Battery cell and preparation method therefor, battery and electric device

Abstract

Provided are a battery cell and a preparation method therefor, a battery and an electric device. The battery cell comprises a positive electrode sheet, a negative electrode sheet and an electrolyte; the electrolyte comprises a first aqueous electrolyte close to the positive electrode sheet and a second non-aqueous electrolyte close to the negative electrode sheet, and the first aqueous electrolyte and the second non-aqueous electrolyte are phase-separated; the first aqueous electrolyte comprises a first solvent and a first lithium salt, and the first solvent comprises water; and the second non-aqueous electrolyte comprises a second solvent and a second lithium salt, and the second solvent comprises a linear monoether solvent. The battery cell has a long cycle life.

Description

Battery cell, preparation method thereof, battery and electric device

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202410864694.7, filed on June 28, 2024, entitled “Battery cell, preparation method thereof, battery and electric device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to a battery cell, a preparation method thereof, a battery and an electric device. BACKGROUND

[0004] The cycle life of a battery cell is crucial to its performance. Currently, the electrolyte of a battery cell usually adopts a non-aqueous carbonate electrolyte. However, the non-aqueous carbonate electrolyte has limited ionic conductivity and is flammable during the long cycle of the battery cell. An aqueous electrolyte has much higher ionic conductivity and is non-flammable than the commercial non-aqueous carbonate electrolyte, which is expected to greatly improve the performance of the battery cell. However, due to the limitation of the high hydrogen evolution reduction potential of water molecules, the aqueous electrolyte is difficult to be compatible with the current negative electrode, thereby limiting the practical application of the aqueous electrolyte and failing to fully exert its high ionic conductivity advantage.

[0005] SUMMARY

[0006] The present application provides a battery cell, a preparation method thereof, a battery and an electric device, which can make the battery cell have a long cycle life.

[0007] In a first aspect, the present application provides a battery cell, comprising a positive electrode sheet, a negative electrode sheet and an electrolyte, the electrolyte comprising a first aqueous electrolyte close to the positive electrode sheet and a second non-aqueous electrolyte close to the negative electrode sheet, the first aqueous electrolyte and the second non-aqueous electrolyte being separated; the first aqueous electrolyte comprises a first solvent and a first lithium salt, the first solvent comprising water; the second non-aqueous electrolyte comprises a second solvent and a second lithium salt, the second solvent comprising a chain single ether solvent.

[0008] The first solvent includes water, so that the first aqueous electrolyte has the characteristics of high ionic conductivity and non-flammability, thereby facilitating efficient conduction of lithium ions in the battery cell and improving the cycle life of the battery cell. Water molecules have strong oxidative stability, and being arranged close to the positive electrode can improve the stability of the positive electrode interface, that is, the first aqueous electrolyte and the positive electrode are more compatible. The second solvent includes a chain monoether solvent, and the chain monoether molecule has strong reduction stability, and being arranged close to the negative electrode can improve the stability of the negative electrode interface, that is, the second non-aqueous electrolyte and the negative electrode are more compatible. Therefore, arranging the first aqueous electrolyte close to the positive electrode sheet and the second non-aqueous electrolyte close to the negative electrode sheet can widen the actual electrochemical window of the electrolyte and make the battery cell have good positive and negative electrode stability. In addition, arranging the first aqueous electrolyte close to the positive electrode sheet and the second non-aqueous electrolyte close to the negative electrode sheet can also effectively reduce the hydrogen evolution side reaction of water molecules on the negative electrode side and effectively reduce the oxidative decomposition side reaction of chain monoether molecules on the positive electrode side.

[0009] Therefore, the battery cell provided by the embodiments of the present application not only retains the advantages of high ionic conductivity, non-flammability, and good oxidative stability of the aqueous electrolyte, but also makes the aqueous electrolyte compatible with the negative electrode, thereby having a long cycle life.

[0010] In some embodiments, the chain monoether solvent includes C2 to C10 chain monoether solvent. Optionally, the chain monoether solvent includes one or more of diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, methyl propyl ether, methyl n-butyl ether, and methyl tert-butyl ether.

[0011] The chain monoether solvent described above has weak molecular polarity and good reduction resistance, and is used on the negative electrode side of the battery cell, which can not only realize spontaneous phase separation of the first aqueous electrolyte and the second non-aqueous electrolyte, effectively reduce the diffusion of water molecules to the negative electrode to cause hydrogen evolution side reaction, but also improve the negative electrode interface stability of the battery cell.

[0012] In some embodiments, the first lithium salt includes one or more of lithium bisfluorosulfonylimide, lithium bis(trifluoromethyl)sulfonylimide, lithium bis(pentafluoroethylsulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium nitrate, and lithium hexafluorophosphate.

[0013] The first lithium salt is within the above range, which can make the first aqueous electrolyte have strong dissociation ability and good electrochemical stability.

[0014] In some embodiments, the second lithium salt includes one or more of lithium bisfluorosulfonylimide, lithium bis(trifluoromethyl)sulfonylimide, lithium bis(pentafluoroethylsulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium hexafluorophosphate.

[0015] The second lithium salt is within the above range, and can make the second non-aqueous electrolyte have strong dissociation ability and good electrochemical stability.

[0016] In some embodiments, the lithium salt concentration of the first aqueous electrolyte is 0.5 mol / L-60 mol / L, which can be 5 mol / L-30 mol / L.

[0017] The lithium salt concentration of the first aqueous electrolyte is within the above range, and can make the first aqueous electrolyte have high ionic conductivity, thereby being conducive to the wettability of the first aqueous electrolyte to the positive electrode sheet, and being conducive to improving the migration rate of lithium ions and reducing polarization, thereby being conducive to improving the cycle life of the battery cell.

[0018] In some embodiments, the lithium salt concentration of the second non-aqueous electrolyte is 1 mol / L-3 mol / L.

[0019] The lithium salt concentration of the second non-aqueous electrolyte is within the above range, and can make the second non-aqueous electrolyte have high ionic conductivity, thereby being conducive to the wettability of the second non-aqueous electrolyte to the negative electrode sheet, and being conducive to improving the migration rate of lithium ions and reducing polarization, thereby being conducive to improving the cycle life of the battery cell.

