Preparation method of electrode with polymer solid electrolyte and lithium battery

Abstract

The invention provides a preparation method of an electrode with a polymer solid electrolyte and a lithium battery, and the preparation method comprises the following steps: S1, adding an adhesive and a conductive agent into an electrode material, dissolving in N-methyl pyrrolidone, and mixing and stirring to form slurry; and S2, coating a current collector with the slurry to form a pole piece. And S3, drying the coated pole piece, then rolling the pole piece, and recording the pole piece as a marked pole piece. S4, adding a lithium salt into the polymer to form a first solution; uniformly stirring and mixing the first solution, and adding an initiator to obtain a precursor solution; and S5, adding a surfactant into the precursor solution to form an active precursor solution. And S6, dropwise adding the active precursor solution on the marked electrode plate, and carrying out high-temperature standing operation on the marked electrode plate for 5-300min in a temperature range of 30-100 DEG C to obtain the electrode with the polymer solid electrolyte.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a method for preparing an electrode with a polymer solid electrolyte and a lithium battery. Background Art

[0002] With the continuous development of society, the market demand for battery performance continues to increase, especially for energy density and safety performance. The energy density of current system batteries is becoming more and more extreme. As a more cutting-edge battery system, solid-state batteries can replace the diaphragms and electrolytes used in current batteries, thereby greatly improving the energy density of batteries. Compared with liquid batteries, solid-state batteries have stronger safety performance, but the solid-solid interface between the electrode and the electrolyte will produce a large resistance, which will have a negative effect on the transmission of ions during battery charging and discharging. The traditional method of in-situ polymerization can greatly reduce the interface resistance between the electrode and the electrolyte, but there is still a certain gap compared to the liquid state, and for conventional in-situ polymerization, there is almost no contact between the electrolyte and the active material close to the foil, which will also cause the internal resistance of the battery to increase. Therefore, solid-state batteries made by traditional in-situ polymerization methods have the technical problem of poor battery performance.

[0003] Therefore, it is necessary to provide a method for preparing an electrode with a polymer solid electrolyte and a lithium battery to solve the above technical problems. Summary of the invention

[0004] The present invention provides a method for preparing an electrode with a polymer solid electrolyte and a lithium battery, which effectively solves the technical problem of poor battery performance of solid batteries made by traditional in-situ polymerization methods.

[0005] The present invention provides a method for preparing an electrode having a polymer solid electrolyte, which comprises the following steps:

[0006] S1: adding a binder and a conductive agent to the electrode material, dissolving them in N-methylpyrrolidone, mixing and stirring to form a slurry, wherein the mass ratio of the electrode material, the conductive agent and the binder is 97:1:2, and the N-methylpyrrolidone accounts for 30%-40% of the mass of the slurry;

[0007] S2: applying the slurry on a current collector to form a pole piece;

[0008] S3: drying the coated electrode, then rolling the electrode, and marking the electrode as a marked electrode;

[0009] S4: adding lithium salt to the polymer to form a first solution, wherein the molar ratio of the lithium salt concentration to the first solution is 0.3-2.2 mol / L, stirring and mixing the first solution evenly, and then adding an initiator to obtain a precursor solution, wherein the amount of the initiator accounts for 0.5%-15% of the total mass of the lithium salt and the polymer;

[0010] S5: adding a surfactant to the precursor solution to form an active precursor solution, wherein the mass of the surfactant accounts for 0.05%-5% of the mass of the active precursor solution;

[0011] S6: dripping the active precursor solution onto the marking electrode, and subjecting the marking electrode to a high temperature static operation for 5-300 min in a temperature range of 30-100° C. to obtain an electrode with a polymer solid electrolyte.

[0012] In the method for preparing an electrode with a polymer solid electrolyte described in the present invention, the electrode material is a positive electrode material, and the positive electrode material is composed of one or more of lithium cobalt oxide, lithium iron phosphate or a mixture of ternary materials.

[0013] In the method for preparing an electrode with a polymer solid electrolyte described in the present invention, the electrode material is a negative electrode material, and the negative electrode material is a mixture of one or more of graphite, silicon, silicon oxide, lithium titanate, etc.

