PDOL-based composite solid electrolyte and preparation method thereof
By adding specific additives and inorganic particles to the PDOL solid electrolyte, the polymerization speed is controlled, and the problems of unsatisfactory room temperature conductivity and too fast polymerization speed are solved, thereby achieving efficient electrochemical performance and simple preparation process.
Patent Information
- Application Number
- CN202510221128.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-27
- Publication Date
- 2025-05-30
AI Technical Summary
The conductivity of existing PDOL solid electrolytes is not ideal at room temperature, and a large amount of heat is generated during the polymerization process, which makes the polymerization speed too fast, resulting in difficulty in packaging process.
Using the PDOL-based composite solid electrolyte formula, lithium hexafluorophosphate, lithium salt, organic additives, and inorganic solid electrolyte particles are added, and the suspension is formed by stirring or ultrasonication, and added dropwise or sprayed onto the battery separator at room temperature to control the polymerization speed.
It significantly improves the ionic conductivity at room temperature, up to 7.4×10-4S/cm, simplifies the preparation process, reduces equipment requirements and costs, and is suitable for large-scale industrial production.
Smart Images
Figure CN120073050A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solid electrolytes for lithium batteries, and more specifically, to a PDOL-based composite solid electrolyte and a preparation method thereof. Background Art
[0002] Lithium-ion batteries are one of the most widely used commercial batteries on the market today. Their high energy density and high energy efficiency make them the main power source in energy storage fields such as portable electronic devices and electric vehicles. However, with the development of social economy, people's demand for battery performance has also been increasing continuously. Today, the most advanced LIBs can reach a volumetric energy density of 770 Wh·L -1 and a gravimetric energy density of 260 Wh·kg -1 , which is close to the theoretical energy density limit of LIBs. At the same time, the demand for battery performance in portable electronic devices, electric vehicles, and grid energy storage systems is growing continuously. There is an urgent need to develop batteries with higher energy density, longer cycle life, higher safety level, and lower cost.
[0003] Solid-state lithium batteries are regarded as the forefront of future energy storage technologies due to their excellent energy density and safety. In solid-state lithium batteries, the solid electrolyte is a core component, which plays a crucial role in the electrochemical performance and thermal stability of the battery. Poly(1,3-dioxolane) (PDOL), as a polymer solid electrolyte that is easy to polymerize and has a relatively high ionic conductivity at room temperature, is usually prepared using LiTFSI as the lithium salt and LiPF 6 as the initiator. Considering the cost-effectiveness of LiPF 6 , it can completely replace LiTFSI. However, when completely replaced, a large amount of heat is generated during the polymerization process, and the polymerization rate is too fast, which poses challenges to the battery packaging process. In addition, the conductivity of pure PDOL solid electrolyte at room temperature is not ideal. Therefore, how to effectively control the polymerization rate of the electrolyte and further improve its room temperature conductivity has become a key technical problem to be solved urgently. Summary of the Invention
[0004] The purpose of the present invention is to provide a PDOL-based composite solid electrolyte formulation with excellent ionic conductivity at room temperature and a preparation method thereof.
[0005] To achieve the above purpose, the present invention adopts the following technical solutions: A PDOL-based composite solid electrolyte is composed of lithium hexafluorophosphate, a lithium salt, an organic additive, inorganic solid electrolyte particles, and 1,3-dioxolane monomers. The ratio is 8 - 32 grams of lithium hexafluorophosphate, 1 - 10 grams of organic additive, 0.1 - 50 grams of inorganic solid electrolyte particles, and 0 - 50 grams of lithium salt per 100 grams of 1,3-dioxolane.
[0006] Preferably, the lithium salt is any one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium difluoro(oxalato)borate (LiDFOB).
[0007] Preferably, the organic additive is any one or more of fluoroethylene carbonate (FEC), succinonitrile (SN), and ethylene carbonate (EC).
[0008] Preferably, the inorganic solid electrolyte particles are any one or more of lithium lanthanum zirconium tantalum oxide (LLZTO), lithium aluminum titanium phosphate (LATP), and lithium lanthanum titanium oxide (LLTO), and the particle size range thereof is 0.1 - 10 μm.
[0009] A method for preparing a PDOL-based composite solid electrolyte includes the following steps: (1) Add lithium hexafluorophosphate, lithium salt, organic additive, and inorganic solid electrolyte particles to 1,3-dioxolane monomer, mix evenly at room temperature, and form a suspension by stirring or ultrasonic method; (2) Drop or spray the suspension obtained in step (1) onto the surface of the battery separator, with an addition amount of 20 - 500 μL of the suspension dropped or sprayed per square centimeter of the battery separator, and let it stand at room temperature until the self-polymerization of 1,3-dioxolane is completed, then the PDOL-based composite solid electrolyte can be obtained.
