Solid-state battery and preparation method thereof

Abstract

The invention provides a solid-state battery and a preparation method thereof. The preparation method of the solid-state battery comprises the following steps that a positive plate, a negative plate and a diaphragm are obtained, a positive slurry layer is attached to the positive plate, the positive slurry layer comprises a lithium-rich agent, a positive active material, a porous solid-state electrolyte, a positive binder and a conductive agent, a negative slurry layer is attached to the negative plate, and the negative slurry layer comprises a lithium-rich agent, a negative active material, a porous solid-state electrolyte and a conductive agent; the negative electrode slurry layer is coated with a porous solid electrolyte layer; laminating the positive plate, the diaphragm and the negative plate into a shell, so that the positive plate and the negative plate are separately arranged through the diaphragm and are accommodated in the battery shell together; injecting an electrolyte into the battery shell to carry out infiltration solid-state treatment, so that the electrolyte is adsorbed on the positive plate, the diaphragm and the porous solid-state electrolyte layer; and packaging and forming the battery shell to obtain the solid-state battery. According to the preparation method of the solid-state battery, the impedance of the battery can be well reduced, so that the rate capability and the temperature rise performance of the battery are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a solid-state battery and a preparation method thereof. Background Art

[0002] In a solid-state battery, a solid electrolyte is used instead of an electrolyte solution. For example, in the invention patent application with the application number CN202410129968.8, a lithium supplementation layer, an active layer, and an electrolyte layer are sequentially formed on at least one side surface of a current collector. The electrolyte layer is formed on the active layer by coating. However, the process requirements for coating the electrolyte layer on the active layer are relatively high. Otherwise, there is likely to be a situation where there is partial non-adhesive contact between the electrolyte layer and the active layer, which will result in a relatively high impedance of the battery and affect the rate performance and temperature rise performance of the battery.

[0003] In order to reduce the influence on the rate performance and temperature rise performance of the battery, currently, a solid electrolyte is compounded with a slurry and coated on the current collector together. For example, in the invention patent application with the application number CN202311321485.X, but the addition of the solid electrolyte greatly reduces the energy density of the battery, and the preparation of its solid electrolyte still requires the positive electrode slurry layer to contact the solid electrolyte layer on the separator to form a solid-state battery. Thus, there is still a poor local fitting effect between the positive electrode slurry layer and the solid electrolyte layer, which in turn results in a relatively high impedance of the battery and affects the rate performance and temperature rise performance of the battery. Summary of the Invention

[0004] An object of the present invention is to overcome the deficiencies in the prior art and provide a solid-state battery and a preparation method thereof that can better reduce the impedance of the battery, thereby ensuring the rate performance and temperature rise performance of the battery.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] A preparation method of a solid-state battery includes the following steps:

[0007] Obtain a positive electrode sheet, a negative electrode sheet, and a separator. Among them, a positive electrode slurry layer is attached to the positive electrode sheet. The positive electrode slurry layer includes a lithium-rich agent, a positive electrode active material, a porous solid electrolyte, a positive electrode binder, and a conductive agent. A negative electrode slurry layer is attached to the negative electrode sheet, and a porous solid electrolyte layer is coated on the negative electrode slurry layer;

[0008] Perform a lamination and casing process on the positive electrode sheet, the separator, and the negative electrode sheet, so that the positive electrode sheet and the negative electrode sheet are separated by the separator and are accommodated in a battery casing together;

[0009] Inject an electrolyte solution into the battery casing for wetting and solidifying treatment, so that the electrolyte solution is adsorbed on the positive electrode sheet, the separator, and the porous solid electrolyte layer;

[0010] The battery housing is encapsulated and formed to obtain a solid-state battery.

[0011] In one embodiment, the positive electrode paste layer comprises the following components in parts by mass:

[0012] Lithium-rich agent: 3 to 5 parts;

[0013] Positive electrode active material: 88 to 92 parts;

[0014] Porous solid electrolyte: 6 to 10 parts;

[0015] Positive electrode binder: 1 to 2 parts;

[0016] Conductive agent: 0.5 to 1.5 parts.

[0017] In one embodiment, the lithium-rich agent is lithium-rich lithium nickelate and / or lithium-rich lithium ferrate.

[0018] In one embodiment, the positive electrode active material is at least one of lithium manganate, lithium nickel cobalt manganate, lithium iron phosphate, lithium manganese iron phosphate, lithium cobaltate, and lithium nickel cobalt aluminate.

[0019] In one embodiment, the positive electrode binder is at least one of polyvinylidene fluoride, polyvinylpyrrolidone, polymethyl methacrylate, polyacrylonitrile, and polytetrafluoroethylene.

[0020] In one embodiment, the porous solid electrolyte layer comprises the following components in parts by mass:

[0021] Porous solid electrolyte: 55 to 70 parts;

[0022] Conductive agent: 8 to 30 parts;

[0023] Negative electrode binder: 8 to 25 parts.

[0024] In one embodiment, the porous solid electrolyte is porous lithium titanium aluminum phosphate, porous lithium lanthanum titanium oxide, porous lithium lanthanum zirconium oxide, or porous lithium polyphosphide sulfide.

[0025] In one embodiment, the conductive agent is at least one of carbon black, conductive graphite, carbon nanotubes, and graphene.

[0026] In one embodiment, the particle size D50 of the porous solid electrolyte is ≤270 nm.

[0027] In one embodiment, the negative electrode binder is styrene-butadiene rubber.

[0028] In one embodiment, the thickness of the positive electrode paste layer is 230 μm to 290 μm.

[0029] In one embodiment, the areal density of the positive electrode paste layer is 450 g / m 2 ~550 g / m 2 .

[0030] In one embodiment, the particle size D50 of the lithium-rich agent is 500 nm to 1 μm.

[0031] In one embodiment, the thickness of the porous solid electrolyte layer is 0.8 μm to 2 μm.

