A semi-solid battery and a preparation method and application thereof

Abstract

The application provides a semi-solid battery and a preparation method and application thereof, the semi-solid battery comprises an organic positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, the surface of the organic positive electrode sheet comprises a CEI film, the surface of the negative electrode sheet comprises a SEI film, the electrolyte comprises a first lithium salt, a solvent and a diluent, and does not comprise an additive. The organic positive electrode sheet of the semi-solid battery has a CEI film itself, the negative electrode sheet has a SEI film itself, no other additive needs to be additionally added in the electrolyte of the semi-solid battery, the problems of poor flowability and low conductivity of the electrolyte of the semi-solid battery are avoided, the semi-solid battery has a high specific capacity, good rate performance and super-long cycle stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion batteries, and relates to a semi-solid battery and a preparation method and application thereof. BACKGROUND

[0002] The semi-solid battery is a battery with a semi-solid gel state of electrolyte, and is considered as one of the most promising power sources for next-generation electric vehicles and energy storage products due to its high energy density, high safety and long service life. The semi-solid battery cathode material refers to the cathode material in the semi-solid battery, which directly affects the performance and service life of the battery. Currently, commonly used semi-solid battery cathode materials include lithium cobaltate, lithium manganate, lithium iron phosphate and nickel-cobalt-manganese ternary cathode materials.

[0003] In recent years, organic cathode materials have attracted widespread attention due to their rich carbon, hydrogen and oxygen elements, renewable, green, low cost and high capacity. Among them, the conductive polymer in the organic cathode material refers to a polymer with a highly π-π conjugated polymer chain. The conductive polymer polypyrrole is applied in supercapacitors, modified electrodes of photochemical cells and electrode materials of storage batteries due to its excellent charge transport property, reversible electrochemical redox property, simple preparation, environmental friendliness and mechanical flexibility.

[0004] The common classification of polypyrrole includes: 1. Polypyrrole derivatives: In order to improve the conductivity and stability of polypyrrole, various polypyrrole derivatives are synthesized and studied in the prior art. These derivatives include doped polypyrrole, functionalized polypyrrole and the like. By introducing different functional groups or dopants into the structure of polypyrrole, the conductivity and electrochemical behavior thereof can be controlled, and the application range of pyrrole materials is expanded; 2. Polypyrrole nanofiber: In recent years, polypyrrole nanofiber has been successfully prepared by electrospinning and other methods in the prior art; 3. Pyrrole conjugated polymer: In addition to polypyrrole, common pyrrole conjugated polymers include polycarbazole, polybenzocarbazole and the like; 4. Pyrrole carbon material: By carbonization and graphitization, pyrrole materials can be converted into carbon materials with high specific surface area and excellent conductivity, such as pyrrole graphene and pyrrole carbon nanotube.

[0005] However, polypyrrole materials also have the following disadvantages: 1. Capacity attenuation: Pyrrole-based cathode materials may have capacity attenuation problems during long-term use, and their cycle life needs to be further improved; 2. Safety consideration: Since pyrrole-based cathode materials are usually organic materials, they may have safety hazards under extreme conditions such as high temperature, overcharge and overdischarge, and more stringent safety measures and management are needed; 3. Greater solubility in organic electrolyte: Since pyrrole-based cathode materials have not been stably developed in liquid lithium ion batteries, they have not been directly used as single cathode materials in semi-solid batteries.

[0006] Based on the above research, it is necessary to provide a semi-solid battery which can overcome the problems of poor electrolyte fluidity and low conductivity of the semi-solid battery electrolyte, and high specific capacity, good rate performance and super-long cycle stability of the semi-solid battery. SUMMARY

[0007] The purpose of the present application is to provide a semi-solid battery and its preparation method and application, which has a CEI film on the surface of the organic positive electrode sheet and a SEI film on the surface of the negative electrode sheet, without the need to add other additives to the electrolyte of the semi-solid battery, avoiding the problems of poor electrolyte fluidity and low conductivity of the semi-solid battery, and having high specific capacity, good rate performance and super-long cycle stability.

[0008] To achieve this purpose, the present application adopts the following technical solutions:

[0009] In a first aspect, the present application provides a semi-solid battery, which comprises an organic positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, the surface of the organic positive electrode sheet comprises a CEI film, the surface of the negative electrode sheet comprises a SEI film, the electrolyte comprises a first lithium salt, a solvent and a diluent, and does not comprise an additive.

[0010] In the semi-solid battery of the present application, the organic positive electrode sheet itself comprises a CEI film, and the negative electrode sheet itself comprises a SEI film, which can still have excellent high specific capacity, good rate performance and super-long cycle stability in the case of not including any additives in the electrolyte and having an organic positive electrode sheet, solving the problems of poor electrolyte fluidity and low conductivity of the semi-solid battery. Therefore, the present application omits all additives in the electrolyte and only contains the basic components of the electrolyte, which still does not affect the performance of the semi-solid battery, and can also improve the electrochemical performance of the semi-solid electrolyte.

[0011] Preferably, the positive electrode material of the organic positive electrode sheet comprises polypyrrole.

[0012] Preferably, the polypyrrole is formed in situ during the preparation of the organic positive electrode sheet.

[0013] Preferably, the CEI film is formed during the preparation of the organic positive electrode sheet.