[0014] In the method for preparing an electrode with a polymer solid electrolyte described in the present invention, the current collector is a positive electrode current collector, and the positive electrode current collector is any one of aluminum foil, composite aluminum foil, and corroded aluminum foil.

[0015] In the method for preparing an electrode with a polymer solid electrolyte described in the present invention, the current collector is a negative electrode current collector, and the negative electrode current collector is a copper foil.

[0016] In the preparation method of the electrode with polymer solid electrolyte described in the present invention, the polymer is composed of a mixture of one or more of polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, butyl acrylate, ethylene glycol methyl ether acrylate, polyethylene glycol methyl ether, triethylene glycol diacrylate, pentaerythritol tetraacrylate, vinylene carbonate, vinyl ethylene carbonate, propylene carbonate, trimethylene carbonate, 1,3,5-trioxane, etc.

[0017] In the method for preparing an electrode with a polymer solid electrolyte described in the present invention, the lithium salt is a mixture of one or more of lithium difluorooxalate, lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide), lithium difluorobis(oxalyl)phosphate, lithium hexafluorophosphate, and the like.

[0018] In the method for preparing an electrode with a polymer solid electrolyte of the present invention, the initiator is composed of a mixture of one or more of azobisisobutyronitrile and aluminum trifluoromethanesulfonate.

[0019] In the preparation method of the electrode with polymer solid electrolyte described in the present invention, the surfactant is composed of a mixture of one or more of stearic acid, sodium dodecylbenzene sulfonate, quaternary ammonium, amino acid type, fatty acid glyceride, fatty alcohol polyoxyacetic acid ether lithium sulfate, alkylbenzene sulfonate lithium, alkyl glycerol ether sulfonate lithium, perfluoroalkyl polyoxyethylene alcohol surfactants, etc.

[0020] A lithium battery comprises an electrode having a polymer solid electrolyte prepared by any one of the above preparation methods.

[0021] Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a method for preparing a lithium battery containing a polymer solid electrolyte, and the preparation method can add a certain amount of surfactant to the precursor solution. The surfactant can reduce the surface tension of the liquid, so that the active precursor solution is easy to infiltrate into the electrode. Therefore, when the initiator initiates polymerization, the electrolyte can take into account the electrode close to the foil side. Therefore, compared with the conventional method, the preparation method can increase the transmission speed of ions in the electrode, thereby effectively improving the performance of the battery. The technical problem of poor battery performance of solid-state batteries made by traditional in-situ polymerization methods is effectively solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. The drawings described below are only drawings corresponding to some embodiments of the present invention.

[0023] Figure 1 The present invention is a process flow chart of the method for preparing an electrode having a polymer solid electrolyte of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the invention will be described in detail below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the invention and are not used to limit the scope of the invention. After reading the invention, various equivalent forms of modifications to the invention made by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0025] The terms "first", "second", etc. in the present invention are used for descriptive purposes only and should not be understood as indicating or implying relative importance, and should not be used as a limitation on the order of precedence.

[0026] The present invention provides a method for preparing an electrode having a polymer solid electrolyte, which comprises the following steps:

[0027] S1: adding a binder and a conductive agent to the electrode material, dissolving them in N-methylpyrrolidone, mixing and stirring to form a slurry, wherein the mass ratio of the electrode material, the conductive agent and the binder is 97:1:2, and the N-methylpyrrolidone accounts for 30%-40% of the mass of the slurry;

[0028] S2: applying the slurry on the current collector to form a pole piece;

[0029] S3: drying the coated electrode, then rolling the electrode, and marking the electrode as a marked electrode;

[0030] S4: adding lithium salt to the polymer to form a first solution, wherein the molar ratio of the lithium salt concentration to the first solution is 0.3-2.2 mol / L, stirring and mixing the first solution evenly, and then adding an initiator to obtain a precursor solution, wherein the amount of the initiator accounts for 0.5%-15% of the total mass of the lithium salt and the polymer;

[0031] S5: adding a surfactant to the precursor solution to form an active precursor solution, wherein the mass of the surfactant accounts for 0.05%-5% of the mass of the active precursor solution;

[0032] S6: dropping the active precursor solution onto the marking electrode, and placing the marking electrode at a high temperature within a temperature range of 30-100° C. for 5-300 minutes to obtain an electrode having a polymer solid electrolyte.