[0020] In some embodiments, the second non-aqueous electrolyte further includes an additive, and the additive includes one or more of 1,3-propanesulfonic acid lactone, ethylene sulfate, 1,3-dioxolane, lithium nitrate, tetraethylammonium nitrate, and tetrabutylammonium nitrate.

[0021] The additive is within the above range, and can further improve the interface stability of the second non-aqueous electrolyte to the negative electrode, and be conducive to further improving the cycle performance of the battery cell.

[0022] In some embodiments, the mass of the additive is 0.5%-10% of the total mass of the second non-aqueous electrolyte.

[0023] The mass fraction of the additive is within the above range, and is conducive to further improving the cycle performance of the battery cell.

[0024] In some embodiments, the mass ratio of the first aqueous electrolyte to the second non-aqueous electrolyte is 0.1:1-10:1.

[0025] Adjusting the mass ratio of the first aqueous electrolyte to the second non-aqueous electrolyte can further improve the cycle life of the battery cell.

[0026] In some embodiments, the positive electrode sheet includes one or more of lithium-containing phosphates and lithium transition metal oxides.

[0027] In some embodiments, the negative electrode sheet comprises one or more of lithium titanate, a carbon-based material, a silicon-based material, a tin-based material, and lithium metal.

[0028] In a second aspect, the present application provides a method for preparing a battery cell, comprising the following steps: providing a positive electrode sheet, a separator, a negative electrode sheet, a first aqueous electrolyte, and a second non-aqueous electrolyte, wherein the first aqueous electrolyte comprises a first solvent and a first lithium salt, the first solvent comprises water, the second non-aqueous electrolyte comprises a second solvent and a second lithium salt, and the second solvent comprises a chain single ether solvent; assembling the positive electrode sheet, the separator, and the negative electrode sheet to obtain a battery cell to be injected with electrolyte, injecting the first aqueous electrolyte between the separator and the positive electrode sheet, and then injecting the second non-aqueous electrolyte between the separator and the negative electrode sheet to obtain the battery cell.

[0029] In a third aspect, the present application provides a battery comprising the battery cell of the first aspect of the present application or prepared by the method of the second aspect of the present application.

[0030] In a fourth aspect, the present application provides an electric device comprising the battery of the third aspect of the present application.

[0031] The electric device of the present application comprises the battery provided by the present application, and thus has at least the same advantages as the battery. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the drawings.

[0033] FIG. 1 is a schematic diagram of an embodiment of the battery cell of the present application.

[0034] FIG. 2 is a schematic diagram of an embodiment of the battery module of the present application.

[0035] FIG. 3 is a schematic diagram of an embodiment of the battery pack of the present application.

[0036] FIG. 4 is an exploded schematic diagram of the embodiment of the battery pack shown in FIG. 3.

[0037] FIG. 5 is a schematic diagram of an embodiment of an electric device comprising the battery of the present application as a power source.

[0038] In the drawings, the drawings are not necessarily drawn according to the actual scale.

[0039] The reference signs are explained as follows: 1, battery pack; 2, upper case; 3, lower case; 4, battery module; 5, battery cell. DETAILED DESCRIPTION

[0040] Hereinafter, embodiments of the battery cell and the method for manufacturing the same, the battery, and the electric device according to the present application are specifically explained with appropriate reference to the accompanying drawings. However, there are cases where unnecessary detailed explanations are omitted. For example, there are cases where detailed explanations of matters well-known, repeated explanations of substantially identical structures are omitted. This is to avoid the following explanation from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the accompanying drawings and the following explanation are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0041] The "ranges" disclosed in the present application are defined in the form of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. In addition, if a minimum range value of 1 and 2 is listed, and if a maximum range value of 3, 4, and 5 is listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise stated, a numerical range "a-b" represents a shorthand manner of describing all of the individual real combinations of values between "a" and "b", where "a" and "b" are both real numbers. For example, the numerical range "0-5" indicates that all of the real numbers between "0" and "5" have been listed herein, and "0-5" is merely a shorthand manner of describing these combinations of values. In addition, when it is stated that a parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and the like.

[0042] If not specifically stated, all of the embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0043] If not specifically stated, all of the technical features and optional technical features of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0044] If not otherwise specified, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method comprising steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method comprising step (c) means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0045] Unless otherwise specified, the terms used in the present application have the meanings commonly understood by a person skilled in the art.

[0046] Unless otherwise specified, the values of the parameters mentioned in the present application can be measured by various test methods commonly used in the art, for example, according to the test methods given in the examples of the present application. Unless otherwise specified, the test temperature of each parameter is 25°C.

[0047] The battery mentioned in the examples of the present application can comprise one or more battery cells to provide a single physical module with higher voltage and capacity. For example, the battery mentioned in the present application can comprise a battery cell, a battery module or a battery pack, etc.

[0048] The battery cell is the smallest unit that constitutes the battery, which can realize the function of charging and discharging by itself. The battery cell can be in the shape of a cylinder, a cuboid or other shapes, which are not limited in the examples of the present application. For example, FIG. 1 is a battery cell 5 in the shape of a cuboid as an example.

[0049] When there are multiple battery cells, the multiple battery cells are connected in series, in parallel or in a mixed manner by a busbar. In some examples, the battery can be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module. In some examples, the battery can be a battery pack, which comprises a box body and battery cells, and the battery cells or battery modules are contained in the box body. In some examples, the box body can be part of the chassis structure of the vehicle. For example, part of the box body can be at least part of the floor of the vehicle, or part of the box body can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0050] In some examples, the battery can be an energy storage device. The energy storage device comprises an energy storage container, an energy storage cabinet, etc.

[0051] In some embodiments, the battery cells can be assembled into a battery module, and the number of battery cells included in the battery module can be plural, and the specific number can be adjusted according to the application and capacity of the battery module. FIG. 2 is a schematic view of a battery module 4 as an example. As shown in FIG. 2, in the battery module 4, a plurality of battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, other arbitrary arrangements can also be used. The plurality of battery cells 5 can be further fixed by fasteners.

