Electrolyte, battery and preparation method therefor, and electric device

Abstract

Provided are an electrolyte, a battery and a preparation method therefor, and an electric device. The electrolyte comprises a magnetic additive, and the magnetic additive comprises magnetic nanoparticles.

Description

Electrolyte, battery, preparation method thereof and electric equipment

[0001] The present application claims priority to the Chinese patent application No. 202411068997.4, filed on August 6, 2024, and entitled "Electrolyte, battery, preparation method thereof and electric equipment", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of batteries, in particular to an electrolyte, a battery, a preparation method thereof and an electric equipment. BACKGROUND

[0003] In an electrochemical system such as a lithium ion battery, the movement of active ions (such as lithium ions) in the electrolyte is crucial for ion transport and reaction rate, which affects the impedance and cycle life of the battery and other performances. At present, due to the diffusion rate of active ions in the electrolyte and other factors, the battery generally has problems such as large internal resistance and short cycle life. For example, in a lithium ion battery, lithium ions in the electrolyte form solvated lithium with solvent molecules, and the solvated lithium diffuses in the liquid phase under the driving of potential difference and concentration difference. With the rapid development of electric vehicles, portable electronic devices and energy storage systems, the performance requirements of the battery, such as power density and charging rate, are becoming higher and higher. Due to the limitation of the diffusion rate of lithium ions in the electrolyte and other factors, the lithium ion battery has inherent defects such as large internal resistance. SUMMARY

[0004] The present application provides an electrolyte, a battery, a preparation method thereof and an electric equipment, which can reduce the internal resistance of the battery, improve the cycle life and other performances of the battery, and effectively overcome the defects in the prior art.

[0005] In one aspect of the present application, an electrolyte is provided, which comprises a magnetic additive, wherein the magnetic additive comprises magnetic nanoparticles.

[0006] According to an embodiment of the present application, the magnetic additive further comprises a functional modification layer existing on the surface of the magnetic nanoparticles, and the functional modification layer comprises an organic matrix material containing oxygen element and / or nitrogen element.

[0007] According to an embodiment of the present application, the organic matrix material contains one or more of carboxyl, ether group, carbonyl group, amino group and pyridyl group.

[0008] According to an embodiment of the present application, the thickness of the functional modification layer is 2nm-10nm.

[0009] According to an embodiment of the present application, the magnetic nanoparticles comprise one or more of magnetic metal oxide nanoparticles, metal nanoparticles and alloy nanoparticles.

[0010] According to an embodiment of the present application, the magnetic metal oxide nanoparticles comprise ferriferrous oxide nanoparticles, the metal nanoparticles comprise one or more of cobalt nanoparticles, nickel nanoparticles and iron nanoparticles, and the alloy nanoparticles comprise iron-cobalt alloy nanoparticles and / or iron-nickel alloy nanoparticles.

[0011] According to an embodiment of the present application, the mass percentage of the magnetic additive in the electrolyte is 0.01% to 3%.

[0012] According to an embodiment of the present application, the electrolyte further comprises a first solvent, and the first solvent comprises an organic solvent, and the organic solvent comprises one or more of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate and methyl ethyl carbonate.

[0013] According to an embodiment of the present application, the electrolyte further comprises a lithium salt, and the lithium salt comprises one or more of lithium hexafluorophosphate, lithium tetrafluoroborate and lithium bisfluorosulfonylimide.

[0014] According to another aspect of the present application, a preparation method of the electrolyte is provided, and the method comprises the following steps: mixing the magnetic additive, the first solvent and the electrolyte salt to obtain the electrolyte.

[0015] According to an embodiment of the present application, the mixing of the magnetic additive, the first solvent and the electrolyte salt to obtain the electrolyte specifically comprises: mixing the magnetic additive, the first solvent and the electrolyte salt, and then stirring for 2h to 8h to obtain the electrolyte.

[0016] According to an embodiment of the present application, the preparation process of the magnetic additive comprises: performing a first silane modification treatment on the magnetic nanoparticles by using a first silane coupling agent containing oxygen and / or nitrogen elements, to form a functional modification layer on the surface of the magnetic nanoparticles, thereby obtaining the magnetic additive.

[0017] According to an embodiment of the present application, the first silane modification treatment is performed at a temperature of 25°C to 80°C for a time of 6h to 12h.

[0018] According to an embodiment of the present application, the first silane coupling agent comprises one or more of 3-aminopropyl triethoxysilane, 3-aminopropyl trimethylsilane, 3-aminopropyl triethylsilane and (3-trimethoxysilylpropyl)-4-pyridine.

[0019] According to an embodiment of the present application, the preparation process of the magnetic additive comprises: performing a second silane modification treatment on the magnetic nanoparticles by using a second silane coupling agent to obtain silane-modified magnetic nanoparticles; and reacting the silane-modified magnetic nanoparticles with a functional modification agent to form a functional modification layer on the surface of the magnetic nanoparticles to obtain the magnetic additive; wherein at least one of the second silane coupling agent and the functional modification agent comprises an organic compound containing oxygen and / or nitrogen elements.

[0020] According to an embodiment of the present application, the temperature of the second silane modification treatment is 25-80°C, and the time is 6-12 hours.

[0021] According to an embodiment of the present application, the reaction conditions of the reaction between the silane-modified magnetic nanoparticles and the functional modification agent are as follows: the reaction temperature is 25-80°C, and the reaction time is 3-12 hours.

[0022] According to an embodiment of the present application, the functional modification agent comprises one or more of succinic anhydride, oxirane, trimethylacetyl chloride, and pyridine.

[0023] According to an embodiment of the present application, the second silane coupling agent comprises one or more of 3-aminopropyltriethoxysilane, (3-chloropropyl)trimethoxysilane, (3-iodopropyl)trimethoxysilane, trichlorosilane, 3-aminopropyltrimethylsilane, and 3-aminopropyltriethylsilane.

[0024] According to another aspect of the present application, a battery is provided, comprising a positive electrode sheet, a separator, a negative electrode sheet, and the above-mentioned electrolyte or an electrolyte prepared according to the preparation method of the above-mentioned electrolyte.

[0025] According to an embodiment of the present application, the battery is a lithium ion battery.

[0026] According to another aspect of the present application, a preparation method of a battery is provided, comprising the following steps: placing an electrode core in a shell, adding an electrolyte to the shell to obtain a battery precursor; and placing the battery precursor in a magnetic field for magnetic field induction treatment to obtain the battery; wherein the electrode core comprises a positive electrode sheet, a separator, and a negative electrode sheet, and the electrolyte comprises the above-mentioned electrolyte or an electrolyte prepared according to the preparation method of the above-mentioned electrolyte.

[0027] According to an embodiment of the present application, the magnetic field strength of the magnetic field is 0.1-0.5 T.

[0028] According to an embodiment of the present application, the magnetic field direction of the magnetic field is parallel to the thickness direction of the electrode core.

[0029] According to an embodiment of the present application, the preparation method of the battery further comprises a process of aging, formation and aging treatment of the battery precursor, and the process of aging, formation and aging treatment is performed during the process of subjecting the battery precursor to the magnetic field induction treatment.

[0030] According to an embodiment of the present application, the magnetic field induction treatment is performed for 56-66 hours.

[0031] According to another aspect of the present application, a power consuming device is provided, which comprises the battery or the battery prepared according to the preparation method of the battery.

[0032] According to an embodiment of the present application, the power consuming device further comprises a second magnetic field device for applying a magnetic field to the battery.

[0033] The electrolyte, the battery and the preparation method and the power consuming device provided by the present application can improve the diffusion rate of active ions (such as lithium ions in lithium ion batteries) in the electrolyte and the wettability of the electrolyte to the battery cell, thereby reducing the internal resistance of the battery and improving the performance of the battery such as fast charging and low temperature charging and discharging, and improving the cycle life of the battery and other performances. BRIEF DESCRIPTION OF DRAWINGS

[0034] FIG. 1 is a structural schematic diagram of the magnetic additive according to an embodiment of the present application.