[0033] In the present invention, the electrode material is a positive electrode material, and the positive electrode material is composed of one or more mixtures of lithium cobalt oxide, lithium iron phosphate or ternary materials.

[0034] In the present invention, the electrode material is a negative electrode material, and the negative electrode material is a mixture of one or more of graphite, silicon, silicon oxide, lithium titanate, etc.

[0035] In the present invention, the current collector is a positive electrode current collector, and the positive electrode current collector is any one of aluminum foil, composite aluminum foil, and corroded aluminum foil.

[0036] In the present invention, the current collector is a negative electrode current collector, and the negative electrode current collector is a copper foil.

[0037] In the present invention, the polymer is composed of a mixture of one or more of polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, butyl acrylate, ethylene glycol methyl ether acrylate, polyethylene glycol methyl ether, triethylene glycol diacrylate, pentaerythritol tetraacrylate, vinylene carbonate, vinyl ethylene carbonate, propylene carbonate, trimethylene carbonate, 1,3,5-trioxane, etc.

[0038] In the present invention, the lithium salt is composed of a mixture of one or more of lithium difluorooxalate, lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide), lithium difluorobis(oxalyl)phosphate, lithium hexafluorophosphate and the like.

[0039] In the present invention, the initiator is a mixture of one or more of azobisisobutyronitrile and aluminum trifluoromethanesulfonate.

[0040] In the present invention, the surfactant is a mixture of one or more of stearic acid, sodium dodecylbenzene sulfonate, quaternary ammonium compounds, amino acids, fatty acid glycerides, fatty alcohol polyoxyacetic acid ether lithium sulfate, alkylbenzene sulfonate lithium, alkyl glycerol ether sulfonate lithium, perfluoroalkyl polyoxyethylene alcohol surfactants, etc.

[0041] The present invention also provides a lithium battery, which comprises an electrode having a polymer solid electrolyte prepared by any of the above preparation methods, wherein the electrode can be a positive electrode of the lithium battery, or the electrode can also be a negative electrode of the lithium battery.

[0042] The following are preferred embodiments of the method for preparing the electrode having a polymer solid electrolyte, wherein Embodiment 1 is as follows:

[0043] Step S1 is to add a binder and a conductive agent to lithium cobalt oxide, dissolve them in N-methyl pyrrolidone, mix and stir to form a slurry, wherein the mass ratio of lithium cobalt oxide, conductive agent and binder is 97:1:2, and N-methyl pyrrolidone accounts for 30%-40% of the mass of the slurry.

[0044] Step S2 is to apply the slurry on the aluminum foil to form a pole piece.

[0045] Step S3 is to dry the coated electrode, then roll the electrode, and mark the electrode as the first marked electrode;

[0046] Step S4 is adding lithium hexafluorophosphate to ethylene glycol dimethacrylate to form a first solution, wherein the molar ratio of the lithium hexafluorophosphate concentration to the first solution is 1.2 mol / L, stirring and mixing the first solution evenly, and then adding azobisisobutyronitrile to obtain a precursor solution, wherein the amount of azobisisobutyronitrile accounts for 3% of the total mass of lithium hexafluorophosphate and ethylene glycol dimethacrylate;

[0047] Step S5 is to add a surfactant to the precursor solution to form a first active precursor solution. In this embodiment, the mass of the surfactant accounts for 0% of the mass of the active precursor solution.

[0048] Step S6 is to drip the first active precursor solution onto the first marking electrode, and to perform a high temperature static operation on the first marking electrode at a temperature range of 80° C. for 30 minutes to obtain an electrode with a polymer solid electrolyte, and mark the electrode as the first electrode.

[0049] The positive electrode of the lithium battery is prepared by the above-mentioned preparation method, and the negative electrode of the lithium battery is prepared by metallic lithium. Therefore, the positive electrode and the negative electrode can be used to assemble the first solid-state battery.