[0052] Optionally, the battery module 4 can further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0053] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0054] FIGS. 3 and 4 are schematic views of a battery pack 1 as an example. As shown in FIGS. 3 and 4, the battery pack 1 can include a box body and a plurality of battery modules 4 arranged in the box body. The box body includes an upper box body 2 and a lower box body 3, the upper box body 2 is used to cover the lower box body 3, and forms a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the box body in any manner.

[0055] Embodiments of the present application provide a battery cell, which includes a lithium ion battery cell, a lithium metal battery cell, a negative electrode-free lithium metal battery cell, etc. The negative electrode-free lithium metal battery cell generally refers to a battery cell that does not actively set up a negative electrode active material layer on the negative electrode side during the manufacturing process of the battery cell, for example, does not set up a negative electrode active material layer by coating or depositing a carbon-based active material layer at the negative electrode during the manufacturing process of the battery cell. During the first charging, ions obtain electrons on the negative electrode side and deposit on the surface of the negative electrode current collector to form a metal phase. During discharging, the metal can be converted into metal ions to return to the positive electrode, realizing cyclic charging and discharging. Compared with other battery cells, the negative electrode-free lithium metal battery cell does not have a negative electrode active material layer, thereby achieving higher energy density. In some embodiments, in order to improve the performance of the battery cell, some substances that can be used as negative electrode active materials, such as carbon materials, etc., can also be set up on the negative electrode side of the negative electrode-free lithium metal battery cell. Although these substances have a certain capacity, due to their small amount and not being used as the main negative electrode active material in the battery cell, the battery cell thus constituted can still be regarded as a negative electrode-free lithium metal battery cell. The CB value of the negative electrode-free lithium metal battery cell is usually very small, for example, in some embodiments, the CB value of the negative electrode-free lithium metal battery cell can be less than or equal to 0.1. The CB value is the capacity per unit area of the negative electrode in the battery cell divided by the capacity per unit area of the positive electrode. Since the negative electrode-free lithium metal battery cell does not contain or contains only a small amount of negative electrode active material, the capacity per unit area of the negative electrode is small, and thus the CB value is very small, for example, usually less than or equal to 0.1.

[0056] The battery cell provided by the embodiments of the present application includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a separator, and a negative electrode sheet. The electrode assembly can be in a wound structure or a stacked structure, which is not limited in the embodiments of the present application. The battery cell can further include an outer package, which can be used to package the electrode assembly and the electrolyte. The outer package can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, such as one or more of aluminum plastic film, polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0057] The electrolyte includes a first aqueous electrolyte close to the positive electrode sheet and a second non-aqueous electrolyte close to the negative electrode sheet, and the first aqueous electrolyte and the second non-aqueous electrolyte are separated. The first aqueous electrolyte includes a first solvent and a first lithium salt, and the first solvent includes water; the second non-aqueous electrolyte includes a second solvent and a second lithium salt, and the second solvent includes a chain single ether solvent.

[0058] The water molecule has strong polarity and high dielectric constant, and the chain single ether molecule has weak polarity and low dielectric constant. The intrinsic chemical polarity difference between the two can induce the spontaneous phase separation of the first aqueous electrolyte and the second non-aqueous electrolyte. That is, there is a clear liquid-liquid interface between the first aqueous electrolyte and the second non-aqueous electrolyte.

[0059] The first solvent includes water, so that the first aqueous electrolyte has the characteristics of high ionic conductivity and non-flammability, which is conducive to the efficient conduction of lithium ions in the battery cell and the improvement of the cycle life of the battery cell. The water molecule has strong oxidation stability, and setting it close to the positive electrode can improve the stability of the positive electrode interface, that is, the first aqueous electrolyte and the positive electrode are more compatible. The second solvent includes a chain single ether solvent, and the chain single ether molecule has strong reduction stability. Setting it close to the negative electrode can improve the stability of the negative electrode interface, that is, the second non-aqueous electrolyte and the negative electrode are more compatible. Therefore, setting the first aqueous electrolyte close to the positive electrode plate and the second non-aqueous electrolyte close to the negative electrode plate can widen the actual electrochemical window of the electrolyte and make the battery cell have good positive and negative electrode stability. In addition, setting the first aqueous electrolyte close to the positive electrode plate and the second non-aqueous electrolyte close to the negative electrode plate can also effectively reduce the hydrogen evolution side reaction of water molecules on the negative electrode side and effectively reduce the oxidation and decomposition side reaction of chain single ether molecules on the positive electrode side.

[0060] Therefore, the battery cell provided by the embodiments of the present application not only retains the advantages of high ionic conductivity, non-flammability, and good oxidation stability of the aqueous electrolyte, but also makes the aqueous electrolyte compatible with the negative electrode, so that the battery cell has a long cycle life.

[0061] In some embodiments, the first lithium salt can include one or more of lithium bisfluorosulfonylimide (LiFSI), lithium bis(trifluoromethyl)sulfonylimide (LiTFSI), lithium bis(pentafluoroethylsulfonyl)imide (LiBETI), lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide (LiFTFSI), lithium trifluoromethanesulfonate (LiOTf), lithium nitrate (LiNO3), and lithium hexafluorophosphate (LiPF6).

[0062] The first lithium salt is within the above range, which can make the first aqueous electrolyte have strong dissociation ability and good electrochemical stability.

[0063] Optionally, the first lithium salt can include one or more of lithium bisfluorosulfonylimide (LiFSI) and lithium bis(trifluoromethyl)sulfonylimide (LiTFSI).

[0064] In some embodiments, the lithium salt concentration of the first aqueous electrolyte can be 0.5 mol / L-60 mol / L, for example, can be 0.5 mol / L, 1 mol / L, 3 mol / L, 5 mol / L, 7 mol / L, 10 mol / L, 15 mol / L, 20 mol / L, 25 mol / L, 30 mol / L, 35 mol / L, 40 mol / L, 45 mol / L, 50 mol / L, 55 mol / L, 60 mol / L, or a range consisting of any of the above values.

