An integrated solid-state battery, a preparation method thereof, a battery module, and a power-using device

Abstract

The application relates to the technical field of all-solid-state batteries, in particular to an integrated solid-state battery, a preparation method thereof, a battery module and an electric equipment, which comprises the following steps: taking an electrolyte precursor with a lithium content lower than a theoretical stoichiometric ratio of a target sulfide solid-state electrolyte, mixing the electrolyte precursor with a conductive agent, a binder and corresponding electrode materials to obtain positive and negative electrode mixtures; loading the electrode mixtures on current collectors respectively and compacting to obtain positive and negative electrode pre-prepared electrodes; taking the electrolyte precursor and mixing the electrolyte precursor with a binder and compacting to obtain an electrolyte precursor layer; pressing the pre-prepared electrodes and the electrolyte precursor layer to obtain positive and negative composite electrodes; performing a lithiation reaction on the composite electrodes to obtain in-situ lithiated positive and negative composite electrodes; and assembling the positive and negative composite electrodes into a pre-prepared battery and sintering the pre-prepared battery in an inert atmosphere to obtain the integrated solid-state battery. The nanoscale interface fusion between the electrolyte and the electrode material is realized, the solid-solid interface impedance is significantly reduced, and the battery rate performance and the cycle stability are improved.

Description

Technical Field

[0001] This invention relates to the field of all-solid-state battery technology, specifically to an integrated solid-state battery and its preparation method, battery module, and electrical device. Background Technology

[0002] With the rapid development of industries such as new energy vehicles, portable digital devices, and large-scale energy storage power stations, the market is placing higher demands on the energy density, safety performance, and cycle life of energy storage batteries. Traditional liquid lithium-ion batteries use organic electrolytes, which pose safety hazards such as electrolyte leakage, high-temperature fire and explosion, and poor low-temperature performance, making them unsuitable for high-end energy storage scenarios.

[0003] All-solid-state batteries use inorganic solid-state electrolytes instead of liquid electrolytes, offering advantages such as non-flammability, high voltage, and high energy density, making them a core development direction for next-generation energy storage devices. Among them, sulfide solid-state electrolytes can achieve room-temperature ionic conductivity of up to 10⁻⁶. -3 ~10 -2 Its S / cm ratio is much higher than that of oxide and polymer solid electrolytes, indicating huge potential for industrialization.

[0004] Current sulfide solid-state battery fabrication processes mostly employ a modular approach: separately fabricating the positive electrode, solid electrolyte membrane, and negative electrode, then assembling them via hot-pressing. This method has significant drawbacks: The electrodes and solid electrolyte are physically bonded together, and there are a large number of micron-level gaps between the two phases. The solid-solid interface contact is poor and the interface impedance is extremely high, which greatly reduces the rate performance of the battery. The interfacial bonding of the layered stacked structure is weak. During the charging and discharging process of the battery, the electrode material undergoes volume expansion and contraction, which makes it very easy for the interface to delaminate, resulting in a rapid decline in cycle life. The electrolyte layer and electrode sheet are prepared separately, which is a lengthy process. Multiple coating and die-cutting processes increase production costs and are not conducive to large-scale mass production. Sulfide electrolytes are sensitive to water and air. During the multi-step separate processing, they are exposed to air multiple times, which can easily lead to hydrolysis and deterioration, reducing battery consistency.

[0005] Therefore, there is an urgent need to develop an integrated in-situ synthesis process that simultaneously achieves deep fusion of the electrode and solid electrolyte interface, simplifies the preparation process, and solves the problems of high interface impedance, poor cycle stability, and complex process of traditional split solid-state batteries. Summary of the Invention

[0006] The purpose of this invention is to provide an integrated solid-state battery preparation method. Through an integrated process of co-pressure composite of electrode and electrolyte precursors + in-situ electrochemical lithiation + inert atmosphere solid-state sintering, a sulfide solid electrolyte is generated in situ, eliminating the interfacial gap between the electrode and the electrolyte and reducing the interfacial impedance. It also simplifies the solid-state battery production process, reduces the contact time between the sulfide precursor and air, improves product stability, and is suitable for industrial mass production.

[0007] Another objective of this invention is to provide an integrated solid-state battery in which the electrodes and solid electrolyte are fused at the nanoscale interface, resulting in excellent rate performance, long cycle life, and high safety.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing an integrated solid-state battery, comprising the following steps: S1. Prepare electrode mixture.

