Solid-state battery preparation method based on thermal expansion compensation mechanism
By assembling the cells at low temperatures and utilizing the thermal expansion force of materials to achieve densification, the solid-solid interface contact problem in all-solid batteries has been solved, improving battery safety and cycle life, reducing production costs, and providing feasibility for large-scale manufacturing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGDE COSPOWERS NEW ENERGY TECH CO LTD
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-21
AI Technical Summary
In all-solid-state batteries, the point contact mode between the electrode and the solid electrolyte leads to high interfacial impedance and unstable interfacial chemistry, which affects battery performance and safety. Existing technologies struggle to dynamically maintain interfacial stability during cycling.
The in-situ thermal expansion self-densification structure is adopted to assemble the battery cell at low temperature. The thermal expansion force when the material is heated back to achieve densification from the inside out, dynamically maintaining the interface contact. The solid-solid interface integrated design through dry powder pressing eliminates the problems of solvent residue and drying stress.
It effectively reduces interfacial gaps, dynamically maintains excellent interfacial contact, suppresses lithium dendrites, improves safety and cycle life, while reducing production costs and increasing production efficiency, making large-scale manufacturing feasible.
Smart Images
Figure CN121905972A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery technology, and more specifically to a method for preparing solid-state batteries based on a thermal expansion compensation mechanism. Background Technology
[0002] Energy shortages and environmental pollution have become key challenges hindering the sustainable development of modern society. Against the backdrop of energy structure transformation and the rapid proliferation of portable electronic devices and electric vehicles, the performance bottlenecks of traditional lithium-ion batteries in terms of energy density and safety are becoming increasingly apparent. In this context, all-solid-state batteries are considered one of the most promising next-generation electrochemical energy storage technologies due to their inherently high safety resulting from the complete elimination of flammable organic electrolytes, their enormous potential for achieving higher energy densities through compatibility with high-capacity metal anodes (such as lithium metal), and their wider operating temperature range and longer cycle life.
[0003] However, the commercialization of all-solid-state batteries is still limited by their inherent solid-solid interface challenges. The point contact mode between the electrode and the solid electrolyte not only results in extremely high interfacial impedance, limiting the rate performance of the battery, but also the unstable interfacial chemistry easily leads to continuous side reactions, accelerating the degradation of battery performance.
[0004] To address these issues, researchers have explored various technical approaches, such as improving physical contact through external pressure, incorporating solid electrolytes into the cathode, adding flexible interface layers, and surface modification to enhance compatibility. However, these methods often involve complex processes, introduce inactive materials that reduce energy density, and struggle to dynamically maintain interface stability during cycling, thus failing to provide a simple and universally applicable fundamental solution. Summary of the Invention
[0005] This invention provides an in-situ thermal expansion self-densification structure. By assembling the battery cell at low temperature, the material's own thermal expansion during rewarming achieves continuous densification from the inside out, thereby reducing interface gaps, compensating for electrode volume changes, dynamically maintaining good interface contact, suppressing lithium dendrites, and improving safety and cycle life. At the same time, this battery structure has high modularity and scalability, providing a feasible technical route for low-cost and large-scale manufacturing of solid-state batteries.
[0006] To achieve the above objectives, this invention discloses a solid-state battery fabrication method based on a thermal expansion compensation mechanism, comprising the following steps: Step 1: Preparation of electrode materials: The positive electrode active material, conductive agent and solid electrolyte are mixed in a certain proportion and thoroughly ground to make them uniformly mixed, so as to obtain the positive electrode material that can be used to prepare the battery cell; similarly, the negative electrode active material, conductive agent and solid electrolyte are mixed in a certain proportion to obtain the negative electrode material that can be used to prepare the battery cell.
[0007] Step 2: Preparation of solid electrolyte: Solid electrolyte powder, lithium salt and corresponding solvent are mixed in a certain proportion and stirred to form a completely dissolved homogeneous solution. The solution is then poured onto a glass plate, scraped into a thin film with a scraper, and dried for a period of time before being transferred to a vacuum drying oven. After vacuum drying, a solid electrolyte film that can be used to assemble battery cells is obtained.