[0065] The lithium salt concentration of the first aqueous electrolyte in the above range can make the first aqueous electrolyte have high ionic conductivity, thereby being conducive to the first aqueous electrolyte wetting the positive electrode sheet, being conducive to improving the migration rate of lithium ions and reducing polarization, and thereby being conducive to improving the cycle life of the battery cell.

[0066] Optionally, the lithium salt concentration of the first aqueous electrolyte can be 5 mol / L-30 mol / L, 7 mol / L-30 mol / L, 10 mol / L-30 mol / L.

[0067] The chain single ether solvent refers to a chain ether containing only one ether oxygen functional group in the molecular structure.

[0068] In some embodiments, the chain single ether solvent can include C2 to C10 chain single ether solvents, for example, the C2 to C10 chain single ether solvents can include one or more of C2 chain single ether solvents, C3 chain single ether solvents, C4 chain single ether solvents, C5 chain single ether solvents, C6 chain single ether solvents, C7 chain single ether solvents, C8 chain single ether solvents, C9 chain single ether solvents, C10 chain single ether solvents. The chain single ether solvent can be a branched structure or a branched structure.

[0069] Optionally, the chain single ether solvent can include one or more of diethyl ether (DEE), dipropyl ether (DPE), dibutyl ether (DBE), dipentyl ether (DPeE), methyl propyl ether (MPE), methyl n-butyl ether (MBE), methyl tert-butyl ether (MTBE).

[0070] The above chain single ether solvent has weak molecular polarity and good reduction resistance, and is used at the negative side of the battery cell, which can not only realize spontaneous phase separation of the first aqueous electrolyte and the second non-aqueous electrolyte, effectively reduce the diffusion of water molecules to the negative electrode to cause hydrogen evolution side reactions, but also improve the negative electrode interface stability of the battery cell.

[0071] Optionally, the chain single ether solvent can include one or more of diethyl ether (DEE), dipropyl ether (DPE), dibutyl ether (DBE), dipentyl ether (DPeE).

[0072] More optionally, the chain-like mono-ether solvent can include dibutyl ether (DBE).

[0073] In some embodiments, the chain-like mono-ether solvent can have a relative dielectric constant of 2-6, optionally 2.5-5. The test temperature can be 20-25℃.

[0074] The relative dielectric constant of the solvent has the meaning known in the art and can be tested by using the instruments and methods known in the art.

[0075] In some embodiments, the second lithium salt can include one or more of lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethyl)sulfonylimide (LiTFSI), lithium bis(pentafluoroethylsulfonyl)imide (LiBETI), lithium (fluorosulfonyl)(trifluoromethylsulfonyl)imide (LiFTFSI), lithium trifluoromethanesulfonate (LiOTf), lithium hexafluorophosphate (LiPF6).

[0076] The second lithium salt can be within the above range, which can enable the second non-aqueous electrolyte to have strong dissociation ability and good electrochemical stability.

[0077] Optionally, the second lithium salt can include one or more of lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethyl)sulfonylimide (LiTFSI), lithium bis(pentafluoroethylsulfonyl)imide (LiBETI), lithium (fluorosulfonyl)(trifluoromethylsulfonyl)imide (LiFTFSI).

[0078] More optionally, the second lithium salt can include one or more of lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethyl)sulfonylimide (LiTFSI).

[0079] In some embodiments, the lithium salt concentration of the second non-aqueous electrolyte can be 1-3 mol / L, for example, can be 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.7 mol / L, 2.8 mol / L, 2.9 mol / L, 3 mol / L, or a range consisting of any of the above values.

[0080] The lithium salt concentration of the second non-aqueous electrolyte can be within the above range, which can enable the second non-aqueous electrolyte to have high ionic conductivity, thereby being conducive to the second non-aqueous electrolyte wetting the negative electrode sheet, being conducive to improving the migration rate of lithium ions and reducing polarization, and thereby being conducive to improving the cycle life of the battery cell.

[0081] In some embodiments, the second non-aqueous electrolyte can further include an additive, which can include one or more of 1,3-propanesultone (1,3-PS), vinyl sulfonate (DTD), 1,3-dioxolane (DOL), lithium nitrate (LiNO3), tetraethylammonium nitrate (TEA NO3), tetrabutylammonium nitrate (TBA NO3).

[0082] The additive can be within the above range, which can further improve the interface stability of the second non-aqueous electrolyte to the negative electrode, and is beneficial to further improve the cycle performance of the battery cell.

[0083] In some embodiments, the mass of the additive can be 0.5%-10% of the total mass of the second non-aqueous electrolyte, for example, can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or a range consisting of any of the above values.

[0084] The mass fraction of the additive can be within the above range, which is beneficial to further improve the cycle performance of the battery cell.

[0085] Optionally, the mass of the additive can be 0.5%-8%, 0.5%-6%, 1%-8%, 1%-6% of the total mass of the second non-aqueous electrolyte.

[0086] In some embodiments, the mass ratio of the first aqueous electrolyte to the second non-aqueous electrolyte can be 0.1:1-10:1, for example, can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.5:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or a range consisting of any of the above values.

[0087] Adjusting the mass ratio of the first aqueous electrolyte to the second non-aqueous electrolyte can further improve the cycle life of the battery cell.

[0088] Optionally, the mass ratio of the first aqueous electrolyte to the second non-aqueous electrolyte can be 0.1:1-5:1, 0.1:1-4:1, 0.1:1-3:1, 0.1:1-2:1, 0.1:1-1.6:1, 0.1:1-1:1, 0.2:1-5:1, 0.2:1-4:1, 0.2:1-3:1, 0.2:1-2:1, 0.2:1-1.6:1, 0.2:1-1:1, 0.3:1-5:1, 0.3:1-4:1, 0.3:1-3:1, 0.3:1-2:1, 0.3:1-1.6:1, 0.3:1-1:1.

[0089] [Positive electrode tab]

[0090] In some embodiments, the positive electrode tab can include a positive current collector and a positive film layer disposed on at least one surface of the positive current collector, the positive film layer including a positive active material. For example, the positive current collector has two surfaces opposite in the thickness direction of the positive current collector, and the positive film layer is disposed on either one or both of the two opposite surfaces of the positive current collector.