[0014] The present application uses a single polypyrrole as a positive electrode material, which has strong conductivity. The polypyrrole is not directly used to prepare the organic positive electrode sheet, but is formed in situ during the preparation of the organic positive electrode sheet by in-situ polymerization, which improves the ion mobility of the polypyrrole and reduces the solubility of the electrolyte, so that the prepared polypyrrole positive electrode material has high specific capacity, good rate performance and super-long cycle stability.

[0015] Preferably, the SEI film is formed when the negative electrode sheet is prepared.

[0016] The CEI film and the SEI film of the present application are both formed when the positive electrode sheet and the negative electrode sheet are prepared, not formed after the semi-solid battery is assembled into a formed battery.

[0017] Preferably, the concentration of the first lithium salt in the electrolyte is 0.1-1 mol / L, for example, it can be 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L or 1 mol / L, but is not limited to the listed values, other values not listed within the value range are also applicable, preferably 0.1-0.5 mol / L.

[0018] The electrolyte of the present application has a lower molar ratio of lithium salt than the conventional amount without adding any additives, and even in a semi-solid battery with poor fluidity, only a lower amount is required.

[0019] Preferably, the volume ratio of the solvent and the diluent is (0.5-3):(7-9.5), for example, it can be 0.5:7, 2:8 or 3:9.5, but is not limited to the listed values, other values not listed within the value range are also applicable.

[0020] Preferably, the diluent includes a fluorine-based solvent.

[0021] Preferably, the fluorine-based solvent has weak solvating ability.

[0022] The fluorine-based solvent with weak solvating ability of the present application includes any one or a combination of at least two of bis(2,2) difluoroethyl ether, 2,2,2-trifluoroethyl methyl ether or 2,2,2-trifluoroethyl ether.

[0023] Preferably, the solvent includes an ionic liquid solvent.

[0024] Preferably, the anion of the ionic liquid solvent contains fluorine elements.

[0025] The ionic liquid solvent of the present application includes one or a combination of at least two of 1-nitrile propyl-1-methyl pyrrolidine bis(trifluoromethane sulfonate) imidate, 1-methoxyethyl-3-methyl imidazole tetrafluoroborate or ethyl tributyl phosphonium bis(trifluoromethane sulfonate) imidate. The gel component of the present application is mainly a positive electrode material, and the ionic liquid electrolyte itself has a large viscosity, similar to a gel state.

[0026] Preferably, the separator includes a base film, a first coating layer and a second coating layer, wherein the first coating layer is towards the negative electrode, and the second coating layer is towards the positive electrode.

[0027] Preferably, the first coating layer comprises a layer of acrylic glue.

[0028] Preferably, the second coating layer comprises a ceramic layer, and the ceramic layer comprises alumina.

[0029] Preferably, the thickness of the base film is 9-20 μm, for example, 9 μm, 15 μm or 20 μm, the thickness of the layer of acrylic glue is 1-2 μm, for example, 1 μm, 1.5 μm or 2 μm, and the thickness of the ceramic layer is 2-4 μm, for example, 2 μm, 3 μm or 4 μm, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0030] Preferably, the base film comprises polypropylene (PP) or polyethylene (PE).

[0031] In a second aspect, the present application provides a preparation method of the semi-solid battery according to the first aspect, and the preparation method comprises the following steps:

[0032] The organic positive electrode sheet with the surface comprising the CEI film, the separator and the negative electrode sheet with the surface comprising the SEI film are made into an electric core, and then an electrolyte is injected into the electric core to obtain the semi-solid battery.

[0033] The present application directly uses the organic positive electrode sheet with the surface comprising the CEI film and the negative electrode sheet with the surface comprising the SEI film to assemble the battery.

[0034] The method for preparing the organic positive electrode sheet with the surface comprising the CEI film comprises:

[0035] The organic positive electrode slurry is coated on the surface of the positive electrode current collector, then soaked in a first functional solution, and then dried and rolled to obtain the organic positive electrode sheet with the surface comprising the CEI film.

[0036] Preferably, the soaking temperature is 20-25℃, for example, 20℃, 22.5℃ or 25℃, and the dew point environment is -30-70℃, for example, -30℃, -10℃, 0℃, 20℃, 40℃, 60℃ or 70℃, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0037] Preferably, the soaking time is 6-48 h, for example, 6 h, 20 h, 40 h or 48 h, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0038] The soaking temperature and time of the present application affect the curing and film forming effect, if the soaking temperature is too high, the ether solvent is easy to decompose, and if the soaking temperature is too low, the soaking effect is affected, and the soaking of the present application is in a dew point environment, which can ensure that the moisture of the positive electrode and the electrolyte does not exceed the standard.

[0039] Preferably, the positive electrode current collector is an aluminum foil with a thickness of 6-12 μm, for example, it can be 6 μm, 8 μm, 10 μm or 12 μm, but is not limited to the listed values, and other unlisted values within the value range are also applicable.

[0040] Preferably, the first functional solution comprises an ether solvent and a CEI film-forming additive.