[0035] Legend: 1: magnetic nanoparticle; 2: functional modification layer. DETAILED DESCRIPTION

[0036] In order for those skilled in the art to better understand the scheme of the present application, the present application will be further described in detail below. The following specific embodiments are only used to describe the principles and characteristics of the present application, and the examples are used to explain the present application, but not to limit the scope of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0037] An electrolyte is provided according to an embodiment of the present application, as shown in FIG. 1, which comprises a magnetic additive, and the magnetic additive comprises a magnetic nanoparticle 1.

[0038] The electrolyte of the embodiment of the present application is a magnetic nanofluid electrolyte. The magnetic additive in the electrolyte can interact with active ions in the electrolyte, indirectly endowing the active ions with magnetic properties, improving the diffusion rate of lithium ions in the electrolyte and the wettability of the electrolyte to the battery cell. Meanwhile, the diffusion of the active ions can be precisely controlled by an external magnetic field. Compared with the driving mode generated by the electrochemical reaction based on the potential difference between the positive and negative electrodes (the driving mode includes electric field driving and concentration gradient driving), the driving mode is more controllable and flexible, and can improve the transmission rate of the active ions in the electrolyte, reduce the internal resistance of the battery, and improve the cycle life and other performances of the battery.

[0039] According to further research by the inventor, as shown in FIG. 1, the above-mentioned magnetic additive can further include a functional modification layer 2 existing on the surface of the magnetic nanoparticle 1. The functional modification layer 2 includes an organic matrix material containing oxygen elements (O) and / or nitrogen elements (N), which is beneficial to further reduce the battery impedance, improve the fast charging and low-temperature charging and discharging performances of the battery, and improve the cycle life and other performances of the battery. The analysis reason is that the surface of the magnetic nanoparticle 1 in the magnetic additive has an organic matrix material containing oxygen elements and / or nitrogen elements, which can not only improve the dispersibility of the magnetic additive in the electrolyte, but also coordinate with active ions (such as lithium ions in lithium ion batteries) in the electrolyte to form solventated structures (i.e. solventated ions such as solventated lithium ions) with magnetic properties, thereby playing the role of carrier and conducting ions in the battery, improving the diffusion rate of lithium ions in the electrolyte and the wettability of the electrolyte to the battery cell. Meanwhile, the flow of the electrolyte can be regulated by an external magnetic field driving force, the wettability and ion transmission rate of the electrolyte can be enhanced, the internal resistance of the battery can be reduced, the charging rate of the battery can be improved, and the cycle life and other performances of the battery can be improved.

[0040] Through further research, the above-mentioned organic matrix material can contain one or more of carboxyl, ether, carbonyl, amino, and pyridyl groups, so that the organic matrix material contains oxygen elements and / or nitrogen elements. By using an organic matrix material having at least one of these groups to form the functional modification layer 2, it is beneficial to improve the cycle life of the battery while reducing the internal resistance of the battery. The analysis reason is that when the functional modification layer 2 includes an organic matrix material containing at least one of these groups, it is beneficial to improve the dispersibility of the magnetic additive in the electrolyte, and it is easy for the magnetic additive to coordinate with active ions such as lithium ions, to improve the ion transmission rate of the electrolyte and the wettability to the battery cell, to reduce the internal resistance of the battery, and to improve the cycle life and other performances of the battery.

[0041] Specifically, the functional modification layer 2 can include one or more of a first silane coupling agent grafted on the surface of the magnetic nanoparticle 1, and a reaction product of a second silane coupling agent and a functional modification agent.

[0042] When the functional modification layer 2 comprises the first silane coupling agent grafted on the surface of the magnetic nanoparticle 1, the first silane coupling agent contains oxygen element and / or nitrogen element, and specifically can contain one or more of carboxyl, ether group, carbonyl, amino, pyridyl, so that the organic matrix material of the formed functional modification layer 2 contains oxygen element and / or nitrogen element, and specifically can contain one or more of carboxyl, ether group, carbonyl, amino, pyridyl.

[0043] Illustratively, the organic matrix material of the functional modification layer 2 contains amino, and the first silane coupling agent used comprises a silane compound containing amino, and specifically can comprise one or more of 3-aminopropyl triethoxysilane (APTES), 3-aminopropyl trimethylsilane, 3-aminopropyl triethylsilane.

[0044] Illustratively, the organic matrix material of the functional modification layer 2 contains pyridyl, and the first silane coupling agent used comprises a silane compound containing pyridyl group, and specifically can comprise (3-trimethoxysilylpropyl)-4-pyridine.

[0045] In some embodiments, the first silane coupling agent can comprise one or more of 3-aminopropyl triethoxysilane, 3-aminopropyl trimethylsilane, 3-aminopropyl triethylsilane, (3-trimethoxysilylpropyl)-4-pyridine.

[0046] In some embodiments, the magnetic additive can be prepared by a process comprising the following steps: performing a first silane modification treatment on the magnetic nanoparticle 1 with the first silane coupling agent to form the functional modification layer 2 on the surface of the magnetic nanoparticle 1 (i.e., reacting the magnetic nanoparticle 1 with the first silane coupling agent to graft the first silane coupling agent on the surface thereof to form the functional modification layer 2), to obtain the magnetic additive. The temperature of the first silane modification treatment can be 25-80°C, and the time can be 6-12h.

[0047] When the functional modification layer 2 comprises the reaction product of the second silane coupling agent grafted on the surface of the magnetic nanoparticle 1 and the functional modification agent, at least one of the second silane coupling agent and the functional modification agent contains oxygen element and / or nitrogen element, and specifically at least one of the second silane coupling agent and the functional modification agent comprises an organic compound containing oxygen element and / or nitrogen element, so that the reaction product of the second silane coupling agent grafted on the surface of the magnetic nanoparticle 1 and the functional modification agent contains oxygen element and / or nitrogen element, and specifically can contain one or more of carboxyl, ether group, carbonyl, amino, pyridyl, and further so that the organic matrix material of the formed functional modification layer 2 contains oxygen element and / or nitrogen element, and specifically can contain one or more of carboxyl, ether group, carbonyl, amino, pyridyl.

[0048] For example, the second silane coupling agent can contain oxygen and / or nitrogen elements, and the functional modifier does not contain oxygen and / or nitrogen elements, or the second silane coupling agent does not contain oxygen and / or nitrogen elements, and the functional modifier contains oxygen and / or nitrogen elements, or the second silane coupling agent contains oxygen and / or nitrogen elements, and the functional modifier also contains oxygen and / or nitrogen elements.

[0049] In some embodiments, the magnetic additive can be prepared by a process comprising the following steps: subjecting the magnetic nanoparticles 1 to a second silane modification treatment with a second silane coupling agent to obtain silane-modified magnetic nanoparticles; and reacting the silane-modified magnetic nanoparticles with a functional modifier to form a functional modification layer 2 on the surface of the magnetic nanoparticles 1 to obtain the magnetic additive. In this preparation process, the magnetic nanoparticles 1 are first reacted with the second silane coupling agent to graft the second silane coupling agent on the surface of the magnetic nanoparticles 1 to obtain the silane-modified magnetic nanoparticles; and then the silane-modified magnetic nanoparticles are reacted with the functional modifier. In this reaction process, the second silane coupling agent grafted on the surface of the magnetic nanoparticles 1 reacts with the functional modifier to form a reaction product of the second silane coupling agent and the functional modifier grafted on the surface of the magnetic nanoparticles 1, thereby forming the functional modification layer 2 on the surface of the magnetic nanoparticles 1 to obtain the magnetic additive.

[0050] The temperature of the second silane modification treatment can be 25-80°C, and the time can be 6-12 hours.