[0010] Preferably, in step (1), the stirring speed is 0 - 1000 rpm, and the stirring time is 1 - 60 min; the ultrasonic frequency of the ultrasonic treatment is 20 - 100 kHz, and the ultrasonic time is 1 - 30 min.
[0011] Preferably, in step (2), the battery separator is any one of a PE separator, a PP separator, and a glass fiber separator.
[0012] Compared with the prior art, the present invention has the following beneficial effects: (1) Compared with other polymer substrates, the 1,3-dioxolane polymer substrate used in the present invention has a higher room-temperature ionic conductivity, which means that this substrate can transfer ions more effectively at room temperature, thereby improving the performance and response speed of electrochemical devices. The room-temperature ionic conductivity of the PDOL-based composite solid electrolyte obtained in the present invention is 2×10 -4 -7.4×10 -4 S / cm. In addition, the polymerization process of 1,3-dioxolane can occur at room temperature without additional operations (such as ultraviolet light irradiation or heating), which simplifies the preparation process.
[0013] (2) By adding inorganic solid electrolyte particles, the present invention utilizes the surface alkalinity of the particles to neutralize the protonic acid generated by LiPF 6 , thereby slowing down the polymerization rate of 1,3-dioxolane. Meanwhile, the interface formed between the inorganic particles and the polymer matrix has excellent ionic conductivity, greatly enhancing the ionic conductivity of the overall material, which can reach up to 7.4×10 -4 S / cm at room temperature.
[0014] (3) The PDOL-based solid electrolyte synthesized in the present invention has a simple preparation process, low equipment requirements, and low cost, and can be used for large-scale industrial production. Description of the Drawings
[0015] Figure 1 Impedance diagrams of the PDOL-based solid electrolytes obtained in Example 1, Example 2, and Comparative Example 1; Figure 2 Impedance diagrams of the PDOL-based solid electrolytes obtained in Example 3 and Comparative Example 2; Figure 3 Raman spectra of the PDOL-based solid electrolytes obtained in Example 1, Example 2, and Comparative Example 1; Figure 4 Cycling performance diagrams of lithium / iron phosphate batteries using the PDOL-based solid electrolytes obtained in Example 1, Example 2, and Comparative Example 1. Detailed Embodiments
[0016] Next, the technical solutions of the present invention will be further described in conjunction with the embodiments and the drawings. The described embodiments are only a part of the embodiments of the present invention, rather than 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 efforts fall within the scope of protection of the present invention. The methods or operations used in the embodiments, unless otherwise specified, are conventional methods or operations in the art. Example 1:
[0017] Preparation of the solid electrolyte: (1) Take 0.4 mL of 1,3-dioxolane monomer, with a mass of 418 mg, and add 60.8 mg of LiPF 6 , 12.5 mg of FEC, and 0.8 mg of LLZTO solid electrolyte particles with a particle size of about 0.5 μm. Then, stir with a magnetic stirrer at 500 rpm for 10 min at room temperature to obtain a uniformly dispersed suspension.
[0018] (2) Take 70 μL of the suspension obtained by stirring evenly in step (1) and load it into a PP diaphragm with a diameter of 16 mm. Place it in a button cell at room temperature and let it stand still until the self-polymerization of 1,3-dioxolane is completed, then the PDOL-based composite solid electrolyte sample 1 can be obtained.
[0019] Preparation of solid-state battery: In a glove box filled with argon with the water and oxygen content both less than 0.1 ppm, take 35 μL of the above-mentioned suspension and drop it on the negative electrode side. Cover it with a glass fiber diaphragm with a diameter of 16 mm and then drop 35 μL of the suspension again. Subsequently, place the positive electrode plate and encapsulate the battery. In the solid-state battery prepared in the present invention, lithium metal is selected as the negative electrode and lithium iron phosphate is selected as the positive electrode.
[0020] Example 2: Preparation of solid electrolyte: (1) Take 0.4 mL of 1,3-dioxolane monomer with a mass of 418 mg, add 60.8 mg of LiPF 6 , 12.5 mg of FEC and 4.2 mg of LLZTO solid electrolyte particles with a particle size of about 0.5 μm. Then stir at a speed of 500 rpm with a magnetic stirrer at room temperature for 10 min to obtain a uniformly dispersed suspension.
