Electrolyte and battery and vehicle using same
By using electrolyte with flame retardant organic solvents and additives in lithium-ion batteries, the problems of thermal runaway and fire safety hazards of lithium-ion batteries are solved, and higher safety and electrochemical performance are achieved.
Patent Information
- Application Number
- CN202510165712.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-14
- Publication Date
- 2025-05-13
AI Technical Summary
Lithium-ion batteries are prone to thermal out of control when facing thermal abuse, electrical abuse, mechanical abuse and other working conditions, resulting in fire accidents. The existing technology is difficult to effectively solve this safety hazard, while taking into account electrochemical performance.
An electrolyte including a lithium salt, an organic solvent with flame retardant effect and an additive is used. The organic solvent decomposes at high temperature to produce phosphorus or fluorine radicals, capture hydrogen or hydrogen-oxygen radicals, and produce non-combustible compounds, achieving flame retardant effects. The additives form a double-layer interface mask to improve the battery's cycle stability and high-temperature storage performance.
It significantly improves the safety of lithium-ion batteries, extends the time of thermal runaway, and improves the electrochemical performance and product performance of the battery.
Smart Images
Figure CN119994200A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of new energy technology, and in particular to an electrolyte and a battery and a vehicle using the electrolyte. Background Art
[0002] Lithium-ion batteries are a very common type of battery in mobile devices, electric vehicles, and energy storage fields. Especially in the field of new energy vehicles, lithium-ion batteries have a huge application prospect. However, lithium-ion batteries also generally have the potential safety hazard of fire, which has caused people to worry about the safety of lithium-ion batteries. Fire accidents of lithium-ion batteries are often caused by thermal runaway of the battery. The so-called thermal runaway refers to the phenomenon that when lithium-ion batteries face thermal abuse (overheating), electrical abuse (overcharge and over-discharge), mechanical abuse (impact), etc., short circuits cause violent exothermic reactions between the components inside the lithium-ion battery, and cause uncontrollable temperature rise inside the lithium-ion battery. How to solve the above problems, improve the safety of lithium-ion batteries and take into account the electrochemical properties of lithium-ion batteries is what technicians in this field need to consider. Summary of the invention
[0003] In order to solve the above problems, the embodiments of the present application provide an electrolyte and a battery and a vehicle using the same.
[0004] An embodiment of the present application provides an electrolyte, which includes a lithium salt, an organic solvent and an additive; the lithium salt is used to provide lithium ions; the organic solvent includes an organic matter containing phosphorus or fluorine, and the organic solvent has a flame retardant effect; the additive includes a first compound additive component and / or a second compound additive component, the first compound additive component can form an interface film containing an organic component on the surface of the battery electrode, and the second compound additive component can form an interface film containing an inorganic component on the surface of the battery electrode.
[0005] Furthermore, in the electrolyte provided by the embodiment of the present application, the organic solvent includes an organic substance containing phosphorus or fluorine, and the organic solvent can decompose at high temperature to produce phosphorus-based free radicals or fluorine-based free radicals, and the phosphorus-based free radicals or fluorine-based free radicals can capture hydrogen free radicals and / or hydroxyl free radicals to generate non-flammable phosphorus or fluorine compounds, thereby achieving flame retardancy. The first compounded additive component and the second compounded additive component can cooperate with each other to form a double-layer interface film with an inner layer containing organic components and an outer layer containing inorganic components, so that the battery using the electrolyte has better cycle stability and high-temperature storage performance.
[0006] In one embodiment, the organic solvent includes one or more of trimethyl phosphate, triethyl phosphate, dimethyl methyl phosphate, ethyl trifluoroacetate, methyl trifluoroacetate, ethyl 2,2-trifluorobutyrate, bis(2,2,2)trifluoromethyl carbonate, bis(2,2,2)trifluoroethyl phosphite, perfluoromethyl nonafluorobutyl ether, 1,1,2,2(tetrafluoromethyl)-2,2,3,3(tetrafluoropropyl) ether, ethoxypentafluorocyclotriphosphazene, hexafluorocyclotriphosphazene, hexachlorocyclotriphosphazene, hexa(2,2,3,3,3-pentafluoropropoxy)cyclotriphosphazene, tris(2,2,2)trifluoroethyl phosphate, and tris(2,2,2-trifluoroethyl)borate.
[0007] In one embodiment, the organic solvent accounts for 82% to 85% of the electrolyte in terms of weight percentage.
[0008] In one embodiment, the first composite additive component includes ethylene carbonate, tris(pentafluorophenyl)borane, hexafluorobutane anhydride, carbitol acrylate, trifluoropropylene carbonate, tetraethoxysilane, 2-methyl-2-methoxysilane, 1,3-propane sultone, lithium difluorobis(oxalato)borate, ethylene sulfite (ES), diethyl sulfite, vinyl sulfate, methylene disulfonate, succinic anhydride, 4-methylethylene sulfate, ethyl propylene carbonate, tris(trimethylsilyl)phosphite, tris(trimethylsilyl borate, lithium bis(trifluoromethylsulfonyl imide), lithium bis(fluorosulfonyl imide), succinonitrile, 2,4-fluorobenzonitrile, and one or more of triisopropylethylsulfonyl(pentafluorophenyl)phosphine.