[0051] The reaction conditions of the silane-modified magnetic nanoparticles and the functional modifier can be a reaction temperature of 25-80°C and a reaction time of 3-12 hours.

[0052] Specifically, the functional modifier can include an organic compound, which can specifically include one or more of an acid anhydride compound, an epoxy compound, an acyl halide compound, and a pyridine compound. The acid anhydride compound can include succinic anhydride; the epoxy compound can include an alkylene oxide compound, which can specifically include ethylene oxide; the halogen in the acyl halide compound can include one or more of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), and the acyl halide compound can include trimethylacetyl halide, which can specifically include trimethylacetyl chloride; and the pyridine compound can include pyridine.

[0053] In some embodiments, the functional modifier can include one or more of succinic anhydride, ethylene oxide, trimethylacetyl chloride, and pyridine, which is beneficial to reduce the internal resistance of the battery and improve the cycle life and other performances of the battery.

[0054] Further, the second silane coupling agent can include a silane compound containing an amino group and / or a silane compound containing a halogen, and the halogen in the silane compound containing a halogen can include one or more of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0055] Specifically, the silane compound containing an amino group can include one or more of 3-aminopropyltriethoxysilane (APTES), 3-aminopropyltrimethylsilane, and 3-aminopropyltriethylsilane.

[0056] Specifically, the silane compound containing a halogen can include one or more of (3-chloropropyl)trimethoxysilane, (3-iodopropyl)trimethoxysilane (IPTMS), and trichlorosilane.

[0057] In some embodiments, the second silane coupling agent can include one or more of 3-aminopropyltriethoxysilane (APTES), (3-chloropropyl)trimethoxysilane, (3-iodopropyl)trimethoxysilane (IPTMS), trichlorosilane, 3-aminopropyltrimethylsilane, and 3-aminopropyltriethylsilane.

[0058] Exemplarily, the functional modification agent includes an acid anhydride compound, and the acid anhydride compound (such as succinic anhydride) can react with the silane compound containing an amino group (such as APTES) to generate a reaction product containing a carboxyl group (-COOH), so as to introduce the carboxyl group into the formed functional modification layer 2.

[0059] Exemplarily, the functional modification agent includes an epoxy compound, and the epoxy compound (such as oxirane) can react with the silane compound containing a halogen (such as (3-chloropropyl)trimethoxysilane) to generate a reaction product containing an ether group, so as to introduce the ether group into the formed functional modification layer 2.

[0060] Exemplarily, the functional modification agent includes an acyl halide compound, and the acyl halide compound (such as trimethylacetyl chloride) can react with the silane compound containing an amino group (such as APTES) to generate a reaction product containing a carbonyl group, so as to introduce the carbonyl group into the formed functional modification layer 2. Taking trimethylacetyl chloride and APTES as an example, in the preparation process of the magnetic additive, APTES is first reacted with the magnetic nanoparticles 1 (i.e., the second silane modification treatment), APTES is grafted on the surface of the magnetic nanoparticles 1, and the amino group is introduced into the magnetic nanoparticles 1, and then the trimethylacetyl chloride is reacted, the carbonyl carbon atom in the trimethylacetyl chloride reacts with the nitrogen atom in the amino group to generate a reaction product containing a carbonyl group.

[0061] Exemplarily, the functional modification agent includes a pyridine compound, the pyridine compound (such as pyridine) can react with a halogen-containing silane compound (such as (3-chloropropyl)trimethoxysilane) to generate a reaction product containing a pyridyl group, so as to introduce the pyridyl group in the formed functional modification layer 2.

[0062] In addition, in the above-mentioned magnetic additive, the thickness of the functional modification layer 2 can be 2 nm to 10 nm, for example, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm or a range consisting of any two of them. Within this range, it is beneficial to reduce the internal resistance of the battery and improve the cycle life and other performances of the battery. At the same time, in combination with considering the active sites and other factors that the surface of the magnetic nanoparticle 1 can be attached with an organic matrix material, by controlling the thickness of the functional modification layer 2 within the above-mentioned range (2 nm to 10 nm), it is also beneficial to the preparation of the magnetic additive.

[0063] Specifically, the magnetic nanoparticle 1 can include one or more of a magnetic metal oxide nanoparticle, a metal nanoparticle, and an alloy nanoparticle, which is beneficial to reduce the internal resistance of the battery and improve the cycle life and other performances of the battery.

[0064] In some embodiments, the magnetic metal oxide nanoparticle can include a magnetite (Fe3O4) nanoparticle.

[0065] In some embodiments, the metal nanoparticle can include one or more of a cobalt nanoparticle, a nickel nanoparticle, and an iron nanoparticle.

[0066] In some embodiments, the alloy nanoparticle can include a cobalt-iron alloy nanoparticle (iron-cobalt alloy nanoparticle) and / or a nickel-iron alloy nanoparticle (iron-nickel alloy nanoparticle).

[0067] According to the further research of the inventors, the mass percentage content of the magnetic additive in the electrolyte (i.e., the proportion of the mass of the magnetic additive to the total mass of the electrolyte) can be 0.01% to 3%, for example, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3% or a range consisting of any two of them. In this way, more magnetic additives can be contained in the electrolyte, the internal resistance of the battery can be reduced and the cycle life and other performances of the battery can be improved, and at the same time, it is beneficial for the electrolyte to have suitable viscosity and other properties, improve the wettability of the electrolyte to the battery cell, and further reduce the internal resistance of the battery and improve the cycle life and other performances of the battery.

[0068] Generally, the electrolyte further includes a first solvent and an electrolyte salt, and the concentration of the electrolyte salt in the electrolyte can be 0.5 mol / L to 3 mol / L, for example, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, or a range formed by any two of them.

[0069] In the embodiments of the present application, the electrolyte can be a non-aqueous electrolyte, and the first solvent includes an organic solvent, which can include one or more of ethylene carbonate (EC), propylene carbonate, diethyl carbonate, dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). By using the organic solvent, it is beneficial to adapt to the above-mentioned magnetic additive, improve the wettability and ion diffusion rate of the electrolyte, reduce the internal resistance of the battery, and improve the cycle life and other performances of the battery.

[0070] Specifically, the above-mentioned electrolyte salt can include a lithium salt, which can include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate, and lithium bisfluorosulfonylimide. The aforementioned lithium salt is beneficial to adapt to the above-mentioned magnetic additive, improve the wettability and ion diffusion rate of the electrolyte, reduce the internal resistance of the battery, and improve the cycle life and other performances of the battery.

[0071] The embodiments of the present application also provide a preparation method of the above-mentioned electrolyte, including the following steps: mixing the magnetic additive, the first solvent, and the electrolyte salt to obtain the electrolyte.

[0072] In some embodiments, the magnetic additive, the first solvent, and the electrolyte salt are mixed to obtain the electrolyte, specifically including: after mixing the magnetic additive, the first solvent, and the electrolyte salt, stirring for 2 h to 8 h, for example, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, or a range formed by any two of them, to obtain the electrolyte. Wherein, the stirring time in the range of 2 h to 8 h can improve the dispersibility of the magnetic additive in the electrolyte, further reduce the internal resistance of the battery, improve the cycle life and other performances of the battery, and at the same time avoid the influence of the preparation efficiency of the electrolyte due to too long stirring time.

[0073] In addition, the preparation method of the above-mentioned electrolyte further includes a preparation process of the magnetic additive.

[0074] As mentioned above, in some embodiments, the preparation process of the magnetic additive can include: using a first silane coupling agent containing oxygen element and / or nitrogen element to perform a first silane modification treatment on the magnetic nanoparticles 1 to form a functional modification layer 2 on the surface of the magnetic nanoparticles 1, thereby obtaining the magnetic additive.

[0075] The temperature of the first silane modification treatment can be 25-80°C, such as 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, or a range defined by any two of them, which is conducive to forming the functional modification layer 2, improving the performance of the magnetic additive and the preparation efficiency, and reducing energy consumption.