[0041] After the organic positive electrode slurry is coated, it is directly immersed in the first functional solution for curing and film formation, realizing polymerization of the pyrrole monomer and formation of the CEI film; wherein the ether reagent in the first functional solution is an oxidizing reagent, which plays a curing role, and the principle is as follows: an electrically neutral polypyrrole monomer molecule is oxidized to lose an electron under the action of the oxidizing agent (ether reagent) to become a cationic radical, and then two cationic radicals collide and combine into a dicationic dimeric pyrrole in the system, at this time the dicationic dimeric pyrrole is generated by dismutation in the system to generate an electrically neutral dimeric pyrrole; the electrically neutral dimeric pyrrole is combined with the cationic radical in the system to generate a trimeric pyrrole cationic radical, which is dismutated to generate a trimeric polypyrrole, and the process is repeated to ultimately generate a long-chain polypyrrole.

[0042] Preferably, the content of the CEI film-forming additive in the first functional solution is 0.05-2.5 wt%, for example, it can be 0.05 wt%, 0.1 wt%, 1 wt%, 1.5 wt%, 2 wt% or 2.5 wt%, but is not limited to the listed values, and other unlisted values within the value range are also applicable.

[0043] Preferably, the ether solvent comprises any one or a combination of at least two of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or tetraethylene glycol dimethyl ether.

[0044] Preferably, the CEI film-forming additive comprises any one or a combination of at least two of lithium bis(oxalato)borate, lithium tetrafluoroborate, lithium difluorophosphate, lithium difluoro(oxalato)borate, tripropargyl phosphate, N,O-bis(trimethylsilyl)trifluoroacetamide, 1-cyanopropyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt or tetrabutyl(trifluoromethanesulfonyl)imide salt.

[0045] Preferably, the first functional solution further comprises a second lithium salt.

[0046] The additional lithium salt in the first functional solution can enable the lithium salt to enter the positive electrode layer during curing, thereby improving the electrical conductivity of the organic positive electrode layer.

[0047] Preferably, the concentration of the second lithium salt in the first functional solution is 0.1-1 mol / L, for example, it can be 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.7 mol / L, 0.9 mol / L or 1 mol / L, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0048] Preferably, the second lithium salt includes any one or a combination of at least two of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide or lithium hexafluorophosphate.

[0049] Preferably, the organic positive electrode slurry includes a pyrrole-based organic monomer, a binder and a conductive agent.

[0050] Preferably, the mass ratio of the pyrrole-based organic monomer, the binder and the conductive agent is (96-99):(0.1-3):(0.1-3), for example, it can be 96:1:3, 97.5:0.5:2 or 99:0.5:0.5, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0051] Preferably, the pyrrole-based organic monomer includes any one or a combination of at least two of 2-pyrrolidone, 3-fluoro-2-pyrrolidone, pyrrolidone, pyrrole-2-carbonitrile, 3-pyrrolidone, 3-pyrroline, 2-pyrroline or 3,3,3-triphenylpyrrole acid.

[0052] Preferably, the binder includes any one or a combination of at least two of PVA (polyvinyl alcohol), PTFE (polytetrafluoroethylene) or PVDF (polyvinylidene fluoride).

[0053] Preferably, the conductive agent includes carbon black and / or conductive graphite.

[0054] Preferably, the dispersion solvent of the organic positive electrode slurry includes any one or a combination of at least two of anhydrous ethanol, N-methyl pyrrolidone or dimethylformamide.

[0055] Preferably, the method for preparing the negative electrode sheet having the surface including the SEI film includes:

[0056] Spraying the second functional solution on the surface of the negative electrode sheet, and then drying to obtain the negative electrode sheet having the surface including the SEI film.

[0057] Preferably, the second functional solution includes an SEI film-forming additive and a liquid compound.

[0058] Preferably, the content of the SEI film forming additive in the second functional solution is 0.03-0.5wt%, for example, it can be 0.03wt%, 0.05wt%, 0.1wt%, 0.2wt%, 0.3wt% or 0.5wt%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0059] The application further coats a film forming solution on the surface of the negative electrode sheet to form an SEI film, but the content of the SEI film forming additive should not be too high, otherwise the SEI film will be too thick, the impedance will increase, and if the content of the SEI film forming additive is too low, the film forming effect will decrease, which is not conducive to the improvement of the battery performance.

[0060] Preferably, the SEI film forming additive includes any one of 2-fluoropyridine, 5-fluoropyridine, hexafluorotriphosphazene, N,O-bis(trimethylsilyl) trifluoroacetamide, lithium nitrate, aluminum triflate or magnesium bis(trifluoromethylsulfonyl) imide or a combination of at least two thereof.

[0061] Preferably, the liquid compound includes any one of N-methylpyrrolidone, dimethylformamide or dimethyl sulfoxide or a combination of at least two thereof.

[0062] Preferably, the negative electrode sheet includes a copper-lithium composite tape, wherein the two-sided surface of the copper tape is provided with a lithium tape, the thickness of the copper tape is 5-8μm, for example, it can be 5μm, 6μm, 7μm or 8μm, the thickness of the single-sided lithium tape is 4-10μm, for example, it can be 4μm, 6μm, 8μm or 10μm, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0063] The drying of the organic positive electrode sheet and the negative electrode sheet is carried out in an environment with a dew point of-45℃ or lower, for example, it can be-45℃, -50℃, -55℃ or-60℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0064] As a preferred technical scheme of the semi-solid state battery, the preparation method includes the following steps:

[0065] (1) coating an organic positive electrode slurry on the surface of a positive electrode current collector, then soaking in a first functional solution, and then drying and rolling to obtain an organic positive electrode sheet with a CEI film on the surface;

[0066] The first functional solution includes an ether solvent, 0.05-2.5wt% of a CEI film forming additive and 0.1-1mol / L of a second lithium salt, and the ether solvent includes any one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or tetraethylene glycol dimethyl ether or a combination of at least two thereof.

