Aging-responsive slow-release film electrolyte and lithium ion battery
Patent Information
- Application Number
- CN202610964150.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-30
- Publication Date
- 2026-10-13
AI Technical Summary
[0006]为了解决上述技术问题，本公开提供了一种老化响应型缓释补膜电解液，以解决现有技术中界面成膜添加剂在电池初始循环过程中快速消耗、难以持续发挥界面修复作用，以及长期循环过程中界面持续劣化导致电池容量衰减和阻抗增加的问题，从而显著提升锂离子电池的长循环性能和界面稳定性
（1）本公开通过引入酸响应型缓释补膜添加剂，可利用电池长期循环过程中产生的HF等酸性老化产物作为触发信号，实现补膜组分的阶段性释放，从而避免传统添加剂在初始循环过程中快速消耗。
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Abstract
Description
Technical Field
[0001] This disclosure relates to the field of lithium-ion battery technology, and in particular to an aging-responsive slow-release electrolyte and a lithium-ion battery. Background Technology
[0002] With the widespread application of lithium-ion batteries in electrochemical energy storage, electric vehicles, and portable electronic devices, the requirements for battery cycle life and long-term stability are constantly increasing. Especially in large-capacity energy storage batteries and under high-load conditions, batteries typically need to undergo hundreds to thousands of charge-discharge cycles. During long-term cycling, complex electrode / electrolyte interface reactions continuously occur inside the battery, which can easily lead to continuous consumption of active lithium, electrolyte decomposition, and degradation of the electrode interface structure. This results in capacity decay and increased internal resistance, ultimately affecting the battery's lifespan and operational safety.
[0003] Currently, optimizing the electrolyte system is considered one of the important technical means to improve the long-cycle performance of lithium-ion batteries. By introducing functional additives into the electrolyte, stable solid electrolyte interphase (SEI) and positive electrode electrolyte interphase (CEI) films can be formed on the electrode surface, thereby reducing side reactions and improving interface stability. For example, additives such as vinylene carbonate (VC), fluoroethylene carbonate (FEC), lithium difluorooxalate borate (LiDFOB), 1,3-propane sulcolone (PS), and vinyl sulfate (DTD) have been widely used in commercial electrolyte systems. These additives can usually preferentially participate in interfacial reactions during the initial cycling stage of the battery, forming a protective interfacial film on the electrode surface, thereby improving the initial cycle performance of the battery.
[0004] However, existing interfacial film-forming additives are typically consumed in large quantities during the initial battery cycling process, with their effects mainly concentrated in the early interface construction stage. As the number of cycles increases, the interfacial film continuously breaks down, reconstructs, and evolves during electrochemical cycling and volume changes. The consumed additives are unable to continue their interface repair function, leading to further exacerbation of electrolyte decomposition, side reactions, and increased interfacial impedance during subsequent cycles. Furthermore, during long-term battery cycling, aging products such as HF, PF5, and transition metal ions may gradually form in the electrolyte system, further promoting interface degradation and electrolyte decomposition, thus further reducing the battery's long-term cycle stability. Therefore, traditional electrolyte systems often struggle to balance initial interface stability with long-term interface repair capabilities, failing to meet the development requirements of long-life lithium-ion batteries.
[0005] Therefore, developing an electrolyte system that can achieve continuous interface regulation and dynamic repair during long-term battery cycling, thereby inhibiting continuous interface degradation and improving the long-cycle performance of the battery, is of great significance for the development of high-performance lithium-ion batteries. Summary of the Invention
[0006] To address the aforementioned technical problems, this disclosure provides an aging-responsive slow-release electrolyte to solve the issues in the prior art where interfacial film-forming additives are rapidly consumed during the initial battery cycle, making it difficult to continuously exert their interfacial repair function, and where continuous interface degradation during long-term cycling leads to battery capacity decay and increased impedance. This significantly improves the long-cycle performance and interfacial stability of lithium-ion batteries.