[0032] In one embodiment, the positive electrode paste layer is obtained by coating a positive electrode paste on a positive electrode sheet;

[0033] The preparation method of the positive electrode paste comprises the following steps:

[0034] Obtain a porous solid electrolyte dispersion and a lithium-rich agent;

[0035] Perform gas flow dispersion treatment on the lithium-rich agent so that the lithium-rich agent is in a dispersed state under the action of the gas flow;

[0036] Perform ultrasonic atomization coating operation on the lithium-rich agent in the dispersed state with the porous solid electrolyte dispersion so that the porous solid electrolyte dispersion is ultrasonically atomized and dispersed, and is carried by the gas to the surface of the lithium-rich agent and coated on the lithium-rich agent to obtain a coated lithium-rich agent;

[0037] Add a positive electrode active material, a positive electrode binder, and a conductive agent to the coated lithium-rich agent and perform a mixing operation to obtain the positive electrode paste.

[0038] A solid-state battery is prepared by the preparation method of the solid-state battery according to any one of the above embodiments.

[0039] Compared with the prior art, the present invention has at least the following advantages:

[0040] The preparation method of the solid-state battery of the present invention enables the positive electrode paste attached to the positive electrode sheet to contain a lithium-rich agent and a porous solid electrolyte, and a porous solid electrolyte layer is attached to the negative electrode paste layer of the negative electrode sheet. Furthermore, in combination with the injected electrolyte, the electrolyte is fully adsorbed in the positive electrode paste layer, the separator, and the porous solid electrolyte layer, and there is actually no flowable electrolyte in the battery case, realizing the preparation of the solid-state battery. Moreover, the electrolyte and the porous solid electrolyte cooperate to achieve sufficient contact between the positive electrode sheet, the separator, and the negative electrode sheet, and form a channel conducive to lithium ion conduction, preferably realizing a reduction in the impedance of the battery, and further effectively improving the rate performance and temperature rise performance of the solid-state battery. Brief Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.

[0042] Figure 1 It is a flowchart of a preparation method of a solid-state battery according to an embodiment of the present invention. Detailed Embodiments

[0043] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0044] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may also be a middle element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a middle element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only embodiment.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0046] The present application provides a method for preparing a solid-state battery. The method for preparing the solid-state battery includes the following steps: obtaining a positive electrode sheet, a negative electrode sheet, and a separator, wherein a positive electrode paste layer is attached to the positive electrode sheet, and the positive electrode paste layer includes a lithium-rich agent, a positive electrode active material, a porous solid electrolyte, a positive electrode binder, and a conductive agent; a negative electrode paste layer is attached to the negative electrode sheet, and a porous solid electrolyte layer is coated on the negative electrode paste layer; laminating the positive electrode sheet, the separator, and the negative electrode sheet into a battery case, so that the positive electrode sheet and the negative electrode sheet are separated by the separator and are disposed together in the battery case; injecting an electrolyte into the battery case for wetting and solidifying treatment, so that the electrolyte is adsorbed on the positive electrode sheet, the separator, and the porous solid electrolyte layer; packaging and forming the battery case to obtain a solid-state battery.

[0047] In the above method for preparing a solid-state battery, the positive electrode paste attached to the positive electrode sheet contains a lithium-rich agent and a porous solid electrolyte, and a porous solid electrolyte layer is attached to the negative electrode paste layer of the negative electrode sheet. Then, in combination with the injected electrolyte, the electrolyte is fully adsorbed in the positive electrode paste layer, the separator, and the porous solid electrolyte layer, and there is actually no flowable electrolyte in the battery case, realizing the preparation of the solid-state battery. Moreover, the electrolyte and the porous solid electrolyte cooperate to achieve sufficient contact between the positive electrode sheet, the separator, and the negative electrode sheet, and form a channel conducive to lithium-ion conduction, preferably reducing the impedance of the battery, and thus effectively improving the rate performance and temperature rise performance of the solid-state battery.

[0048] It should be noted that if both the positive electrode paste and the negative electrode paste are mixed with a solid electrolyte but not a porous solid electrolyte, the wetting effect of the electrolyte on the positive electrode sheet and the negative electrode sheet is poor, and it is difficult for the electrolyte to cooperate with the solid electrolyte to form a fast lithium-ion conduction channel, and the impedance of the formed solid-state battery is relatively high.

[0049] If only a solid electrolyte layer is coated on the positive electrode sheet and the negative electrode sheet to form a solid-state battery, if no electrolyte is injected, it will have a great impact on the impedance of the solid-state battery. If an electrolyte is injected, it is difficult for the electrolyte to cooperate with the solid electrolyte to form a fast lithium-ion transmission channel. Thus, the impedance of the formed solid-state battery is still relatively high.

[0050] In addition, if the solid electrolyte layer coated on the positive electrode sheet and the negative electrode sheet is not formed of a porous solid electrolyte, the impedance of the formed solid-state battery is further relatively high.

[0051] It should also be noted that if the porous solid electrolyte on the negative electrode sheet is directly mixed with the negative electrode paste and coated, the electrolyte on the negative electrode sheet will be fully absorbed in the negative electrode sheet. In this way, more active materials are needed to form the SEI film, which will greatly affect the rate performance and cycle charging of the solid-state battery.

[0052] To better understand the preparation method of the solid-state battery of the present application, the following further explains the preparation method of the solid-state battery of the present application:

[0053] Please refer to Figure 1 , the preparation method of the solid-state battery in one embodiment includes the following steps:

[0054] S100. Obtain a positive electrode sheet, a negative electrode sheet, and a separator. Among them, a positive electrode paste layer is attached to the positive electrode sheet. The positive electrode paste layer includes a lithium-rich agent, a positive electrode active material, a porous solid electrolyte, a positive electrode binder, and a conductive agent. A negative electrode paste layer is attached to the negative electrode sheet, and a porous solid electrolyte layer is coated on the negative electrode paste layer. It can be understood that the porous solid electrolyte is contained in the positive electrode paste of the positive electrode sheet, and the porous structure of the porous solid electrolyte is beneficial to the construction of the lithium-ion conduction channel. In addition, the porous solid electrolyte layer is attached to the negative electrode paste layer on the negative electrode sheet, which is beneficial to the construction of the solid-state battery.