[0076] In addition, the first silane modification treatment can be performed for 6-12 hours, such as 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, or a range defined by any two of them, which is conducive to forming the functional modification layer 2, improving the performance of the magnetic additive and the preparation efficiency.

[0077] In addition, the first silane modification treatment can be performed in a second solvent, which can include an organic solvent and water, i.e., the second solvent can be a mixed solvent containing an organic solvent and water. In such a mixed solvent system, the first silane coupling agent is hydrolyzed, thereby being grafted onto the surface of the magnetic nanoparticle 1 to form the functional modification layer 2 and produce the magnetic additive.

[0078] Specifically, the organic solvent used in the second solvent can include an alcohol solvent, i.e., the second solvent can include an alcohol solvent and water, and the alcohol solvent can specifically include ethanol.

[0079] In some embodiments, the second solvent includes ethanol and water, i.e., a mixed solvent containing ethanol and water is used as the second solvent, which is conducive to improving the preparation efficiency and performance of the magnetic additive.

[0080] Specifically, in the second solvent, the volume ratio of water to organic solvent can be 1:(0.5-2), such as 1:0.5, 1:0.8, 1:1, 1:1.3, 1:1.5, 1:1.8, 1:2, or a range defined by any two of them.

[0081] Specifically, the first silane modification treatment can be performed in an inert atmosphere, such as a nitrogen atmosphere and / or an argon atmosphere, etc., which is not particularly limited.

[0082] In specific implementation, the magnetic nanoparticle 1 can be dispersed in the second solvent under an inert atmosphere to obtain a dispersion system, and then the first silane coupling agent is added to the dispersion system for reaction (i.e., the first silane modification treatment), after the reaction is completed, the unreacted first silane coupling agent (silanization agent) is removed by centrifugation and washing, etc., to obtain the magnetic additive.

[0083] In some embodiments, the preparation process of the magnetic additive can include: performing a second silane modification treatment on the magnetic nanoparticles 1 by using a second silane coupling agent to obtain silane-modified magnetic nanoparticles; and reacting the silane-modified magnetic nanoparticles with a functional modification agent to form the functional modification layer 2 on the surface of the magnetic nanoparticles 1; wherein at least one of the second silane coupling agent and the functional modification agent comprises an organic compound containing oxygen and / or nitrogen elements.

[0084] In the preparation process of the magnetic additive, the second silane modification treatment is performed to couple the magnetic nanoparticles with the second silane coupling agent, i.e., to graft the second silane coupling agent on the surface of the magnetic nanoparticles 1 (i.e., the silane-modified magnetic nanoparticles are mainly formed by the magnetic nanoparticles 1 and the second silane coupling agent grafted on the magnetic nanoparticles 1), and then, in the process of reacting the silane-modified magnetic nanoparticles with the functional modification agent, the functional modification agent and the second silane coupling agent in the silane-modified magnetic nanoparticles are coupled, so that the functional modification agent wraps the magnetic nanoparticles 1 through the second silane coupling agent, thereby forming the functional modification layer 2 on the surface of the magnetic nanoparticles 1 to obtain the magnetic additive.

[0085] In addition, the second silane modification treatment can be performed in a third solvent, and the third solvent includes an organic solvent and water, i.e., the third solvent can be a mixed solvent containing an organic solvent and water. In such a mixed solvent system, the second silane coupling agent is hydrolyzed, thereby being grafted on the surface of the magnetic nanoparticles 1, and then, in the subsequent functional modification process (i.e., the process of reacting the silane-modified magnetic nanoparticles with the functional modification agent), the functional modification layer 2 is formed on the surface of the magnetic nanoparticles 1 to obtain the magnetic additive.

[0086] Specifically, the organic solvent used in the third solvent can include an alcohol solvent, i.e., the third solvent can include an alcohol solvent and water, and the alcohol solvent can specifically include ethanol.

[0087] In some embodiments, the third solvent includes ethanol and water, i.e., a mixed solvent containing ethanol and water is used as the third solvent, which is conducive to improving the preparation efficiency and performance of the magnetic additive.

[0088] Specifically, the volume ratio of water to the organic solvent in the third solvent can be 1:(0.5-2), such as 1:0.5, 1:0.8, 1:1, 1:1.3, 1:1.5, 1:1.8, 1:2, or a range formed by any two of them.

[0089] Specifically, the silane modification treatment can be performed in an inert atmosphere, such as a nitrogen atmosphere and / or an argon atmosphere, etc., which is not particularly limited.

[0090] Specifically, the temperature of the second silane modification treatment can be 25℃-80℃, such as 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, or a range consisting of any two of them, which is conducive to the formation of the functional modification layer 2, improves the performance and preparation efficiency of the magnetic additive, and reduces energy consumption.

[0091] In addition, the time of the second silane modification treatment can be 6h-12h, such as 6h, 7h, 8h, 9h, 10h, 11h, 12h, or a range consisting of any two of them, which is conducive to the formation of the functional modification layer 2, improves the performance and preparation efficiency of the magnetic additive.

[0092] In addition, the process of the reaction between the above-mentioned silane-modified magnetic nanoparticles and the functional modification agent can be carried out in a fourth solvent, and the fourth solvent includes an organic solvent, which can include one or more of toluene, ethanol, dichloromethane, and tetrahydrofuran (THF), wherein the ethanol used can be anhydrous ethanol.

[0093] Specifically, the process of the reaction between the silane-modified magnetic nanoparticles and the functional modification agent can be carried out in an inert atmosphere, such as a nitrogen atmosphere and / or an argon atmosphere, etc., without particular limitation.

[0094] Specifically, the reaction temperature of the reaction between the silane-modified magnetic nanoparticles and the functional modification agent can be 25℃-80℃, such as 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, or a range consisting of any two of them, which is conducive to the formation of the functional modification layer 2, improves the performance and preparation efficiency of the magnetic additive, and reduces energy consumption.

[0095] In addition, the time of the reaction between the silane-modified magnetic nanoparticles and the functional modification agent is 3h-12h, such as 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, or a range consisting of any two of them, which is conducive to the formation of the functional modification layer, improves the performance and preparation efficiency of the magnetic additive.

[0096] In specific implementation, the magnetic nanoparticles 1 can be dispersed in a third solvent under an inert atmosphere, and then a second silane coupling agent is added thereto for reaction (i.e., a second silane modification treatment), after the reaction is completed, the unreacted second silane coupling agent (silanization agent) is removed by centrifugation and washing, etc., to obtain silane-modified magnetic nanoparticles; then, the silane-modified magnetic nanoparticles (i.e., the magnetic nanoparticles after surface treatment) and the functional modification agent can be dispersed in a fourth solvent and placed in an inert atmosphere for reaction, to obtain a magnetic additive (i.e., the magnetic nanoparticles 1 with a functional modification layer 2 on the surface).

[0097] In the preparation of the above magnetic additive, the first silane coupling agent, the second silane coupling agent, the functional modifier and other materials used in the preparation process are described above and will not be described again.

[0098] In the embodiments of the present application, the magnetic nanoparticles can be obtained by conventional methods in the art, for example, can be commercially available or self-made according to conventional methods in the art. For example, Fe3O4 nanoparticles can be prepared by reacting a ferric salt and a ferrous salt. The reaction of the ferric salt and the ferrous salt can generally be carried out under alkaline conditions, and the alkaline conditions can be provided by an alkaline compound such as ammonia. The ferric salt includes a water-soluble ferric salt, and specifically can include ferric chloride (FeCl3). The ferrous salt includes a water-soluble ferrous salt, and specifically can include ferrous chloride (FeCl2). In specific implementations, a hydrate of ferric chloride (e.g., FeCl3·6H2O) and a hydrate of ferrous chloride (e.g., FeCl2·4H2O) can be used to prepare Fe3O4 nanoparticles.