[0009] In one embodiment, the first compounded additive component accounts for 0.1% to 5% of the electrolyte in terms of weight percentage.
[0010] In one embodiment, the general structural formula of the second compounded additional component is as follows:
[0011]
[0012] Wherein, R is one or more of alkoxy, cycloalkane, benzene and the like.
[0013] In one embodiment, the second compounded additive component is one of the following three structural formulas:
[0014]
[0015] In one embodiment, the second compounded additive component accounts for 0.5% to 1% of the electrolyte in terms of weight percentage.
[0016] An embodiment of the present application also provides a battery, which includes the electrolyte as described in any one of the above embodiments.
[0017] An embodiment of the present application further provides a vehicle, which includes a second main body and the battery as described in the above embodiment, wherein the battery is electrically connected to the second main body.
[0018] Furthermore, the batteries and vehicles provided in the embodiments of the present application have corresponding electrolytes with better flame retardant effects and better electrochemical properties, so that the batteries and vehicles have better product performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 Schematic diagram of the results of conductivity testing of the electrolytes corresponding to Examples 1 to 6 and Comparative Examples 1 to 2 provided in the present application.
[0020] Figure 2 Schematic diagram of the results of limiting oxygen index testing of the electrolytes corresponding to Examples 1 to 6 and Comparative Examples 1 to 2 provided in the present application.
[0021] Figure 3 A schematic diagram of parameter results of hot box testing of batteries with electrolytes corresponding to Example 2, Comparative Example 1 and Comparative Example 2 provided in the present application.
[0022] Figure 4 A schematic diagram of another parameter result of hot box testing of batteries with electrolytes corresponding to Example 2, Comparative Example 1 and Comparative Example 2 provided in the present application.
[0023] Figure 5 A schematic diagram of another parameter result of hot box testing of batteries with electrolytes corresponding to Example 2, Comparative Example 1 and Comparative Example 2 provided in the present application.
[0024] Figure 6 Schematic diagram of disassembly of batteries after capacity division of electrolytes corresponding to Example 2, Comparative Example 1 and Comparative Example 2 provided in the present application.
[0025] Figure 7 A schematic diagram of the structure of a battery provided in an embodiment of the present application.
[0026] Figure 8 A schematic diagram of the structure of a vehicle provided in an embodiment of the present application.
[0027] Main component symbols
[0028] Electrolyte 10
[0029] Battery 1
[0030] First body portion 11
[0031] Vehicle 2
[0032] The second main body 21
[0033] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION
[0034] The following description will refer to the accompanying drawings to more fully describe the content of the present application. Shown in the accompanying drawings are exemplary embodiments of the present application. However, the present application can be implemented in many different forms and should not be construed as being limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided to make the present application thorough and complete, and to fully convey the scope of the present application to those skilled in the art. Similar reference numerals represent identical or similar components.
[0035] The terms used herein are only used for the purpose of describing specific exemplary embodiments and are not intended to limit the present application. As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to also include the plural forms. In addition, when used herein, "including" and / or "comprising" and / or "having", integers, steps, operations, components and / or components, but do not exclude the existence or addition of one or more other features, regions, integers, steps, operations, components and / or groups thereof.
[0036] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. In addition, unless explicitly defined herein, terms such as those defined in general dictionaries should be interpreted as having a meaning consistent with their meaning in the relevant technology and the content of this application, and will not be interpreted as an idealized or overly formal meaning.
[0037] Usually, fire accidents of lithium-ion batteries are often caused by thermal runaway of the battery. The so-called thermal runaway refers to the phenomenon that when the lithium-ion battery faces thermal abuse (overheating), electrical abuse (overcharge and over-discharge), mechanical abuse (impact), etc., a short circuit causes a violent exothermic reaction between the components inside the lithium-ion battery, causing an uncontrollable temperature rise inside the lithium-ion battery. When thermal runaway occurs, the internal flammable organic electrolyte volatilizes or leaks into the outside air, and a serious fire will occur when the temperature reaches its ignition point. Therefore, it can be considered that the flammable organic carbonate electrolyte is one of the direct causes of the fire. In order to solve this problem, most of the development of liquid high-safety electrolytes is based on adding a certain proportion of organic phosphate or phosphazene flame retardant additives to the original carbonate electrolyte to improve the safety of the electrolyte. However, the use of these electrolyte additives will deteriorate the electrochemical properties of the battery (including rate performance, long cycle performance, etc.), and the low addition ratio may have no obvious effect on safety.
[0038] Correspondingly, the present application provides an electrolyte and a battery and a vehicle using the same. The electrolyte includes a lithium salt, an organic solvent and an additive; the lithium salt is used to provide lithium ions; the organic solvent includes an organic substance containing phosphorus or fluorine, and the organic solvent has a flame retardant effect; the additive includes a first compound additive component and / or a second compound additive component, the first compound additive component can form an interface film containing an organic component on the surface of the battery electrode, and the second compound additive component can form an interface film containing an inorganic component on the surface of the battery electrode. The battery includes the electrolyte. The vehicle includes a second main body and the battery, and the battery is electrically connected to the second main body.
