Formation process of semi-solid-state battery and formed semi-solid-state battery

Abstract

The invention provides a formation process of a semi-solid-state battery and a formed semi-solid-state battery, the formation process comprises the following steps: the semi-solid-state battery injected with electrolyte is charged and discharged at least once in a constant temperature environment, the charging and discharging comprises charging and discharging which are performed in sequence, and the formed semi-solid-state battery is obtained; the electrolyte contains LiPF6 (LiPF6); the temperature of the constant-temperature environment is-30 DEG C to 3 DEG C. According to the present invention, the reaction between the electrolyte and the positive electrode can be effectively controlled by using the low-temperature constant-temperature formation environment, and the low formation temperature facilitates the reduction of the reaction rate and the formation of the continuous and compact CEI film on the surface of the positive electrode so as to improve the high-temperature cycle stability of the battery; the lower formation temperature is also beneficial to the reaction kinetics of LiF formation, so that the content of LiF in the CEI film can be effectively increased; therefore, the formed semi-solid battery obtained by the formation process has excellent high-temperature cycling stability.

Description

Technical Field

[0001] The invention belongs to the technical field of electric vehicle batteries and relates to a formation process of a semi-solid battery, in particular to a formation process of a semi-solid battery and a semi-solid battery after formation. Background Art

[0002] Current lithium batteries have the problem of poor high-temperature cycle stability, mainly because they use electrolyte as a lithium ion transmission medium. On the one hand, high temperature may cause changes in the structure of the positive electrode material, inducing a reaction between the electrolyte and the electrode material, inducing decomposition of the electrolyte. On the other hand, high temperature will accelerate the decomposition of the electrolyte.

[0003] In the prior art, a coating is formed on the surface of the positive electrode active material to isolate the electrolyte from the positive electrode active material. However, if the coating layer is too thin, the barrier effect is limited. If the coating layer is too thick, the transmission of lithium ions will be affected. On the other hand, the introduction of the coating layer will reduce the energy density of the battery. Moreover, the additional coating process makes the process complicated and the cost increased. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a formation process for a semi-solid-state battery and a semi-solid-state battery after formation. The present invention improves the formation process to form a continuous and dense CEI film rich in LiF on the positive electrode side, which can effectively isolate the contact between the electrolyte and the positive electrode active material. The semi-solid-state battery after formation obtained by the formation process has excellent high-temperature cycle stability.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a formation process for a semi-solid-state battery, the formation process comprising:

[0007] The semi-solid battery after being injected with electrolyte is charged and discharged at least three times in a constant temperature environment, wherein the charging and discharging include charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0008] The electrolyte contains LiPF6; the temperature of the constant temperature environment is -30 to 3°C.

[0009] In one embodiment, the electrolyte includes a solvent and an electrolyte salt, and the electrolyte salt includes LiPF6.

[0010] In one embodiment, the mass fraction of LiPF6 in the electrolyte is 5-30wt%.

[0011] In one embodiment, the temperature of the constant temperature environment is -20 to -10°C.

[0012] In one embodiment, the charging and discharging are performed in a negative pressure environment.

[0013] In one embodiment, the pressure of the negative pressure environment is -20 to -80 kPa.

[0014] In one embodiment, the charging includes constant current charging with a first preset current to a first cut-off voltage.

[0015] In one embodiment, the first preset current is 0.05-0.3C.

[0016] In one embodiment, the first cut-off voltage is 4.5-5.0V.

[0017] In one embodiment, the charging further comprises constant voltage charging after the constant current charging.

[0018] In one embodiment, the constant voltage charging includes performing constant voltage charging at a first cut-off voltage until the current decreases to a first cut-off current.

[0019] In one embodiment, the first cut-off current is 0.01-0.1C.

[0020] In one embodiment, the discharging includes discharging at a second preset current to a second cut-off voltage.

[0021] In one embodiment, the second preset current is 0.05-0.3C.

[0022] In one embodiment, the second cut-off voltage is 3.0-3.6V.

[0023] In one embodiment, the number of charge and discharge is 5 to 10 times.

[0024] In one embodiment, the charging and discharging process further includes allowing the semi-solid battery to stand still after the electrolyte is injected.

[0025] In one embodiment, the standing time is 0.5 to 4 hours.

[0026] In one embodiment, the cathode material of the semi-solid state battery includes a high voltage cathode active material.

[0027] The high voltage positive electrode active material in the present invention is a positive electrode active material having a continuous decomposition voltage of not less than 4.5V.

[0028] In one embodiment, the high voltage positive electrode active material includes a high voltage lithium nickel manganese oxide positive electrode material and / or a lithium-rich manganese-based positive electrode material.

[0029] In a second aspect, the present invention provides a formed semi-solid battery, wherein the formed semi-solid battery is obtained by the formation process described in the first aspect.