[0099] In some embodiments, the preparation process of the Fe3O4 nanoparticles can include: dissolving the ferric salt and the ferrous salt in water under an inert atmosphere, adding an aqueous ammonia solution to provide alkaline conditions, and carrying out the reaction under the alkaline conditions to obtain the Fe3O4 nanoparticles. After the reaction is completed, the Fe3O4 nanoparticles can be purified by magnetic separation, washing, drying and the like.

[0100] In specific implementations, FeCl3·6H2O and FeCl2·4H2O can be dissolved in 100 mL of water in a molar ratio of 2:1 under an inert atmosphere, an aqueous ammonia solution can be slowly added until the pH value of the solution is about 10, and the reaction can be carried out for 3 hours. After the reaction, the Fe3O4 nanoparticles can be obtained by magnetic separation, washing and drying.

[0101] The embodiments of the present application also provide a battery including the above electrolyte or the electrolyte prepared according to the preparation method of the above electrolyte. The battery has the advantages corresponding to the above electrolyte, and will not be described again.

[0102] The battery of the embodiments of the present application can be a lithium ion battery (such as a lithium ion power battery), a solar cell, or other new energy storage batteries.

[0103] For the battery driven by the diffusion of active ions generated by the electrochemical reaction based on the potential difference between the positive and negative electrodes, the driving mode of the diffusion of active ions mainly includes electric field driving and concentration gradient driving. Specifically, there is a potential difference between the positive and negative electrodes, and the positive and negative electrode materials undergo electrochemical reaction, the generated electric field drives the diffusion of active ions such as lithium ions, at the same time, the electrode surface reaction is fast, so that the active ion concentration of the region close to the electrode surface is relatively low, and the active ion concentration of the region far away from the electrode surface is relatively high, thereby making the active ions move (diffuse) in the direction close to the electrode. In the embodiments of the present application, by introducing the electrolyte containing the above-mentioned magnetic additive into such a battery (such as a lithium ion battery), the lithium ions and other active ions are indirectly endowed with the characteristics of magnetism, which can improve the diffusion rate of active ions in the electrolyte and the wettability of the electrolyte to the battery cell, and at the same time, through the external magnetic field (for example, applying a magnetic field during the preparation of the battery and / or applying a magnetic field during the use of the battery), the diffusion of lithium ions and other active ions can be accurately controlled. Compared with the driving mode generated by the electrochemical reaction based on the potential difference between the positive and negative electrodes (such as battery driving and concentration gradient driving), the external electric field driving is more controllable and flexible, which can improve the controllability and flexibility during the preparation and use of the battery, and can improve the transmission rate of active ions in the electrolyte, reduce the internal resistance of the battery, improve the fast charging performance of the battery, and improve the cycle life and other performances of the battery.

[0104] Generally, the battery includes a battery cell and a shell encapsulating the battery cell, and the electrolyte is injected into the battery cell in the shell. The battery cell includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet. The battery cell can be a laminated battery cell, that is, the battery cell is formed by interleaving and stacking the positive electrode sheet, the separator and the negative electrode sheet.

[0105] Specifically, the positive electrode sheet includes a positive electrode current collector and a positive electrode coating on at least one side surface of the positive electrode current collector. Specifically, the positive electrode coating can be arranged on one side surface of the positive electrode current collector, or the positive electrode coating can be arranged on both side surfaces of the positive electrode current collector in the thickness direction.

[0106] Specifically, the positive electrode coating (positive electrode active material layer) can include a positive electrode active material, a conductive agent, and a binder, each of which can be a conventional material in the art. For example, the positive electrode active material can include one or more of lithium iron phosphate, lithium cobaltate, lithium manganate, a positive electrode ternary material, which can include a nickel-cobalt-manganese ternary material and / or a nickel-cobalt-aluminum ternary material; the conductive agent can include one or more of conductive carbon black, carbon nanotubes (CNTs), acetylene black, graphene, ketjen black, carbon fibers; and the binder can include one or more of polyvinylidene fluoride (PVDF), polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, polyvinyl chloride, carboxylated polyvinyl chloride, an oxirane-containing polymer, polyvinylpyrrolidone, polyurethane, and the like.

[0107] Embodiments of the present application can employ a conventional positive electrode current collector in the art, for example, the positive electrode current collector includes a copper foil.

[0108] In embodiments of the present application, the positive electrode sheet can be prepared by a conventional method in the art, for example, by a coating method. Specifically, the positive electrode active material, the conductive agent, the binder, and the like, which are components for forming the positive electrode coating, can be dispersed in a fifth solvent, for example, including N-methyl pyrrolidone (NMP), to prepare a positive electrode slurry, which is then coated on the surface of the positive electrode current collector, and after processes such as drying and rolling, the positive electrode sheet is prepared. The coating, drying, rolling, and the like, involved in the processes are conventional operations for preparing a positive electrode sheet by a coating method, and are not particularly limited.

[0109] Specifically, the negative electrode sheet includes a negative electrode current collector, and a negative electrode coating on at least one side surface of the negative electrode current collector, and specifically, the negative electrode coating can be provided on one side surface of the negative electrode current collector, or the negative electrode coating can be provided on each of the opposite side surfaces in the thickness direction of the negative electrode current collector.

[0110] Specifically, the negative electrode coating (negative electrode active material layer) can include a negative electrode active material, a conductive agent, and a binder, each of which can be a conventional material in the art. For example, the negative electrode active material can include graphite; the conductive agent can include one or more of conductive carbon black, carbon nanotubes (CNTs), acetylene black, graphene, ketjen black, carbon fibers; and the binder can include one or more of sodium carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an oxirane-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate.

[0111] Embodiments of the present application can employ a conventional negative electrode current collector in the art, for example, the negative electrode current collector includes a copper foil.

[0112] In the embodiments of the present application, the negative electrode sheet can be prepared by conventional methods in the art, for example, by a coating method. Specifically, the negative electrode active material, the conductive agent, the binder and other components used to form the negative electrode coating can be dispersed in a sixth solvent, for example, water, to prepare a negative electrode slurry, which is then coated on the surface of the negative electrode current collector, and then subjected to drying, rolling and other processes to prepare the negative electrode sheet. The coating, drying, rolling and other processes are conventional operations for preparing the negative electrode sheet by the coating method, and are not particularly limited.

[0113] In the embodiments of the present application, the separator is used to separate the positive electrode sheet and the negative electrode sheet to prevent short circuit caused by contact between the positive electrode sheet and the negative electrode sheet. The separator used in the embodiments of the present application can be a conventional separator in the art, for example, a polypropylene film (PP film), but is not limited thereto.

[0114] In the embodiments of the present application, the battery cell can be packaged by using a conventional casing material in the art, for example, a soft packaging material such as an aluminum plastic film (in this case, the battery is a soft package battery), but is not limited thereto.

[0115] The embodiments of the present application can reduce the internal resistance of the battery and improve the cycle life and other performances of the battery. Specifically, the 50% SOC charge direct current resistance (DCIR) of the battery can be lower than (less than or equal to) 52.5%, further lower than 50%, and further lower than 45%. The capacity retention rate of the battery after 800 cycles at 0.5C under normal temperature (about 25°C) conditions can be higher than (greater than or equal to) 91%, further higher than 92%, further higher than 93%, and further higher than 94%. The test process of the 50% SOC charge direct current resistance of the battery and the test process of the capacity retention rate of the battery after 800 cycles at 0.5C are described in detail in the following specific embodiment section, and are not described herein again.

[0116] The embodiments of the present application also provide a preparation method of the above-mentioned battery, which comprises the following steps: placing a battery cell in a casing, adding an electrolyte to the casing to prepare a battery precursor; and placing the battery precursor in a magnetic field for magnetic field induction treatment to prepare a battery. The battery cell comprises a positive electrode sheet, a separator and a negative electrode sheet, and the electrolyte comprises the above-mentioned electrolyte or an electrolyte prepared according to the preparation method of the above-mentioned electrolyte.