[0039] It can be understood that in the electrolyte provided in the embodiment of the present application, the organic solvent includes an organic substance containing phosphorus or fluorine, and the organic solvent can decompose at high temperature to produce phosphorus-based free radicals or fluorine-based free radicals, and the phosphorus-based free radicals or fluorine-based free radicals can capture hydrogen free radicals and / or hydroxyl free radicals to generate non-flammable phosphorus or fluorine compounds, thereby achieving flame retardancy. The first compounded additive component and the second compounded additive component can cooperate with each other to form a double-layer interface film with an inner layer containing organic components / an outer layer containing inorganic components, so that the battery using the electrolyte has better cycle stability and high-temperature storage performance. The battery and vehicle provided in the embodiment of the present application, and the corresponding electrolyte have better flame retardant effect and better electrochemical performance, so that the battery and vehicle have better product performance.
[0040] Those skilled in the art can understand that "electrolyte" refers to a medium widely used in devices such as batteries and electrolytic capacitors, and its main function is to conduct ions and ensure that the chemical reaction inside the battery can proceed smoothly. The composition and properties of the electrolyte have a crucial impact on the performance, life and safety of the battery.
[0041] Those skilled in the art can understand that "flame retardant" can be determined by conducting a limiting oxygen index test on the electrolyte. When the limiting oxygen index (LOI) is greater than 27%, the electrolyte can be considered non-flammable; when the limiting oxygen index (LOI) is less than 21%, the electrolyte can be considered flammable.
[0042] Those skilled in the art can understand that "interface film" refers to SEI film and / or CEI film. Among them, SEI film, the full name of Solid Electrolyte Interface (SEI), refers to the passivation film formed on the negative electrode-electrolyte interface during the first charge and discharge process of lithium-ion batteries. This film is reduced by the solvent and additives in the electrolyte on the negative electrode surface, and has the characteristics of conducting lithium ions and isolating electrons. Among them, the CEI film (Cathode Electrolyte Interface), that is, the positive electrode / electrolyte interface film, is a thin film formed on the surface of the positive electrode material of the battery. It is a solid electrolyte interface membrane through which ions can pass but electrons cannot pass.
[0043] The specific implementation methods of the present application are further described in detail below with reference to the accompanying drawings.
[0044] The embodiment of the present application provides an electrolyte, which is a flame retardant electrolyte and includes a lithium salt, an organic solvent with flame retardant effect, and an additive.
[0045] In one embodiment, the lithium salt includes an inorganic salt or an organic salt containing lithium element, which is used to provide lithium ions.
[0046] In this embodiment, the lithium salt includes one or more of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiFSI), lithium difluorooxalatoborate (LiODFB) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).
[0047] In one embodiment, the ratio of the lithium salt to the total mass of the electrolyte is in a range of 10% to 14%.
[0048] In this embodiment, the proportion of the lithium salt to the total mass of the electrolyte may specifically be 11%, 11.5%, 12%, 12.5%, 13%, or 13.5%.
[0049] In one embodiment, the organic solvent includes an organic substance containing phosphorus or fluorine, and the organic solvent has a flame retardant effect.
[0050] In this embodiment, the organic solvent includes trimethyl phosphate (TMP), triethyl phosphate (TEP), dimethyl methyl phosphate (DMMP), ethyl trifluoroacetate (TFA), methyl trifluoroacetate (TFMA), ethyl 2,2-trifluorobutyrate (TFEB), bis (2,2,2) trifluoromethyl carbonate (DFEC), bis (2,2,2) trifluoroethyl phosphite (DFEP), perfluoromethyl nonafluorobutyl ether (MFE), 1,1,2,2 (tetrafluoromethyl) -2,2,3,3 (tetrafluoropropyl) ether (HFE), ethoxy pentafluorocyclotriphosphazene (PFPN), hexafluorocyclotriphosphazene (HFPN), hexachlorocyclotriphosphazene (HCPN), hexa(2,2,3,3,3-pentafluoropropoxy) cyclotriphosphazene (PFPN), tris(2,2,2) trifluoroethyl phosphate (TFEP), tris(2,2,2-trifluoroethyl) borate (FTEB) One or more.
[0051] In one embodiment, the organic solvent accounts for 82% to 85% of the total mass of the electrolyte.
[0052] In this embodiment, the proportion of the organic solvent to the total mass of the electrolyte may specifically be 82.5%, 83%, 83.5%, 84%, or 84.5%.
[0053] It can be understood that the organic solvent includes the above-mentioned organic matter containing phosphorus element or fluorine element, and the organic solvent can decompose at high temperature to produce phosphorus-based free radicals or fluorine-based free radicals. The phosphorus-based free radicals or fluorine-based free radicals can capture hydrogen free radicals and / or hydroxyl free radicals to generate non-flammable phosphorus or fluorine compounds (such as fluorine hydride, hydrofluoric acid), thereby achieving flame retardancy.
[0054] In one embodiment, the additive includes a first compound additive component and / or a second compound additive component, wherein the first compound additive component can form an interface film containing an organic component on the surface of the battery electrode, and the second compound additive component can form an interface film containing an inorganic component on the surface of the battery electrode.