[0055] S200. Perform a lamination and housing process on the positive electrode sheet, the separator, and the negative electrode sheet so that the positive electrode sheet and the negative electrode sheet are separated by the separator and are accommodated together in the battery housing.

[0056] S300. Inject an electrolyte into the battery housing for infiltration and solidification treatment so that the electrolyte is adsorbed on the positive electrode sheet, the separator, and the porous solid electrolyte layer. It can be understood that in the presence of the porous solid electrolyte in the positive electrode paste of the positive electrode sheet and the porous solid electrolyte layer of the negative electrode paste layer of the negative electrode sheet, further combined with the injection of the electrolyte, the electrolyte is fully adsorbed outside the separator, and the electrolyte is also fully adsorbed in the porous solid electrolyte. On the basis of no flow of the electrolyte in the battery housing, it is fully filled to act as a bridge for the conduction of lithium ions at the gaps between the positive electrode sheet, the separator, and the negative electrode sheet. In this way, the impedance of the solid-state battery is better reduced, and the rate performance and temperature rise performance of the solid-state battery are better improved. In addition, the pores of the porous solid electrolyte in the positive electrode paste are fully filled with the electrolyte, and the porous solid electrolyte cooperates with the electrolyte to form a fast conduction channel for lithium ions, further improving the rate performance and cycle performance of the solid-state battery.

[0057] S400. Package and form the battery housing to obtain a solid-state battery.

[0058] The above method for preparing a solid-state battery enables the positive electrode paste attached to the positive electrode sheet to contain a lithium-rich agent and a porous solid electrolyte, and a porous solid electrolyte layer is attached to the negative electrode paste layer of the negative electrode sheet. Then, in combination with the injected electrolyte, the electrolyte is fully adsorbed in the positive electrode paste layer, the separator, and the porous solid electrolyte layer, and there is actually no flowable electrolyte inside the battery case, realizing the preparation of the solid-state battery. Moreover, the electrolyte and the porous solid electrolyte cooperate to achieve sufficient contact between the positive electrode sheet, the separator, and the negative electrode sheet, and form a channel conducive to lithium-ion conduction, preferably realizing a reduction in the impedance of the battery, and further effectively improving the rate performance and temperature rise performance of the solid-state battery.

[0059] In one embodiment, the positive electrode paste layer comprises the following components in parts by mass: 3 to 5 parts of a lithium-rich agent; 88 to 92 parts of a positive electrode active material; 6 to 10 parts of a porous solid electrolyte; 1 to 2 parts of a positive electrode binder; 0.5 to 1.5 parts of a conductive agent.

[0060] In one embodiment, the lithium-rich agent is lithium-rich lithium nickelate and / or lithium-rich lithium ironate.

[0061] In one embodiment, the positive electrode active material is at least one of lithium manganate, lithium nickel cobalt manganate, lithium iron phosphate, lithium manganese iron phosphate, lithium cobaltate, and lithium nickel cobalt aluminate.

[0062] In one embodiment, the positive electrode binder is at least one of polyvinylidene fluoride, polyvinylpyrrolidone, polymethyl methacrylate, polyacrylonitrile, and polytetrafluoroethylene.

[0063] In one embodiment, the porous solid electrolyte layer comprises the following components in parts by mass: 55 to 70 parts of a porous solid electrolyte; 8 to 30 parts of a conductive agent; 8 to 25 parts of a negative electrode binder.

[0064] In one embodiment, the porous solid electrolyte is porous lithium titanium aluminum phosphate, porous lithium lanthanum titanium oxide, porous lithium lanthanum zirconium oxide, or porous polyphosphorus sulfide lithium.

[0065] In one embodiment, the conductive agent is at least one of carbon black, conductive graphite, carbon nanotubes, and graphene.

[0066] In one embodiment, the particle size D50 of the porous solid electrolyte ≤ 270 nm. Further, the particle diameter of the porous solid electrolyte is 100 nm to 500 nm. Further, the porosity of the porous solid electrolyte is 45% to 60%.

[0067] In one embodiment, the negative electrode binder is styrene-butadiene rubber.

[0068] In one embodiment, the thickness of the positive electrode paste layer is 230 μm to 290 μm.

[0069] In one embodiment, the areal density of the positive electrode paste layer is 450 g / m 2 ~550 g / m 2 .

[0070] In one embodiment, the particle size D50 of the lithium-rich agent is 500 nm to 1 μm.

[0071] In one embodiment, the thickness of the porous solid electrolyte layer is 0.8 μm to 2 μm.

[0072] In one embodiment, the positive electrode paste layer is obtained by coating a positive electrode paste on a positive electrode sheet and then drying. Further, the drying temperature is 100°C to 150°C. It can be understood that the operation of drying after coating the positive electrode paste is the same as the conventional one and will not be elaborated here.

[0073] Further, the method for preparing the positive electrode paste includes the following steps:

[0074] Obtain a porous solid electrolyte dispersion and a lithium-rich agent;

[0075] Perform a gas flow dispersion treatment on the lithium-rich agent so that the lithium-rich agent is in a dispersed state under the action of the gas flow;

[0076] Perform an ultrasonic atomization coating operation on the lithium-rich agent in the dispersed state with the porous solid electrolyte dispersion so that the porous solid electrolyte dispersion is ultrasonically atomized and dispersed, and is carried by the gas to the surface of the lithium-rich agent and coated on the lithium-rich agent to obtain a coated lithium-rich agent;

[0077] Add a positive electrode active material, a positive electrode binder, and a conductive agent to the coated lithium-rich agent and perform a mixing operation to obtain a positive electrode paste.