[0008] Step 3: Design the cell structure: Based on the size and shape of the target cell, design and prepare a matching cell shell. Its size and shape must match the loose volume and target compaction density of the positive and negative electrode material powders obtained in Step 1, and reserve space for the placement of the solid electrolyte film.
[0009] Step 4: Low-Temperature Cell Assembly: The entire structural assembly and materials are transferred to a low-temperature environment. Then, a layer of solid electrolyte powder is pre-laid inside the cell casing. Next, negative electrode material powder, negative electrode current collector, negative electrode material powder, and solid electrolyte film are added sequentially, followed by positive electrode material powder, positive electrode current collector, positive electrode material powder, and solid electrolyte film, repeating this process. After completion, under low-temperature conditions, a certain pressure is applied for multiple cold pressing processes, causing the powder, film, and current collector to composite and form a complete solid-state battery cell.
[0010] Furthermore, the cathode material mentioned in step one can be lithium iron phosphate, ternary lithium, lithium manganese iron phosphate, transition metal oxides, polyanionic compounds and Prussian blue compounds, etc., which are active cathode materials that can be used in lithium batteries or sodium batteries; the addition ratio is 70% to 99%.
[0011] Furthermore, the negative electrode material mentioned in step one can be silicon-based materials, carbon-based materials, alloy materials, titanium-based materials, and organic materials, which are negative electrode active materials that can be used in lithium batteries or sodium batteries; the addition ratio is 70%~99%.
[0012] Furthermore, the conductive agent material mentioned in step one can be conductive carbon black, carbon nanotubes, graphene, or other conductive agent materials that can be used for the positive and negative electrodes of lithium batteries or sodium batteries; the addition ratio is 1% to 10%.
[0013] Furthermore, the electrolyte material mentioned in step one can be a polymer, oxide, sulfide, or other material suitable for solid electrolytes; its addition ratio is 1% to 10%.
[0014] Furthermore, the active material, conductive agent, and solid electrolyte mentioned in step one can be thoroughly dispersed and mixed using a high-speed disperser, followed by thorough grinding to ensure uniform mixing.
[0015] Furthermore, the solid electrolyte mentioned in step two can be made of materials such as polymers, oxides, and sulfides that can be used as solid electrolytes, and the lithium salt can be made of materials such as LiTFSI, LiFSI, LiPF6, and LiClO4.
[0016] Furthermore, the solvent mentioned in step two can be any solvent suitable for preparing solid electrolytes, such as NMP, anhydrous ethanol, or acetic acid.
[0017] Furthermore, the low-temperature environment described in step four is controlled at ≤5 ℃, and the temperature can be adjusted according to the characteristics of the material.
[0018] Furthermore, the pressure mentioned in step four is maintained above 50 MPa, and the pressure is adjusted according to the cell structure and material characteristics.
[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention provides an in-situ thermal expansion self-densification structure. By utilizing the thermophysical properties of the material itself, the cell is assembled at a low temperature. When it recovers to the operating temperature, the material itself undergoes slight thermal expansion. This expansion force from the inside out is uniform and continuous, which can make the internal structure of the battery more compact, reduce the interface gap, effectively compensate for the volume change of the electrode during cycling, dynamically maintain excellent interface contact, and help suppress lithium dendrites, improve safety and cycle life; (2) This invention provides a solution to the problem of solid-solid interface contact. The electrode is not made by the traditional coating process, but by dry powder pressing of active material, conductive agent and other materials. This solid-solid interface integrated design based on powder pressing eliminates the solvent residue and drying stress problems of the traditional wet process, and creates an interface structure in which active material, conductive agent and electrolyte particles are in close contact at the microscale. This greatly improves the contact problem between the electrode and the solid electrolyte layer, and largely solves the core problem of high solid-solid interface impedance in solid batteries. (3) This invention provides a customizable cell structure design. The cell design has a clear hierarchical structure and modular materials, which provides excellent production flexibility and scalability. It is no longer limited by the size and capacity of traditional cells. By designing molds of different shapes and sizes, it can be directly pressed into large-volume or irregularly shaped cells suitable for specific equipment needs, realizing the advanced design concept of "cell as structural component". This provides a brand-new solution for the large-scale and personalized integration of power battery packs, energy storage cell components, consumer electronics and special equipment. (4) This invention provides a simple and low-cost all-solid-state battery cell manufacturing scheme. The dry electrode process and low-temperature self-densification structure design adopted by the battery cell eliminate the complex and energy-intensive processes such as coating, drying, liquid injection, and formation. In actual production, the equipment cost is greatly reduced and the production efficiency is further improved, providing a feasible technical route for low-cost and large-scale manufacturing of solid-state batteries. Attached Figure Description
[0020] Figure 1 This is a perspective view of the battery cell structure proposed in this invention.