[0055] In one embodiment, the additive may include at least one of a first compounded additive component and a second compounded additive component; preferably, the additive includes both the first compounded additive component and the second compounded additive component.
[0056] In one embodiment, the first compound additive component includes ethylene carbonate (EC), tris(pentafluorophenyl)borane (TFFPB), hexafluorobutane anhydride (HFA), carbitol acrylate (EOEOEA), trifluoropropylene carbonate (TFPC), tetraethoxysilane (TEOS), 2-methyl-2-methoxysilane (DODSi), 1,3-propane sultone (PS), lithium difluorobis(oxalate)borate (LiODFP), ethylene sulfite (ES), diethyl sulfite (DES), ethylene sulfate (D The invention can be selected from the group consisting of TD), methylene methanedisulfonate (MMDS), succinic anhydride (SA), 4-methylethylene sulfate (MDTD), propylene ethyl carbonate (AEC), tris(trimethylsilyl) phosphite (TMSPi), tris(trimethylsilyl borate) (TMSB), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), succinonitrile (SN), 2,4-fluorobenzonitrile (MSDS), and triisopropylethylsulfonyl (pentafluorophenyl)phosphine (TPFPP).
[0057] In one embodiment, the ratio of the first compounded additive component to the total mass of the electrolyte is in a range of 0.1% to 5%.
[0058] In this embodiment, the proportion of the first composite additive component to the total mass of the electrolyte may specifically be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or 4.5%.
[0059] In a preferred embodiment, the first compounded additive component includes tris(trimethylsilyl)phosphite (TMSPi) accounting for 0.5% of the total mass of the electrolyte and ethylene carbonate (EC) accounting for 2% of the total mass of the electrolyte.
[0060] It is understandable that tris(trimethylsilyl)phosphite (TMSPi) has the function of removing water and inhibiting acid, and can protect the positive electrode of the battery. Ethylene carbonate (EC) can form an interface film containing organic components (such as alkyl lithium) on the surface of the negative electrode of the battery, thereby giving the interface film good elasticity. It is understandable that the interface film containing organic components (such as alkyl lithium) is elastic, and the interface film is not easy to be damaged during the cycle, protecting the electrode surface, and at the same time facilitating lithium ion transmission.
[0061] In one embodiment, the general structural formula of the second compounded additional component is as follows:
[0062]
[0063] Wherein, R is one or more of alkoxy, cycloalkane, benzene and the like.
[0064] It can be understood that the second composite additive component having the above structure can effectively protect the electrode material and form an interface film containing inorganic components (such as lithium fluoride, lithium borate, and lithium sulfonate); in addition, it can effectively reduce the dissolution of transition metals, and the interface film of inorganic components (such as lithium fluoride, lithium borate, and lithium sulfonate) has good rigidity and smaller pores, which can reduce the direct contact between the electrolyte and the electrode material, thereby improving the long cycle performance, high temperature storage performance, and low temperature performance of the battery having the electrolyte.
[0065] In this embodiment, the structural formula of the second composite additive component is one of the following three structures:
[0066]
[0067] In one embodiment, the proportion of the second compounded additive component to the total mass of the electrolyte is in a range of 0.5% to 1%.
[0068] In this embodiment, the proportion of the second composite additive component to the total mass of the electrolyte may specifically be 0.6%, 0.7%, 0.8%, or 0.9%.
[0069] It can be understood that the second composite additive component is rich in fluorine (F), sulfur (S) and boron (B), which can form an interface film containing inorganic components on the surface of the positive electrode and / or negative electrode of the battery, prevent the interface film from becoming thicker, and inhibit the continuous decomposition of the organic solvent to produce side reactions, which is beneficial to the lithium ion (Li + On the other hand, the second compound additive component can cooperate with the first compound additive component (especially ethylene carbonate (EC)) to form a double-layer interface film with an inner layer containing organic components and an outer layer containing inorganic components, so that the battery using the electrolyte has better cycle stability and high-temperature storage performance.
[0070] In a preferred embodiment, the second composite additive component accounts for 0.5% of the total mass of the electrolyte.
[0071] Comparative Example 1
[0072] The electrolyte is prepared in a glove box, and the environmental parameters of the glove box are: O2≤0.01ppm, H2O≤0.01ppm, and the filling gas is high-purity argon. By mass percentage, the electrolyte contains 10% lithium difluorooxalatoborate (LiODFB), and the rest is an organic solvent, and the organic solvent includes tris (2,2,2) trifluoroethyl borate (FTEB), triethyl phosphate (TEP), and tris (2,2,2) trifluoroethyl phosphate (TFEP) mixed in a mass ratio of 15:45:40.
[0073] Comparative Example 2
[0074] The electrolyte is prepared in a glove box, and the environmental parameters of the glove box are: O2≤0.01ppm, H2O≤0.01ppm, and the filling gas is high-purity argon. By mass percentage, the electrolyte contains 10% lithium hexafluorophosphate (LiPF6), 0.5% vinylene carbonate (VC), 0.5% fluoroethylene carbonate (FEC), and the rest is an organic solvent, which includes ethylene carbonate (EC) and ethyl methyl carbonate (EMC) mixed in a mass ratio of 3:7.