[0067] The organic positive electrode paste comprises a pyrrole organic monomer, a binder and a conductive agent in a mass ratio of (96-99):(0.1-3):(0.1-3);

[0068] (2) spraying a second functional solution on the surface of the negative electrode sheet, and then drying to obtain the negative electrode sheet with the surface comprising the SEI film;

[0069] The second functional solution comprises an SEI film-forming additive and a liquid compound, and the content of the SEI film-forming additive is 0.03-0.5wt%;

[0070] (3) assembling an electric core by using the organic positive electrode sheet with the surface comprising the CEI film of step (1), the separator and the negative electrode sheet with the surface comprising the SEI film of step (2), and then injecting an electrolyte into the electric core to obtain the semi-solid battery.

[0071] In a third aspect, the present application provides an electronic device comprising the semi-solid battery of the first aspect.

[0072] Compared with the prior art, the present application has the following beneficial effects:

[0073] The semi-solid battery of the present application has the surface of the organic positive electrode sheet comprising the CEI film and the surface of the negative electrode sheet comprising the SEI film before assembly. The organic positive electrode with the CEI film and the negative electrode with the SEI film can avoid the problems of poor electrolyte flowability and low conductivity of the semi-solid battery without adding any additives, so that the semi-solid battery has high specific capacity, good rate performance and ultra-long cycle stability. DETAILED DESCRIPTION

[0074] The technical solutions of the present application will be further described through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations on the present application.

[0075] Embodiment 1

[0076] The present embodiment provides a semi-solid battery, which comprises an organic positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, the surface of the organic positive electrode sheet comprises a CEI film, and the surface of the negative electrode sheet comprises an SEI film; the electrolyte comprises a first lithium salt, a solvent and a diluent, and does not comprise an additive, wherein the concentration of the first lithium salt is 0.2mol / L, the first lithium salt is lithium hexafluorophosphate, the diluent is bis(2,2) difluoroethyl ether, the solvent is 1-nitrile propyl-1-methyl pyrrolidine bis(trifluoromethane sulfonate) imidate, and the volume ratio of the solvent to the diluent is 2:8.1;

[0077] The positive electrode material of the organic positive electrode sheet comprises polypyrrole, the polypyrrole is in-situ polymerized to form during preparation of the organic positive electrode sheet, the CEI film is formed during preparation of the organic positive electrode sheet; and the SEI film is formed during preparation of the negative electrode sheet;

[0078] The separator comprises a polypropylene-based film, a acrylic adhesive layer of the polypropylene-based film facing the negative electrode sheet, a ceramic layer of the polypropylene-based film facing the organic positive electrode sheet, the thickness of the polypropylene-based film is 9 μm, the thickness of the acrylic adhesive layer is 1 μm, and the ceramic layer is an aluminum oxide ceramic layer with a thickness of 3 μm;

[0079] The preparation method of the semi-solid-state battery comprises the following steps:

[0080] (1) coating an organic positive electrode slurry on the surface of an aluminum foil with a thickness of 6 μm, then soaking in a first functional solution, the soaking temperature is 22℃, the dew point environment is -20℃, the soaking time is 11 h, then drying overnight at -45℃ dew point environment for 24 h, and finally rolling to obtain the organic positive electrode sheet with the surface comprising a CEI film;

[0081] The first functional solution comprises an ether solvent, 0.1wt% of a CEI film-forming additive, and 0.5 mol / L of a second lithium salt, the ether solvent is tetraethylene glycol dimethyl ether, the CEI film-forming additive is tripropargyl phosphate, and the second lithium salt is lithium bis(trifluoromethanesulfonyl)imide;

[0082] The organic positive electrode slurry comprises 3-pyrrolidone, PTFE, and conductive graphite at a mass ratio of 97:1:2, and the dispersion solvent of the organic positive electrode slurry is dimethylformamide;

[0083] (2) ultrasonic spraying (using an ultrasonic sprayer, model MSK-SP-01A) a second functional solution on the surface of the negative electrode sheet, then drying overnight at -45℃ dew point environment to obtain the negative electrode sheet with the surface comprising a SEI film, wherein the negative electrode sheet is a copper-lithium composite tape, lithium tapes are arranged on the double sides of the copper tape, the thickness of the copper tape is 6 μm, and the thickness of the single-side lithium tape is 10 μm;

[0084] The second functional solution comprises a SEI film-forming additive and dimethylformamide, the content of the SEI film-forming additive is 0.05wt%, and the SEI film-forming additive is bis(trifluoromethanesulfonyl)imide magnesium;

[0085] (3) stacking the organic positive electrode sheet with the surface comprising a CEI film of step (1), the separator, and the negative electrode sheet with the surface comprising a SEI film of step (2) through a lamination process to obtain a lithium metal battery with three positive electrodes and four negative electrodes, and a capacity of 1600 mAh, then injecting an electrolyte into the battery cell to obtain the semi-solid-state battery.