[0021] (2) Take 70 μL of the suspension obtained by stirring evenly in step (1) and load it into a PP diaphragm with a diameter of 16 mm. Place it in a button cell at room temperature and let it stand still until the self-polymerization of 1,3-dioxolane is completed, then the PDOL-based composite solid electrolyte sample 2 can be obtained.
[0022] Preparation of solid-state battery: In a glove box filled with argon with the water and oxygen content both less than 0.1 ppm, take 35 μL of the above-mentioned suspension and drop it on the negative electrode side. Cover it with a glass fiber diaphragm with a diameter of 16 mm and then drop 35 μL of the suspension again. Subsequently, place the positive electrode plate and encapsulate the battery. In the solid-state battery prepared in the present invention, lithium metal is selected as the negative electrode and lithium iron phosphate is selected as the positive electrode.
[0023] Example 3 Preparation of solid electrolyte: (1) Take 0.4 mL of 1,3-dioxolane monomer with a mass of 418 mg, add 30.4 mg of LiPF 6 , 104.5 mg of LiTFSI, 12.5 mg of FEC and 4.2 mg of LLZTO solid electrolyte particles with a particle size of about 0.5 μm. Then stir at a speed of 500 rpm with a magnetic stirrer at room temperature for 10 min to obtain a uniformly dispersed suspension.
[0024] (2) Take 70 μL of the suspension obtained by stirring evenly in step (1) and load it into a PP diaphragm with a diameter of 16 mm. Place it in a button battery at room temperature and let it stand still until the self-polymerization of 1,3-dioxolane is completed, then the PDOL-based composite solid electrolyte sample 3 can be obtained.
[0025] Preparation of solid-state battery: In a glove box filled with argon with the water and oxygen content both less than 0.1 ppm, take 35 μL of the above-mentioned suspension and drop it on the negative electrode side. After covering a glass fiber diaphragm with a diameter of 16 mm, drop 35 μL of the suspension again, then place the positive electrode plate and encapsulate the battery. In the solid-state battery prepared in the present invention, lithium metal is selected as the negative electrode and lithium iron phosphate is selected as the positive electrode.
[0026] Comparative Example 1 Preparation of solid electrolyte: The difference from Example 1 is that inorganic solid electrolyte particles are not added in step (1).
[0027] (1) Take 0.4 mL of 1,3-dioxolane monomer, with a mass of 418 mg, add 60.8 mg of LiPF 6 , 12.5 mg of FEC. Then stir with a magnetic stirrer at a speed of 500 rpm for 10 min at room temperature to obtain a clear solution.
[0028] (2) Take 70 μL of the suspension obtained by stirring evenly in step (1) and load it into a PP diaphragm with a diameter of 16 mm. Place it in a button battery at room temperature and let it stand still until the self-polymerization of 1,3-dioxolane is completed, then the PDOL-based solid electrolyte sample 4 can be obtained.
[0029] Preparation of solid-state battery: In a glove box filled with argon with the water and oxygen content both less than 0.1 ppm, take 35 μL of the above-mentioned suspension and drop it on the negative electrode side. After covering a glass fiber diaphragm with a diameter of 16 mm, drop 35 μL of the suspension again, then place the positive electrode plate and encapsulate the battery. In the solid-state battery prepared in the present invention, lithium metal is selected as the negative electrode and lithium iron phosphate is selected as the positive electrode.
[0030] Comparative Example 2 Preparation of solid electrolyte: The difference from Example 3 is that inorganic solid electrolyte particles are not added in step (1).
[0031] (1) Take 0.4 mL of 1,3-dioxolane monomer, with a mass of 418 mg, add 30.4 mg of LiPF 6, 104.5 mg of LiTFSI and 12.5 mg of FEC. Subsequently, it was stirred at 500 rpm for 10 min with a magnetic stirrer at room temperature to obtain a clear solution.
[0032] (2) Take 70 μL of the suspension obtained by stirring evenly in step (1) and load it into a PP diaphragm with a diameter of 16 mm. Place it in a button battery at room temperature and let it stand still until the self-polymerization of 1,3-dioxolane is completed, then a PDOL-based solid electrolyte sample 5 can be obtained.
[0033] Preparation of solid-state battery: In a glove box filled with argon with the water and oxygen content less than 0.1 ppm, take 35 μL of the above-mentioned suspension and drop it on the negative electrode side. After covering a glass fiber diaphragm with a diameter of 16 mm, drop 35 μL of the suspension again, and then place the positive electrode plate and encapsulate the battery. In the solid-state battery prepared in the present invention, lithium metal is selected as the negative electrode and lithium iron phosphate is selected as the positive electrode.
