this comparative example, fluoroethylene carbonate (FEC), 3-Propane Sulfonate (PS), ethylene carbonate (VEC) and VEC were added as additives in a mass ratio of 10:4:5, respectively, to prepare an electrolyte of comparative example 3 (the electrolyte includes 19.0wt% of the additive, 73.0wt% of the solvent and 8.0wt% of lithium hexafluorophosphate).
TABLE 1
In summary, the electrolyte provided by the invention improves the ratio of the additive to the metal salt, properly reduces the dosage of the solvent, reduces the contact between solvent molecules and the electrode, and improves the stability of the electrolyte.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that fall within the technical scope of the present invention disclosed herein are within the scope of the present invention.

Claims (10)

1. An electrolyte is characterized by comprising more than or equal to 13 weight percent of additive, less than or equal to 72 weight percent of solvent and the balance of metal salt, wherein the mass percent of the electrolyte is 100 weight percent;
The additive comprises any one or a combination of at least two of fluoroethylene carbonate, 1, 3-propane sulfonate, ethylene carbonate or lithium dioxalate borate.
2. The electrolyte according to claim 1, wherein the electrolyte comprises, in mass percent, 13 to 18wt% of the additive, 67 to 70wt% of the solvent, and 12 to 18wt% of the metal salt.
3. Electrolyte according to claim 1, characterized in that the solvent comprises methyl ethyl carbonate and/or ethylene carbonate.
4. The electrolyte of claim 3 wherein the solvent comprises a combination of ethyl methyl carbonate and ethylene carbonate;
And/or the mass ratio of the methyl ethyl carbonate to the ethylene carbonate is 1:1 to 4:1.
5. The electrolyte of claim 1 wherein the additive comprises a combination of fluoroethylene carbonate, 1, 3-propane sulfonate lactone, and ethylene carbonate.
6. The electrolyte according to claim 5, wherein the electrolyte comprises, in mass percent, the electrolyte comprises medium ethylene carbonate the mass percent of the ethyl ester is 1 to 5 percent.
7. The electrolyte of any one of claim 5 wherein the additive further comprises lithium dioxalate borate;
In terms of mass percent, the components are mixed, the electrolyte comprises 0.5 to 2 weight percent of lithium dioxalate borate.
8. The electrolyte of claim 1 wherein the metal salt is a lithium salt;
and/or the lithium salt comprises any one or a combination of at least two of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate or lithium hexafluoroarsenate.
9. A lithium ion battery, characterized in that it comprises the electrolyte according to any one of claims 1 to 8.
10. The lithium ion battery of claim 9, wherein the negative active material of the lithium ion battery comprises a graphite negative material.
CN202411643361.8A 2024-11-15 2024-11-15 Electrolyte and lithium ion battery Pending CN119230952A (en)

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