[0030] In one embodiment, based on the mass fraction of the positive electrode CEI film of the semi-solid battery after formation as 100%, the mass fraction of LiF in the positive electrode CEI film is not less than 10 wt %.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] In the formation process provided by the present invention, by adopting a constant temperature formation environment with a relatively low temperature, the reaction between the electrolyte and the positive electrode can be effectively controlled. The relatively low formation temperature is conducive to reducing the reaction rate and forming a relatively continuous and dense CEI film on the surface of the positive electrode, thereby improving the high temperature cycle stability of the battery. In addition, since the formation of LiF at the positive electrode is an exothermic reaction, the relatively low formation temperature is also conducive to the reaction kinetics of LiF formation, thereby effectively improving the content of LiF in the CEI film. Therefore, the semi-solid battery after formation obtained by the formation process has excellent high temperature cycle stability.

[0033] Furthermore, multiple small current charging and discharging in a low temperature environment is beneficial to improving the continuity and density of the CEI film, improving the mechanical strength of the generated CEI film, and improving the high temperature cycle stability of the battery. DETAILED DESCRIPTION

[0034] References to embodiments of the present application will now be provided in detail, one or more examples of which are described below. Each example is provided as an explanation rather than a limitation of the present application. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the present application without departing from the scope or spirit of the present application. For example, a feature described or described as part of one embodiment may be used in another embodiment to produce a further embodiment.

[0035] Therefore, it is intended that the present application covers such modifications and variations that fall within the scope of the appended claims and their equivalents. Other objects, features and aspects of the present application are disclosed in or are apparent from the following detailed description. It will be appreciated by those of ordinary skill in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the present application.

[0036] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0037] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0038] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0039] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0040] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, it is mentioned that the method may also include step (c), which means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0041] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0042] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0043] In a first aspect, the present invention provides a formation process for a semi-solid-state battery, the formation process comprising:

[0044] The semi-solid battery after being injected with electrolyte is charged and discharged at least three times in a constant temperature environment, wherein the charging and discharging include charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0045] The electrolyte contains LiPF6; the temperature of the constant temperature environment is -30 to 3°C.

[0046] The temperature of the constant temperature environment described in the present invention is -30 to 3°C, for example, it can be -30°C, -28°C, -25°C, -22°C, -20°C, -18°C, -15°C, -12°C, -10°C, -8°C, -5°C, -3°C, 0°C or 3°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] In the formation process provided by the present invention, by adopting a constant temperature formation environment with a relatively low temperature, the reaction between the electrolyte and the positive electrode can be effectively controlled. The relatively low formation temperature is conducive to reducing the reaction rate and forming a relatively continuous and dense CEI film on the surface of the positive electrode, thereby improving the high temperature cycle stability of the battery. In addition, since the formation of LiF at the positive electrode is an exothermic reaction, the relatively low formation temperature is also conducive to the reaction kinetics of LiF formation, thereby effectively improving the content of LiF in the CEI film. Therefore, the semi-solid battery after formation obtained by the formation process has excellent high temperature cycle stability.

[0048] In one embodiment, the electrolyte includes a solvent and an electrolyte salt, and the electrolyte salt includes LiPF6.

[0049] In one embodiment, the mass fraction of LiPF6 in the electrolyte is 5 to 30wt%, for example, it can be 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 28wt% or 30wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] In one embodiment, the temperature of the constant temperature environment is -20 to -10°C, for example, it can be -20°C, -18°C, -16°C, -14°C, -12°C or -10°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] In one embodiment, the charging and discharging are performed in a negative pressure environment.

[0052] Since gas production occurs during the formation process of semi-solid batteries, a negative pressure environment is conducive to the discharge of gas produced by the semi-solid batteries, thereby preventing the semi-solid batteries from swelling.

[0053] In one embodiment, the pressure of the negative pressure environment is -20 to -80 kPa, for example, it can be -20 kPa, -30 kPa, -40 kPa, -50 kPa, -60 kPa, -70 kPa or -80 kPa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] In one embodiment, the charging includes constant current charging with a first preset current to a first cut-off voltage.

[0055] In one embodiment, the first preset current is 0.05-0.3C, for example, 0.05C, 0.08C, 0.1C, 0.2C, 0.3C, 0.4C or 0.5C, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0056] In one embodiment, the first cut-off voltage is 4.5-5.0V, for example, 4.5V, 4.6V, 4.7V, 4.8V, 4.9V or 5V, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0057] The selection of the first cut-off voltage in the present invention is related to the positive and negative electrode materials of the battery, and those skilled in the art can set it according to the selection of the positive and negative electrode materials; for example, when the positive electrode active material is lithium nickel manganese oxide, the first cut-off voltage is 4.9 to 5.0V, and the second cut-off voltage is 3.4 to 3.6V.

[0058] In one embodiment, the charging further comprises constant voltage charging after the constant current charging.

[0059] In one embodiment, the constant voltage charging includes performing constant voltage charging at a first cut-off voltage until the current decreases to a first cut-off current.

[0060] In one embodiment, the first cut-off current is 0.01-0.1C, for example, it can be 0.01C, 0.02C, 0.03C, 0.04C, 0.05C, 0.06C, 0.07C, 0.08C, 0.09C or 0.1C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0061] In one embodiment, the discharging includes discharging at a second preset current to a second cut-off voltage.