[0075] Example 1
[0076] The electrolyte is prepared in a glove box, the environmental parameters of the glove box are: O2≤0.01ppm, H2O≤0.01ppm, and the filling gas is high-purity argon. In terms of mass percentage, the electrolyte contains 10% (-0.8M) lithium difluorooxalatoborate (LiODFB), 0.5% tris(trimethylsilyl)phosphite (TMSPi), 2% ethylene carbonate (EC) and 0.5% of the structure (a), and the rest is an organic solvent, which includes tris(2,2,2)trifluoroethylborate (FTEB), triethyl phosphate (TEP), and tris(2,2,2)trifluoroethylphosphate (TFEP) mixed in a mass ratio of 15:45:40.
[0077] Example 2
[0078] The electrolyte is prepared in a glove box, the environmental parameters of the glove box are: O2≤0.01ppm, H2O≤0.01ppm, and the filling gas is high-purity argon. In terms of mass percentage, the electrolyte contains 10% lithium difluorooxalatoborate (LiODFB), 0.5% tris(trimethylsilyl)phosphite (TMSPi), 2% ethylene carbonate (EC) and 0.5% of the structure (b), and the rest is an organic solvent, which includes tris(2,2,2)trifluoroethylborate (FTEB), triethyl phosphate (TEP), and tris(2,2,2)trifluoroethylphosphate (TFEP) mixed in a mass ratio of 15:45:40.
[0079] Example 3
[0080] The electrolyte is prepared in a glove box, the environmental parameters of the glove box are: O2≤0.01ppm, H2O≤0.01ppm, and the filling gas is high-purity argon. In terms of mass percentage, the electrolyte contains 10% lithium difluorooxalatoborate (LiODFB), 0.5% tris(trimethylsilyl)phosphite (TMSPi), 2% ethylene carbonate (EC) and 0.5% of the structure (c), and the rest is an organic solvent, and the organic solvent includes tris(2,2,2)trifluoroethylborate (FTEB), triethyl phosphate (TEP), and tris(2,2,2)trifluoroethylphosphate (TFEP) mixed in a mass ratio of 15:45:40.
[0081] Example 4
[0082] The electrolyte is prepared in a glove box, the environmental parameters of the glove box are: O2≤0.01ppm, H2O≤0.01ppm, and the filling gas is high-purity argon. In terms of mass percentage, the electrolyte contains 10% lithium difluorooxalatoborate (LiODFB), 0.5% tris(trimethylsilyl)phosphite (TMSPi), 2% ethylene carbonate (EC) and 1% of the structure (a), and the rest is an organic solvent, and the organic solvent includes tris(2,2,2)trifluoroethylborate (FTEB), triethyl phosphate (TEP), and tris(2,2,2)trifluoroethylphosphate (TFEP) mixed in a mass ratio of 15:45:40.
[0083] Example 5
[0084] The electrolyte is prepared in a glove box, the environmental parameters of the glove box are: O2≤0.01ppm, H2O≤0.01ppm, and the filling gas is high-purity argon. In terms of mass percentage, the electrolyte contains 10% lithium difluorooxalatoborate (LiODFB), 0.5% tris(trimethylsilyl)phosphite (TMSPi), 2% ethylene carbonate (EC) and 1% of the structure (b), and the rest is an organic solvent, and the organic solvent includes tris(2,2,2)trifluoroethylborate (FTEB), triethyl phosphate (TEP), and tris(2,2,2)trifluoroethylphosphate (TFEP) mixed in a mass ratio of 15:45:40.
[0085] Example 6
[0086] The electrolyte is prepared in a glove box, the environmental parameters of the glove box are: O2≤0.01ppm, H2O≤0.01ppm, and the filling gas is high-purity argon. In terms of mass percentage, the electrolyte contains 10% lithium difluorooxalatoborate (LiODFB), 0.5% tris(trimethylsilyl)phosphite (TMSPi), 2% ethylene carbonate (EC) and 1% of the structure (c), and the rest is an organic solvent, and the organic solvent includes tris(2,2,2)trifluoroethylborate (FTEB), triethyl phosphate (TEP), and tris(2,2,2)trifluoroethylphosphate (TFEP) mixed in a mass ratio of 15:45:40.
[0087] Example 7
[0088] The electrolyte is prepared in a glove box, and the environmental parameters of the glove box are: O2≤0.01ppm, H2O≤0.01ppm, and the filling gas is high-purity argon. By mass percentage, the electrolyte contains 10% lithium difluorooxalatoborate (LiODFB) and 0.5% tris(trimethylsilyl)phosphite (TMSPi), and the rest is an organic solvent, and the organic solvent includes tris(2,2,2)trifluoroethylborate (FTEB), triethyl phosphate (TEP), and tris(2,2,2)trifluoroethylphosphate (TFEP) mixed in a mass ratio of 15:45:40.