[0009] Weigh an electrolyte precursor with a lithium content lower than the theoretical stoichiometry of the target sulfide solid electrolyte, and mix it with a conductive agent, a binder, and the corresponding electrode active material to obtain a positive electrode mixture and a negative electrode mixture.

[0010] When obtaining the positive electrode mixture, the electrode active material is selected from at least one of ternary materials, lithium cobalt oxide, and lithium iron phosphate. The general chemical formula of the ternary material is Li. 1±a Ni x Co y Mn 1-x-y O2; Where, 0≤a≤0.2, 0≤x≤1, 0≤y≤1; When obtaining the negative electrode mixture, the electrode active material is selected from at least one of low-expansion silicon-based physical modified materials, carbon-based materials, low-expansion tin-based physical modified materials, or metallic lithium. The low-expansion silicon-based physical modified material is a silicon-carbon composite material prepared by composite modification technology or a mixed material prepared by blending silicon and graphite in a certain proportion. Low-expansion tin-based physical modified materials are tin-carbon composite materials prepared by composite modification technology or mixed materials made by blending tin and graphite in a certain proportion.

[0011] The electrolyte precursor includes a phosphorus source, a sulfur source, and a halogen source, wherein the halogen source is selected from at least one of lithium chloride, lithium bromide, or lithium iodide. Alternatively, the electrolyte precursor may also include at least one of a phosphorus source, a sulfur source, and a germanium, tin, or silicon source.

[0012] S2. Prepare the pre-fabricated electrode.

[0013] The electrode mixture obtained in step S1 is loaded onto the surface of the metal current collector and compacted by roller pressing to obtain a pre-made electrode; the pre-made electrodes are divided into two categories: positive pre-made electrodes and negative pre-made electrodes.

[0014] S3. Prepare the electrolyte precursor layer.

[0015] A sulfide electrolyte precursor with a lithium content lower than the theoretical stoichiometry of the target sulfide solid electrolyte is weighed separately, mixed evenly with a binder and a small amount of solvent, and then compacted by roller pressing to obtain a dense electrolyte precursor layer.

[0016] The compaction pressure is 10MPa to 500MPa, and the compaction temperature is 50℃ to 150℃.

[0017] S4. Prepare composite electrodes.

[0018] The positive electrode preform and negative electrode preform obtained in step S2 are aligned and stacked with the electrolyte precursor layer obtained in step S3, and then rolled and laminated to obtain a positive electrode double-layer composite electrode and a negative electrode double-layer composite electrode.

[0019] The pressure of the pressing process is 10MPa to 500MPa, and the pressing temperature is 50℃ to 150℃.

[0020] S5, in-situ electrochemical lithiation treatment.

[0021] The positive and negative double-layer composite electrodes obtained in step S4 are placed in an electrochemical reaction cell, with a lithium metal sheet as the counter electrode. An electrolyte containing lithium salt is injected to isolate the air, and a constant current is applied to carry out an electrochemical lithiation reaction. An external lithium source is embedded inside the composite electrode and reacts with a sulfur source to generate a lithium sulfide precursor in situ, thus obtaining a lithiation positive composite electrode and a lithiation negative composite electrode.

[0022] The lithiation reaction process uses an ether electrolyte containing lithium salts; the lithiation reaction formula is: 2Li + S → Li₂S; The current density at which the lithiation reaction occurs is 0.1–10 mA / cm², and the lower cutoff voltage relative to the lithium metal reference electrode is 2.0 V.

[0023] S6, Prefabricated battery assembly.

[0024] Lithium-ionized positive electrode composite electrode and lithium-ionized negative electrode composite electrode are stacked alternately to form a multilayer electrode prefabricated battery.

[0025] S7. In-situ sintering under inert atmosphere.

[0026] The pre-fabricated battery is placed in a tubular sintering furnace and an inert protective atmosphere such as argon and nitrogen is introduced. When the material combination selected for the negative electrode active material contains lithium metal, the sintering temperature is 155-180°C. When the material combination selected for the negative electrode material does not contain lithium metal, the sintering temperature is 200-400°C, and the temperature is held for 2-10 hours. During the sintering process, the lithium sulfide precursor inside the composite electrode undergoes a solid-phase reaction with the remaining low-lithium sulfide precursor, and sulfide solid electrolyte is continuously generated in situ inside the electrode and at the interface between the electrode and the intermediate layer, finally obtaining an integrated solid-state battery.

[0027] The final sulfide solid electrolyte is the target sulfide solid electrolyte.