[0062] In one embodiment, the second preset current is 0.05-0.3C, for example, 0.05C, 0.1C, 0.15C, 0.2C, 0.25C or 0.3C, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0063] In one embodiment, the second cut-off voltage is 3.0-3.6V, for example, 3.0V, 3.1V, 3.2V, 3.3V, 3.4V, 3.5V or 3.6V, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0064] In one embodiment, the number of charge and discharge cycles is 5 to 10 times, for example, 5 times, 7 times, 9 times or 10 times, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0065] Furthermore, multiple small current charging and discharging in a low temperature environment is beneficial to improving the continuity and density of the CEI film, improving the mechanical strength of the generated CEI film, and improving the high temperature cycle stability of the battery.

[0066] In one embodiment, the charging and discharging process further includes allowing the semi-solid battery to stand still after the electrolyte is injected.

[0067] In one embodiment, the standing time is 0.5 to 4 hours, for example, 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours or 4 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0068] In one embodiment, the cathode material of the semi-solid state battery includes a high voltage cathode active material.

[0069] The high voltage positive electrode active material in the present invention is a positive electrode active material having a continuous decomposition voltage of not less than 4.5V.

[0070] In one embodiment, the high voltage positive electrode active material includes a high voltage lithium nickel manganese oxide positive electrode material and / or a lithium-rich manganese-based positive electrode material.

[0071] In a second aspect, the present invention provides a formed semi-solid battery, wherein the formed semi-solid battery is obtained by the formation process described in the first aspect.

[0072] In one embodiment, based on the mass fraction of the positive electrode CEI film of the semi-solid battery after formation, the mass fraction of LiF in the positive electrode CEI film is not less than 10wt%, for example, it can be 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 20wt%, 22wt%, 25wt% or 30wt%, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0073] positive electrode:

[0074] In some embodiments of the present invention, the secondary battery provided by the present invention includes a positive electrode, the positive electrode includes a positive electrode current collector and a positive electrode material layer disposed on the positive electrode current collector, and the positive electrode material layer includes a positive electrode active material. The positive electrode active material includes a compound that reversibly embeds and deintercalates lithium ions. In the present invention, the positive electrode active material includes one or a combination of high-voltage lithium nickel manganese oxide and lithium-rich manganese-based positive electrode materials.

[0075] In some embodiments of the present invention, the positive electrode material layer further includes a binder, which improves the bonding between the positive electrode active material particles and also improves the bonding between the positive electrode material layer and the positive electrode current collector.

[0076] In some embodiments of the present invention, non-limiting examples of binders include polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, and the like.

[0077] In some embodiments of the present invention, the cathode material layer includes a conductive agent to impart conductivity to the electrode. The conductive agent may include any conductive material as long as it does not cause chemical changes. Non-limiting examples of conductive materials include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., including, for example, copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives) and mixtures thereof.

[0078] In some embodiments of the present invention, the positive electrode sheet includes a positive electrode current collector. Exemplarily, the positive electrode current collector may be aluminum (Al), but is not limited thereto.

[0079] In some embodiments of the present invention, the positive electrode plate provided by the present invention further includes solid electrolyte powder for improving the ionic conductivity of the composite positive electrode. The present invention does not limit the type of solid electrolyte powder, which may be oxide solid electrolyte powder, sulfide solid electrolyte powder, or halide solid electrolyte powder. Optionally, the mass of the solid electrolyte powder accounts for 1%-20% of the mass of the positive electrode plate; preferably 5%-20%.

[0080] In some embodiments of the present invention, the positive electrode plate provided by the present invention further includes a solid electrolyte layer disposed on the surface of the positive electrode material layer.

[0081] In some embodiments of the present invention, the thickness of the positive electrode material layer in the positive electrode plate provided by the present invention is 30-400 μm, for example, 30 μm, 40 μm, 50 μm, 80 μm, 110 μm, 200 μm, 300 μm, 400 μm, preferably 50-110 μm.

[0082] Negative electrode:

[0083] In some embodiments of the present invention, the negative electrode sheet includes a current collector and a negative electrode active material layer disposed on the current collector.

[0084] In the present invention, the specific types of negative electrode active materials are not subject to specific restrictions and can be selected according to needs. Specifically, the negative electrode active material is selected from natural graphite, artificial graphite, mesophase microcarbon beads (MCMB for short), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, spinel structured lithiated TiO2-Li4Ti5O 12 , Li-Al alloy. Non-limiting examples of carbon materials include crystalline carbon, amorphous carbon and mixtures thereof. Crystalline carbon can be amorphous or flake-shaped, platelet-shaped, spherical or fibrous natural graphite or artificial graphite. Amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbide, calcined coke, etc.

[0085] In some embodiments of the present invention, metal elements and metal compounds can also be selected as negative electrode active materials, such as compounds containing metals or metalloids such as Li, Ag, Al, Bi, Cu, Ga, Ge, In, Ni, Pb, Sb, Si, Sn, Sr, and Zn.