[0078] It can be understood that the lithium-rich agent is coated in the porous solid electrolyte, reducing the interaction between the lithium-rich agent added to the positive electrode paste and polyvinylidene fluoride, thereby reducing the influence on the preparation of the positive electrode paste, and reducing the exacerbation of the generation of by-products of the lithium-rich agent and the electrolyte. In addition, the lithium ions in the lithium-rich agent can quickly replenish the missing lithium ions, thereby effectively improving the cycling performance of the solid-state battery.

[0079] In one embodiment, a fluidized bed is used to perform a gas flow dispersion treatment on the lithium-rich agent.

[0080] In one embodiment, the steps for performing a gas flow dispersion treatment on the lithium-rich agent are as follows: Add the lithium-rich agent to the fluidized bed. The gas flow rate of the fluidized bed is 0.1 m / s to 0.6 m / s, the temperature is 50°C to 120°C, and the fluidization time is 3 min to 7 min.

[0081] In one embodiment, the porous solid electrolyte dispersion is obtained through the following specific steps: adding a solvent and a dispersant to the porous solid electrolyte and mixing them by stirring, with the stirring speed being 600 rpm to 800 rpm and the stirring time being 0.5 h to 2 h. Further, the solvent is at least one of N-methylpyrrolidone, dimethylformamide, tetrahydrofuran, acetonitrile, acetone, ethanol, and toluene. Further, the dispersant is at least one of polyvinylpyrrolidone, herring oil, and polyethylene glycol. Further, the porous solid electrolyte dispersion comprises the following components in parts by mass: 0.1 to 0.6 parts of the dispersant; 45 to 70 parts of the porous solid electrolyte; and 16 to 25 parts of the solvent.

[0082] In one embodiment, the ultrasonic atomization coating operation is performed on the lithium-rich agent in a dispersed state using the porous solid electrolyte dispersion, and the specific steps are as follows: placing the porous solid electrolyte dispersion in an ultrasonic atomizer for ultrasonic atomization, with the oscillation frequency being 0.8 Hz to 1.2 Hz, the power being 35 W to 50 W, the aperture of the nozzle being 5 μm to 12 μm, and the atomization rate being 1 mL / min to form droplets of the porous solid electrolyte dispersion, and bringing the droplets to the lithium-rich agent through the airflow of a fluidized bed so that the droplets of the porous solid electrolyte dispersion contact and coat the surface of the lithium-rich agent. Further, the airflow of the fluidized bed is formed by introducing an inert gas. Further, the inert gas is nitrogen or / and helium.

[0083] In one embodiment, the following specific steps are taken to perform a slurrying operation on the coated lithium-rich agent by adding a cathode active material, a cathode binder, and a conductive agent: adding the cathode active material and the cathode binder to the coated lithium-rich agent for a primary mixing operation to obtain a mixed material. Further, the stirring speed of the primary mixing operation is 500 rpm to 600 rpm, and the stirring time is 0.5 h to 1 h. Further, a solvent is added to the mixed material for slurrying treatment. Further, a solvent is added to the mixed material and stirred to form a slurry, with the stirring speed being 600 rpm to 700 rpm and the stirring time being 0.5 h to 1 h. Further, a conductive agent is added to the mixed material subjected to the slurrying treatment for a secondary mixing operation to obtain a cathode slurry. Further, the stirring speed of the secondary mixing operation is 800 rpm to 900 rpm, and the stirring time is 0.8 h to 2 h. Further, the solvent is at least one of N-methylpyrrolidone, dimethylformamide, tetrahydrofuran, acetonitrile, acetone, ethanol, and toluene.

[0084] In one embodiment, the negative electrode slurry layer is obtained by coating a negative electrode slurry on a negative electrode sheet and then drying; the negative electrode slurry comprises the following components in parts by mass: 1 to 2 parts of single-walled carbon nanotubes; 1 to 2 parts of sodium carboxymethylcellulose; 4 to 5 parts of styrene-butadiene rubber latex; 10 to 15 parts of graphite; 80 to 89 parts of silicon oxide; 95 to 99 parts of deionized water. Further, the drying temperature is 90°C to 110°C. It can be understood that the operation of drying after coating the negative electrode slurry is the same as the conventional one and will not be elaborated here. Further, the preparation method of the negative electrode slurry is as follows: stir graphite and silicon oxide at a stirring speed of 600 rpm to 800 rpm for 0.5 h to 1.5 h, then add single-walled carbon nanotubes for mixing, stir at a stirring speed of 600 rpm to 800 rpm for 0.5 h to 1.5 h, and then add sodium carboxymethylcellulose, styrene-butadiene rubber latex and deionized water for homogenization, stir at a stirring speed of 1200 rpm to 1500 rpm for 0.5 h to 1 h. Further, the thickness and surface density of the negative electrode slurry layer are the same as the conventional ones and will not be elaborated here.

[0085] In one embodiment, the porous solid electrolyte layer is obtained by coating a porous solid electrolyte slurry on the negative electrode slurry layer and then drying. Further, the drying temperature is 100°C to 150°C. Further, the thickness of the porous solid electrolyte layer is 1 μm to 3 μm. Further, the preparation method of the porous solid electrolyte slurry comprises the following steps: place the porous solid electrolyte, the conductive agent and the negative electrode binder together in a solvent and stir at a stirring speed of 800 rpm to 1000 rpm for 1.5 to 2 h. Further, the solvent is at least one of N-methylpyrrolidone, dimethylformamide, tetrahydrofuran, acetonitrile, acetone, ethanol and toluene.

[0086] In one embodiment, the separator is a polyethylene non-woven fabric separator.