[0021] Figure 2 This is a top view of the battery cell structure proposed in this invention.
[0022] Figure 3 The solid electrolyte film added in Example 1.
[0023] Figure 4 This is a SEM image of the positive electrode active material used in Example 1.
[0024] Figure 5 This is a SEM image of the negative electrode active material used in Example 1. Detailed Implementation
[0025] To better understand the content of this invention, it will be further described below with reference to specific embodiments and accompanying drawings. The following embodiments are based on the technology of this invention and provide detailed implementation methods and operating steps, but the scope of protection of this invention is not limited to the following embodiments. Example 1
[0026] (1) Preparation of electrode materials: Lithium iron phosphate, carbon black and lithium aluminum titanium phosphate (LATP) are mixed in a ratio of 8:1:1. First, a high-speed disperser is used to disperse the mixture at a speed of 8000 r / min for 45 min, and then it is thoroughly ground for 30 min to make the mixture uniform, so as to obtain the positive electrode material that can be used to prepare the battery cell. Similarly, graphite, carbon black and LATP are mixed in a ratio of 8:1:1. First, a high-speed disperser is used to disperse the mixture at a speed of 8000 r / min for 45 min, and then it is thoroughly ground for 30 min to make the mixture uniform, so as to obtain the negative electrode material that can be used to prepare the battery cell.
[0027] (2) Preparation of solid electrolyte: LATP powder and phosphate ester are dissolved in anhydrous ethanol and stirred for 10 h. After stirring, a completely dissolved homogeneous solution is formed. The solution is then poured onto a glass plate, scraped into a thin film with a scraper, dried for a period of time, and then transferred to a vacuum drying oven. After vacuum drying, a solid electrolyte film that can be used to assemble battery cells is obtained.
[0028] (3) Low-temperature cell assembly: The materials are first transferred to a liquid nitrogen environment for pre-cooling treatment, and then the cells are assembled in a -40℃ environment. Assembly steps: A layer of LATP powder is first pre-laid inside the cell casing, and then negative electrode material powder, negative electrode current collector, negative electrode material powder, solid electrolyte film are added in sequence, followed by positive electrode material powder, positive electrode current collector, positive electrode material powder, and solid electrolyte film, and the process is repeated. After the layering is completed, a pressure of 20~80 MPa is applied for multiple cold pressings to obtain a solid-state battery cell. Example 2
[0029] (1) Preparation of electrode materials: Lithium iron phosphate, carbon black and lithium aluminum titanium phosphate (LATP) are mixed in a ratio of 9:0.4:0.6. First, a high-speed disperser is used to disperse the mixture at a speed of 8000 r / min for 45 min, and then it is thoroughly ground for 30 min to make the mixture uniform, so as to obtain the positive electrode material that can be used to prepare the battery cell. Similarly, graphite, carbon black and LATP are mixed in a ratio of 9:0.4:0.6. First, a high-speed disperser is used to disperse the mixture at a speed of 8000 r / min for 45 min, and then it is thoroughly ground for 30 min to make the mixture uniform, so as to obtain the negative electrode material that can be used to prepare the battery cell.