[0089] Example 8
[0090] The electrolyte is prepared in a glove box, and the environmental parameters of the glove box are: O2≤0.01ppm, H2O≤0.01ppm, and the filling gas is high-purity argon. By mass percentage, the electrolyte contains 10% lithium difluorooxalatoborate (LiODFB) and 2% ethylene carbonate (EC), and the rest is an organic solvent, and the organic solvent includes tris (2,2,2) trifluoroethyl borate (FTEB), triethyl phosphate (TEP), and tris (2,2,2) trifluoroethyl phosphate (TFEP) mixed in a mass ratio of 15:45:40.
[0091] Example 9
[0092] The electrolyte is prepared in a glove box, and the environmental parameters of the glove box are: O2≤0.01ppm, H2O≤0.01ppm, and the filling gas is high-purity argon. In terms of mass percentage, the electrolyte contains 10% lithium difluorooxalatoborate (LiODFB), 0.5% tris(trimethylsilyl)phosphite (TMSPi) and 2% ethylene carbonate (EC), and the rest is an organic solvent, and the organic solvent includes tris(2,2,2)trifluoroethylborate (FTEB), triethyl phosphate (TEP), and tris(2,2,2)trifluoroethylphosphate (TFEP) mixed in a mass ratio of 15:45:40.
[0093] The specific formulas of Examples 1 to 9 and Comparative Examples 1 to 2 are shown in Table 1 below, wherein the total amount of each component is 100%.
[0094] Table 1
[0095]
[0096]
[0097] Based on the electrolytes of Examples 1 to 9 and Comparative Examples 1 to 2, LiNi 0.6 Co 0.2 Mn 0.2 O2 / / Gr is the experimental battery cell; and the liquid is injected in the glove box, and after the injection is completed, normal formation and other processes are further carried out to obtain a battery that can be tested; the environmental parameters of the glove box are: O2≤0.01ppm, H2O≤0.01ppm, and the filling gas is high-purity argon.
[0098] The batteries made based on the electrolytes of Comparative Example 1, Comparative Example 2 and Examples 1 to 9 were subjected to room temperature cycle tests, high temperature cycle performance tests, high temperature storage performance tests, room temperature EIS tests, and room temperature DCR tests, respectively, and the corresponding electrochemical performance data were obtained. The electrochemical performance test results are shown in Table 2 below.
[0099] Table 2
[0100]
[0101] Combined with Table 2 and Figures 1 to 6 , the electrolytes of Examples 1 to 9 of the present application and Comparative Examples 1 to 2 were analyzed.
[0102] Compared with Comparative Example 2, the corresponding 25°C capacity retention rate, 45°C capacity retention rate, 60°C storage capacity retention rate, and 60°C storage capacity recovery rate of Examples 1 to 9 are all better; compared with Comparative Example 2, the corresponding 25°C capacity retention rate, 45°C capacity retention rate, and 60°C storage capacity recovery rate of Comparative Example 1 are all better, and the data of 60°C storage capacity retention rate are roughly the same.
[0103] It can be understood that the organic solvents with flame retardant effects in Examples 1 to 9 and Comparative Example 1 contain fluorine elements, which can form an interface film containing inorganic LiF, and can effectively protect the positive / negative electrodes, so their electrochemical performance is better. Comparative Example 2 is a carbonate electrolyte using a general formula. For carbonate electrolytes, the corresponding film-forming components are mainly alkyl organic matter decomposed from carbonates. This substance cannot simply and effectively protect the positive and negative electrode materials, and may cause the electrolyte to continuously decompose. Therefore, its electrochemical performance is poor and the impedance is higher. Therefore, the organic solvent provided in the embodiments of the present application has a flame retardant effect, but its chemical properties do not show disadvantages; that is, it maintains good electrochemical performance.
[0104] Compared with Comparative Example 1, the corresponding 25°C capacity retention rate, 45°C capacity retention rate, 60°C storage capacity retention rate, and 60°C storage capacity recovery rate of Examples 1 to 9 are all better.
[0105] It is understandable that the electrolytes of Examples 1 to 9 all contain additives, which can help film formation, thereby effectively protecting the electrode material, reducing lithium dendrites, and thus improving the overall safety and electrochemical performance of the battery. Therefore, on the basis of already containing the organic solvent, further adding additives to the electrolyte can improve the normal high temperature cycle capacity retention rate of the battery.
[0106] Compared with Comparative Example 1, the corresponding 25°C capacity retention rate, 45°C capacity retention rate, 60°C storage capacity retention rate, and 60°C storage capacity recovery rate of Examples 7 to 9 are all better. Compared with Examples 7 and 8, the corresponding 25°C capacity retention rate, 45°C capacity retention rate, and 60°C storage capacity retention rate of Example 9 are all better.
[0107] It can be understood that single-component additives are added in both Example 7 and Example 8, wherein Example 7 adds 0.5% tris(trimethylsilyl)phosphite (TMSPi), and Example 8 adds 2% ethylene carbonate (EC), and the high temperature storage and cycle functions and normal temperature cycle performance of the corresponding batteries are improved respectively. Example 9 adds 0.5% tris(trimethylsilyl)phosphite (TMSPi) and 2% ethylene carbonate (EC) at the same time, and its normal high temperature cycle and storage performance can be significantly improved, reflecting that tris(trimethylsilyl)phosphite (TMSPi) and ethylene carbonate (EC) have a good synergistic effect on improving electrochemical performance.