[0087] In one embodiment, the electrolyte is a non-aqueous electrolyte. Further, the electrolyte is LiPF 6 The non-aqueous electrolyte, LiPF6 non-aqueous electrolyte is the LiPF used in conventional lithium-ion batteries 6 electrolyte and will not be elaborated here.

[0088] In one embodiment, the operations of liquid injection encapsulation and formation are the same as those of conventional lithium batteries and will not be elaborated here.

[0089] The present application also provides a solid-state battery, which is prepared by the preparation method of the solid-state battery in any of the above embodiments. Further, in this embodiment, the preparation method of the solid-state battery includes the following steps: obtaining a positive electrode sheet, a negative electrode sheet and a separator, wherein a positive electrode paste layer is attached to the positive electrode sheet, and the positive electrode paste layer includes a lithium-rich agent, a positive electrode active material, a porous solid electrolyte, a positive electrode binder and a conductive agent; a negative electrode paste layer is attached to the negative electrode sheet, and a porous solid electrolyte layer is coated on the negative electrode paste layer; laminating the positive electrode sheet, the separator and the negative electrode sheet into a battery case, so that the positive electrode sheet and the negative electrode sheet are separated by the separator and are accommodated in the battery case together; injecting an electrolyte into the battery case for wetting and solidifying treatment, so that the electrolyte is adsorbed on the positive electrode sheet, the separator and the porous solid electrolyte layer; encapsulating and forming the battery case to obtain a solid-state battery.

[0090] The above solid-state battery is obtained by the preparation method of the solid-state battery, effectively improving the rate performance and temperature rise performance of the solid-state battery.

[0091] Compared with the prior art, the present invention has at least the following advantages:

[0092] The preparation method of the solid-state battery of the present invention enables the positive electrode paste attached to the positive electrode sheet to contain a lithium-rich agent and a porous solid electrolyte, and a porous solid electrolyte layer is attached to the negative electrode paste layer of the negative electrode sheet. Then, in cooperation with the injected electrolyte, the electrolyte is fully adsorbed in the positive electrode paste layer, the separator and the porous solid electrolyte layer, and there is actually no flowable electrolyte in the battery case, realizing the preparation of the solid-state battery. Moreover, the electrolyte and the porous solid electrolyte cooperate to achieve full contact between the positive electrode sheet, the separator and the negative electrode sheet, and form a channel conducive to lithium ion conduction, preferably realizing the reduction of the impedance of the battery, and further effectively improving the rate performance and temperature rise performance of the solid-state battery.

[0093] The following list some specific embodiments. If "% " is mentioned, it means by weight percentage. It should be noted that the following embodiments do not exhaust all possible situations, and the materials used in the following embodiments can be obtained from commercial channels without special instructions.

[0094] Example 1

[0095] Preparation of positive electrode sheet:

[0096] Add 0.7 kg of porous lithium titanium aluminum phosphate with a porosity of 60% and a D50 pore diameter of 270 nm to 0.25 kg of N-methylpyrrolidone and 0.006 kg of polyvinylpyrrolidone, stir and mix at a stirring speed of 800 rpm for 0.5 h to obtain a porous lithium titanium aluminum phosphate dispersion for later use;

[0097] Add 0.5 kg of lithium-rich lithium nickelate with a D50 of 1 μm to a fluidized bed and keep it in a fluidized state through an air stream. The air stream velocity is 0.6 m / s, the temperature is 120 °C. After fluidizing for 3 min, add the lithium titanium aluminum phosphate porous dispersion to an ultrasonic nebulizer. The oscillation frequency is 1.2 HZ, the power is 50 W, the aperture of the nozzle is 12 μm, the atomization rate is 1 mL / min, and it enters the fluidized bed through the nozzle and is carried by the air stream to the lithium titanium aluminum phosphate porous for mixing and drying to obtain the lithium-rich material;

[0098] Add the lithium-rich material to 9.2 kg of lithium manganate and 0.2 kg of polyvinylidene fluoride and stir. The stirring speed is 600 rpm and the stirring time is 0.5 h. Then add 8.5 kg of N-methylpyrrolidone and stir. The stirring speed is 700 rpm and the stirring time is 0.5 h. Then add 0.15 kg of multi-walled carbon nanotubes and stir. The stirring speed is 900 rpm and the stirring time is 0.8 h to obtain the positive electrode paste, which is coated on an aluminum foil and dried. The drying temperature is 150 °C to obtain a positive electrode sheet with a thickness of 290 μm and a surface density of 550 g / m 2 ².

[0099] Preparation of the negative electrode sheet:

[0100] Stir 1.5 kg of graphite and 8.9 kg of silicon oxide at a stirring speed of 800 rpm for 0.5 h. Then, add 0.2 kg of single-walled carbon nanotubes for mixing at a stirring speed of 800 rpm for 0.5 h. Then add 0.2 kg of sodium carboxymethylcellulose, 0.82 kg of styrene-butadiene rubber latex with a solid content of 60% and 9.9 kg of deionized water for homogenization operation at a stirring speed of 1500 rpm for 0.5 h to obtain the negative electrode paste, which is coated on a copper foil and dried. The drying temperature is 110 °C to form a negative electrode paste layer on the copper foil for use;

[0101] Stir and mix 7.0 kg of lithium titanium aluminum phosphate porous with a porosity of 60% and a D50 of 270 nm, 3.0 kg of carbon nanotubes and 2.5 kg of styrene-butadiene rubber at a stirring speed of 1000 rpm for 1.5 h. Then coat it on the side of the negative electrode paste layer away from the copper foil and dry. The drying temperature is 150 °C to form a porous solid electrolyte layer with a thickness of 3 μm on the negative electrode paste layer to obtain the negative electrode sheet.