[0050] Example 2 is as follows,

[0051] Step S1 is to add a binder and a conductive agent to lithium cobalt oxide, dissolve them in N-methyl pyrrolidone, mix and stir to form a slurry, wherein the mass ratio of lithium cobalt oxide, conductive agent and binder is 97:1:2, and N-methyl pyrrolidone accounts for 30%-40% of the mass of the slurry.

[0052] Step S2 is to apply the slurry on the aluminum foil to form a pole piece.

[0053] Step S3 is to dry the coated electrode, then roll the electrode, and mark the electrode as the second marked electrode;

[0054] Step S4 is adding lithium hexafluorophosphate to ethylene glycol dimethacrylate to form a first solution, wherein the molar ratio of the lithium hexafluorophosphate concentration to the first solution is 1.2 mol / L, stirring and mixing the first solution evenly, and then adding azobisisobutyronitrile to obtain a precursor solution, wherein the amount of azobisisobutyronitrile accounts for 3% of the total mass of lithium hexafluorophosphate and ethylene glycol dimethacrylate;

[0055] Step S5 is to add a surfactant to the precursor solution to form a second active precursor solution. In this embodiment, the mass of the surfactant accounts for 0.05% of the mass of the active precursor solution.

[0056] Step S6 is to drip the second active precursor solution onto the second marking electrode, and to perform a high temperature static operation on the second marking electrode at a temperature range of 80° C. for 30 minutes to obtain an electrode with a polymer solid electrolyte, and mark the electrode as the second electrode.

[0057] The positive electrode of the lithium battery is prepared by the above-mentioned preparation method, and the negative electrode of the lithium battery is prepared by metallic lithium. Therefore, the positive electrode and the negative electrode can be used to assemble the second solid-state battery.

[0058] Example 3 is as follows,

[0059] Step S1 is to add a binder and a conductive agent to lithium cobalt oxide, dissolve them in N-methyl pyrrolidone, mix and stir to form a slurry, wherein the mass ratio of lithium cobalt oxide, conductive agent and binder is 97:1:2, and N-methyl pyrrolidone accounts for 30%-40% of the mass of the slurry.

[0060] Step S2 is to apply the slurry on the aluminum foil to form a pole piece.

[0061] Step S3 is to dry the coated electrode, then roll the electrode, and mark the electrode as a third marked electrode;

[0062] Step S4 is adding lithium hexafluorophosphate to ethylene glycol dimethacrylate to form a first solution, wherein the molar ratio of the lithium hexafluorophosphate concentration to the first solution is 1.2 mol / L, stirring and mixing the first solution evenly, and then adding azobisisobutyronitrile to obtain a precursor solution, wherein the amount of azobisisobutyronitrile accounts for 3% of the total mass of lithium hexafluorophosphate and ethylene glycol dimethacrylate;

[0063] Step S5 is to add a surfactant to the precursor solution to form a third active precursor solution. In this embodiment, the mass of the surfactant accounts for 0.2% of the mass of the active precursor solution.

[0064] Step S6 is to drop the third active precursor solution onto the third marking electrode, and to perform a high temperature static operation on the third marking electrode at a temperature range of 80° C. for 30 minutes to obtain an electrode with a polymer solid electrolyte, and mark the electrode as the third electrode.

[0065] The positive electrode of the lithium battery is prepared by the above-mentioned preparation method, and the negative electrode of the lithium battery is prepared by metallic lithium. Therefore, the positive electrode and the negative electrode can be used to assemble the third solid-state battery.

[0066] Example 4 is as follows,

[0067] Step S1 is to add a binder and a conductive agent to lithium cobalt oxide, dissolve them in N-methyl pyrrolidone, mix and stir to form a slurry, wherein the mass ratio of lithium cobalt oxide, conductive agent and binder is 97:1:2, and N-methyl pyrrolidone accounts for 30%-40% of the mass of the slurry.

[0068] Step S2 is to apply the slurry on the aluminum foil to form a pole piece.