[0086] Example 2

[0087] The embodiment provides a semi-solid battery, which comprises an organic positive electrode sheet, a negative electrode sheet, a diaphragm and an electrolyte, a surface of the organic positive electrode sheet comprises a CEI film, a surface of the negative electrode sheet comprises an SEI film; the electrolyte comprises a first lithium salt, a solvent and a diluent, and does not comprise an additive, wherein the concentration of the first lithium salt is 0.5 mol / L, the first lithium salt is lithium hexafluorophosphate, the diluent is 2,2,2-trifluoroethyl methyl ether, the solvent is 1-methoxyethyl-3-methyl imidazole tetrafluoroborate, and the volume ratio of the solvent to the diluent is 0.5:9.5;

[0088] The positive electrode material of the organic positive electrode sheet comprises polypyrrole, the polypyrrole is formed in situ during preparation of the organic positive electrode sheet, and the CEI film is formed during preparation of the organic positive electrode sheet; and the SEI film is formed during preparation of the negative electrode sheet;

[0089] The diaphragm comprises a polypropylene-based film, a layer of acrylic glue of the polypropylene-based film faces the negative electrode sheet, a ceramic layer of the polypropylene-based film faces the organic positive electrode sheet, the thickness of the polypropylene-based film is 9 μm, the thickness of the layer of acrylic glue is 2 μm, and the ceramic layer is an aluminum oxide ceramic layer with a thickness of 4 μm;

[0090] The preparation method of the semi-solid battery comprises the following steps:

[0091] (1) coating an organic positive electrode slurry on the surface of an aluminum foil with a thickness of 6 μm, then soaking in a first functional solution, the soaking temperature is 25 ℃, the dew point environment is-30 ℃, the soaking time is 48 h, then drying overnight at-45 ℃ dew point environment for 24 h, and finally rolling to obtain the organic positive electrode sheet with the surface comprising the CEI film;

[0092] The first functional solution comprises an ether solvent, 0.3 wt% of a CEI film-forming additive and 1 mol / L of a second lithium salt, the ether solvent is ethylene glycol dimethyl ether, and the CEI film-forming additive is N,O-bis(trimethylsilyl) trifluoroacetamide;

[0093] The organic positive electrode slurry comprises 2-pyrrolidone, PTFE and conductive graphite at a mass ratio of 97:1:2, and the dispersion solvent of the organic positive electrode slurry is dimethylformamide;

[0094] (2) ultrasonic spraying (using an ultrasonic sprayer, model MSK-SP-01A) a second functional solution on the surface of the negative electrode sheet, then drying overnight at-45 ℃ dew point environment to obtain the negative electrode sheet with the surface comprising the SEI film, wherein the negative electrode sheet is a copper-lithium composite strip, lithium strips are arranged on the two surfaces of a copper strip, the thickness of the copper strip is 6 μm, and the thickness of a single lithium strip is 10 μm;

[0095] The second functional solution comprises SEI film-forming additives and dimethylformamide, the content of the SEI film-forming additives is 0.03wt%, and the SEI film-forming additives are aluminum triflate;

[0096] (3) The organic positive electrode sheet, the separator and the negative electrode sheet with the surface comprising the SEI film obtained in step (2) are stacked into a lithium metal battery with a capacity of 1600 mAh through a lamination process, and then the electrolyte is injected into the battery cell to obtain the semi-solid battery.

[0097] Embodiment 3

[0098] The embodiment provides a semi-solid battery, which comprises an organic positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, the surface of the organic positive electrode sheet comprises a CEI film, the surface of the negative electrode sheet comprises an SEI film, the electrolyte comprises a first lithium salt, a solvent and a diluent, and does not comprise an additive, wherein the concentration of the first lithium salt is 0.1 mol / L, the first lithium salt is lithium hexafluorophosphate, the diluent is 2,2,2-trifluoroethanol, the solvent is ethyl tributyl phosphonium bis(trifluoromethanesulfonyl) imide salt, and the volume ratio of the solvent to the diluent is 3:7.

[0099] The positive electrode material of the organic positive electrode sheet comprises polypyrrole, the polypyrrole is polymerized in situ to form during preparation of the organic positive electrode sheet, and the CEI film is formed during preparation of the organic positive electrode sheet; and the SEI film is formed during preparation of the negative electrode sheet.

[0100] The separator comprises a polypropylene-based film, a acrylic adhesive layer of the polypropylene-based film facing the negative electrode sheet, and a ceramic layer of the polypropylene-based film facing the organic positive electrode sheet, the thickness of the polypropylene-based film is 10 μm, the thickness of the acrylic adhesive layer is 1 μm, and the ceramic layer is an aluminum oxide ceramic layer with a thickness of 2 μm.

[0101] The preparation method of the semi-solid battery comprises the following steps:

[0102] (1) Organic positive electrode slurry is coated on the surface of an aluminum foil with a thickness of 6 μm, then soaked in a first functional solution, the soaking temperature is 25℃, the dew point environment is 70℃, the soaking time is 6 h, then dried overnight for 24 h in an environment with a dew point below-45℃, and finally rolled to obtain the organic positive electrode sheet with the surface comprising the CEI film;

[0103] The first functional solution comprises an ether solvent, 2.5wt% of CEI film-forming additives and 0.1 mol / L of a second lithium salt, the ether solvent is tetraethylene glycol dimethyl ether, the CEI film-forming additives comprise tripropargyl phosphate, and the second lithium salt comprises lithium bis(trifluoromethanesulfonyl) imide.