[0102] Stack and wind the positive electrode sheet, polyethylene non-woven fabric separator and negative electrode sheet, then put them into an aluminum-plastic shell and inject the LiPF6 electrolyte. The added dimethyl carbonate has a concentration of 1.2 mol / L and an addition amount of 52 ± 0.75 g to completely infiltrate the positive electrode sheet, separator and negative electrode sheet, and there is no flowing electrolyte. Then encapsulate and form to obtain the battery.

[0103] Example 2

[0104] Preparation of the positive electrode sheet:

[0105] Add 0.6 kg of porous lithium titanium aluminum phosphate with a porosity of 52% and a pore size D50 of 180 nm to 0.15 kg of N-methylpyrrolidone, 0.07 kg of acetone, and 0.004 kg of polyvinylpyrrolidone, and stir and mix at a stirring speed of 700 rpm for 1.2 h to obtain a porous lithium titanium aluminum phosphate dispersion for use;

[0106] Add 0.4 kg of lithium-rich nickelate with D50 of 800 nm to a fluidized bed and keep it in a fluidized state through air flow. The air flow speed is 0.3 m / s, the temperature is 100 °C. After fluidizing for 5 min, add the porous lithium titanium aluminum phosphate dispersion to an ultrasonic nebulizer. The oscillation frequency is 1.0 HZ, the power is 42 W, the aperture of the nozzle is 8 μm, the atomization amount is 1 mL / min, and it enters the fluidized bed through the nozzle and is carried by the air flow to the lithium-rich nickelate for mixing and drying to obtain a lithium-rich material;

[0107] Add the lithium-rich material to 9.0 kg of lithium cobaltate and 0.15 kg of polyvinylidene fluoride and stir at a stirring speed of 550 rpm for 0.8 h. Then add 8.0 kg of N-methylpyrrolidone and stir at a stirring speed of 650 rpm for 0.8 h. Then add 0.1 kg of multi-walled carbon nanotubes and stir at a stirring speed of 850 rpm for 1.5 h to obtain a positive electrode paste, coat it on an aluminum foil, and dry it at a drying temperature of 120 °C to obtain a positive electrode sheet with a thickness of 260 μm and a surface density of 500 g / m 2 ².

[0108] Preparation of the negative electrode sheet:

[0109] Stir 1.2 kg of graphite and 8.5 kg of silicon oxide at a stirring speed of 700 rpm for 0.2 h. Then, add 0.15 kg of single-walled carbon nanotubes for mixing at a stirring speed of 700 rpm for 1.1 h. Then add 0.15 kg of sodium carboxymethylcellulose, 0.72 kg of styrene-butadiene rubber latex with a solid content of 60%, and 9.7 kg of deionized water for homogenization operation at a stirring speed of 1350 rpm for 0.8 h to obtain a negative electrode paste, coat it on a copper foil and dry it at a drying temperature of 100 °C to form a negative electrode paste layer on the copper foil for use;

[0110] 6.2 kg of porous lithium titanium aluminum phosphate with a porosity of 52% and a pore diameter D50 of 180, 1.8 kg of carbon nanotubes, and 1.8 kg of styrene-butadiene rubber were stirred and mixed together at a stirring speed of 900 rpm for 1.8 h. Then, it was coated on the side of the negative electrode paste layer away from the copper foil and dried at a drying temperature of 120 °C to form a porous lithium titanium aluminum phosphate layer with a thickness of 2 μm on the negative electrode paste layer, obtaining a negative electrode sheet.

[0111] The positive electrode sheet, polyethylene non-woven fabric separator, and negative electrode sheet were stacked and wound, then placed in an aluminum-plastic shell, and injected with LiPF6 electrolyte. The added dimethyl carbonate had a concentration of 1.2 mol / L and an addition amount of 52 ± 0.75 g, so that the positive electrode sheet, separator, and negative electrode sheet were completely wetted and there was no flowable electrolyte. Then, it was encapsulated and formed to obtain a battery.

[0112] Example 3

[0113] Preparation of positive electrode sheet:

[0114] 0.55 kg of porous lithium titanium aluminum phosphate with a porosity of 45% and a pore diameter D50 of 100 nm was added to 0.15 kg of N-methylpyrrolidone, 0.05 kg of ethanol, and 0.002 kg of polyvinylpyrrolidone and stirred and mixed at a stirring speed of 600 rpm for 2 h to obtain a porous lithium titanium aluminum phosphate dispersion for use.

[0115] 0.3 kg of lithium-rich lithium ferrite with a D50 of 500 nm was added to a fluidized bed and was in a fluidized state by air flow. The air flow speed was 0.1 m / s, the temperature was 50 °C. After fluidizing for 7 min, the porous lithium titanium aluminum phosphate dispersion was added to an ultrasonic nebulizer with an oscillation frequency of 0.8 HZ, a power of 35 W, a nozzle aperture of 5 μm, and an atomization amount of 1 mL / min, and entered the fluidized bed through a nozzle, and was carried by the air flow to the lithium-rich lithium ferrite for mixing and drying to obtain a lithium-rich material.

[0116] The lithium-rich material was added to 8.8 kg of lithium cobaltate and 0.1 kg of polyvinylidene fluoride and stirred at a stirring speed of 500 rpm for 1 h. Then, 7.5 kg of N-methylpyrrolidone was added and stirred at a stirring speed of 600 rpm for 1 h. Then, 0.05 kg of multi-walled carbon nanotubes was added and stirred at a stirring speed of 800 rpm for 2 h to obtain a positive electrode paste, which was coated on aluminum foil and dried at a drying temperature of 100 °C to obtain a positive electrode sheet with a thickness of 230 μm and a surface density of 450 g / m 2 2.