[0034] In order to prove the effectiveness of the poly(1,3-dioxolane) (PDOL)-based composite solid electrolyte formulation provided by the present invention that can self-polymerize and effectively control the self-polymerization rate, electrochemical impedance spectroscopy comparative tests were respectively carried out on the ionic conductivities of Example 1, Example 2, Comparative Example 1, Example 3, and Comparative Example 2. The test frequency range was 1 MHz to 1 Hz, and the test temperature was 25 °C. The test results are as Figure 1 , Figure 2 shown. The electrolyte thickness was uniformized to 40 μm, and the specific values are shown in Table 1.
[0035]
[0036] In addition, Raman spectra of Example 1, Example 2, and Comparative Example 1 at different polymerization times were also compared, as Figure 3 shown. The three curves in the figure respectively represent the Raman spectra of Example 1 polymerized for 5 d, Example 2 polymerized for 7 d, and Comparative Example 1 polymerized for 6 h. The peak at about 845 cm -1 represents the out-of-plane rotation of the C-H bond and the vertical vibration of the C-O bond. The appearance of this peak indicates the successful polymerization of the molecular long chain. It can be seen from Figure 3 that the sample of Comparative Example 1 had completed polymerization 6 h after preparation; while Example 1 was completely polymerized 5 d after preparation; for Example 2, even after standing still for 7 d after preparation, it was not completely polymerized. The above information shows that the addition of inorganic solid particles has a very significant effect on the polymerization rate.
[0037] The performance comparison diagrams of the solid-state batteries assembled in Example 1, Example 2, and Comparative Example 1 are as Figure 4As shown, the test conditions are as follows: the voltage range is 2.5 - 4.0 V, the current density is 0.3 C (1 C = 170 mA g -1 ), and the test temperature is set at 30 °C.
[0038] Finally, it should be noted that the above are only several specific embodiments of the present invention and should not be construed as limiting the protection scope of the present invention. Any improvements made to the embodiments of the present invention, the selection of specific methods, the equivalent replacement of technical solutions, etc. should all be within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.
Claims
1. A PDOL-based composite solid electrolyte, characterized in that It is composed of lithium hexafluorophosphate, lithium salt, organic additives, inorganic solid electrolyte particles and 1,3-dioxolane monomer, and its ratio is 8-32 grams of lithium hexafluorophosphate, 1-10 grams of organic additives, 0.1-50 grams of inorganic solid electrolyte particles and 0-50 grams of lithium salt per 100 grams of 1,3-dioxolane.
2. The PDOL-based composite solid electrolyte according to claim 1, characterized in that: The lithium salt is any one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide and lithium difluorooxalatoborate.
3. The PDOL-based composite solid electrolyte according to claim 1, characterized in that: The organic additive is any one or more of fluoroethylene carbonate, succinonitrile and vinyl carbonate.
4. The PDOL-based composite solid electrolyte according to claim 1, characterized in that: The inorganic solid electrolyte particles are any one or more of lithium lanthanum zirconium tantalum oxide, lithium aluminum titanium phosphate, and lithium lanthanum titanium oxide, and the particle size range is 0.1 to 10 μm.
5. A method for preparing a PDOL-based composite solid electrolyte as claimed in claim 1, characterized in that The following steps are involved: (1) adding lithium hexafluorophosphate, lithium salt, organic additives, and inorganic solid electrolyte particles to 1,3-dioxolane monomer, mixing them uniformly at room temperature, and forming a suspension by stirring or ultrasonic method; (2) The suspension obtained in step (1) is dripped or sprayed onto the surface of the battery separator. The amount of suspension added is 20-500 μL per square meter of the battery separator. The suspension is allowed to stand at room temperature until the self-polymerization of 1,3-dioxolane is completed, thereby obtaining a PDOL-based composite solid electrolyte.
6. The method for preparing the PDOL-based composite solid electrolyte according to claim 5, characterized in that: The stirring speed in step (1) is 0-1000 rpm, and the stirring time is 1-60 min; the ultrasonic frequency of the ultrasound is 20-100 kHz, and the ultrasonic time is 1-30 min.
7. The method for preparing a PDOL-based composite solid electrolyte according to claim 5, characterized in that: The battery separator described in step (2) is any one of a PE separator, a PP separator, and a glass fiber separator.