[0007] In a first aspect, this disclosure provides an aging-responsive slow-release membrane replenishing electrolyte, the aging-responsive slow-release membrane replenishing electrolyte comprising a lithium salt, an organic solvent, and a slow-release membrane replenishing additive; the slow-release membrane replenishing additive comprising a membrane replenishing component and an acid-responsive carrier, the membrane replenishing component being encapsulated within the acid-responsive carrier or bonded to the acid-responsive carrier through a pyrolytic linkage structure; the acid-responsive carrier comprising one or more of polyurethane, polyurea, acetal-containing polymers, siloxane-containing polymers, ester-containing polymers, and imine-containing polymers.
[0008] In this disclosure, the slow-release film-repairing additive includes a film-repairing component and an acid-responsive carrier, wherein the film-repairing component is encapsulated within the acid-responsive carrier or bound to the acid-responsive carrier through a pyrolytic linking structure. During the initial cycling phase of the battery, due to the low content of acidic aging products such as HF (including one or more of HF, PF5, Lewis acid, and acidic decomposition products) in the electrolyte system, the acid-responsive carrier remains relatively stable, maintaining a low-release state for the film-repairing component and thus avoiding the rapid consumption of traditional interface additives during the initial cycling process. As cycling progresses, acidic substances such as HF gradually accumulate in the electrolyte, causing the acid-responsive carrier to undergo pyrolysis, swelling, or permeability changes, thereby gradually releasing the film-repairing component. The released film-repairing component further participates in the electrode interface film-forming process, achieving continuous repair and dynamic regulation of the electrode interface, inhibiting continuous degradation of the interface film and electrolyte decomposition side reactions, thereby reducing capacity decay and interfacial impedance growth, and significantly improving the long-cycle performance of the lithium-ion battery.
[0009] In some embodiments, the membrane-repairing component is selected from one or more of vinylene carbonate, fluoroethylene carbonate, lithium difluorooxalate borate, lithium bis(oxalate borate), lithium difluorophosphate, nitrile additives, and phosphate ester additives.
[0010] In some preferred embodiments, the sustained-release membrane-repairing additive is an acid-responsive polyurea microcapsule. The preparation method of the acid-responsive polyurea microcapsule includes the following steps: dissolving VC and LiDFOB in ethylene carbonate, adding an aqueous solution of polyvinyl alcohol for emulsification, and then adding isophorone diisocyanate and ethylenediamine for interfacial polymerization.
[0011] In some preferred embodiments, the content of the sustained-release membrane additive is 0.005 wt%-5 wt%, based on the total mass of the aging-responsive sustained-release membrane electrolyte. For example, 0.005 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%. More preferably, the content of the sustained-release membrane additive is 0.1 wt%-2 wt%. For example, 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%.
[0012] In some preferred embodiments, the particle size of the sustained-release film-forming additive is 50 nm to 2000 nm. For example, 50 nm, 200 nm, 400 nm, 600 nm, 800 nm, 1000 nm, 1200 nm, 1400 nm, 1600 nm, 1800 nm, and 2000 nm. More preferably, the particle size of the sustained-release film-forming additive is 100 nm to 500 nm. For example, 100 nm, 200 nm, 300 nm, 400 nm, and 500 nm.
[0013] In some embodiments, the lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium difluorooxalateborate.
[0014] In some preferred embodiments, the lithium salt content is 5 wt%-25 wt% based on the total mass of the aging-responsive slow-release electrolyte. For example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%.
[0015] In some preferred embodiments, the organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluorocarbonate solvents, and ether solvents.
[0016] In a second aspect, this disclosure provides a lithium-ion battery, including a positive electrode, a negative electrode, a separator, and the aging-responsive slow-release electrolyte described in the first aspect.
[0017] The technical solution provided in this disclosure has the following advantages compared with the prior art: (1) By introducing an acid-responsive slow-release membrane additive, this disclosure can utilize acidic aging products such as HF generated during long-term battery cycling as a trigger signal to achieve phased release of the membrane component, thereby avoiding the rapid consumption of traditional additives during the initial cycling process.