[0091] The positive active material includes a material capable of deintercalating and intercalating lithium, and optionally, the positive active material can include, but is not limited to, one or more of lithium-containing phosphates, lithium transition metal oxides. Examples of the lithium-containing phosphates can include, but are not limited to, one or more of lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon, and respective modified compounds thereof. Examples of the lithium transition metal oxides can include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and respective modified compounds thereof.

[0092] In some embodiments, as an example, the positive active material can include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 0.5 Mn 1.5 O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2O2(simplified as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(simplified as NCM811), LiNi 0.96 Co 0.02 Mn 0.02 O2(simplified as Ni96), LiNi 0.80 Co 0.15 Al 0.05 O2, LiFePO4, LiMnPO4, and their respective modified compounds.

[0093] The modified compounds of each of the above positive electrode active materials can be doped modification and / or surface coating modification to the positive electrode active material.

[0094] The battery cell will be accompanied by Li deintercalation and consumption during charging and discharging process, and the molar content of Li element is different when the battery cell is discharged to different states. In the above enumeration of specific substances of positive electrode active materials, the molar content of Li element is the initial state, i.e. the state before feeding, and the positive electrode active material is applied to the battery cell, and after charging and discharging cycle, the molar content of Li element may change. Similarly, in the above enumeration of specific substances of positive electrode active materials, the molar content of O element is only the theoretical state value, and the lattice oxygen release will cause the molar content of O element to change, and the molar content of O element may appear to float.

[0095] In some embodiments, the positive electrode film layer can further include a positive electrode conductive agent. As an example, the positive electrode conductive agent can include, but is not limited to, one or more of super P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0096] In some embodiments, the positive electrode film layer can further include a positive electrode binder. As an example, the positive electrode binder can include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic ester resin.

[0097] In some embodiments, the positive current collector can employ a metal foil or a composite current collector. As an example of a metal foil, an aluminum foil can be employed. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material can include, but is not limited to, one or more of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. As an example, the polymer material base layer can include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0098] The positive electrode film layer can be formed by coating a positive electrode slurry on the positive electrode current collector, drying, and cold-pressing. The positive electrode slurry is generally formed by dispersing and uniformly stirring a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and any other components in a solvent. The solvent can be N-methyl pyrrolidone (NMP), but is not limited thereto.

[0099] [Negative electrode tab]

[0100] Embodiments of the present application provide a battery cell, which can include a lithium ion battery cell, a lithium metal battery cell, a negative electrode-free lithium metal battery cell, and the like. Depending on the specific type of the battery cell, the structure and composition of the negative electrode tab can vary.

[0101] In some embodiments, the negative electrode tab can include a negative electrode current collector and a negative electrode film layer on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material, the negative electrode active material can include one or more of lithium titanate, a carbon-based material, a silicon-based material, a tin-based material, and lithium metal.

[0102] Optionally, the carbon-based material can include, but is not limited to, one or more of artificial graphite, natural graphite, soft carbon, hard carbon, and mesocarbon microbeads. Optionally, the silicon-based material can include, but is not limited to, one or more of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material. Optionally, the tin-based material can include, but is not limited to, one or more of elemental tin, tin oxide, and tin alloy material.

[0103] In some embodiments, the negative electrode film layer can further include a negative electrode conductive agent. As an example, the negative electrode conductive agent can include, but is not limited to, one or more of super-conductive carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0104] In some embodiments, the negative electrode film layer can further include a negative electrode binder. As an example, the negative electrode binder can include, but is not limited to, one or more of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethylacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0105] In some embodiments, the negative electrode film layer can further include other auxiliary agents. As an example, the other auxiliary agents can include a thickening agent, such as carboxymethyl cellulose sodium (CMC), PTC thermistor material, etc.

[0106] In some embodiments, the negative electrode current collector can employ a metal foil or a composite current collector. As an example of the metal foil, a copper foil, a copper alloy foil, a nickel foil, a nickel alloy foil can be employed. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material can include, but is not limited to, one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer can include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0107] In some embodiments, the negative electrode tab can include a negative electrode current collector and a lithium metal layer disposed on at least one surface of the negative electrode current collector.

[0108] Due to the relatively high theoretical gravimetric capacity of lithium metal and the relatively low density and negative electrode potential, using lithium metal as the negative electrode active material can significantly improve the energy density of the battery cell. In this case, the battery cell can be referred to as a lithium metal battery cell.

[0109] In some embodiments, the negative electrode tab can include a negative electrode current collector and not include a lithium metal layer. In this case, the battery cell can be referred to as a negative electrode-free lithium metal battery cell.

[0110] The second non-aqueous electrolyte includes a chain-like monoether solvent, which has high compatibility with the lithium metal negative electrode and can regulate uniform deposition of lithium metal; the chain-like monoether molecule also has strong reduction stability, which can improve the lithium deposition and stripping efficiency, thereby enabling the lithium metal battery cell and the negative electrode-free lithium metal battery cell to have both high energy density and long cycle life.

[0111] [Separator film]

[0112] The isolation film is arranged between the positive electrode tab and the negative electrode tab, and mainly functions to prevent internal short circuit. The type of the isolation film is not particularly limited in the present application, and any known porous structure film with good chemical stability and mechanical stability can be selected. In some embodiments, the material of the isolation film can include, but is not limited to, one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and polyimide. The isolation film can be a single-layer film or a multi-layer composite film. When the isolation film is a multi-layer composite film, the materials of the layers can be the same or different.

[0113] In some embodiments, the isolation film can further include a heat-resistant coating layer to improve the heat resistance of the isolation film. Optionally, the heat-resistant coating layer can include, but is not limited to, one or more of alumina, boehmite, silicon oxide, zirconium dioxide, magnesium oxide, titanium dioxide, zinc oxide, barium sulfate, boron nitride, aluminum nitride, and magnesium nitride.

[0114] The present application also provides a preparation method of a battery monomer, which can prepare the battery monomer provided by the present application.