[0117] Preparation of negative electrode sheet:

[0118] Stir 1.0 kg of graphite and 8.0 kg of silicon oxide at a stirring speed of 600 rpm for 1.5 h. Then, add 0.1 kg of single-walled carbon nanotubes for mixing at a stirring speed of 600 rpm for 1.5 h. Next, add 0.1 kg of sodium carboxymethylcellulose, 0.68 kg of styrene-butadiene rubber latex with a solid content of 60%, and 9.5 kg of deionized water for homogenization at a stirring speed of 1200 rpm for 1 h to obtain a negative electrode paste. Coat the paste on a copper foil and dry it at a drying temperature of 90 °C to form a negative electrode paste layer on the copper foil for later use.

[0119] Stir and mix 5.5 kg of porous lithium titanium aluminum phosphate with a porosity of 45% and a pore diameter D50 of 100 nm, 0.8 kg of carbon nanotubes, and 0.8 kg of styrene-butadiene rubber at a stirring speed of 800 rpm for 2 h. Then, coat it on the side of the negative electrode paste layer away from the copper foil and dry it at a drying temperature of 100 °C to form a porous lithium titanium aluminum phosphate layer with a thickness of 1 μm on the negative electrode paste layer, obtaining a negative electrode sheet.

[0120] Stack and wind the positive electrode sheet, polyethylene non-woven fabric separator, and negative electrode sheet, then place them in an aluminum-plastic shell and inject a LiPF6 electrolyte. Add dimethyl carbonate with a concentration of 1.2 mol / L and an addition amount of 52 ± 0.75 g to fully immerse the positive electrode sheet, separator, and negative electrode sheet without any flowing electrolyte. Then, encapsulate and form the battery.

[0121] Example 4

[0122] Preparation of positive electrode sheet:

[0123] Add 0.4 kg of lithium-rich nickelate with D50 of 800 nm and 0.6 kg of porous lithium titanium aluminum phosphate with a porosity of 52% and a pore diameter D50 of 180 nm to 0.15 kg of N-methylpyrrolidone, 0.07 kg of acetone, and 0.004 kg of polyvinylpyrrolidone, stir and mix at a stirring speed of 700 rpm for 1.2 h. Then, add it to 9.0 kg of lithium cobaltate and 0.15 kg of polyvinylidene fluoride for stirring at a stirring speed of 550 rpm for 0.8 h. Next, add 8.0 kg of N-methylpyrrolidone for stirring at a stirring speed of 650 rpm for 0.8 h. Then, add 0.1 kg of multi-walled carbon nanotubes for stirring at a stirring speed of 850 rpm for 1.5 h to obtain a positive electrode paste. Coat the paste on an aluminum foil and dry it at a drying temperature of 120 °C to obtain a positive electrode sheet with a thickness of 260 μm and a surface density of 500 g / m 2 ².

[0124] Preparation of negative electrode sheet:

[0125] Stir 1.2 kg of graphite and 8.5 kg of silicon oxide at a stirring speed of 700 rpm for 0.2 h. Then, add 0.15 kg of single-walled carbon nanotubes and mix them at a stirring speed of 700 rpm for 1.1 h. Next, add 0.15 kg of sodium carboxymethylcellulose, 0.72 kg of styrene-butadiene rubber latex with a solid content of 60%, and 9.7 kg of deionized water for homogenization. Stir at a speed of 1350 rpm for 0.8 h to obtain the negative electrode paste, which is then coated on a copper foil and dried at a temperature of 100 °C to form a negative electrode paste layer on the copper foil for later use.

[0126] Stir and mix 6.2 kg of porous lithium titanium aluminum phosphate with a porosity of 52% and a pore diameter D50 of 180, 1.8 kg of carbon nanotubes, and 1.8 kg of styrene-butadiene rubber at a stirring speed of 900 rpm for 1.8 h. Then, coat it on the side of the negative electrode paste layer away from the copper foil and dry it at a temperature of 120 °C to form a porous lithium titanium aluminum phosphate layer with a thickness of 2 μm on the negative electrode paste layer, obtaining the negative electrode sheet.

[0127] Stack and wind the positive electrode sheet, polyethylene non-woven fabric separator, and negative electrode sheet, then place them in an aluminum-plastic shell and inject the LiPF6 electrolyte. Add dimethyl carbonate with a concentration of 1.2 mol / L and an addition amount of 52 ± 0.75 g to completely soak the positive electrode sheet, separator, and negative electrode sheet, and there is no flowing electrolyte. Then, encapsulate and form the battery.

[0128] Comparative Example 1

[0129] Preparation of positive electrode sheet:

[0130] Add 0.4 kg of lithium-rich nickelate with D50 of 800 nm and 0.6 kg of porous lithium titanium aluminum phosphate with a porosity of 52% and a pore diameter D50 of 180 nm to 0.15 kg of N-methylpyrrolidone, 0.07 kg of acetone, and 0.004 kg of polyvinylpyrrolidone, stir and mix at a stirring speed of 700 rpm for 1.2 h. Then, add it to 9.0 kg of lithium cobaltate and 0.15 kg of polyvinylidene fluoride and stir at a stirring speed of 550 rpm for 0.8 h. Next, add 8.0 kg of N-methylpyrrolidone and stir at a stirring speed of 650 rpm for 0.8 h. Then, add 0.1 kg of multi-walled carbon nanotubes and stir at a stirring speed of 850 rpm for 1.5 h to obtain the positive electrode paste, which is then coated on an aluminum foil and dried at a temperature of 120 °C to obtain a positive electrode sheet with a thickness of 260 μm and a surface density of 500 g / m 2 ².

[0131] Preparation of negative electrode sheet:

[0132] 1.2 kg of graphite and 8.5 kg of silicon oxide were stirred at a stirring speed of 700 rpm for 0.2 h. Then, 0.15 kg of single-walled carbon nanotubes was added for mixing, and the stirring speed was 700 rpm for 1.1 h. Subsequently, 0.15 kg of sodium carboxymethylcellulose, 0.72 kg of styrene-butadiene rubber latex with a solid content of 60%, and 9.7 kg of deionized water were added for homogenization operation. The stirring speed was 1350 rpm, and stirring was carried out for 0.8 h to obtain a negative electrode slurry, which was coated on a copper foil and dried at a drying temperature of 100 °C to obtain a negative electrode sheet.