[0018] (2) The slow-release film-repairing additive described in this disclosure can continuously participate in the interfacial film formation and repair process during the long-term cycling of the battery, which is conducive to building a stable electrode interface structure, reducing the consumption of active lithium and the increase of interfacial impedance, thereby significantly improving the cycle life of lithium-ion batteries.
[0019] (3) Compared with the direct addition of a large amount of interfacial film-forming additives, this disclosure can achieve continuous interfacial repair in the later stage while maintaining a low initial impedance, thereby taking into account both the initial electrochemical performance and long-term cycling stability.
[0020] (4) The electrolyte system described in this disclosure has good compatibility with existing commercial electrolytes and battery manufacturing processes, and does not require significant adjustments to existing manufacturing processes, thus having good application prospects. Detailed Implementation
[0021] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.
[0022] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.
[0023] The range endpoints and arbitrary values disclosed herein are not limited to the exact values; these ranges should be understood to include values close to these ranges. For numerical ranges, the endpoint values, the endpoint values and individual point values, and the individual point values can be combined to form one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0024] Unless otherwise specified, all raw materials used in the following embodiments are commercially available products.
[0025] Lithium hexafluorophosphate (LiPF6, CAS No.: 21324-40-3) was purchased from Shenzhen Xinzhoubang Technology Co., Ltd. Ethylene carbonate (EC, CAS No.: 96-49-1), dimethyl carbonate (DMC, CAS No.: 616-38-6) and ethyl methyl carbonate (EMC, CAS No.: 623-53-0) were purchased from Sinopharm Chemical Reagent Co., Ltd. Vinyl carbonate (VC, CAS No.: 872-36-6) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Lithium difluorooxalate borate (LiDFOB, CAS No.: 409071-16-5) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Isophorone diisocyanate (IPDI, CAS No.: 4098-71-9) was purchased from Aladdin; Ethylenediamine (EDA, CAS No.: 107-15-3) was purchased from Sinopharm Group; Polyvinyl alcohol (PVA, CAS No.: 9002-89-5) was purchased from Sigma-Aldrich; The polyolefin separator uses Celgard 2400 separator with a thickness of 25 μm; Commercial lithium iron phosphate cathode: areal density 12 mg / cm³ 2 ; Commercial graphite anode: areal density 5.8 mg / cm³ 2 .
[0026] In the following content, room temperature refers to 25±2 ℃.
[0027] Preparation Example 1 VC and LiDFOB were weighed and dissolved in an appropriate amount of ethylene carbonate at a mass ratio of 3:1 to form a core material solution. The core material solution was added to an aqueous solution containing polyvinyl alcohol and emulsified at 10,000 rpm for 15 min. Subsequently, isophorone diisocyanate and ethylenediamine were added to carry out an interfacial polymerization reaction, which was carried out by stirring at room temperature for 4 h. The product was collected by centrifugation and washed three times successively with deionized water and ethanol, and dried under vacuum for 12 h to obtain an acid-responsive polyurea microcapsule sustained-release film-forming additive. The obtained microcapsules had a particle size of approximately 250 nm.
[0028] Preparation Example 2 In Preparation Example 1, the acid-responsive carrier was changed from polyurea to polyurethane, while other aspects remained the same as in Preparation Example 1, resulting in an acid-responsive polyurethane microcapsule sustained-release film-forming additive.
[0029] Example 1 An aging-responsive sustained-release membrane replenishing electrolyte comprises, based on the total mass of the aging-responsive sustained-release membrane replenishing electrolyte, a lithium salt (LiPF6: 12 wt%) and a sustained-release membrane replenishing additive (acid-responsive polyurea microcapsules prepared in Preparation Example 1) (0.5 wt%); the remainder is an organic solvent (EC:DMC:EMC = 3:4:3 (mass ratio)).
[0030] The above components were mixed evenly in an argon glove box to obtain the aging-responsive slow-release membrane electrolyte of this embodiment.
[0031] Example 2 An aging-responsive sustained-release electrolyte for membrane replenishment differs from Example 1 in that the content of acid-responsive polyurea microcapsules is 0.2 wt%. The rest is the same as in Example 1.