[0030] (2) Preparation of solid electrolyte: LATP powder and phosphate ester are dissolved in anhydrous ethanol and stirred for 10 h. After stirring, a completely dissolved homogeneous solution is formed. The solution is then poured onto a glass plate, scraped into a thin film with a scraper, dried for a period of time, and then transferred to a vacuum drying oven. After vacuum drying, a solid electrolyte film that can be used to assemble battery cells is obtained.
[0031] (3) Low-temperature cell assembly: The materials are first transferred to a liquid nitrogen environment for pre-cooling treatment, and then the cells are assembled in a -40℃ environment. Assembly steps: A layer of LATP powder is first pre-laid inside the cell casing, and then negative electrode material powder, negative electrode current collector, negative electrode material powder, solid electrolyte film are added in sequence, followed by positive electrode material powder, positive electrode current collector, positive electrode material powder, and solid electrolyte film, and the process is repeated. After the layering is completed, a pressure of 20~80 MPa is applied for multiple cold pressings to obtain a solid-state battery cell. Example 3
[0032] (1) Preparation of electrode materials: Lithium iron phosphate, carbon black and polyethylene oxide (PEO) are mixed in a ratio of 8:1:1. First, a high-speed disperser is used to disperse the mixture at a speed of 10,000 r / min for 40 min, and then it is ground thoroughly for 30 min to make the mixture uniform, so as to obtain the positive electrode material that can be used to prepare the battery cell. Similarly, graphite, carbon black and PEO are mixed in a ratio of 8:1:1. First, a high-speed disperser is used to disperse the mixture at a speed of 10,000 r / min for 40 min, and then it is ground thoroughly for 30 min to make the mixture uniform, so as to obtain the negative electrode material that can be used to prepare the battery cell.
[0033] (2) Preparation of solid electrolyte: PEO powder and phosphate ester are dissolved in anhydrous ethanol and stirred for 10 h. After stirring, a completely dissolved homogeneous solution is formed. The solution is then poured onto a glass plate, scraped into a thin film with a scraper, dried for a period of time, and then transferred to a vacuum drying oven. After vacuum drying, a solid electrolyte film that can be used to assemble battery cells is obtained.
[0034] (3) Low-temperature cell assembly: The materials are transferred to a -30℃ environment for pre-cooling for more than 3 hours, and then the cells are assembled. Assembly steps: First, a layer of PEO powder is pre-laid inside the cell casing. Then, negative electrode material powder, negative electrode current collector, negative electrode material powder, solid electrolyte film are added in sequence. Then, positive electrode material powder, positive electrode current collector, positive electrode material powder, and solid electrolyte film are added. This process is repeated. After the layering is completed, a pressure of 30~100 MPa is applied for multiple cold pressings to obtain a solid-state battery cell.
[0035] Figure 1 The diagram above is a schematic diagram of the cell structure proposed in this invention. It can be seen that the structure adopts an integrated solid-solid interface design, which creates an interface structure in which the active material, conductive agent and electrolyte particles are in close contact at the microscale. This greatly improves the contact problem between the electrode and the solid electrolyte layer, and largely solves the core problem of high solid-solid interface impedance in solid batteries.
[0036] Combination Figure 1 and Figure 2 It has been discovered that this invention provides a customizable battery cell structure design. By designing molds of different shapes and sizes, large-volume or irregularly shaped battery cells suitable for specific equipment needs can be directly pressed, realizing the advanced design concept of "battery cell as structural component".
[0037] Figure 3 , Figure 4 and Figure 5These are the solid electrolyte, positive electrode material, and negative electrode material used to assemble the battery cell. By utilizing the thermophysical properties of these materials, the battery cell is assembled at low temperatures. When it returns to its operating temperature, the materials undergo slight thermal expansion. This expansion force, which is uniform and continuous from the inside out, makes the internal structure of the battery more compact, reduces interfacial gaps, effectively compensates for the volume changes of the electrodes during cycling, dynamically maintains excellent interfacial contact, and helps suppress lithium dendrites, thereby improving safety and cycle life.