[0069] Step S3 is to dry the coated electrode piece, then roll the electrode piece, and mark the electrode piece as the fourth marked electrode piece;

[0070] Step S4 is adding lithium hexafluorophosphate to ethylene glycol dimethacrylate to form a first solution, wherein the molar ratio of the lithium hexafluorophosphate concentration to the first solution is 1.2 mol / L, stirring and mixing the first solution evenly, and then adding azobisisobutyronitrile to obtain a precursor solution, wherein the amount of azobisisobutyronitrile accounts for 3% of the total mass of lithium hexafluorophosphate and ethylene glycol dimethacrylate;

[0071] Step S5 is to add a surfactant to the precursor solution to form a fourth active precursor solution. In this embodiment, the mass of the surfactant accounts for 0.7% of the mass of the active precursor solution.

[0072] Step S6 is to drop the fourth active precursor solution onto the fourth marking electrode, and to perform a high temperature static operation on the fourth marking electrode at a temperature range of 80° C. for 30 minutes to obtain an electrode with a polymer solid electrolyte, and mark the electrode as the fourth electrode.

[0073] The positive electrode of the lithium battery is prepared by the above-mentioned preparation method, and the negative electrode of the lithium battery is prepared by metallic lithium. Therefore, the positive electrode and the negative electrode can be used to assemble the fourth solid-state battery.

[0074] Example 5 is as follows,

[0075] Step S1 is to add a binder and a conductive agent to lithium cobalt oxide, dissolve them in N-methyl pyrrolidone, mix and stir to form a slurry, wherein the mass ratio of lithium cobalt oxide, conductive agent and binder is 97:1:2, and N-methyl pyrrolidone accounts for 30%-40% of the mass of the slurry.

[0076] Step S2 is to apply the slurry on the aluminum foil to form a pole piece.

[0077] Step S3 is to dry the coated electrode, then roll the electrode, and mark the electrode as the fifth marked electrode;

[0078] Step S4 is adding lithium hexafluorophosphate to ethylene glycol dimethacrylate to form a first solution, wherein the molar ratio of the lithium hexafluorophosphate concentration to the first solution is 1.2 mol / L, stirring and mixing the first solution evenly, and then adding azobisisobutyronitrile to obtain a precursor solution, wherein the amount of azobisisobutyronitrile accounts for 3% of the total mass of lithium hexafluorophosphate and ethylene glycol dimethacrylate;

[0079] Step S5 is to add a surfactant to the precursor solution to form a fifth active precursor solution. In this embodiment, the mass of the surfactant accounts for 1% of the mass of the active precursor solution.

[0080] Step S6 is to drop the fifth active precursor solution onto the fifth marked electrode, and to perform a high temperature static operation on the fifth marked electrode at a temperature range of 80° C. for 30 minutes to obtain an electrode with a polymer solid electrolyte, and mark the electrode as the fifth electrode.

[0081] The positive electrode of the lithium battery is prepared by the above-mentioned preparation method, and the negative electrode of the lithium battery is prepared by metallic lithium. Therefore, the positive electrode and the negative electrode can be used to assemble the fifth solid-state battery.

[0082] Example 6 is as follows,

[0083] Step S1 is to add a binder and a conductive agent to lithium cobalt oxide, dissolve them in N-methyl pyrrolidone, mix and stir to form a slurry, wherein the mass ratio of lithium cobalt oxide, conductive agent and binder is 97:1:2, and N-methyl pyrrolidone accounts for 30%-40% of the mass of the slurry.

[0084] Step S2 is to apply the slurry on the aluminum foil to form a pole piece.

[0085] Step S3 is to dry the coated electrode, then roll the electrode, and mark the electrode as the sixth marked electrode;

[0086] Step S4 is adding lithium hexafluorophosphate to ethylene glycol dimethacrylate to form a first solution, wherein the molar ratio of the lithium hexafluorophosphate concentration to the first solution is 1.2 mol / L, stirring and mixing the first solution evenly, and then adding azobisisobutyronitrile to obtain a precursor solution, wherein the amount of azobisisobutyronitrile accounts for 3% of the total mass of lithium hexafluorophosphate and ethylene glycol dimethacrylate;

[0087] Step S5 is to add a surfactant to the precursor solution to form a sixth active precursor solution. In this embodiment, the mass of the surfactant accounts for 2% of the mass of the active precursor solution.