[0104] The organic positive electrode slurry comprises 3-pyrrolidone, PTFE and conductive graphite in a mass ratio of 97:1:2, and the dispersion solvent of the organic positive electrode slurry is dimethylformamide;

[0105] (2) ultrasonic spraying (using an ultrasonic sprayer, model MSK-SP-01A) the second functional solution on the surface of the negative electrode sheet, and then drying overnight in an environment below a dew point of -45℃ to obtain the negative electrode sheet with the surface comprising an SEI film, wherein the negative electrode sheet is a copper-lithium composite tape, lithium tapes are arranged on both surfaces of the copper tape, the thickness of the copper tape is 6 μm, and the thickness of the single-sided lithium tape is 10 μm;

[0106] The second functional solution comprises an SEI film-forming additive and dimethylformamide, the content of the SEI film-forming additive is 0.5 wt%, and the SEI film-forming additive is magnesium bis(trifluoromethylsulfonyl)imide, aluminum trifluoromethanesulfonate;

[0107] (3) stacking the organic positive electrode sheet with the surface comprising a CEI film in step (1), the separator and the negative electrode sheet with the surface comprising an SEI film in step (2) into three positive and four negative through a lamination process to obtain a lithium metal battery with a capacity of 1600 mAh, and then injecting the electrolyte into the battery cell to obtain the semi-solid battery.

[0108] Example 4

[0109] The present embodiment provides a semi-solid battery, which is the same as that in Example 1 except that the 3-pyrrolidone (molecular weight 85.104) in step (1) is replaced by poly-pyrrolidone (molecular weight 111.14) in the preparation method of the semi-solid battery.

[0110] Example 5

[0111] The present embodiment provides a semi-solid battery, which is the same as that in Example 1 except that the ether solvent in step (1) is replaced by an ester solvent, i.e. ethyl acetate, in the preparation method of the semi-solid battery.

[0112] Example 6

[0113] The present embodiment provides a semi-solid battery, which is the same as that in Example 1 except that the second lithium salt is not contained in the first functional solution in step (1) in the preparation method of the semi-solid battery.

[0114] Example 7

[0115] The present example provides a semi-solid battery, which is the same as example 1 except that the soaking time in step (1) of the preparation method is 3h, and the semi-solid battery is changed accordingly.

[0116] Example 8

[0117] The present example provides a semi-solid battery, which is the same as example 1 except that the soaking time in step (1) of the preparation method is 52h, and the semi-solid battery is changed accordingly.

[0118] Example 9

[0119] The present example provides a semi-solid battery, which is the same as example 1 except that the content of the SEI film forming additive in step (2) of the preparation method is 0.01wt%, and the semi-solid battery is changed accordingly.

[0120] Example 10

[0121] The present example provides a semi-solid battery, which is the same as example 1 except that the content of the SEI film forming additive in step (2) of the preparation method is 0.7wt%, and the semi-solid battery is changed accordingly.

[0122] Comparative Example 1

[0123] The present comparative example provides a semi-solid battery, which is the same as example 1 except that the organic positive electrode slurry coating in step (1) of the preparation method is directly dried without soaking in the first functional solution, and the semi-solid battery is changed accordingly.

[0124] Comparative Example 2

[0125] The present comparative example provides a semi-solid battery, which is the same as example 1 except that the negative electrode sheet in step (2) of the preparation method is not sprayed, and the semi-solid battery is changed accordingly.

[0126] Comparative Example 3

[0127] The present comparative example provides a semi-solid battery, which is the same as example 1 except that the electrolyte contains 0.1wt% CEI film forming additive and 0.05wt% SEI film forming additive, and in the preparation method, the first functional solution in step (1) does not contain CEI film forming additive, and step (2) is not sprayed, and the semi-solid battery is changed accordingly.

[0128] The electrochemical performance of the semi-solid-state batteries obtained in the above examples and comparative examples was tested under the following conditions:

[0129] First efficiency: Charge the battery at 25℃ with a constant current of 0.05C to 1.8V, then charge it at a constant current of 0.2C to 2.8V, and then charge it at a constant voltage of 2.8V until the cutoff current is 0.05C. Then discharge the battery at a constant current of 0.1C to 1.7V. First efficiency = discharge capacity / charge capacity * 100%.

[0130] Capacity retention rate / %: Charge the battery at 0.2C constant current to 2.8V at 25℃, charge at 2.8V constant voltage to the cutoff current of 0.05C, and then discharge the battery at 0.2C constant current to 1.7V; the discharge capacity is recorded as C1. Repeat the charge and discharge steps N times to obtain the discharge capacity CN of the Nth cycle. The capacity retention rate of the Nth cycle = CN / C1*100%. The coulombic efficiency of the Nth cycle / %: discharge capacity of the Nth cycle / charge capacity of the Nth cycle *100%.

[0131] The average Coulomb efficiency for the first N laps is the average Coulomb efficiency for the first N laps.