Claims
1. A method for fabricating solid-state batteries based on a thermal expansion compensation mechanism, characterized by comprising the following steps: Step 1: Preparation of electrode materials: The positive electrode active material, conductive agent and solid electrolyte are mixed in a certain proportion and thoroughly ground to make the mixture uniform, so as to obtain the positive electrode material that can be used to prepare the battery cell; similarly, the negative electrode active material, conductive agent and solid electrolyte are mixed in a certain proportion to obtain the negative electrode material that can be used to prepare the battery cell. Step 2: Preparation of solid electrolyte: Solid electrolyte powder, lithium salt and corresponding solvent are mixed in a certain proportion and stirred to form a completely dissolved homogeneous solution. The solution is then poured onto a glass plate, scraped into a thin film with a scraper, dried for a period of time, and then transferred to a vacuum drying oven. After vacuum drying, a solid electrolyte film that can be used to assemble battery cells is obtained. Step 3: Design the cell structure: Based on the size and shape of the target cell, design and prepare a matching cell shell. Its size and shape must match the loose volume and target compaction density of the positive and negative electrode material powders obtained in Step 1, and reserve space for the placement of the solid electrolyte film. Step 4: Low-Temperature Cell Assembly: The entire structural assembly and materials are transferred to a low-temperature environment. Then, a layer of solid electrolyte powder is pre-laid inside the cell casing. Next, negative electrode material powder, negative electrode current collector, negative electrode material powder, and solid electrolyte film are added sequentially, followed by positive electrode material powder, positive electrode current collector, positive electrode material powder, and solid electrolyte film, repeating this process. After completion, under low-temperature conditions, a certain pressure is applied for multiple cold pressing processes, causing the powder, film, and current collector to composite and form a complete solid-state battery cell.
2. The solid-state battery fabrication method based on a thermal expansion compensation mechanism as described in claim 1, characterized in that... The cathode material mentioned in step one can be lithium iron phosphate, ternary lithium, lithium manganese iron phosphate, transition metal oxides, polyanionic compounds and Prussian blue compounds, etc., which are active cathode materials that can be used in lithium batteries or sodium batteries; the addition ratio is 70%~99%.
3. The solid-state battery fabrication method based on a thermal expansion compensation mechanism as described in claim 1, characterized in that... The negative electrode material mentioned in step one can be silicon-based materials, carbon-based materials, alloy materials, titanium-based materials, and organic materials, which are negative electrode active materials that can be used in lithium batteries or sodium batteries. Its inclusion rate is 70% to 99%.
4. The solid-state battery fabrication method based on a thermal expansion compensation mechanism as described in claim 1, characterized in that... The conductive agent material mentioned in step one can be conductive carbon black, carbon nanotubes, graphene, or other conductive agent materials that can be used for the positive and negative electrodes of lithium batteries or sodium batteries; its addition ratio is 1% to 10%.
5. The solid-state battery fabrication method based on a thermal expansion compensation mechanism as described in claim 1, characterized in that... The electrolyte material mentioned in step one can be a polymer, oxide, sulfide, or other material suitable for solid electrolytes. The proportion of its addition is 1% to 10%.
6. The solid-state battery fabrication method based on a thermal expansion compensation mechanism as described in claim 1, characterized in that... The solid electrolyte mentioned in step two can be made of materials such as polymers, oxides, and sulfides that can be used for solid electrolytes, and the lithium salt can be made of materials such as LiTFSI, LiFSI, LiPF6, and LiClO4 that can be used to prepare solid electrolytes.
7. The solid-state battery fabrication method based on a thermal expansion compensation mechanism as described in claim 1, characterized in that... The solvent mentioned in step two can be any solvent suitable for preparing solid electrolytes, such as NMP, anhydrous ethanol, or acetic acid.
8. The solid-state battery fabrication method based on a thermal expansion compensation mechanism as described in claim 1, characterized in that... The low-temperature environment described in step four is controlled at ≤5 ℃, and the temperature can be adjusted according to the characteristics of the material.
9. The solid-state battery fabrication method based on a thermal expansion compensation mechanism as described in claim 1, characterized in that... The pressure mentioned in step four is maintained above 50 MPa, and the pressure is adjusted according to the cell structure and material characteristics.