[0032] Example 3 An aging-responsive sustained-release electrolyte for membrane replenishment differs from Example 1 in that the content of acid-responsive polyurea microcapsules is 1 wt%. The rest is the same as in Example 1.
[0033] Example 4 An aging-responsive sustained-release electrolyte for membrane replenishment differs from Example 1 in that the mass ratio of VC to LiDFOB in the preparation process of the acid-responsive polyurea microcapsules is adjusted to 1:1. The rest is the same as in Example 1.
[0034] Example 5 An aging-responsive sustained-release electrolyte for membrane replenishment differs from Example 1 in that the mass ratio of VC to LiDFOB in the preparation process of the acid-responsive polyurea microcapsules is adjusted to 5:1. The rest is the same as in Example 1.
[0035] Example 6 An aging-responsive sustained-release electrolyte for membrane replenishment differs from Example 1 in that the acid-responsive polyurea microcapsules are replaced with the acid-responsive polyurethane microcapsules prepared in Preparation Example 2. The rest is the same as in Example 1.
[0036] Comparative Example 1 An aging-responsive slow-release membrane-replenishing electrolyte differs from Example 1 in that it does not contain a slow-release membrane-replenishing additive. Otherwise, it is the same as Example 1.
[0037] Comparative Example 2 An aging-responsive slow-release membrane electrolyte differs from Example 1 in that the slow-release membrane additive is replaced with equal amounts of VC and LiDFOB (mass ratio 3:1). The rest is the same as Example 1.
[0038] Comparative Example 3 An aging-responsive sustained-release membrane-replenishing electrolyte differs from Example 1 in that the sustained-release membrane-replenishing additive is replaced with non-acid-responsive PMMA microcapsules. Otherwise, it is the same as Example 1.
[0039] Comparative Example 4 An aging-responsive sustained-release membrane-replenishing electrolyte differs from Example 1 in that the sustained-release membrane-replenishing additive is replaced with polyurea microcapsules (i.e., without membrane-replenishing components). Otherwise, it is the same as Example 1.
[0040] Application Example 1 A CR2032 coin cell was assembled using a commercial lithium iron phosphate cathode, a commercial graphite anode, a Celgard 2400 separator, and the aging-responsive slow-release electrolyte obtained in Example 1, thus obtaining a lithium-ion battery.
[0041] The battery assembly process was carried out in an argon glove box, where the contents of H2O and O2 were both controlled to be below 0.1 ppm.
[0042] Application Example 2-6 The same method as in Application Example 1 was followed, except that the aging-responsive slow-release electrolyte in Example 1 was replaced with the aging-responsive slow-release electrolyte prepared in Examples 2-6.
[0043] Compare and contrast examples 1-4 The same method as in Application Example 1 was followed, except that the aging-responsive slow-release membrane replenishing electrolyte in Example 1 was replaced with the aging-responsive slow-release membrane replenishing electrolyte prepared in Comparative Examples 1-4.
[0044] Test case The aging-responsive slow-release electrolyte and lithium-ion battery prepared above were subjected to performance tests, including transition metal ion migration tests, battery cycle performance tests, electrochemical impedance tests, and electrode interface analysis tests.
[0045] Test Example 1: Slow-Release Behavior Test The release behavior of the sustained-release membrane additive was tested using HF triggering conditions. 0 ppm HF, 50 ppm HF, 100 ppm HF, and 200 ppm HF were added to the aging-responsive sustained-release membrane electrolyte of Example 1, respectively, and the electrolyte was allowed to stand at 45 °C for 7 days. Changes in VC concentration in the electrolyte were measured using high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS).
[0046] The test results are shown in Table 1. As can be seen from Table 1, the release of VC is low under HF-free conditions, while the release ratio of VC gradually increases with the increase of HF concentration, indicating that the acid-responsive carrier of this disclosure can respond to the acidic environment and realize the release of membrane-replenishing components.