[0028] When the crystal form of the target sulfide solid electrolyte is silver-germanium sulfide, the electrolyte precursor is prepared according to the corresponding Li 7- n PS 6-n X n The chemical formula uses the molar ratio of elements from phosphorus source, sulfur source, and halogen source, where X includes at least one of Cl, Br, and I, and 0 <n≤1.8; When the crystal form of the target sulfide solid electrolyte is LGPS, the electrolyte precursor is prepared according to the corresponding Li 11-n M 2- n P 1+n S 12 The chemical formula uses phosphorus, sulfur, germanium, tin, and silicon as source materials, where M includes at least one of Ge, Sn, and Si, and 0. <n≤1.8。

[0029] An integrated solid-state battery is prepared by the above-described method. The integrated solid-state battery has an integrated symbiotic structure consisting of a positive electrode containing a solid electrolyte, an intermediate solid electrolyte layer, and a negative electrode containing a solid electrolyte. The sulfide solid electrolyte penetrates the gaps between the active particles of the electrode, and there are no obvious layering gaps at the interface between the electrode and the solid electrolyte, thus achieving nanoscale interface fusion.

[0030] The integrated solid-state battery does not require an additional independent separator; the in-situ generated sulfide solid electrolyte layer serves both as an ion conductor and an electronic insulating barrier.

[0031] A battery module comprising at least one of the aforementioned integrated solid-state batteries.

[0032] An electrical device includes the aforementioned integrated solid-state battery or the aforementioned battery module.

[0033] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention relates to a method for fabricating an integrated solid-state battery, which employs a precursor co-pressure composite followed by in-situ sintering to generate a solid electrolyte. The electrolyte is directly generated in-situ between electrode particles and at the interface between the electrode and the intermediate layer, achieving nanoscale interface fusion. This eliminates the micron-level interface voids caused by traditional physical stacking, significantly reduces solid-solid interface impedance, and effectively improves the battery's rate charge and discharge performance.

[0034] 2. The present invention relates to an integrated solid-state battery preparation method in which the electrode and electrolyte precursor are compositely formed in one step, eliminating the need for separate preparation of solid electrolyte membrane and multi-layer hot pressing stacking process, shortening the production line process and reducing equipment investment.

[0035] 3. The method for preparing an integrated solid-state battery according to the present invention uses low-lithium raw materials for the precursors throughout the process, which reduces the sensitivity of sulfide materials to decomposition when exposed to water and air; the overall assembly and sintering process reduces the number of times materials are exposed to air, resulting in higher consistency of the finished battery.

[0036] 4. The present invention relates to an integrated solid-state battery in which the electrode and the solid electrolyte are in situ co-existing in one structure. During the charging and discharging process, when the volume of the electrode material expands and contracts, the electrolyte and the electrode deform synchronously, avoiding interface peeling and significantly extending the battery cycle life.

[0037] 5. The present invention relates to an integrated solid-state battery in which an in-situ generated sulfide electrolyte layer simultaneously undertakes the functions of ion conduction and electron isolation, eliminating the need for traditional polymer / ceramic separators, increasing the proportion of effective active materials inside the battery, and significantly improving the overall energy density. Attached Figure Description

[0038] Figure 1 This is a schematic diagram illustrating the microstructure evolution of an integrated solid-state battery according to the present invention. Figure 2 These are scanning electron microscope (SEM) images of the composite electrode microstructure of the batteries prepared in Example 1 and Comparative Example 1 of this invention. Figure 3 The graph shows the cycle performance test results of the integrated solid-state battery prepared in Example 1 of this invention. Figure 4 The graph shows the cycle performance test results of the solid-state battery prepared in Comparative Example 1 of this invention. Figure 5 These are scanning electron microscope (SEM) images of the electrode microstructures of the batteries prepared in Example 2 and Comparative Example 2 of this invention. Figure 6 The graph shows the cycle performance test results of the solid-state battery prepared in Example 2 of this invention. Figure 7 The graph shows the cycle performance test results of the solid-state battery prepared in Comparative Example 2 of this invention. Detailed Implementation

[0039] The following will refer to the accompanying drawings in the embodiments of the present invention ( Figures 1 to 7 The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1: The integrated solid-state battery fabrication method includes the following steps: S1. Prepare electrode mixture.