[0115] The preparation method of the battery monomer includes the following steps: providing a positive electrode tab, an isolation film, a negative electrode tab, a first aqueous electrolyte, and a second non-aqueous electrolyte, the first aqueous electrolyte including a first solvent and a first lithium salt, the first solvent including water, the second non-aqueous electrolyte including a second solvent and a second lithium salt, the second solvent including a chain single ether solvent; assembling the positive electrode tab, the isolation film, and the negative electrode tab to obtain a to-be-liquid-injected battery monomer, injecting the first aqueous electrolyte between the isolation film and the positive electrode tab, and then injecting the second non-aqueous electrolyte between the isolation film and the negative electrode tab to obtain the battery monomer.

[0116] The first aqueous electrolyte cannot infiltrate the isolation film, so the first aqueous electrolyte is injected between the isolation film and the positive electrode tab, and then the second non-aqueous electrolyte is injected between the isolation film and the negative electrode tab, which can make the first aqueous electrolyte close to the positive electrode and the second non-aqueous electrolyte close to the negative electrode.

[0117] The preparation method of the to-be-liquid-injected battery monomer is known. In some embodiments, the positive electrode tab, the isolation film, and the negative electrode tab can be formed into an electrode assembly through a winding process and / or a stacking process, and the electrode assembly is placed in an outer package to obtain the to-be-liquid-injected battery monomer.

[0118] The embodiments of the present application also provide a power consuming device, which comprises the battery provided by the embodiments of the present application. The battery can be used as a power source of the power consuming device, or can be used as an energy storage unit of the power consuming device. The power consuming device can be, but is not limited to, a mobile device (such as a mobile phone, a tablet computer, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.

[0119] The power consuming device can select the type of the battery (such as a battery monomer, a battery module or a battery pack) according to the use requirement of the power consuming device.

[0120] FIG. 5 is a schematic diagram of a power consuming device as an example. The power consuming device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirement of high power and high energy density of the power consuming device, a battery pack or a battery module can be used.

[0121] The power consuming device as another example can be a mobile phone, a tablet computer, a notebook computer, etc. The power consuming device usually requires thinning, and a battery monomer can be used as a power source.

[0122] Embodiments

[0123] The embodiments described below more specifically describe the disclosure of the present application, which are only used for illustrative explanation, because various modifications and changes within the scope of the disclosure of the present application are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods, and can be used directly without further treatment, and the instruments used in the embodiments are commercially available.

[0124] Embodiment 1

[0125] The positive electrode active material LiMn2O4, the positive electrode conductive agent acetylene black, and the positive electrode binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 98:1:1, added into a solvent N-methyl pyrrolidone (NMP), and stirred until the system is uniformly dispersed to obtain a positive electrode slurry; the positive electrode slurry is uniformly coated on a positive electrode current collector aluminum foil, dried after air-drying, then transferred to an oven for further drying at 120°C, and then cut into a 40mm×50mm rectangle as a positive electrode sheet for standby.

[0126] A lithium strip with a thickness of 20μm is covered on a 12μm copper foil by rolling, and then cut into a 41mm×51mm rectangle as a negative electrode sheet for standby.

[0127] A polypropylene porous membrane coated with a double-sided alumina ceramic heat-resistant coating was selected and cut into a rectangle of 45 mm x 55 mm as a separator film, ready for use.

[0128] The first lithium salt lithium bis(trifluoromethyl)sulfonylimide (LiTFSI) was stirred uniformly with the first solvent water to obtain a first aqueous electrolyte, ready for use. The concentration of LiTFSI was 10 mol / L.

[0129] The second lithium salt lithium bisfluorosulfonylimide (LiFSI) was stirred uniformly with the second solvent dibutyl ether (DBE) to obtain a second non-aqueous electrolyte, ready for use. The concentration of LiFSI was 2 mol / L.

[0130] The cut positive electrode sheet and the cut negative electrode sheet were matched, and the above-mentioned separator film was placed in the middle to separate the positive electrode sheet and the negative electrode sheet to obtain a laminated electrode assembly, which was then wrapped in an aluminum plastic film bag to form a to-be-liquid-injected lithium metal battery monomer; 0.1 g of the first aqueous electrolyte was injected between the positive electrode sheet and the separator film, and after the positive electrode sheet was fully soaked with the first aqueous electrolyte, 0.1 g of the second non-aqueous electrolyte was injected between the negative electrode sheet and the separator film, and after the injection was completed, the aluminum plastic film bag was vacuum heat-pressed and packaged, and was placed at 45°C for 10 h to obtain a lithium metal battery monomer, which can be subjected to subsequent cycle performance test. The rated capacity of the lithium metal battery monomer was 70 mAh.

[0131] Example 2

[0132] The preparation method of the lithium metal battery monomer was the same as that of Example 1, except that the composition of the first aqueous electrolyte was different.

[0133] The first lithium salt lithium bisfluorosulfonylimide (LiFSI) was stirred uniformly with the first solvent water to obtain a first aqueous electrolyte, ready for use. The concentration of LiFSI was 10 mol / L.

[0134] Example 3

[0135] The preparation method of the lithium metal battery monomer was the same as that of Example 1, except that the composition of the second non-aqueous electrolyte was different.

[0136] The second lithium salt lithium bisfluorosulfonylimide (LiFSI) and lithium bis(trifluoromethyl)sulfonylimide (LiTFSI) were stirred uniformly with the second solvent dibutyl ether (DBE) to obtain a second non-aqueous electrolyte, ready for use. The concentration of LiFSI was 1 mol / L, and the concentration of LiTFSI was 1 mol / L.

[0137] Example 4

[0138] The preparation method of the lithium metal battery monomer was the same as that of Example 1, except that the composition of the first aqueous electrolyte was different.

[0139] The first lithium salt lithium bis(trifluoromethyl)sulfonylimide (LiTFSI) is stirred uniformly with the first solvent water to obtain a first aqueous electrolyte, which is ready for use. The concentration of LiTFSI is 21 mol / L.

[0140] Example 5

[0141] The preparation method of the lithium metal battery cell is the same as that in Example 1, except that the composition of the second non-aqueous electrolyte is different.

[0142] The second lithium salt lithium bisfluorosulfonylimide (LiFSI) is stirred uniformly with the second solvent dibutyl ether (DBE) to obtain a second non-aqueous electrolyte, which is ready for use. The concentration of LiFSI is 1 mol / L.