[0086] In some embodiments of the present invention, the mass percentage of the negative electrode active material contained in the negative electrode active material layer can be 80%-99%, for example, 80%, 85%, 90%, 95%, 97%, 99%, etc., preferably 95%-97%.

[0087] In some embodiments of the present invention, the negative electrode material layer may include a binder; the binder improves the bonding between negative electrode active material particles and the bonding between the negative electrode active material and the current collector.

[0088] In some embodiments of the present invention, non-limiting examples of binders include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, and the like.

[0089] In some embodiments of the present invention, the negative electrode active material layer can be obtained by coating a negative electrode slurry on a negative electrode current collector and then drying the negative electrode slurry, wherein the negative electrode slurry includes at least a negative electrode active material and a negative electrode binder. When an aqueous solvent is used as a liquid medium for forming the negative electrode slurry, a thickener is preferably used for slurrying, and the thickener can generally be used to adjust the viscosity of the slurry.

[0090] In some embodiments of the present invention, the aforementioned thickener may be one or more of the following: carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein and salts thereof.

[0091] In some embodiments of the present invention, the mass proportion of the thickener in the negative electrode slurry can be 0.1%-5%, for example, 0.1%, 0.2%, 0.5%, 0.6%, 1%, 2%, 3%, 4%, 5%, etc., preferably 0.5%-3%, and more preferably 0.6%-2%.

[0092] In some embodiments of the present invention, the negative electrode active material layer includes a conductive material, so that the electrode has conductivity. The conductive material may include any conductive material as long as it does not cause chemical changes. Non-limiting examples of conductive materials include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., such as copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives) and mixtures thereof.

[0093] In some embodiments of the present invention, the negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0094] Diaphragm:

[0095] In some embodiments of the present invention, the lithium battery and electrochemical device of the present invention are provided with a separator between the positive electrode and the negative electrode to prevent short circuit. The material and shape of the separator used in the electrochemical device of the present invention are not particularly limited, and it can be any technology disclosed in the prior art.

[0096] In some embodiments of the present invention, the separator includes a polymer or an inorganic substance formed of a material that is stable to the electrolyte of the present application.

[0097] In some embodiments of the present invention, the separator may include a substrate layer and a surface treatment layer. The substrate layer is a non-woven fabric, a film or a composite film with a porous structure, and the material of the substrate layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide.

[0098] In some embodiments of the present invention, the separator further comprises a solid electrolyte coating.

[0099] Electrolyte:

[0100] The lithium battery and electrochemical device of the present invention also include an electrolyte.

[0101] In some embodiments of the present invention, the electrolyte includes a lithium salt and a solvent.

[0102] In some embodiments of the present invention, the lithium salt includes at least one of an organic lithium salt or an inorganic lithium salt. In some embodiments of the present invention, the lithium salt includes, but is not limited to: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), bistrifluoromethanesulfonyl imide lithium LiN(CF3SO2)2 (LiTFSI), bis(fluorosulfonyl)imide lithium Li(N(SO2F)2) (LiFSI), lithium bis(oxalate borate) LiB(C2O4)2 (LiBOB) or lithium di(oxalate borate) LiBF2(C2O4) (LiDFOB).

[0103] In some embodiments of the present invention, the solvent can be selected from one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and diethyl sulfone (ESE).

[0104] In some embodiments of the present invention, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high temperature performance, additives that improve battery low temperature performance, etc.

[0105] In some embodiments of the present invention, the aforementioned additives include at least one of 1,3-propane sultone, 1,4-butane sultone, propenyl-1,3-sultone, vinyl sulfate, 4-methyl vinyl sulfate, propenyl sulfate, saturated phosphate compounds and unsaturated phosphate compounds, tris(trimethylsilane) phosphate, tris(trimethylsilane) borate, tris(triethylsilane) borate, succinonitrile, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrinitrile, adiponitrile, pimelonitrile, suberonitrile, azelaic acid nitrile, and sebaconitrile.

[0106] Semi-solid-state batteries:

[0107] In some embodiments of the present invention, the semi-solid battery of the present invention comprises the above-mentioned positive electrode sheet, negative electrode sheet, separator, electrolyte, etc., but is not limited thereto.

[0108] In some embodiments of the present invention, the semi-solid-state battery of the present invention is made by stacking the above-mentioned positive and negative electrode sheets.

[0109] The present invention will be further described below in conjunction with the examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0110] The present invention is further described below by way of specific examples. The various chemical reagents used in the examples of the present invention are obtained through conventional commercial channels unless otherwise specified. Unless otherwise specified, the contents described below are all weight contents. Unless otherwise specified, it is understood that the process is carried out at room temperature.