[0088] Step S6 is to drop the sixth active precursor solution onto the sixth marked electrode, and to perform a high temperature static operation on the sixth marked electrode at a temperature range of 80° C. for 30 minutes to obtain an electrode with a polymer solid electrolyte, and mark the electrode as the sixth electrode.

[0089] The positive electrode of the lithium battery is prepared by the above-mentioned preparation method, and the negative electrode of the lithium battery is prepared by metallic lithium. Therefore, the positive electrode and the negative electrode can be used to assemble the sixth solid-state battery.

[0090] Example 7 is as follows,

[0091] Step S1 is to add a binder and a conductive agent to lithium cobalt oxide, dissolve them in N-methyl pyrrolidone, mix and stir to form a slurry, wherein the mass ratio of lithium cobalt oxide, conductive agent and binder is 97:1:2, and N-methyl pyrrolidone accounts for 30%-40% of the mass of the slurry.

[0092] Step S2 is to apply the slurry on the aluminum foil to form a pole piece.

[0093] Step S3 is to dry the coated electrode, then roll the electrode, and mark the electrode as the seventh marked electrode;

[0094] Step S4 is adding lithium hexafluorophosphate to ethylene glycol dimethacrylate to form a first solution, wherein the molar ratio of the lithium hexafluorophosphate concentration to the first solution is 1.2 mol / L, stirring and mixing the first solution evenly, and then adding azobisisobutyronitrile to obtain a precursor solution, wherein the amount of azobisisobutyronitrile accounts for 3% of the total mass of lithium hexafluorophosphate and ethylene glycol dimethacrylate;

[0095] Step S5 is to add a surfactant to the precursor solution to form a seventh active precursor solution. In this embodiment, the mass of the surfactant accounts for 3% of the mass of the active precursor solution.

[0096] Step S6 is to drip the seventh active precursor solution onto the seventh marked electrode, and to perform a high temperature static operation on the seventh marked electrode at a temperature range of 80° C. for 30 minutes to obtain an electrode with a polymer solid electrolyte, and mark the electrode as the seventh electrode.

[0097] The positive electrode of the lithium battery is prepared by the above-mentioned preparation method, and the negative electrode of the lithium battery is prepared by metallic lithium. Therefore, the positive electrode and the negative electrode can be used to assemble the seventh solid-state battery.

[0098] Example 8 is as follows,

[0099] Step S1 is to add a binder and a conductive agent to lithium cobalt oxide, dissolve them in N-methyl pyrrolidone, mix and stir to form a slurry, wherein the mass ratio of lithium cobalt oxide, conductive agent and binder is 97:1:2, and N-methyl pyrrolidone accounts for 30%-40% of the mass of the slurry.

[0100] Step S2 is to apply the slurry on the aluminum foil to form a pole piece.

[0101] Step S3 is to dry the coated electrode piece, then roll the electrode piece, and mark the electrode piece as the eighth marked electrode piece;

[0102] Step S4 is adding lithium hexafluorophosphate to ethylene glycol dimethacrylate to form a first solution, wherein the molar ratio of the lithium hexafluorophosphate concentration to the first solution is 1.2 mol / L, stirring and mixing the first solution evenly, and then adding azobisisobutyronitrile to obtain a precursor solution, wherein the amount of azobisisobutyronitrile accounts for 3% of the total mass of lithium hexafluorophosphate and ethylene glycol dimethacrylate;

[0103] Step S5 is to add a surfactant to the precursor solution to form an eighth active precursor solution. In this embodiment, the mass of the surfactant accounts for 4% of the mass of the active precursor solution.

[0104] Step S6 is to drop the eighth active precursor solution onto the eighth marked electrode, and to perform a high temperature static operation on the eighth marked electrode at a temperature range of 80° C. for 30 minutes to obtain an electrode with a polymer solid electrolyte, and mark the electrode as the eighth electrode.

[0105] The positive electrode of the lithium battery is prepared by the above-mentioned preparation method, and the negative electrode of the lithium battery is prepared by metallic lithium. Therefore, the positive electrode and the negative electrode can be used to assemble the eighth solid-state battery.