[0143] Example 6

[0144] The preparation method of the lithium metal battery cell is the same as that in Example 1, except that the composition of the second non-aqueous electrolyte is different.

[0145] The second lithium salt lithium bisfluorosulfonylimide (LiFSI) is stirred uniformly with the second solvent dipropyl ether (DPE) to obtain a second non-aqueous electrolyte, which is ready for use. The concentration of LiFSI is 2 mol / L.

[0146] Example 7

[0147] The preparation method of the lithium metal battery cell is the same as that in Example 1, except that the composition of the positive electrode sheet is different.

[0148] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2, a positive electrode conductive agent acetylene black, and a positive electrode binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 98:1:1, added to a solvent N-methyl pyrrolidone (NMP), and stirred until the system is uniformly dispersed to obtain a positive electrode slurry; the positive electrode slurry is uniformly coated on a positive electrode current collector aluminum foil, dried, transferred to an oven at 120°C for further drying, and then cut into a rectangle of 40 mm x 50 mm as a positive electrode sheet, which is ready for use.

[0149] Example 8

[0150] The preparation method of the lithium metal battery cell is the same as that in Example 1, except that the composition of the positive electrode sheet is different.

[0151] The positive electrode active material LiNi 0.5 Mn 0.5O2, positive electrode conductive agent acetylene black, positive electrode binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 98:1:1, added to the solvent N-methyl pyrrolidone (NMP) and stirred until the system was uniformly dispersed to obtain a positive electrode slurry; the positive electrode slurry was uniformly coated on the positive electrode current collector aluminum foil, dried and then transferred to an oven at 120°C for further drying, and then cut into a 40mm x 50mm rectangle as a positive electrode tab for standby.

[0152] Example 9

[0153] The preparation method of the lithium metal battery monomer was the same as that of Example 1, except that the composition of the positive electrode tab and the composition of the first aqueous electrolyte were different.

[0154] The positive electrode active material LiNi 0.5 Mn 0.5 O2, positive electrode conductive agent acetylene black, positive electrode binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 98:1:1, added to the solvent N-methyl pyrrolidone (NMP) and stirred until the system was uniformly dispersed to obtain a positive electrode slurry; the positive electrode slurry was uniformly coated on the positive electrode current collector aluminum foil, dried and then transferred to an oven at 120°C for further drying, and then cut into a 40mm x 50mm rectangle as a positive electrode tab for standby.

[0155] Lithium bis(trifluoromethyl) sulfonimide (LiTFSI) was stirred uniformly with water to obtain a first aqueous electrolyte with a concentration of 21 mol / L.

[0156] Example 10

[0157] The preparation method of the lithium metal battery monomer was the same as that of Example 1, except that the amount of the first aqueous electrolyte and the second non-aqueous electrolyte was different.

[0158] The cut positive electrode tab was matched with the cut negative electrode tab, and the above-mentioned isolation film was placed in the middle to separate the positive electrode tab and the negative electrode tab to obtain a laminated electrode assembly, which was then wrapped in an aluminum plastic film bag to form a lithium metal battery monomer to be injected; 0.05g of the first aqueous electrolyte was injected between the positive electrode tab and the isolation film, and after the positive electrode tab was fully soaked with the first aqueous electrolyte, 0.15g of the second non-aqueous electrolyte was injected between the negative electrode tab and the isolation film. After the injection was completed, the aluminum plastic film bag was vacuum heat sealed and packaged, and then placed at 45°C for 10h to obtain a lithium metal battery monomer, which can be subjected to subsequent cycle performance test. The rated capacity of the lithium metal battery monomer was 70mAh.

[0159] Example 11

[0160] The preparation method of the lithium metal battery monomer was the same as that of Example 1, except that the amount of the first aqueous electrolyte and the second non-aqueous electrolyte was different.

[0161] The cut positive electrode sheet and the cut negative electrode sheet are matched, the above-mentioned isolation film is placed in the middle to insulate the positive electrode sheet and the negative electrode sheet to obtain a laminated electrode assembly, and then the laminated electrode assembly is wrapped in an aluminum plastic film bag to form a lithium metal battery monomer to be injected with liquid; 0.15 g of the first aqueous electrolyte is injected between the positive electrode sheet and the isolation film, and after the positive electrode sheet is fully soaked with the first aqueous electrolyte, 0.05 g of the second non-aqueous electrolyte is injected between the negative electrode sheet and the isolation film, and after the injection is completed, the aluminum plastic film bag is vacuum heat sealed and packaged, and is placed at 45°C for 10 h to obtain a lithium metal battery monomer, which can be subjected to subsequent cycle performance test. The rated capacity of the lithium metal battery monomer is 70 mAh.

[0162] Comparative Example 1

[0163] The preparation method of the lithium metal battery monomer is the same as that of Example 1, except that the second non-aqueous electrolyte is not added during the assembly process of the lithium metal battery monomer.

[0164] The cut positive electrode sheet and the cut negative electrode sheet are matched, the above-mentioned isolation film is placed in the middle to insulate the positive electrode sheet and the negative electrode sheet to obtain a laminated electrode assembly, and then the laminated electrode assembly is wrapped in an aluminum plastic film bag to form a lithium metal battery monomer to be injected with liquid; 0.2 g of the first aqueous electrolyte is injected into the lithium metal battery monomer to be injected with liquid, and after the injection is completed, the aluminum plastic film bag is vacuum heat sealed and packaged, and is placed at 45°C for 10 h to obtain a lithium metal battery monomer.

[0165] Comparative Example 2

[0166] The preparation method of the lithium metal battery monomer is the same as that of Example 1, except that the first aqueous electrolyte is not added during the assembly process of the lithium metal battery monomer.