[0041] According to the component ratio required for preparing Li7PS6Cl sulfide solid electrolyte (Li2S:P2S5:LiCl=7:3:1), the reaction raw materials for in-situ generation of Li2S, elemental S powder (sulfur source), P2S5 powder and LiCl powder, were calculated and weighed as electrolyte precursor raw materials and ball-milled and blended. The above raw materials were further mixed with LiCoO2 active material, conductive carbon black (Super P) and PTFE binder at a mass ratio of 15:80:2:3 for 4 hours by high-speed stirring to obtain a uniform positive electrode mixture. The negative electrode uses graphite active material and is formulated with the same precursor, conductive agent and binder system.

[0042] S2. Prepare the pre-fabricated electrode.

[0043] The positive electrode mixture is loaded onto the surface of an aluminum current collector, and the negative electrode mixture is coated onto the surface of a copper current collector. The mixtures are then rolled and compacted to an electrode thickness of 40 μm to obtain the positive and negative electrode prefabrications.

[0044] S3. Prepare the electrolyte precursor layer.

[0045] Weigh out S powder (sulfur source), P2S5 powder and LiCl powder in the same proportion as in step S1 as electrolyte precursor raw materials, add 0.1 wt% PTFE, and roll press to obtain an electrolyte precursor layer with a thickness of 10 μm.

[0046] S4. Preparation of composite electrode.

[0047] The positive electrode prefabricated electrode and the electrolyte precursor are stacked and rolled at 80°C to obtain the positive electrode composite electrode; the same operation is repeated on the negative electrode prefabricated electrode to obtain the negative electrode composite electrode.

[0048] S5, in-situ electrochemical lithiation.

[0049] The positive and negative composite electrodes were placed in an electrolytic cell inside an argon glove box, with metallic lithium as the counter electrode. The lithium was lithiated to 1.8V under a constant current of 0.1mA / cm². The precursor reacted with the lithium source to generate a lithium sulfide precursor, thus obtaining the lithiated positive and negative composite electrodes.

[0050] S6, Prefabricated battery assembly.

[0051] Lithium-ionized positive electrode composite electrode and lithium-ionized negative electrode composite electrode are stacked alternately to assemble a multilayer prefabricated battery, which is then sealed to isolate it from air.

[0052] S7, inert atmosphere sintering.

[0053] The pre-supported battery was placed in an argon-protected tube furnace and kept at 200°C for 5 hours. The precursor solid-phase reaction generated Li7PS6Cl sulfide solid electrolyte in situ, resulting in an integrated solid-state battery.

[0054] Comparative Example 1: Traditional Split-Stack Solid-State Batteries Lithium cobalt oxide cathode, Li7PS6Cl solid electrolyte membrane, and graphite anode were prepared separately; the three layers were stacked in sequence and hot-pressed together at 120°C to assemble a split solid-state battery. The remaining raw materials and sintering parameters were completely consistent with those in Example 1.

[0055] The solid-state batteries prepared in Example 1 and Comparative Example 1 were subjected to performance tests, and the test results are shown in Table 1.

[0056] Table 1

[0057] Interface structure analysis: such as Figure 2 As shown, scanning electron microscopy and energy dispersive spectroscopy analysis revealed that the battery of Example 1 formed a continuous lithium-rich transition layer at the interface of the positive electrode / electrolyte / negative electrode, exhibiting an interface structure with a gradient ion conductivity distribution, while the interface of Comparative Example 1 showed obvious delamination.

[0058] Example 2: Preparation of an integrated solid-state battery.

[0059] The pre-formed positive electrode was prepared according to steps S1 and S2 of Example 1, with the positive electrode active material replaced by NCM811; the electrolyte precursor layer was prepared according to step S3 of Example 1; the other raw material ratios and in-situ lithiation steps were kept consistent with Example 1; metallic lithium was used as the negative electrode, and the in-situ sintering temperature was 155℃ for 10 hours.

[0060] Comparative Example 2: Preparation of a traditional split-type solid-state battery.

[0061] NCM811 composite cathode and Li7PS6Cl solid electrolyte membrane were prepared separately, with lithium metal as the anode; the three layers were stacked sequentially and hot-pressed together at 120°C to assemble a split solid-state battery without in-situ lithiation; the remaining raw materials and sintering parameters were completely consistent with those in Example 2.

[0062] The test results above show that the integrated solid-state battery prepared by this invention has excellent electrochemical performance, low interfacial impedance and long cycle life, and the process simplification and performance optimization are achieved through the electrochemical in-situ reaction mechanism and integrated preparation process.