[0106] Example 9 is as follows,

[0107] Step S1 is to add a binder and a conductive agent to lithium cobalt oxide, dissolve them in N-methyl pyrrolidone, mix and stir to form a slurry, wherein the mass ratio of lithium cobalt oxide, conductive agent and binder is 97:1:2, and N-methyl pyrrolidone accounts for 30%-40% of the mass of the slurry.

[0108] Step S2 is to apply the slurry on the aluminum foil to form a pole piece.

[0109] Step S3 is to dry the coated electrode, then roll the electrode, and mark the electrode as the ninth marked electrode;

[0110] Step S4 is adding lithium hexafluorophosphate to ethylene glycol dimethacrylate to form a first solution, wherein the molar ratio of the lithium hexafluorophosphate concentration to the first solution is 1.2 mol / L, stirring and mixing the first solution evenly, and then adding azobisisobutyronitrile to obtain a precursor solution, wherein the amount of azobisisobutyronitrile accounts for 3% of the total mass of lithium hexafluorophosphate and ethylene glycol dimethacrylate;

[0111] Step S5 is to add a surfactant to the precursor solution to form a ninth active precursor solution. In this embodiment, the mass of the surfactant accounts for 5% of the mass of the active precursor solution.

[0112] Step S6 is to drip the ninth active precursor solution onto the ninth marked electrode, and to perform a high temperature static operation on the ninth marked electrode at a temperature range of 80° C. for 30 minutes to obtain an electrode with a polymer solid electrolyte, and mark the electrode as the ninth electrode.

[0113] The positive electrode of the lithium battery is prepared by the above-mentioned preparation method, and the negative electrode of the lithium battery is prepared by metallic lithium. Therefore, the positive electrode and the negative electrode can be used to assemble the ninth solid-state battery.

[0114] The relationship between the mass of the surfactant in the active precursor solution and the surface tension is shown in Table 1.

[0115]

[0116] Table 1

[0117] The present invention conducts cycle performance experiments on the solid-state batteries of Examples 1 to 9 under EIS characterization and 1C charge and discharge in a voltage range of 3-4.35V and an environment of 25°C, wherein EIS is electrochemical impedance spectroscopy, which is an electrochemical characterization method for analyzing and studying the surface behavior of the electrode kinetic process of the system by measuring the change of the impedance of the target system with a given sinusoidal wave frequency. The experimental results are shown in Table 2:

[0118]

[0119]

[0120] Table 2

[0121] It can be seen from Table 1 that, compared with no surfactant added, after adding a certain proportion of surfactant, the surface tension of the electrode is reduced, so the electrolyte and the active material can be in better contact. As a result, the transmission speed of ions in the electrode can be increased, thereby effectively improving the performance of the battery. In addition, the greater the mass of the surfactant in the active precursor solution, the smaller the surface tension of the electrode. The standard for high battery performance of lithium batteries is set to a surface tension of less than or equal to 18, that is, when the mass of the surfactant in the active precursor solution is 1%, 2%, 3%, 4%, and 5%, the standard is met.

[0122] It can be seen from Table 2 that when the cycle performance is 300 cycles, the best cycle performance can be improved by 5.8 percentage points. When the mass of the surfactant accounts for 0.05% of the mass of the active precursor solution and exceeds 3%, the cycle performance deteriorates to a certain extent. When the mass of the surfactant accounts for 5% of the mass of the active precursor solution, it deteriorates by 3.3% compared to no surfactant added. Therefore, in combination with Table 1 and Table 2, the mass of the surfactant accounts for 1% of the mass of the active precursor solution, that is, Example 5 is a preferred embodiment. Therefore, the performance of the solid-state battery in Example 5 is the best.

[0123] Moreover, for the solution system with extremely low surface tension, the amount of surfactant added can be adjusted, and the mass of the surfactant can account for 0.05% of the mass of the active precursor solution. In addition, the active precursor solution containing 0.05% surfactant is compared with the active precursor solution without surfactant, and the battery performance of the two lithium batteries is compared. Subsequently, experiments with other mass fractions of surfactant are carried out.