[0111] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0112] Example 1

[0113] This embodiment provides a formation process of a semi-solid-state battery, the formation process comprising:

[0114] The semi-solid battery after the electrolyte injection is left to stand for 1 hour, and then the semi-solid battery after the electrolyte injection is charged and discharged 8 times in a constant temperature environment at a temperature of -20°C in a negative pressure environment at a pressure of -60 kPa, wherein the charging and discharging includes charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0115] The charging includes charging at a constant current of 0.1C to 4.9V, and then charging at a voltage of 4.9V until the current decreases to 0.05C;

[0116] The discharging includes discharging to 3.5V at a current of 0.1C;

[0117] The positive electrode material of the semi-solid battery includes a high-voltage positive electrode active material, and the high-voltage positive electrode active material is lithium nickel manganese oxide;

[0118] The electrolyte includes a solvent and an electrolyte salt, the electrolyte salt includes LiPF6, and the mass fraction of LiPF6 in the electrolyte is 15wt%.

[0119] Example 2

[0120] This embodiment provides a formation process of a semi-solid-state battery, the formation process comprising:

[0121] The semi-solid battery after the electrolyte injection is left to stand for 1 hour, and then the semi-solid battery after the electrolyte injection is charged and discharged 8 times in a constant temperature environment at a temperature of -30°C in a negative pressure environment at a pressure of -60 kPa, wherein the charging and discharging includes charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0122] The charging includes charging at a constant current of 0.1C to 4.9V, and then charging at a voltage of 4.9V until the current decreases to 0.05C;

[0123] The discharging includes discharging to 3.5V at a current of 0.1C;

[0124] The positive electrode material of the semi-solid battery includes a high-voltage positive electrode active material, and the high-voltage positive electrode active material is lithium nickel manganese oxide;

[0125] The electrolyte includes a solvent and an electrolyte salt, the electrolyte salt includes LiPF6, and the mass fraction of LiPF6 in the electrolyte is 15wt%.

[0126] Example 3

[0127] This embodiment provides a formation process of a semi-solid-state battery, the formation process comprising:

[0128] The semi-solid battery after the electrolyte injection is left to stand for 1 hour, and then the semi-solid battery after the electrolyte injection is charged and discharged 8 times in a constant temperature environment at a temperature of 3° C. in a negative pressure environment at a pressure of -60 kPa, wherein the charging and discharging includes charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0129] The charging includes charging at a constant current of 0.1C to 4.9V, and then charging at a voltage of 4.9V until the current decreases to 0.05C;

[0130] The discharging includes discharging to 3.5V at a current of 0.1C;

[0131] The positive electrode material of the semi-solid battery includes a high-voltage positive electrode active material, and the high-voltage positive electrode active material is lithium nickel manganese oxide;

[0132] The electrolyte includes a solvent and an electrolyte salt, the electrolyte salt includes LiPF6, and the mass fraction of LiPF6 in the electrolyte is 15wt%.

[0133] Example 4

[0134] This embodiment provides a formation process of a semi-solid-state battery, the formation process comprising:

[0135] The semi-solid battery after the electrolyte injection is left to stand for 1 hour, and then the semi-solid battery after the electrolyte injection is charged and discharged 8 times in a constant temperature environment at a temperature of -10°C in a negative pressure environment at a pressure of -60 kPa, wherein the charging and discharging includes charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0136] The charging includes charging at a constant current of 0.1C to 4.9V, and then charging at a voltage of 4.9V until the current decreases to 0.05C;

[0137] The discharging includes discharging to 3.5V at a current of 0.1C;

[0138] The positive electrode material of the semi-solid battery includes a high-voltage positive electrode active material, and the high-voltage positive electrode active material is lithium nickel manganese oxide;

[0139] The electrolyte includes a solvent and an electrolyte salt, the electrolyte salt includes LiPF6, and the mass fraction of LiPF6 in the electrolyte is 15wt%.

[0140] Example 5

[0141] This embodiment provides a formation process of a semi-solid-state battery, the formation process comprising:

[0142] The semi-solid battery after the electrolyte injection is left to stand for 1 hour, and then the semi-solid battery after the electrolyte injection is charged and discharged 8 times in a constant temperature environment at a temperature of 0° C. in a negative pressure environment at a pressure of -60 kPa, wherein the charging and discharging includes charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0143] The charging includes charging at a constant current of 0.1C to 4.9V, and then charging at a voltage of 4.9V until the current decreases to 0.05C;

[0144] The discharging includes discharging to 3.5V at a current of 0.1C;

[0145] The positive electrode material of the semi-solid battery includes a high-voltage positive electrode active material, and the high-voltage positive electrode active material is lithium nickel manganese oxide;

[0146] The electrolyte includes a solvent and an electrolyte salt, the electrolyte salt includes LiPF6, and the mass fraction of LiPF6 in the electrolyte is 15wt%.