[0132] Note: If the capacity retention rate of the above semi-solid-state battery is less than 80% and the coulombic efficiency is less than 98% during cycle testing, the battery test will be stopped.

[0133] The test results are shown in the table below:

[0134] Table 1

[0135]

[0136]

[0137] As can be seen from the table above:

[0138] (1) The semi-solid battery obtained by the present invention has excellent performance, with an initial efficiency of over 92%, a capacity retention rate of over 98% after 50 cycles, an average coulombic efficiency of over 99.5% after the first 50 cycles, a capacity retention rate of over 88.5% after the 150th cycle, and an average coulombic efficiency of over 99.5% after the first 150 cycles. As can be seen from Example 1 and Comparative Examples 1-2, when step (1) is not soaked or step (2) is not sprayed, the organic positive or negative electrode sheet itself does not have a CEI film or SEI film, and no additives are added to the electrolyte. Therefore, the performance of the obtained battery is greatly reduced. As can be seen from Example 1 and Comparative Example 3, the CEI film-forming additive and SEI film-forming additive of the present invention are added directly to the electrolyte. However, due to factors such as limited fluidity of the electrolyte, the film-forming effect during battery use is low.

[0139] (2) from example 1 and example 4, it can be known that, compared with directly using polypyrrole, the in-situ polymerization of polypyrrole in the application can make electrolyte components also enter the electrode during polymerization, solve the problem of poor infiltration of semi-solid gel electrolyte, and in general, the in-situ polymerization has stronger lithium ion transmission capacity than the way of directly using polypyrrole, thereby the battery performance can be improved; from example 1 and example 5, it can be known that the ether solvent selected by the application is an oxidizing solvent, which can make pyrrole monomers polymerize, thereby in-situ generate polypyrrole, and realize the technical effect of in-situ generating polypyrrole; from example 1 and example 6, it can be known that the application further adds lithium salt in the first functional solution, thereby the performance of the organic positive electrode sheet can be further improved; from example 7-8, it can be known that the soaking time of the application will affect the curing and film forming effect; from example 1 and example 9-10, it can be known that the content of the negative SEI film forming additive in the second functional solution will also affect the film forming effect, thereby affecting the battery performance.

[0140] In summary, the application provides a semi-solid battery and a preparation method and application thereof, the organic positive electrode sheet of the semi-solid battery itself has a CEI film, and the negative electrode sheet itself has a SEI film, without the need to additionally add an additive in the electrolyte of the semi-solid battery, the problems of poor electrolyte flowability and low conductivity of the semi-solid battery are avoided, the semi-solid battery has higher specific capacity, good rate performance and super-long cycle stability.

[0141] The above only describes specific embodiments of the application, but the protection scope of the application is not limited thereto, and those skilled in the art should understand that any changes or replacements within the technical scope disclosed by the application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the application.

Claims

1. A semi-solid battery, characterized by, The semi-solid battery comprises an organic positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, the surface of the organic positive electrode sheet comprises a CEI film, the surface of the negative electrode sheet comprises a SEI film, the electrolyte comprises a first lithium salt, a solvent and a diluent, and does not comprise an additive; The CEI film is formed when the organic positive electrode sheet is prepared, the SEI film is formed when the negative electrode sheet is prepared, and is formed after a formation battery is formed without being assembled into a semi-solid battery; The positive electrode material of the organic positive electrode sheet comprises polypyrrole; The polypyrrole is polymerized in situ to form when the organic positive electrode sheet is prepared; The method for preparing the negative electrode sheet with the surface comprising a SEI film comprises: Spraying a second functional solution on the surface of the negative electrode sheet, and then drying to obtain the negative electrode sheet with the surface comprising a SEI film; The second functional solution comprises a SEI film-forming additive and a liquid compound; The SEI film-forming additive comprises any one or a combination of at least two of 2-fluoropyridine, 5-fluoropyridine, hexafluorotriphosphazene, N,O-bis(trimethylsilyl) trifluoroacetamide, lithium nitrate, aluminum triflate or bis(trifluoromethylsulfonyl) magnesium imide.

2. The semi-solid battery of claim 1, wherein The concentration of the first lithium salt in the electrolyte is 0.1-1 mol / L.

3. The semi-solid battery of claim 2, wherein, The concentration of the first lithium salt in the electrolyte is 0.1-0.5 mol / L.

4. The semi-solid battery of claim 1, wherein The volume ratio of the solvent to the diluent is (0.5-3):(7-9.5).

5. The semi-solid battery of claim 1, wherein The diluent comprises a fluorine-based solvent.

6. The semi-solid battery of claim 5, wherein, The fluorine-based solvent has weak solvating ability.

7. The semi-solid battery of claim 1, wherein, The solvent comprises an ionic liquid solvent.

8. The semi-solid battery of claim 7, wherein, The anion of the ionic liquid solvent contains fluorine elements.

9. The semi-solid battery of claim 1, wherein, The separator comprises a base film, a first coating layer and a second coating layer, wherein the first coating layer faces the negative electrode, and the second coating layer faces the positive electrode.