[0167] The cut positive electrode sheet and the cut negative electrode sheet are matched, the above-mentioned isolation film is placed in the middle to insulate the positive electrode sheet and the negative electrode sheet to obtain a laminated electrode assembly, and then the laminated electrode assembly is wrapped in an aluminum plastic film bag to form a lithium metal battery monomer to be injected with liquid; 0.2 g of the second non-aqueous electrolyte is injected into the lithium metal battery monomer to be injected with liquid, and after the injection is completed, the aluminum plastic film bag is vacuum heat sealed and packaged, and is placed at 45°C for 10 h to obtain a lithium metal battery monomer, which can be subjected to subsequent cycle performance test. The rated capacity of the lithium metal battery monomer is 70 mAh.

[0168] Cycle performance test

[0169] Take the above prepared lithium metal battery monomer, set the ambient temperature to 25℃, use 0.2C constant current charging to reach the upper limit cutoff voltage, then change to constant voltage charging until the current decays to 0.1C; then discharge at 2C constant current to the lower limit cutoff voltage to obtain the first circle discharge capacity. Repeat the above charge and discharge cycle, record the discharge capacity after each cycle. When the discharge capacity decays to 80% of the first circle discharge capacity, the lithium metal battery monomer is considered to have reached the end of life, and the number of cycles experienced by the lithium metal battery monomer at this time is recorded.

[0170] The positive active material is LiMn2O4, the upper limit cutoff voltage is 4.6V, and the lower limit cutoff voltage is 3.4V.

[0171] The positive active material is LiNi 0.8 Co 0.1 Mn 0.1 O2, the upper limit cutoff voltage is 4.6V, and the lower limit cutoff voltage is 3.0V.

[0172] The positive active material is LiNi 0.5 Mn 1.5 O2, the upper limit cutoff voltage is 5.0V, and the lower limit cutoff voltage is 3.7V.

[0173] As can be seen from the test results in Table 1, the lithium metal battery monomer using the phase-separated first aqueous electrolyte and second non-aqueous electrolyte has a long cycle life.

[0174] As can be further seen from the test results of Examples 1 to 6, further adjusting the composition of the first aqueous electrolyte and / or the second non-aqueous electrolyte can further improve the cycle life of the lithium metal battery monomer.

[0175] As can be further seen from the test results of Examples 1, 10 to 11, further adjusting the mass ratio of the first aqueous electrolyte to the second non-aqueous electrolyte can further improve the cycle life of the lithium metal battery monomer.

[0176] The above only takes the lithium metal battery monomer as an example to verify that the lithium metal battery monomer using the phase-separated first aqueous electrolyte and second non-aqueous electrolyte has a long cycle life, and other battery monomers using the phase-separated first aqueous electrolyte and second non-aqueous electrolyte, such as lithium ion battery monomers, negative electrode-free lithium metal battery monomers, etc., can also have a long cycle life.

[0177] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration, function, and effect as the technical idea of the present application are included in the technical scope of the present application. Furthermore, other modes constructed by applying various modifications that can be thought of by those skilled in the art to the embodiments, or by combining part of the constituent elements of the embodiments, are also included in the scope of the present application without departing from the spirit of the present application.

Claims

1. A battery cell, comprising a positive electrode, a negative electrode, and an electrolyte, wherein, The electrolyte includes a first aqueous electrolyte near the positive electrode and a second non-aqueous electrolyte near the negative electrode, wherein the first aqueous electrolyte and the second non-aqueous electrolyte are phase-separated. The first aqueous electrolyte includes a first solvent and a first lithium salt, wherein the first solvent includes water; The second non-aqueous electrolyte includes a second solvent and a second lithium salt, wherein the second solvent includes a chain-like monoether solvent.

2. The battery cell according to claim 1, wherein, The chain-like monoether solvents include C2 to C10 chain-like monoether solvents.

3. The battery cell according to claim 2, wherein, The chain-like monoether solvent includes one or more of diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, methyl propyl ether, methyl n-butyl ether, and methyl tert-butyl ether.

4. The battery cell according to any one of claims 1-3, wherein, The first lithium salt comprises one or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethyl)sulfonylimide, lithium bis(pentafluoroethylsulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium nitrate, and lithium hexafluorophosphate; and / or, The second lithium salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethyl)sulfonylimide, lithium bis(pentafluoroethylsulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, and lithium hexafluorophosphate.

5. The battery cell according to any one of claims 1-4, wherein, The lithium salt concentration of the first aqueous electrolyte is 0.5 mol / L-60 mol / L; and / or, The lithium salt concentration of the second non-aqueous electrolyte is 1 mol / L-3 mol / L.

6. The battery cell according to claim 5, wherein, The lithium salt concentration of the first aqueous electrolyte is 5 mol / L-30 mol / L.

7. The battery cell according to any one of claims 1-6, wherein, The second non-aqueous electrolyte also includes additives, which include one or more of 1,3-propanesulfonate lactone, vinyl sulfate, 1,3-dioxolane, lithium nitrate, tetraethylammonium nitrate, and tetrabutylammonium nitrate.

8. The battery cell according to claim 7, wherein, The mass of the additive is 0.5%-10% of the total mass of the second non-aqueous electrolyte.

9. The battery cell according to any one of claims 1-8, wherein, The mass ratio of the first aqueous electrolyte to the second non-aqueous electrolyte is 0.1:1-10:

1.

10. The battery cell according to any one of claims 1-9, wherein, The positive electrode sheet comprises one or more of lithium phosphate and lithium transition metal oxide; and / or, The negative electrode includes one or more of lithium titanate, carbon-based materials, silicon-based materials, tin-based materials, and lithium metal.

11. A method for preparing a single battery cell, comprising the following steps: A positive electrode, a separator, a negative electrode, a first aqueous electrolyte, and a second non-aqueous electrolyte are provided. The first aqueous electrolyte includes a first solvent and a first lithium salt. The first solvent includes water. The second non-aqueous electrolyte includes a second solvent and a second lithium salt. The second solvent includes a chain-like monoether solvent. The positive electrode, the separator, and the negative electrode are assembled to obtain a battery cell to be injected with electrolyte. First, the first aqueous electrolyte is injected between the separator and the positive electrode, and then the second non-aqueous electrolyte is injected between the separator and the negative electrode to obtain the battery cell.

12. A battery comprising a battery cell according to any one of claims 1-10 or a battery cell prepared by the preparation method according to claim 11.

13. An electrical device comprising the battery of claim 12.

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