[0124] The present invention provides a method for preparing a lithium battery containing a polymer solid electrolyte, wherein a certain amount of surfactant can be added to a precursor solution. The surfactant can reduce the surface tension of the liquid, thereby making it easy for the active precursor solution to be infiltrated in the electrode. Therefore, when the initiator initiates polymerization, the electrolyte can take into account the electrode close to the foil side. Therefore, compared with conventional methods, the preparation method can increase the transmission speed of ions in the electrode, thereby effectively improving the performance of the battery. The technical problem of poor battery performance of solid-state batteries made by traditional in-situ polymerization methods is effectively solved.

[0125] In summary, although the present invention has been disclosed as above in terms of preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A method for preparing an electrode having a polymer solid electrolyte, characterized in that: The following steps are included: S1: adding a binder and a conductive agent to the electrode material, dissolving them in N-methylpyrrolidone, mixing and stirring to form a slurry, wherein the mass ratio of the electrode material, the conductive agent and the binder is 97:1:2, and the N-methylpyrrolidone accounts for 30%-40% of the mass of the slurry; S2: applying the slurry on a current collector to form a pole piece; S3: drying the coated electrode, then rolling the electrode, and marking the electrode as a marked electrode; S4: adding lithium salt to the polymer to form a first solution, wherein the molar ratio of the lithium salt concentration to the first solution is 0.3-2.2 mol / L, stirring and mixing the first solution evenly, and then adding an initiator to obtain a precursor solution, wherein the amount of the initiator accounts for 0.5%-15% of the total mass of the lithium salt and the polymer; S5: adding a surfactant to the precursor solution to form an active precursor solution, wherein the mass of the surfactant accounts for 0.05%-5% of the mass of the active precursor solution; S6: dripping the active precursor solution onto the marking electrode, and subjecting the marking electrode to a high temperature static operation for 5-300 min in a temperature range of 30-100° C. to obtain an electrode with a polymer solid electrolyte.

2. The method for preparing an electrode having a polymer solid electrolyte according to claim 1, characterized in that: The electrode material is a positive electrode material, and the positive electrode material is composed of one or more of lithium cobalt oxide, lithium iron phosphate or a ternary material.

3. The method for preparing an electrode having a polymer solid electrolyte according to claim 1, characterized in that: The electrode material is a negative electrode material, and the negative electrode material is a mixture of one or more of graphite, silicon, silicon oxide, lithium titanate, etc.

4. The method for preparing an electrode having a polymer solid electrolyte according to claim 1, characterized in that: The current collector is a positive electrode current collector, and the positive electrode current collector is any one of aluminum foil, composite aluminum foil, and corroded aluminum foil.

5. The method for preparing an electrode having a polymer solid electrolyte according to claim 1, characterized in that: The current collector is a negative electrode current collector, and the negative electrode current collector is copper foil.

6. The method for preparing an electrode having a polymer solid electrolyte according to claim 1, characterized in that: The polymer is composed of one or more of polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, butyl acrylate, ethylene glycol methyl ether acrylate, polyethylene glycol methyl ether, triethylene glycol diacrylate, pentaerythritol tetraacrylate, vinylene carbonate, vinyl ethylene carbonate, propylene carbonate, trimethylene carbonate, 1,3,5-trioxane, etc.

7. The method for preparing an electrode having a polymer solid electrolyte according to claim 1, characterized in that: The lithium salt is composed of a mixture of one or more of lithium difluorooxalate, lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide), lithium difluorobis(oxalyl)phosphate, lithium hexafluorophosphate, and the like.

8. The method for preparing an electrode having a polymer solid electrolyte according to claim 1, characterized in that: The initiator is composed of a mixture of one or more of azobisisobutyronitrile and aluminum trifluoromethanesulfonate.

9. The method for preparing an electrode having a polymer solid electrolyte according to claim 1, characterized in that: The surfactant is a mixture of one or more of stearic acid, sodium dodecylbenzene sulfonate, quaternary ammonium compounds, amino acids, fatty acid glycerides, fatty alcohol polyoxyacetic acid ether lithium sulfate, alkylbenzene sulfonate lithium, alkyl glycerol ether sulfonate lithium, perfluoroalkyl polyoxyethylene alcohol surfactants, and the like.

10. A lithium battery, characterized in that: The invention comprises an electrode having a polymer solid electrolyte prepared by the preparation method according to any one of claims 1 to 9.

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