[0108] Compared with Comparative Example 1, Examples 1 to 6 all add the first compounded additive component and the second compounded additive component at the same time, the only difference being that the addition ratio of the corresponding second compounded additive component in Examples 1 to 3 is 0.5%, while the addition ratio of the corresponding second compounded additive component in Examples 4 to 6 is 1.0%.
[0109] It can be understood that for Examples 4 to 6 in which the addition ratio of the second composite additive component is 1.0%, although the electrochemical performance can be improved, the addition of 1.0% of the second composite additive component significantly increases the impedance of the battery, resulting in a significant increase in the DC resistance (DCR) of the battery. However, for Examples 1 to 3 in which the addition ratio of the second composite additive component is 0.5%, the DC resistance (DCR) of the battery increases better than that of Examples 4 to 6 and Comparative Example 1.
[0110] Based on Examples 1 to 9 and Comparative Examples 1 and 2, Example 2 has the best overall effect on improving battery performance with an additive comprising 0.5% tris(trimethylsilyl)phosphite (TMSPi) and 2% ethylene carbonate (EC) and 0.5% structure (b).
[0111] The conductivity of the electrolytes corresponding to Examples 1 to 6 and Comparative Examples 1 to 2 was tested, and the results were as follows: Figure 1 As shown. Since the organic solvent with flame retardant effect used in Examples 1 to 6 is highly fluorinated, the conductivity at room temperature is slightly lower than that of Comparative Example 2 using a general carbonate solvent. The amount of the second compounded additive component added in the electrolytes of Examples 1 to 3 is 0.5%, and the conductivity of the electrolytes of Examples 1 to 3 is close to that of the electrolyte of Comparative Example 1. It can be considered that adding 0.5% of the second compounded additive component to the electrolyte has almost no effect on the conductivity of the electrolyte. The amount of the second compounded additive component added in the electrolytes of Examples 4 to 6 is 1.0%, and the conductivity of the electrolytes of Examples 4 to 6 is significantly lower than that of the electrolyte of Comparative Example 1. This phenomenon is mainly related to the reasons that the additives are highly fluorinated, have large polarization and generally low conductivity.
[0112] The limiting oxygen index test was performed on the electrolytes of Examples 1 to 6 and Comparative Examples 1 and 2. The results are as follows: Figure 2As shown; when the limiting oxygen index (LOI) is greater than 27%, the electrolyte can be considered non-flammable; when the limiting oxygen index (LOI) is less than 21%, the electrolyte can be considered flammable. The limiting oxygen index test result of the electrolyte of Comparative Example 2 using a general carbonate solvent is 20%, which belongs to the flammable material. The limiting oxygen index of the electrolyte of Examples 1 to 6 and Comparative Example 1 using organic solvents with flame retardant effects is higher than 28, indicating that the electrolyte itself is non-flammable and has high safety.
[0113] It can be understood that in the electrolytes of Examples 1 to 6 and Comparative Example 1 using organic solvents with flame retardant properties, the organic solvents contain flame retardant elements (fluorine element F and phosphorus element P), which can decompose to produce free radicals containing fluorine element F and phosphorus element P, and then efficiently capture the key free radicals H radical and OH radical in the chain reaction in the combustion reaction, thereby interrupting the chain combustion reaction and achieving a flame retardant effect, so that the electrolyte has a flame retardant effect.
[0114] The electrolytes of Example 2, Comparative Example 1 and Comparative Example 2 were subjected to a hot box test. The results are as follows: Figures 3 to 6 shown.
[0115] Among them, the specific test method of the hot box test is: heat the fully charged battery from room temperature to 80°C at a heating rate of 5°C / min, and maintain this temperature for 30 minutes; then, continue to heat the battery to 150°C at a heating rate of 5°C / min and keep the temperature constant for 1 hour; finally, heat the battery to 180°C at a rate of 2°C / min and keep the temperature constant for 1 hour, and observe whether the battery has thermal runaway.
[0116] In the test, the batteries corresponding to Example 2, Comparative Example 1 and Comparative Example 2 respectively all experienced thermal runaway under the test procedure; however, Figure 3 and Figure 4 As shown, Example 2 and Comparative Example 1 using an organic solvent with flame retardant effect can effectively extend the occurrence time of thermal runaway by about 10 minutes, significantly improving the safety of the battery.
[0117] After the batteries corresponding to Example 2, Comparative Example 1 and Comparative Example 2 were divided into different capacities, EIS tests were performed on them. Figure 5 From the test results shown, it can be seen that the impedance of the battery corresponding to Example 2 is the lowest, and the electrolyte provided in the embodiments of the present application has better electrochemical performance.
[0118] Further integration Figure 6 As shown, after the battery capacity is divided in Example 2, Comparative Example 1 and Comparative Example 2, the fully charged cells are fully charged and disassembled to obtain Figure 6 The test results shown in Figure 6 (a) corresponds to the proportion 2, Figure 6(b) Corresponding proportion 1, Figure 6 (c) corresponds to Example 2. Compared with the batteries corresponding to Comparative Examples 1 and 2, no obvious gas spots, black spots or lithium precipitation were found on the interface of the battery corresponding to Example 2, indicating that the lithium ion transport performance and kinetics of Example 2 are good.