[0063] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for fabricating an integrated solid-state battery, characterized in that, Includes the following steps: S1. Weigh out an electrolyte precursor with a lithium content lower than the theoretical stoichiometry of the target sulfide solid electrolyte, and mix it with a conductive agent, a binder and corresponding electrode active materials to obtain a positive electrode mixture and a negative electrode mixture. S2. Load the positive electrode mixture and the negative electrode mixture onto the current collector and compact them to obtain the positive electrode preform and the negative electrode preform; S3. Weigh out an electrolyte precursor with a lithium content lower than the theoretical stoichiometry of the target sulfide solid electrolyte, mix it with a binder and compact it to obtain an electrolyte precursor layer. S4. The positive electrode pre-fabricated electrode and the negative electrode pre-fabricated electrode are laminated with the electrolyte precursor respectively to obtain the positive electrode double layer composite electrode and the negative electrode double layer composite electrode. S5. The positive electrode double-layer composite electrode and the negative electrode double-layer composite electrode are respectively placed in an electrochemical device with metallic lithium as the counter electrode to carry out lithiation reaction, and lithium sulfide precursor is generated in situ to obtain lithiation positive electrode composite electrode and lithiation negative electrode composite electrode. S6. Alternately stack the lithium-ion positive electrode composite electrode and the lithium-ion negative electrode composite electrode to assemble the prefabricated battery. S7. The pre-fabricated battery is sintered under an inert protective atmosphere, and the precursor undergoes a solid-phase reaction to generate a sulfide solid electrolyte in situ, thus obtaining an integrated solid-state battery.

2. The method for preparing the integrated solid-state battery according to claim 1, characterized in that, In step S1: When obtaining the positive electrode mixture, the electrode active material is selected from at least one of ternary materials, lithium cobalt oxide, and lithium iron phosphate. The general chemical formula of the ternary material is Li. 1±a Ni x Co y Mn 1-x-y O2; Where, 0≤a≤0.2, 0≤x≤1, 0≤y≤1; When obtaining the negative electrode mixture, the electrode active material is selected from at least one of low-expansion silicon-based physical modified materials, carbon-based materials, low-expansion tin-based physical modified materials, or metallic lithium.

3. The method for preparing the integrated solid-state battery according to claim 1, characterized in that: The electrolyte precursor in step S1 includes a phosphorus source, a sulfur source, and a halogen source.

4. The method for preparing the integrated solid-state battery according to claim 1, characterized in that: The electrolyte precursor in step S1 includes at least one of a phosphorus source, a sulfur source, and a germanium, tin, or silicon source.

5. The method for preparing an integrated solid-state battery according to claim 1, characterized in that: The pressure for compaction and pressing in steps S3 and S4 is 10MPa to 500MPa, and the pressing temperature is 50℃ to 150℃.

6. The method for preparing the integrated solid-state battery according to claim 1, characterized in that: The lithiation reaction in step S5 uses an ether electrolyte containing lithium salts; The lithiation reaction formula is as follows: 2Li + S → Li₂S; The current density at which the lithiation reaction occurs is 0.1–10 mA / cm², and the lower cutoff voltage relative to the lithium metal reference electrode is 2.0 V.

7. The method for preparing the integrated solid-state battery according to claim 1, characterized in that: In step S7, when the selected material combination for the negative electrode active material contains lithium metal, the sintering temperature is 155–180°C; when the selected material combination for the negative electrode material does not contain lithium metal, the sintering temperature is 200–400°C, and the sintering holding time is 2–10 h. The generated sulfide solid electrolyte is a sulfide-germanium ore type Li. 7-n PS 6-n X n or LGPS type Li 11-n M 2-n P 1+n S 12 One of them; Wherein, X is at least one of Cl, Br, and I, M is at least one of Ge, Sn, and Si, and 0 < n ≤ 1.

8.

8. An integrated solid-state battery, characterized in that, The integrated solid-state battery is prepared by any one of claims 1 to 7. The integrated solid-state battery has an integrated symbiotic structure consisting of a positive electrode containing a solid electrolyte, an intermediate solid electrolyte layer, and a negative electrode containing a solid electrolyte. The sulfide solid electrolyte penetrates the gaps between the active particles of the electrode, and there are no obvious layering gaps at the interface between the electrode and the solid electrolyte, thus achieving nanoscale interface fusion.

9. A battery module, characterized in that: It includes at least one integrated solid-state battery as described in claim 8.

10. An electrical appliance, characterized in that: Includes one of the integrated solid-state battery as described in claim 8 or the battery module as described in claim 9.

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