[0117] Through the preparation process of the above-mentioned battery, the internal resistance of the prepared battery can be reduced, and the cycle life and other performances of the battery can be improved. The reason is that the electrolyte contains the above-mentioned magnetic additive, the magnetic additive can coordinate with active ions such as lithium ions to form solvated ions, and the solvated ions can be induced to move by the magnetic field during the magnetic field induction treatment of the battery precursor, so as to improve the ion diffusion rate and the wettability of the electrolyte to the battery cell, thereby reducing the internal resistance of the battery and improving the cycle life and other performances of the battery.

[0118] In some embodiments, the magnetic field direction of the magnetic field (magnetic potential line direction) can be substantially parallel to the thickness direction of the battery cell, i.e., the magnetic field direction is substantially parallel to the stacking direction of the positive electrode sheet, the separator and the negative electrode sheet, i.e., the magnetic field direction is substantially perpendicular to the surface of the positive electrode sheet provided with the positive electrode coating, the surface of the negative electrode sheet provided with the negative electrode coating, which is conducive to the diffusion of the solvent ions formed by the coordination of the magnetic additives and the active ions in the stacking direction of the positive electrode sheet, the separator and the negative electrode sheet, further improves the ion diffusion rate and the electrolyte infiltration capacity of the battery cell, reduces the battery internal resistance, and improves the cycle life and other performances of the battery.

[0119] In some embodiments, the magnetic field strength of the magnetic field can be 0.1T-0.5T, for example, 0.1T, 0.2T, 0.3T, 0.4T, 0.5T or a range formed by any two of them, which is conducive to reducing the battery internal resistance, improving the cycle life and other performances of the battery.

[0120] Specifically, the preparation method of the battery further includes the processes of aging, formation and aging treatment of the battery precursor, which can be performed in the process of placing the battery precursor in the magnetic field for magnetic field induction treatment. Specifically, the processes of aging, formation and aging treatment of the battery precursor can be performed in the magnetic field, at this time, the magnetic field induction treatment of the battery precursor is completed while the processes of aging, formation and aging treatment of the battery precursor are performed.

[0121] In the embodiments of the present application, the magnetic field can be provided by a conventional magnetic field application method, for example, a first magnetic field device with a magnetic field generator is used to perform the magnetic field induction treatment of the battery precursor, i.e., the battery precursor is placed in the first magnetic field device, and the magnetic field is generated by the magnetic field generator, thereby realizing the magnetic field induction treatment of the battery precursor.

[0122] In specific implementation, the positive electrode sheet, the separator and the negative electrode sheet can be assembled into a battery cell by conventional methods in the art, for example, the positive electrode sheet, the separator and the negative electrode sheet are stacked to obtain a stacked battery cell; then the battery cell is placed in a shell with a liquid injection port, electrolyte is injected into the shell through the liquid injection port, and then the liquid injection port is closed to obtain a battery precursor; then the battery precursor is placed in a first magnetic field device with a magnetic field, and the processes of aging (static placement), formation and aging treatment are sequentially performed in the first magnetic field device, and the magnetic field induction treatment of the battery precursor is completed in the first magnetic field device at the same time; after the above processes are completed, the battery precursor is taken out of the first magnetic field device, and then the battery is prepared after subsequent processes such as capacity distribution.

[0123] In some embodiments, the time of the magnetic field induction treatment (i.e., the time of placing the battery precursor in the magnetic field) can be 56-66h, for example, 56h, 58h, 60h, 62h, 64h, 66h or a range formed by any two of them.

[0124] In the embodiments of the present application, in addition to the magnetic field induction treatment of the battery precursor, the processes of liquid injection, sealing, aging, formation, aging treatment, and capacity distribution are all conventional battery assembly processes in the art, and are not particularly limited.

[0125] In some embodiments, the temperature of the aging can be 40-50℃, such as 40℃, 43℃, 45℃, 48℃, 50℃, or a range formed by any two of them.

[0126] In some embodiments, the time of the aging can be 20-30h, such as 20h, 23h, 25h, 28h, 30h, or a range formed by any two of them.

[0127] Generally, after the battery precursor is aged, the aged battery precursor is subjected to formation, and after the aged battery precursor is fully charged (i.e., charged to a full state of charge) during the formation, it is subjected to aging treatment.

[0128] In some embodiments, the temperature of the formation can be 20-50℃, such as 20℃, 23℃, 25℃, 28℃, 30℃, or a range formed by any two of them. In particular implementations, the formation can be performed at room temperature (normal temperature).

[0129] In some embodiments, the process of the formation can include: at a formation temperature (such as room temperature), the aged battery precursor is charged at a constant current of 0.05C rate for 3h, rested for 10min, and then charged at a constant current and constant voltage of 0.2C rate, with a cutoff voltage of 4V and a cutoff current of 0.01C (at this time, the battery precursor is fully charged).

[0130] In some embodiments, the temperature of the aging treatment can be 40-50℃, such as 40℃, 43℃, 45℃, 48℃, 50℃, or a range formed by any two of them.

[0131] In some embodiments, the time of the aging treatment can be 20-30h, such as 20h, 23h, 25h, 28h, 30h, or a range formed by any two of them.

[0132] The embodiments of the present application also provide a power consuming device comprising the above-mentioned battery or a battery prepared according to the preparation method of the above-mentioned battery. The power consuming device has advantages corresponding to the above-mentioned battery, which will not be described again.

[0133] The power consuming device of the embodiments of the present application can be a conventional power consuming device in the art, such as a power device, such as an electric vehicle, which is not particularly limited.

[0134] In some embodiments, the electric device can comprise a second magnetic field device for applying a magnetic field to the battery, by applying a magnetic field to the battery, the battery can perform a charging and discharging process in the magnetic field, the movement of the solvated ions in the electrolyte, which are coordinated by the magnetic additives and active ions such as lithium ions, can be induced by the magnetic field, the ion diffusion rate can be improved, the battery impedance can be reduced, and the performance of the battery cycle life can be improved, and the service life of the electric device can be improved.

[0135] In the embodiments of the present application, the second magnetic field device can be a device capable of applying a magnetic field, for example, the second magnetic field device has a cavity for accommodating the battery, and the battery is placed in the cavity; the second magnetic field device can be provided with a magnetic field generator for generating a magnetic field, and the magnetic field generator is used to generate a magnetic field to apply a magnetic field to the battery.

[0136] In the embodiments of the present application, unless otherwise specified, the magnetic field generator and other components are conventional components capable of achieving their functions in the field, and can be connected or assembled into corresponding devices by conventional methods, which are not particularly limited.

[0137] In the embodiments of the present application, the composition and other characteristics of the magnetic additives in the electrolyte can be detected by X-ray photoelectron spectroscopy (XPS) analysis, X-ray diffraction (XRD) analysis, infrared spectrum analysis and the like, for example, the composition of the functional modification layer 2 of the magnetic additives (such as detecting the organic matrix material and the functional groups contained therein) and other characteristics can be detected by infrared spectrum test and the like.

[0138] In the embodiments of the present application, the thickness of the functional modification layer 2 of the magnetic additives can be measured by transmission electron microscopy (TEM). It can be understood that the thickness of the functional modification layer 2 of the magnetic additives is the average thickness, and in specific implementation, the thickness of the functional modification layer 2 of at least 20 magnetic additive particles in the field of view can be tested (specifically, the thickness of the functional modification layer of 100 magnetic additive particles in the field of view can be tested), and the average value is taken as the final determination result.