[0047] Table 1 Release behavior of Fe sustained-release film-forming additives
[0048] Test Example 2: Room Temperature Cycling Performance Test Test conditions: Each lithium-ion battery was activated three times at 0.1 C within the voltage range of 2.5 V-3.65 V, and then charged and discharged at 1 C. The capacity retention rate was recorded after 500 cycles.
[0049] The results are shown in Table 2. As can be seen from Table 2, Examples 1-3 exhibited high capacity retention, indicating that the sustained-release membrane replacement system of this disclosure can effectively improve long-term cycling performance.
[0050] Table 2 Room temperature cycling performance test
[0051] Test Example 3: High Temperature Cyclic Performance Test The batteries in the application examples and comparative application examples were used for testing. They were cycled 300 times at a rate of 1 C within a voltage range of 2.5 V to 3.65 V at 45 ℃, and the capacity retention rate was recorded.
[0052] The results are shown in Table 3. As can be seen from Table 3, the system disclosed in this paper still exhibits excellent cycling stability under high temperature conditions.
[0053] Table 3 High-Temperature Cycling Performance Test
[0054] Test Example 4: Electrochemical Impedance Testing AC impedance testing was performed using an electrochemical workstation. The test frequency range was 100 kHz to 0.01 Hz; the disturbance voltage was 5 mV. Impedance changes were measured in the initial state of the battery and after 500 cycles.
[0055] The results are shown in Table 4. As can be seen from Table 4, the embodiments of this disclosure have a low impedance growth rate.
[0056] Table 4 Impedance Change Test
[0057] It should be noted that, in this document, relational terms such as "first" and "second" are used merely 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 a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0058] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. An aging-responsive slow-release electrolyte, characterized in that, The aging-responsive slow-release membrane replenishing electrolyte includes lithium salt, organic solvent, and slow-release membrane replenishing additive; the slow-release membrane replenishing additive includes a membrane replenishing component and an acid-responsive carrier, wherein the membrane replenishing component is encapsulated inside the acid-responsive carrier or combined with the acid-responsive carrier through a cleavable linkage structure; the acid-responsive carrier includes one or more of polyurethane, polyurea, acetal-containing polymers, siloxane-containing polymers, ester-containing polymers, and imine-containing polymers.
2. The aging-responsive slow-release electrolyte according to claim 1, characterized in that, The film-forming component is selected from one or more of the following: vinylene carbonate, fluoroethylene carbonate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorophosphate, nitrile additives, and phosphate ester additives.
3. The aging-responsive slow-release electrolyte according to claim 1, characterized in that, The sustained-release membrane-repairing additive is an acid-responsive polyurea microcapsule.
4. The aging-responsive slow-release electrolyte according to claim 3, characterized in that, Preparation method of the acid-responsive polyurea microcapsules The process includes the following steps: dissolving VC and LiDFOB in ethylene carbonate, emulsifying with an aqueous solution of polyvinyl alcohol, and then adding isophorone diisocyanate and ethylenediamine for interfacial polymerization.
5. The aging-responsive slow-release electrolyte according to any one of claims 1 to 4, characterized in that, Based on the total mass of the aging-responsive slow-release membrane electrolyte, the content of the slow-release membrane additive is 0.005 wt%-5 wt%.
6. The aging-responsive slow-release electrolyte according to any one of claims 1 to 4, characterized in that, The particle size of the sustained-release membrane additive is 50 nm-2000 nm.
7. The aging-responsive slow-release electrolyte according to any one of claims 1 to 4, characterized in that, The lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium difluorooxalateborate.
8. The aging-responsive slow-release electrolyte according to claim 7, characterized in that, Based on the total mass of the aging-responsive slow-release electrolyte, the lithium salt content is 5 wt%-25 wt%.
9. The aging-responsive slow-release electrolyte according to any one of claims 1 to 4, characterized in that, The organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluorocarbonate solvents, and ether solvents.
10. A lithium-ion battery, characterized in that, It includes a positive electrode, a negative electrode, a separator, and the aging-responsive slow-release electrolyte as described in any one of claims 1 to 9.