10. The semi-solid battery of claim 9, wherein, The first coating layer comprises an acrylic adhesive layer.

11. The semi-solid battery of claim 9, wherein, The second coating layer comprises a ceramic layer.

12. A method of producing the semi-solid battery according to claim 1, characterized by, The preparation method comprises the following steps: The organic positive electrode sheet with the surface comprising a CEI film, the separator and the negative electrode sheet with the surface comprising a SEI film are made into an electric core, and then the electrolyte is injected into the electric core to obtain the semi-solid battery; The method for preparing the negative electrode sheet with the surface comprising a SEI film comprises: Spraying a second functional solution on the surface of the negative electrode sheet, and then drying to obtain the negative electrode sheet with the surface comprising a SEI film; The second functional solution comprises a SEI film-forming additive and a liquid compound; The SEI film-forming additive comprises any one or a combination of at least two of 2-fluoropyridine, 5-fluoropyridine, hexafluorotriphosphazene, N,O-bis(trimethylsilyl) trifluoroacetamide, lithium nitrate, aluminum triflate or bis(trifluoromethylsulfonyl) magnesium imide.

13. The method of claim 12, wherein, The method for preparing the organic positive electrode sheet with the surface comprising a CEI film comprises: The organic positive electrode slurry is coated on the surface of the positive electrode current collector, then soaked in a first functional solution, and then dried and rolled to obtain the organic positive electrode sheet with the surface comprising a CEI film.

14. The method of claim 13, wherein, The soaking temperature is 20-25℃, the dew point environment is -30-70℃, and the time is 6-48h.

15. The preparation method according to claim 13, characterized in that, The first functional solution comprises an ether-based solvent and a CEI film-forming additive.

16. The method of claim 15, wherein, The content of the CEI film-forming additive in the first functional solution is 0.05-2.5wt%.

17. The preparation method according to claim 15, characterized in that, The ether solvent includes any one or a combination of at least two of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or tetraethylene glycol dimethyl ether.

18. The method of claim 15, wherein, The CEI film-forming additive includes any one or a combination of at least two of lithium bisoxalate borate, lithium tetrafluoroborate, lithium difluorophosphate, lithium difluoro oxalate borate, tripropargyl phosphate, N,O-bis(trimethylsilyl) trifluoroacetamide, 1-cyanopropyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide or tetrabutyl (trifluoromethanesulfonyl) imide.

19. The method of claim 15, wherein, The first functional solution further includes a second lithium salt.

20. The method of claim 19, wherein, The concentration of the second lithium salt in the first functional solution is 0.1-1 mol / L.

21. The method of claim 19, wherein, The second lithium salt includes any one or a combination of at least two of lithium bis(trifluoromethanesulfonyl) imide, lithium bis(fluorosulfonyl) imide or lithium hexafluorophosphate.

22. The method of claim 13, wherein, The organic positive electrode slurry includes a pyrrole organic monomer, a binder and a conductive agent.

23. The method of claim 22, wherein, The mass ratio of the pyrrole organic monomer, the binder and the conductive agent is (96-99):(0.1-3):(0.1-3).

24. The method of claim 22, wherein, The pyrrole organic monomer includes any one or a combination of at least two of 2-pyrrolidone, 3-fluoro-2-pyrrolidone, pyrrolidone, pyrrole-2-carbonitrile, 3-pyrrolidone, 3-pyrroline, 2-pyrroline or 3,3,3-triphenylpyrrole acid.

25. The method of claim 13, wherein, The dispersion solvent of the organic positive electrode slurry includes any one or a combination of at least two of anhydrous ethanol, N-methyl pyrrolidone or dimethylformamide.

26. The method of claim 12, wherein, The content of the SEI film-forming additive in the second functional solution is 0.03-0.5 wt%.

27. The method of claim 12, wherein, The liquid compound includes any one or a combination of at least two of N-methyl pyrrolidone, dimethylformamide or dimethyl sulfoxide.

28. The method of claim 12, wherein, The negative electrode sheet includes a copper lithium composite tape, wherein both sides of a copper tape are provided with lithium tapes, the thickness of the copper tape is 5-8 μm, and the thickness of a single-side lithium tape is 4-10 μm.

29. The method of claim 12, wherein, The preparation method includes the following steps: (1) coating the organic positive electrode slurry on the surface of the positive electrode current collector, then soaking in the first functional solution, and then drying and rolling to obtain the organic positive electrode sheet with the surface including the CEI film; wherein the first functional solution includes an ether solvent, 0.05-2.5 wt% of the CEI film-forming additive and 0.1-1 mol / L of the second lithium salt, and the ether solvent includes any one or a combination of at least two of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or tetraethylene glycol dimethyl ether; the organic positive electrode slurry includes a pyrrole organic monomer, a binder and a conductive agent, and the mass ratio of the pyrrole organic monomer, the binder and the conductive agent is (96-99):(0.1-3):(0.1-3); (2) spraying the second functional solution on the surface of the negative electrode sheet, and then drying to obtain the negative electrode sheet with the surface including the SEI film; wherein the second functional solution includes the SEI film-forming additive and a liquid compound, and the content of the SEI film-forming additive is 0.03-0.5 wt%. (3) the organic positive electrode sheet of step (1) comprising a surface of a CEI film, the separator, and the negative electrode sheet of step (2) comprising a surface of a SEI film are made into an electric core, and then an electrolyte is injected into the electric core to obtain the semi-solid battery.

30. An electronic device, comprising: The electronic device comprises the semi-solid battery according to any one of claims 1-11.

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