[0119] It is understandable that the electrolyte provided in the embodiment of the present application includes the organic solvent with flame retardant effect to replace the carbonate solvent in the general electrolyte, which can make the electrolyte body have non-flammable properties. Moreover, since the organic solvent has high chemical stability and almost no side reactions occur, it can improve the thermal runaway temperature of the battery using the electrolyte, improve the thermal runaway process, and improve the safety of the battery. At the same time, the electrolyte provided in the embodiment of the present application includes the additive, which can improve the electrochemical properties of the battery such as cycle performance and rate performance.
[0120] Further integration Figure 7 As shown, the embodiment of the present application further provides a battery 1, which includes a first main body 11 and an electrolyte 10 as described in any one of the aforementioned embodiments.
[0121] It is understandable that the battery 1 can be a simple battery or a cell in a complex battery, and the first main body 11 can include a shell, positive and negative electrodes, a core, etc., which are not described here. The electrolyte 10 is filled in the first main body 11 .
[0122] Further integration Figure 8 As shown, the embodiment of the present application further provides a vehicle 2 , which includes a second main body 21 and a battery 1 (including an electrolyte 10 ) as described in the above embodiment, and the battery 1 is electrically connected to the second main body 21 .
[0123] It is understandable that the second main body 21 of the vehicle 2 may include a frame, an engine and / or a motor, a wiring harness, a sensor system and other structures, which are not described here. The battery 1 is electrically connected to the second main body 21 to provide kinetic energy for the vehicle 2.
[0124] Furthermore, the battery 1 and the vehicle 2 provided in the embodiment of the present application, and the corresponding electrolyte 10 have better flame retardant effect and better electrochemical performance, so that the battery 1 and the vehicle 2 have better product performance.
[0125] In the above, the specific embodiments of the present application are described with reference to the accompanying drawings. However, those skilled in the art will appreciate that various changes and substitutions may be made to the specific embodiments of the present application without departing from the scope of the present application. These changes and substitutions are all within the scope defined by the present application.
Claims
1. An electrolyte, characterized in that: include: Lithium salts for providing lithium ions; An organic solvent, comprising an organic substance containing phosphorus or fluorine, wherein the organic solvent has a flame retardant effect; The additive comprises a first compound additive component and / or a second compound additive component, wherein the first compound additive component is used to form an interface film containing organic components on the electrode surface, and the second compound additive component is used to form an interface film containing inorganic components on the electrode surface.
2. The electrolyte according to claim 1, characterized in that The organic solvent includes one or more of trimethyl phosphate, triethyl phosphate, dimethyl methyl phosphate, ethyl trifluoroacetate, methyl trifluoroacetate, ethyl 2,2-trifluorobutyrate, bis(2,2,2)trifluoromethyl carbonate, bis(2,2,2)trifluoroethyl phosphite, perfluoromethyl nonafluorobutyl ether, 1,1,2,2(tetrafluoromethyl)-2,2,3,3(tetrafluoropropyl) ether, ethoxypentafluorocyclotriphosphazene, hexafluorocyclotriphosphazene, hexachlorocyclotriphosphazene, hexa(2,2,3,3,3-pentafluoropropoxy)cyclotriphosphazene, tris(2,2,2)trifluoroethyl phosphate, and tris(2,2,2-trifluoroethyl)borate.
3. The electrolyte according to claim 2, characterized in that In terms of weight percentage, the organic solvent accounts for 82% to 85% of the electrolyte.
4. The electrolyte according to claim 1, characterized in that The first composite additive component includes one or more of ethylene carbonate, tris(pentafluorophenyl)borane, hexafluorobutane anhydride, carbitol acrylate, trifluoropropylene carbonate, tetraethoxysilane, 2-methyl-2-methoxysilane, 1,3-propane sultone, lithium difluorobis(oxalato)borate, ethylene sulfite (ES), diethyl sulfite, ethylene sulfate, methylene disulfonate, succinic anhydride, 4-methylethylene sulfate, propylene ethyl carbonate, tris(trimethylsilyl)phosphite, tris(trimethylsilyl borate), lithium bis(trifluoromethylsulfonyl imide, lithium bis(fluorosulfonyl imide), succinonitrile, 2,4-fluorobenzonitrile, and triisopropylethylsulfonyl(pentafluorophenyl)phosphine.
5. The electrolyte according to claim 4, characterized in that Calculated by weight percentage, the first compounded additive component accounts for 0.1% to 5% of the electrolyte.
6. The electrolyte according to claim 1, characterized in that The general structural formula of the second composite additive component is as follows: Wherein, R is one or more of alkoxy, cycloalkane, benzene and the like.
7. The electrolyte according to claim 6, characterized in that The second composite additive component is one of the following three structural formulas:
8. The electrolyte according to claim 6, characterized in that Calculated by weight percentage, the ratio of the second composite additive component to the electrolyte is 0.5% to 1%.
9. A battery, characterized in that: Comprising the electrolyte according to any one of claims 1 to 8.
10. A vehicle, characterized in that: The device comprises a second main body portion, and the battery as claimed in claim 9, wherein the battery is electrically connected to the second main body portion.