[0133] The positive electrode sheet, polyethylene non-woven fabric separator, and negative electrode sheet were stacked and wound, then placed in an aluminum-plastic shell, and liquid injection was carried out. The injected LiPF6 electrolyte was added with dimethyl carbonate, with a concentration of 1.2 mol / L and an addition amount of 52 ± 0.75 g, so that the positive electrode sheet, separator, and negative electrode sheet were completely infiltrated, and there was no flowable electrolyte. Then, it was encapsulated and formed to obtain a battery.

[0134] The batteries obtained in Examples 1-4 and the battery obtained in Comparative Example 1 were subjected to electrochemical performance tests, and the test results are shown in Table 1.

[0135] Table 1

[0136]

[0137] It can be seen from Table 1 that the batteries prepared in Examples 1-4 are solid-state batteries. Compared with the solid-state batteries prepared in Comparative Example 1, the rate performance is significantly better, the battery impedance is significantly reduced, and the cycle performance and temperature rise performance are significantly better. It shows that the lithium-rich agent is coated through a porous solid electrolyte and mixed in the positive electrode slurry and coated to form a positive electrode sheet, and a porous solid electrolyte layer is formed on the surface of the negative electrode slurry of the negative electrode sheet. Combined with the injected electrolyte, it is completely absorbed and accommodated by the polyethylene non-woven fabric separator, positive electrode sheet, and negative electrode sheet. At this time, the electrolyte and the porous solid electrolyte form a tightly contacted state between the positive electrode sheet, separator, and negative electrode sheet, and the electrolyte and the porous solid electrolyte provide a fast conduction channel for the conduction of lithium ions, effectively improving the battery rate and temperature rise performance.

[0138] The above embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

Claims

1. A method for preparing a solid-state battery, characterized in that: The steps include: Obtain a positive electrode sheet, a negative electrode sheet and a separator, wherein the positive electrode sheet is attached with a positive electrode slurry layer, the positive electrode slurry layer comprises a lithium-rich agent, a positive electrode active material, a porous solid electrolyte, a positive electrode binder and a conductive agent, and the negative electrode sheet is attached with a negative electrode slurry layer, and the negative electrode slurry layer is coated with a porous solid electrolyte layer; The positive electrode sheet, the separator and the negative electrode sheet are stacked and placed in a shell, so that the positive electrode sheet and the negative electrode sheet are separated by the separator and placed in a battery shell together; Injecting electrolyte into the battery housing for solid-state infiltration treatment, so that the electrolyte is adsorbed on the positive electrode sheet, the separator and the porous solid electrolyte layer; The battery shell is packaged and formed to obtain a solid-state battery.

2. The method for preparing a solid-state battery according to claim 1, characterized in that: The positive electrode slurry layer includes the following components in parts by weight:

3. The method for preparing a solid-state battery according to claim 1 or 2, characterized in that: The lithium-rich agent is lithium-rich nickel oxide and / or lithium-rich iron oxide; and / or, The positive electrode active material is at least one of lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, and lithium nickel cobalt aluminum oxide; and / or, The positive electrode binder is at least one of polyvinylidene fluoride, polyvinyl pyrrolidone, polymethyl methacrylate, polyacrylonitrile and polytetrafluoroethylene.

4. The method for preparing a solid-state battery according to claim 1, characterized in that: The porous solid electrolyte layer comprises the following components in parts by mass: 55 to 70 parts of porous solid electrolyte; Conductive agent 8 to 30 parts; 8 to 25 parts of negative electrode binder.

5. The method for preparing a solid-state battery according to claim 1, 2 or 4, characterized in that: The porous solid electrolyte is porous lithium aluminum titanium phosphate, porous lithium lanthanum titanium oxide, porous lithium lanthanum zirconium oxide or porous lithium polyphosphosulfide; and / or, The conductive agent is at least one of carbon black, conductive graphite, carbon nanotubes and graphene.

6. The method for preparing a solid-state battery according to claim 1, 2 or 4, characterized in that: The particle size D50 of the porous solid electrolyte is ≤270nm.

7. The method for preparing a solid-state battery according to claim 4, characterized in that: The negative electrode binder is styrene-butadiene rubber.

8. The method for preparing a solid-state battery according to claim 1, characterized in that: The thickness of the positive electrode slurry layer is 230 μm to 290 μm; and / or, The surface density of the positive electrode slurry layer is 450 g / m 2 ~550g / m 2 and / or, The particle size D50 of the lithium-rich agent is 500nm to 1μm; and / or, The thickness of the porous solid electrolyte layer is 0.8 μm to 2 μm.

9. The method for preparing a solid-state battery according to claim 1, characterized in that: The positive electrode slurry layer is obtained by coating the positive electrode slurry on the positive electrode sheet; The method for preparing the positive electrode slurry comprises the following steps: obtaining a porous solid electrolyte dispersion and a lithium-rich agent; Performing airflow dispersion treatment on the lithium-rich agent so that the lithium-rich agent is in a dispersed state under the action of the airflow; The porous solid electrolyte dispersion is used to perform ultrasonic atomization coating operation on the lithium-rich agent in a dispersed state, so that the porous solid electrolyte dispersion is ultrasonically atomized and dispersed, and is brought to the surface of the lithium-rich agent by gas and coated on the lithium-rich agent, thereby obtaining a coated lithium-rich agent; A positive electrode active material, a positive electrode binder and a conductive agent are added to the coated lithium-rich agent for mixing to obtain the positive electrode slurry.

10. A solid-state battery, characterized in that: The solid-state battery is prepared by the method for preparing the solid-state battery according to any one of claims 1 to 9.

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