[0139] In specific implementation, the battery can be disassembled, the electrolyte can be obtained, the magnetic additives can be taken out from the electrolyte (specifically, the electrolyte can be dried to obtain the particle product as the magnetic additives, or the magnetic additives in the electrolyte can be sucked out by magnetic attraction and the like), the magnetic additives can be washed with water and ethanol in turn, specifically, the magnetic additives can be washed with water for 3 times, then washed with ethanol for 3 times, and then dried, specifically, the drying can be performed at 60-80°C, and then the magnetic additives can be analyzed by the above-mentioned XPS, XRD, infrared spectrum, TEM and the like to determine the composition and the thickness of the functional modification layer and other characteristics of the magnetic additives.

[0140] The present application is further introduced through specific embodiments as follows.

[0141] Example 1

[0142] 1. Preparation of magnetic additive

[0143] FeCl3·6H2O and FeCl2·4H2O were dissolved in 100 mL of water in a molar ratio of 2:1 under an inert atmosphere, and an ammonia solution was slowly added thereto until the pH value of the resulting solution was about 10, and the reaction was carried out for 3 h, followed by magnetic separation, and then washing and drying to obtain Fe3O4 nanoparticles.

[0144] 0.5 g of the Fe3O4 nanoparticles prepared above were dispersed in 100 mL of a mixed solvent of ethanol and water (volume ratio of ethanol to water: 1:1) under an inert atmosphere, 1 mL of APTES was added thereto, and then the reaction was carried out at 25°C for 6 h (i.e., silanization reaction temperature: 25°C, silanization reaction time: 6 h); after the reaction was completed, the reaction system was centrifuged to obtain a solid product; the solid product was washed with water 3 times and then washed with anhydrous ethanol 3 times to remove unreacted silanization agent, thereby obtaining silane-modified magnetic nanoparticles (i.e., Fe3O4 nanoparticles after surface treatment);

[0145] The silane-modified magnetic nanoparticles prepared above were dissolved in 100 mL of THF together with 0.6 g of trimethylacetyl chloride under an inert atmosphere, and the reaction was carried out at 25°C for 3 h (i.e., functionalization modification temperature: 25°C, functionalization modification time: 3 h) to obtain a magnetic additive (i.e., Fe3O4 nanoparticles having a functionalization modification layer on the surface).

[0146] 2. Preparation of electrolyte

[0147] EC, EMC, DMC and LiPF6 were mixed, and the magnetic additive prepared above was added thereto, and then the mixture was stirred at 25°C for 2 hours to obtain an electrolyte; the mass ratio of EC, EMC and DMC was 1:1:1, the mass percentage of LiPF6 in the electrolyte was 12%, and the mass percentage of the magnetic additive in the electrolyte was 0.01%.

[0148] 3. Preparation of battery

[0149] (1) Preparation of positive electrode sheet

[0150] Lithium iron phosphate, carbon black and PVDF were mixed in a mass ratio of 100:0.8:2.3, and NMP was added and stirred uniformly to prepare a positive electrode slurry.

[0151] The positive electrode slurry above was coated on both surfaces of an aluminum foil, and after drying and rolling, a positive electrode coating layer was formed on both surfaces of the aluminum foil to obtain a positive electrode sheet.

[0152] (2) Preparation of negative electrode sheet

[0153] The graphite, carbon black, SBR, CMC are mixed according to the mass ratio of 100:0.8:1.5:1.7, and deionized water is added, stirred uniformly, and prepared into a negative electrode slurry;

[0154] The above-mentioned negative electrode slurry is coated on the positive and negative surfaces of the copper foil, and after drying and rolling, the negative electrode coating is formed on the positive and negative surfaces of the copper foil, and the negative electrode sheet is prepared.

[0155] (3) Assembly of the battery

[0156] The above-mentioned positive electrode sheet, separator (PP film) and the above-mentioned negative electrode sheet are alternately stacked to assemble a laminated cell;

[0157] The laminated cell is placed in an aluminum plastic film, and a liquid injection port is reserved, the above-mentioned electrolyte is injected into the liquid injection port, and then the liquid injection port is closed to obtain a battery precursor;

[0158] The battery precursor is placed in a magnetic field, and the aging, formation and aging treatment are sequentially carried out in the magnetic field, and the magnetic field induction treatment of the battery precursor is realized at the same time; then the battery precursor is taken out from the magnetic field, and after the process of capacity grading, a soft package lithium ion battery is prepared.

[0159] The temperature of the aging is 45℃, and the time of the aging is 24h.

[0160] The process of the formation is that the battery precursor after the aging is charged at 0.05C constant current for 3h at 25℃, and then rested for 10min, and then charged at 0.2C constant current and constant voltage, the cut-off voltage is 4V, and the cut-off current is 0.01C.

[0161] The temperature of the aging treatment is 45℃, and the time of the aging treatment is 24h.

[0162] The time of the magnetic field induction treatment is about 60h.

[0163] Examples 2-19 and Examples 21-24: The difference from Example 1 is that the conditions in the preparation process of the magnetic additive (the type of silane coupling agent, the silanization reaction temperature, the silanization reaction time, the type of functional modifier, the functional modification temperature, the functional modification time), the thickness of the functional modification layer in the magnetic additive, the stirring time in the preparation process of the electrolyte, the mass percentage of the magnetic additive in the electrolyte, the magnetic field strength and the like are different, see Table 1 and Table 2 for details, and the rest of the conditions are the same as those in Example 1.

[0164] Among them, the difference between Example 7 and Example 1 is that the magnetic additive is a magnetic nanoparticle (Fe3O4 nanoparticle), and the surface of the magnetic nanoparticle is not formed with a functional modification layer, and the rest of the conditions are the same as those in Example 1.

[0165] Example 23 is different from Example 1 in that the magnetic additive is silane-modified magnetic nanoparticles, and the silane-modified magnetic nanoparticles and the functional modifier are not reacted (i.e., the magnetic additive of Example 23 is obtained after the first silane modification treatment of the magnetic nanoparticles (Fe3O4 nanoparticles) using the first silane coupling agent (APTES)), and the rest of the conditions are the same as those of Example 1.

[0166] Comparative Example 1 is different from Example 1 in that no magnetic additive is added to the electrolyte, and the rest of the conditions are the same as those of Example 1.

[0167] Comparative Example 2 is different from Example 1 in that no magnetic additive is added to the electrolyte, and the aging, formation and aging processes of the battery precursor are not carried out in a magnetic field (i.e., no magnetic field is applied to the battery precursor), and the rest of the conditions are the same as those of Example 1.

[0168] The soft package lithium ion batteries of Examples 1-19, Examples 21-24 and Comparative Examples 1-2 are tested for performance by the following processes, respectively, and the results are shown in Table 2:

[0169] (1) Cycle performance (25℃, 0.5C cycle 800 cycles capacity retention rate) test: at 45℃, the soft package lithium ion battery is charged to 3.8V at 0.5C constant current, and is left for 10min; then discharged to 2.0V at 0.5C constant current, and is left for 10min, and is cycled 1000 times; the capacity retention rate = (C 1000 / C1) × 100%, C1 is the discharge capacity of one cycle, and C 1000 is the discharge capacity of 1000 cycles.

[0170] (2) Battery internal resistance (50% SOC charging DCIR) test: after the soft package lithium ion battery is discharged to 2.0V at 1 / 3C, it is charged to 50% SOC at 1 / 3C, and is left for 2h at 25℃, and the voltage value U1 is recorded; the battery is discharged at 1.5C for 30s, and the voltage value U2 is recorded; it is left for 1h, and is charged at 0.1C for 450s, and is left for 1h; then 50% SOC charging DCIR = (U1-U2) / I.

[0171] (3) Battery fast charging performance (fast charging time) test: the soft package lithium ion battery is placed in a 25℃ constant temperature box, and is left for 30min; the soft package lithium ion battery is charged to 3.6V at 3C constant current, and then is charged to 3.8V at 1C constant current, and then is charged at constant voltage until the current is 0.05C, and the charging time of this process is the fast charging time (see Table 2). The fast charging performance of the lithium ion battery is evaluated by the fast charging time of the soft package lithium ion battery, the longer the fast charging time, the worse the fast charging performance, and the shorter the fast charging time, the better the fast charging performance.