[0147] Example 6

[0148] This embodiment provides a formation process of a semi-solid-state battery, the formation process comprising:

[0149] The semi-solid battery after the electrolyte injection is left to stand for 1 hour, and then the semi-solid battery after the electrolyte injection is charged and discharged 5 times in a constant temperature environment at a temperature of -10°C in a negative pressure environment at a pressure of -60 kPa, wherein the charging and discharging includes charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0150] The charging includes charging at a constant current of 0.1C to 4.9V, and then charging at a voltage of 4.9V until the current decreases to 0.05C;

[0151] The discharging includes discharging to 3.5V at a current of 0.1C;

[0152] The positive electrode material of the semi-solid battery includes a high-voltage positive electrode active material, and the high-voltage positive electrode active material is lithium nickel manganese oxide;

[0153] The electrolyte includes a solvent and an electrolyte salt, the electrolyte salt includes LiPF6, and the mass fraction of LiPF6 in the electrolyte is 15wt%.

[0154] Example 7

[0155] This embodiment provides a formation process of a semi-solid-state battery, the formation process comprising:

[0156] The semi-solid battery after the electrolyte injection is left to stand for 1 hour, and then the semi-solid battery after the electrolyte injection is charged and discharged 10 times in a constant temperature environment at a temperature of -10°C in a negative pressure environment at a pressure of -60 kPa, wherein the charging and discharging includes charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0157] The charging includes charging at a constant current of 0.1C to 4.9V, and then charging at a voltage of 4.9V until the current decreases to 0.05C;

[0158] The discharging includes discharging to 3.5V at a current of 0.1C;

[0159] The positive electrode material of the semi-solid battery includes a high-voltage positive electrode active material, and the high-voltage positive electrode active material is lithium nickel manganese oxide;

[0160] The electrolyte includes a solvent and an electrolyte salt, the electrolyte salt includes LiPF6, and the mass fraction of LiPF6 in the electrolyte is 15wt%.

[0161] Example 8

[0162] This embodiment provides a formation process of a semi-solid-state battery, the formation process comprising:

[0163] The semi-solid battery after the electrolyte injection is left to stand for 1 hour, and then the semi-solid battery after the electrolyte injection is charged and discharged three times in a constant temperature environment at a temperature of -10°C in a negative pressure environment at a pressure of -60 kPa, wherein the charging and discharging includes charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0164] The charging includes charging at a constant current of 0.1C to 4.9V, and then charging at a voltage of 4.9V until the current decreases to 0.05C;

[0165] The discharging includes discharging to 3.5V at a current of 0.1C;

[0166] The positive electrode material of the semi-solid battery includes a high-voltage positive electrode active material, and the high-voltage positive electrode active material is lithium nickel manganese oxide;

[0167] The electrolyte includes a solvent and an electrolyte salt, the electrolyte salt includes LiPF6, and the mass fraction of LiPF6 in the electrolyte is 15wt%.

[0168] Example 9

[0169] This embodiment provides a formation process of a semi-solid-state battery, the formation process comprising:

[0170] The semi-solid battery after the electrolyte injection is left to stand for 1 hour, and then the semi-solid battery after the electrolyte injection is charged and discharged 12 times in a negative pressure environment with a pressure of -60 kPa and a constant temperature environment with a temperature of -10°C, wherein the charging and discharging includes charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0171] The charging includes charging at a constant current of 0.1C to 4.9V, and then charging at a voltage of 4.9V until the current decreases to 0.05C;

[0172] The discharging includes discharging to 3.5V at a current of 0.1C;

[0173] The positive electrode material of the semi-solid battery includes a high-voltage positive electrode active material, and the high-voltage positive electrode active material is lithium nickel manganese oxide;

[0174] The electrolyte includes a solvent and an electrolyte salt, the electrolyte salt includes LiPF6, and the mass fraction of LiPF6 in the electrolyte is 15wt%.

[0175] Example 10

[0176] This embodiment provides a formation process of a semi-solid-state battery, the formation process comprising:

[0177] The semi-solid battery after the electrolyte injection is left to stand for 1 hour, and then the semi-solid battery after the electrolyte injection is charged and discharged 8 times in a constant temperature environment at a temperature of -10°C in a negative pressure environment at a pressure of -60 kPa, wherein the charging and discharging includes charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0178] The charging includes charging at a constant current of 0.1C to 4.9V, and then charging at a voltage of 4.9V until the current decreases to 0.05C;

[0179] The discharging includes discharging to 3.5V at a current of 0.1C;

[0180] The positive electrode material of the semi-solid battery includes a high-voltage positive electrode active material, and the high-voltage positive electrode active material is lithium nickel manganese oxide;

[0181] The electrolyte includes a solvent and an electrolyte salt, the electrolyte salt includes LiPF6, and the mass fraction of LiPF6 in the electrolyte is 5wt%.

[0182] Embodiment 11

[0183] This embodiment provides a formation process of a semi-solid-state battery, the formation process comprising:

[0184] The semi-solid battery after the electrolyte injection is left to stand for 1 hour, and then the semi-solid battery after the electrolyte injection is charged and discharged 8 times in a constant temperature environment at a temperature of -10°C in a negative pressure environment at a pressure of -60 kPa, wherein the charging and discharging includes charging and discharging performed sequentially, to obtain a semi-solid battery after formation;

[0185] The charging includes charging at a constant current of 0.1C to 4.9V, and then charging at a voltage of 4.9V until the current decreases to 0.05C;

[0186] The discharging includes discharging to 3.5V at a current of 0.1C;

[0187] The positive electrode material of the semi-solid battery includes a high-voltage positive electrode active material, and the high-voltage positive electrode active material is lithium nickel manganese oxide;

[0188] The electrolyte includes a solvent and an electrolyte salt, the electrolyte salt includes LiPF6, and the mass fraction of LiPF6 in the electrolyte is 30wt%.

[0189] Example 12

[0190] This embodiment provides a formation process for a semi-solid battery, which is the same as that of Embodiment 1 except that the semi-solid battery after being injected with electrolyte is charged and discharged 15 times in a constant temperature environment.

[0191] Embodiment 13

[0192] This embodiment provides a formation process for a semi-solid-state battery, which is the same as that of Embodiment 1 except that the mass fraction of LiPF6 in the electrolyte is 3 wt%.

[0193] Embodiment 14

[0194] This embodiment provides a formation process for a semi-solid-state battery, which is the same as that of Embodiment 1 except that the mass fraction of LiPF6 in the electrolyte is 40wt%.

[0195] Embodiment 15

[0196] This embodiment provides a formation process for a semi-solid-state battery, which is the same as Embodiment 1 except that the negative pressure environment is replaced by a normal pressure environment.

[0197] Example 16

[0198] This embodiment provides a formation process for a semi-solid-state battery, which is the same as Embodiment 1 except that the first preset current is replaced by 1C and the second preset current is replaced by 1C.

[0199] Embodiment 17

[0200] This embodiment provides a formation process for a semi-solid-state battery, which is the same as Embodiment 1 except that the first preset current is replaced by 0.05C and the second preset current is replaced by 0.05C.

[0201] Embodiment 18

[0202] This embodiment provides a formation process for a semi-solid-state battery, which is the same as that of Embodiment 1 except that the first preset current is replaced by 0.3C and the second preset current is replaced by 0.3C.

[0203] Comparative Example 1

[0204] This comparative example provides a formation process for a semi-solid battery, which is the same as Example 1 except that the semi-solid battery after being injected with electrolyte is charged and discharged in a constant temperature environment of -40°C.

[0205] Comparative Example 2

[0206] This comparative example provides a formation process for a semi-solid battery, which is the same as Example 1 except that the semi-solid battery injected with electrolyte is charged and discharged in a constant temperature environment at 25°C.

[0207] The semi-solid battery after the electrolyte is injected is formed by the formation process provided in the above embodiment and comparative example to obtain a formed semi-solid battery;

[0208] Characterization of LiF content in the semi-solid battery after formation: the battery was disassembled in the glove box, the recovered electrode was thoroughly washed three times with anhydrous DMC to remove any residual salt and electrolyte, and then dried in vacuum overnight, and the sample holder was transferred from the glove box to the XPS chamber under argon protection to avoid any air or moisture contamination, and the peak position of XPS was corrected by the C1S peak position and peak separation was performed, and finally the mass fraction of the positive electrode CEI film of the semi-solid battery after formation was obtained as 100%, and the mass fraction of LiF in the positive electrode CEI film is shown in Table 1;

[0209] The high temperature cycle stability test of the semi-solid-state battery after formation was carried out: at 75°C, the charge and discharge test was carried out at 0.1C / 0.1C in the voltage window of 2.8-4.3V to obtain the initial discharge capacity, 0.1C rate performance and capacity retention rate after 100 cycles as shown in Table 1.

[0210] Table 1

[0211]

[0212]

[0213] From Table 1, we can get:

[0214] (1) The semi-solid-state battery after the electrolyte is injected is formed by the formation process of the semi-solid-state battery provided in Examples 1, 3 to 7, 9 to 11 and 17, so that the mass fraction of LiF in the semi-solid-state battery after the formation is high and excellent high-temperature cycle stability is exhibited;

[0215] (2) By comparing Example 1 with Example 2, it can be seen that in the formation process provided in the present invention, the temperature of the constant temperature environment will affect the mass fraction of LiF in the semi-solid battery after formation and the high-temperature cycle stability; when the temperature of the constant temperature environment is -20 to -10°C, it is more conducive to obtaining a higher mass fraction of LiF and better high-temperature cycle stability. This is because when it is in the temperature range, it is conducive to the decomposition of LiPF6 to generate LiF, which is conducive to increasing the LiF content in the CEI film, and can ensure that the reaction rate of the LiPF6 decomposition reaction is not too low, and each reaction of generating the CEI film can proceed normally, which is conducive to forming a complete CEI film with high LiF content and good performance. It can be understood that the above is only a possible speculation on the mechanism of the technical solution of the present application, and does not constitute a limitation on the scope of protection of the present application;