[0172] Example 20: The difference between Example 1 is that: (1) the aging, formation and aging process of the battery precursor is not carried out in the magnetic field; (2) the prepared soft package lithium ion battery is subjected to the above-mentioned cycle performance test, DCIR test and fast charging performance test in a magnetic field with a magnetic field strength of 0.1T, and the results are shown in Table 2; the rest is the same as Example 1.

[0173] Table 1

[0174] Table 2

[0175] As can be seen from Table 2, compared with Comparative Example 1 and Comparative Example 2, the introduction of magnetic additives in the electrolyte of Examples 1-24 can reduce the battery internal resistance, shorten the battery fast charging time, and improve the cycle capacity retention rate of the battery.

[0176] Among them, in Examples 1-5, the mass percentage content of the magnetic additive in the electrolyte is in the range of 0.01%-3% compared with Example 6, which is beneficial to further reduce the battery internal resistance and improve the cycle capacity retention rate of the battery.

[0177] In addition, in Examples 1-6 and Examples 8-24, the magnetic additive includes magnetic nanoparticles and a functional modification layer existing on the surface of the magnetic nanoparticles, compared with Example 7, which is beneficial to further reduce the battery internal resistance, shorten the fast charging time, and improve the cycle capacity retention rate of the battery.

[0178] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrolyte, wherein, The magnetic additive comprises magnetic nanoparticles.

2. The electrolyte of claim 1, wherein, The magnetic additive further comprises a functional modification layer present on the surface of the magnetic nanoparticles, the functional modification layer comprising an organic matrix material containing oxygen element and / or nitrogen element.

3. The electrolyte of claim 2, wherein, The organic matrix material contains one or more of carboxyl group, ether group, carbonyl group, amino group, pyridyl group.

4. The electrolyte of claim 2, wherein, The thickness of the functional modification layer is 2nm-10nm.

5. The electrolyte of claim 1, wherein, The magnetic nanoparticles comprise one or more of magnetic metal oxide nanoparticles, metal nanoparticles, alloy nanoparticles.

6. The electrolyte of claim 5, wherein, The magnetic metal oxide nanoparticles comprise iron trioxide nanoparticles, the metal nanoparticles comprise one or more of cobalt nanoparticles, nickel nanoparticles and iron nanoparticles, and the alloy nanoparticles comprise iron-cobalt alloy nanoparticles and / or iron-nickel alloy nanoparticles.

7. The electrolyte of claim 1, wherein, The mass percentage of the magnetic additive in the electrolyte is 0.01%-3%.

8. The electrolyte of any one of claims 1-7, wherein, The electrolyte further comprises a first solvent, and the first solvent comprises an organic solvent, and the organic solvent comprises one or more of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate and methyl ethyl carbonate.

9. The electrolyte of any one of claims 1-7, wherein, The electrolyte further comprises a lithium salt, and the lithium salt comprises one or more of lithium hexafluorophosphate, lithium tetrafluoroborate and lithium bisfluorosulfonylimide.

10. A process for the preparation of the electrolyte of any one of claims 1 to 9, wherein, The method comprises the following steps: The magnetic additive, the first solvent and the electrolyte salt are mixed to obtain the electrolyte.

11. The method of preparing an electrolyte solution according to claim 10, wherein The mixing of the magnetic additive, the first solvent and the electrolyte salt to obtain the electrolyte specifically comprises: after the mixing of the magnetic additive, the first solvent and the electrolyte salt, stirring for 2h-8h to obtain the electrolyte.

12. The method of preparing an electrolyte solution according to claim 10 or 11, wherein, The preparation process of the magnetic additive comprises: first silane modification treatment of the magnetic nanoparticles by using a first silane coupling agent containing oxygen element and / or nitrogen element to form a functional modification layer on the surface of the magnetic nanoparticles, so as to obtain the magnetic additive.

13. The method of claim 12, wherein the electrolyte is prepared by mixing the components in the following order: the lithium salt, the solvent, the additive, and the electrolyte additive. The temperature of the first silane modification treatment is 25℃-80℃, and the time is 6h-12h.

14. The method of claim 12, wherein the electrolyte is prepared by mixing the components in the following order: the lithium salt, the solvent, the additive, and the electrolyte additive. The first silane coupling agent comprises one or more of 3-aminopropyl triethoxysilane, 3-aminopropyl trimethylsilane, 3-aminopropyl triethylsilane and (3-trimethoxysilylpropyl)-4-pyridine.

15. The method of preparing an electrolyte solution according to claim 10 or 11, wherein, The preparation process of the magnetic additive comprises: Second silane modification treatment of the magnetic nanoparticles by using a second silane coupling agent to obtain silane-modified magnetic nanoparticles; Reaction of the silane-modified magnetic nanoparticles and a functional modification agent to form a functional modification layer on the surface of the magnetic nanoparticles to obtain the magnetic additive; wherein at least one of the second silane coupling agent and the functional modification agent comprises an organic compound containing oxygen element and / or nitrogen element.

16. The method of preparing an electrolyte solution according to claim 15, wherein The temperature of the second silane modification treatment is 25℃-80℃, and the time is 6h-12h.

17. The method of claim 15, wherein the electrolyte is prepared by the steps of: The reaction conditions of the reaction of the silane-modified magnetic nanoparticles and the functional modification agent are: the reaction temperature is 25℃-80℃, and the reaction time is 3h-12h.

18. The method of claim 15, wherein the electrolyte is prepared by the steps of: The functional modification agent comprises one or more of succinic anhydride, oxirane, trimethylacetyl chloride and pyridine.

19. The method of claim 15, wherein the electrolyte is prepared by the steps of: The second silane coupling agent comprises one or more of 3-aminopropyltriethoxysilane, (3-chloropropyl)trimethoxysilane, (3-iodopropyl)trimethoxysilane, trichlorosilane, 3-aminopropyltrimethylsilane, and 3-aminopropyltriethylsilane.

20. A battery, wherein, The battery comprises a positive electrode sheet, a separator, a negative electrode sheet, and the electrolyte of any one of claims 1-9 or the electrolyte prepared according to the preparation method of any one of claims 10-19.

21. The battery of claim 20, wherein, The battery is a lithium ion battery.

22. A method of making a battery, wherein, The method comprises the following steps: placing the battery cell in a shell, adding electrolyte to the shell to obtain a battery precursor; subjecting the battery precursor to magnetic field induction treatment in a magnetic field to obtain the battery; The battery cell comprises a positive electrode sheet, a separator, and a negative electrode sheet, and the electrolyte comprises the electrolyte of any one of claims 1-9 or the electrolyte prepared according to the preparation method of any one of claims 10-19.

23. The method of claim 22, wherein the battery is prepared by the method of claim 21. The magnetic field strength of the magnetic field is 0.1 T to 0.5 T.

24. The method of claim 22, wherein the battery is prepared by the method of claim 21. The magnetic field direction of the magnetic field is parallel to the thickness direction of the battery cell.

25. The method of claim 22, wherein the battery is prepared by the method of claim 22. The method for preparing the battery further comprises the processes of aging, formation, and aging treatment of the battery precursor, and the processes of aging, formation, and aging treatment are performed during the process of subjecting the battery precursor to magnetic field induction treatment in a magnetic field.

26. The method of claim 22, wherein the battery is prepared by a method comprising: The magnetic field induction treatment is performed for 56 to 66 hours.

27. An electrical device, comprising: The battery comprises the battery of claim 20 or 21 or the battery prepared according to the preparation method of any one of claims 22-26.

28. The powered device of claim 27, wherein, The electrical equipment further comprises a second magnetic field device for applying a magnetic field to the battery.

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