[0216] (2) By comparing Example 1 with Examples 6 to 9 and 12, it can be seen that the number of times the semi-solid battery after the electrolyte is injected in the present invention is charged and discharged in a constant temperature environment will affect the mass fraction of LiF in the semi-solid battery after formation and the high-temperature cycle stability; when the number of charge and discharge is 5 to 10 times, it is more conducive to obtaining a higher mass fraction of LiF and better high-temperature cycle stability. This is because multiple charge and discharge with a small current is conducive to the decomposition of LiPF6 and the improvement of the mechanical strength of the CEI film. Too many charging times may cause the CEI film to be too thick, which is not conducive to the performance of the battery, such as the internal resistance of the battery;

[0217] (3) By comparing Example 1 with Examples 10-11 and 13-14, it can be seen that the mass fraction of LiPF6 in the electrolyte of the present invention affects the mass fraction of LiF and the high-temperature cycle stability in the semi-solid battery after formation; when the mass fraction of LiPF6 in the electrolyte is 5-30wt%, it is more conducive to obtaining a higher mass fraction of LiF and better high-temperature cycle stability;

[0218] (4) By comparing Example 1 with Example 15, it can be seen that the pressure environment during charging and discharging in the present invention affects the mass fraction of LiF in the semi-solid battery after formation and the high-temperature cycle stability; when the charging and discharging in the present invention is carried out in a negative pressure environment, since gas generation occurs during the formation process of the semi-solid battery, the negative pressure environment is conducive to the discharge of the gas generated by the semi-solid battery, thereby avoiding the swelling of the semi-solid battery;

[0219] (5) By comparing Example 1 with Examples 16 to 18, it can be seen that the charge and discharge current during charge and discharge in the present invention will affect the high-temperature cycle stability of the semi-solid battery after formation. In a low-temperature environment, charging and discharging with a smaller current (0.05 to 0.3C) is beneficial to improving the continuity and compactness of the CEI film, and is beneficial to improving the mechanical strength of the generated CEI film, which is beneficial to improving the high-temperature cycle stability of the battery;

[0220] (6) By comparing Example 1 with Comparative Examples 1 to 2, it can be seen that in the formation process provided by the present invention, by adopting a relatively low temperature constant temperature environment, the lower formation temperature is conducive to the slow decomposition of LiPF6, thereby forming a relatively continuous and dense LiF on the surface of the positive electrode, thereby improving the high temperature cycle stability of the battery; in addition, since the formation of LiF at the positive electrode is an exothermic reaction, the lower formation temperature is also conducive to the reaction kinetics of LiF formation, thereby increasing the LiF content in the CEI film; therefore, the semi-solid-state battery obtained by the formation process has excellent high temperature cycle stability.

[0221] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A formation process for a semi-solid battery, characterized in that: The chemical formation process comprises: The semi-solid battery after the electrolyte is injected is charged and discharged at least three times in a constant temperature environment, wherein the charging and discharging include charging and discharging performed sequentially to obtain a semi-solid battery after formation; The electrolyte contains LiPF6; the temperature of the constant temperature environment is -30 to 3°C.

2. The chemical formation process according to claim 1, characterized in that: The electrolyte includes a solvent and an electrolyte salt, and the electrolyte salt includes LiPF6; Preferably, the mass fraction of LiPF6 in the electrolyte is 5 to 30 wt%.

3. The chemical formation process according to claim 1 or 2, characterized in that: The temperature of the constant temperature environment is -20 to -10°C.

4. The chemical formation process according to any one of claims 1 to 3, characterized in that: The charging and discharging is carried out in a negative pressure environment; Preferably, the pressure of the negative pressure environment is -20 to -80 kPa.

5. The chemical formation process according to any one of claims 1 to 4, characterized in that: The charging includes constant current charging with a first preset current to a first cut-off voltage; Preferably, the first preset current is 0.05-0.3C; Preferably, the first cut-off voltage is 4.5-5.0V; Preferably, the charging further comprises constant voltage charging after the constant current charging; Preferably, the constant voltage charging includes performing constant voltage charging at a first cut-off voltage until the current decreases to a first cut-off current; Preferably, the first cut-off current is 0.01-0.1C.

6. The chemical formation process according to any one of claims 1 to 5, characterized in that: The discharging includes discharging with a second preset current to a second cut-off voltage; Preferably, the second preset current is 0.05-0.3C; Preferably, the second cut-off voltage is 3.0-3.6V.

7. The chemical formation process according to any one of claims 1 to 6, characterized in that: The number of charge and discharge is 5 to 10 times.

8. The chemical formation process according to any one of claims 1 to 7, characterized in that: Before the charging and discharging, the semi-solid battery after the electrolyte is injected is left to stand; Preferably, the cathode material of the semi-solid battery comprises a high voltage cathode active material; Preferably, the high voltage positive electrode active material comprises a high voltage lithium nickel manganese oxide positive electrode material and / or a lithium-rich manganese-based positive electrode material.

9. A semi-solid battery after formation, characterized in that: The semi-solid-state battery after formation is obtained by the formation process according to any one of claims 1 to 8.

10. The formed semi-solid battery according to claim 9, characterized in that: Taking the mass fraction of the positive electrode CEI film of the semi-solid battery after formation as 100%, the mass fraction of LiF in the positive electrode CEI film is not less than 10 wt %.

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