A lithium ion battery electrolyte and a lithium ion battery
Patent Information
- Application Number
- CN202610964146.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-30
- Publication Date
- 2026-10-09
AI Technical Summary
[0006]为了解决上述技术问题，本公开提供了一种锂离子电池电解液，，以解决现有技术中长期循环过程中产生的过渡金属离子持续迁移和沉积所导致的界面劣化、电解液副反应加剧以及电池容量衰减的问题，从而实现对电池长期循环过程中金属离子行为的动态调控，并提高锂离子电池的循环寿命和界面稳定性
[0014]在本公开电解液中，动态金属离子调控添加剂在电池初始循环阶段主要以自由态形式存在，由于电池内部过渡金属离子浓度较低，其对电解液体系及锂离子传输过程影响较小，从而避免传统强络合剂导致的阻抗增加和离子传输受限问题。随着电池循环进行，正极材料中逐渐溶出的Fe、Mn、Ni等过渡金属离子不断增加，动态金属离子调控添加剂中的配位基团能够与所述过渡金属离子发生动态配位作用，从而形成可逆络合结构，并调控其迁移及界面反应行为。该动态络合结构能够降低过渡金属离子向负极表面的迁移及沉积，减少其诱导的界面膜破裂和副反应发生，从而抑制电解液持续分解以及界面持续劣化，最终提升锂离子电池的长循环性能。
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Abstract
Description
Technical Field
[0001] This disclosure relates to the field of lithium-ion battery technology, and in particular to a lithium-ion battery 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 long cycle life and long-term operational stability are constantly increasing. Especially under conditions of high-capacity energy storage batteries, high load, and high temperature operation, batteries typically need to undergo hundreds to thousands of charge-discharge cycles. During long-term cycling, complex electrode / electrolyte interface reactions and material structure evolution continuously occur inside the battery, leading to the loss of active lithium, degradation of the electrode interface structure, and exacerbation of electrolyte side reactions. This results in capacity decay and increased internal resistance, ultimately affecting the battery's lifespan and safety performance.
[0003] Currently, optimizing the electrolyte system is considered one of the important technical means to improve the cycle performance of lithium-ion batteries. By introducing functional additives into the electrolyte, the stability of the electrode interface can be improved and the occurrence of side reactions can be reduced. For example, vinylene carbonate, fluoroethylene carbonate, phosphorus-containing additives, and nitrile additives can participate in the interfacial film formation process, thereby improving battery cycle performance. In addition, to address the problem of transition metal ion dissolution during long-term cycling, some studies have also focused on introducing complexing agents, chelating agents, and functional molecules to inhibit the migration and deposition of metal ions.
[0004] However, during long-term battery cycling, transition metal ions in the cathode material are prone to dissolution and migration to the anode, especially under high temperature, high voltage, and acidic conditions, where this process is further intensified. The metal ions that migrate to the anode surface may undergo reduction deposition, inducing continuous rupture and reconstruction of the interfacial film, and exacerbating electrolyte side reactions and active lithium consumption. Furthermore, existing metal ion complexation or trapping methods typically rely on strong coordination interactions. While these can reduce metal ion migration to some extent, they may also affect lithium-ion transport processes, leading to increased battery impedance and decreased rate performance. Therefore, traditional technologies struggle to simultaneously achieve both metal ion control capabilities and electrochemical performance stability, failing to meet the development requirements of long-life lithium-ion batteries.
[0005] Therefore, developing an electrolyte system that can respond to the internal aging process of the battery and achieve dynamic regulation of transition metal ions during long-term battery cycling, thereby reducing metal ion migration and continuous interface degradation, is of great significance for improving the long-cycle performance of lithium-ion batteries. Summary of the Invention
[0006] To address the aforementioned technical problems, this disclosure provides a lithium-ion battery electrolyte that solves the problems of interface degradation, exacerbated electrolyte side reactions, and battery capacity decay caused by the continuous migration and deposition of transition metal ions during long-term cycling in the prior art. This enables dynamic control of the behavior of metal ions during long-term battery cycling and improves the cycle life and interface stability of lithium-ion batteries.
[0007] In a first aspect, this disclosure provides a lithium-ion battery electrolyte, the lithium-ion battery electrolyte comprising a lithium salt, an organic solvent, and a dynamic metal ion regulating additive; the dynamic metal ion regulating additive comprises a coordinating group, the coordinating group comprising one or more of pyridyl, nitrile, amide, carboxyl, β-diketone, ether, and crown ether.
[0008] The dynamic metal ion regulation additive can respond to changes in the coordination structure of transition metal ions generated during battery cycling, thereby regulating the transition metal ions (including Fe). 2+ Fe 3+ Mn 2+ Ni 2+ Co 2+ The migration and interfacial reaction processes of one or more of these processes are used to suppress the continuous degradation of the electrode interface.
[0009] As a preferred embodiment of this disclosure, the dynamic metal ion regulating additive comprises one or more of the following: amide-pyridine structure, nitrile-pyridine structure, carboxyl-pyridine structure, and silane-containing coordination structure. More preferably, the dynamic metal ion regulating additive comprises an amide-pyridine structure (obtained by reacting 4-aminopyridine with succinic anhydride).
[0010] As a preferred embodiment of this disclosure, based on the total mass of the lithium-ion battery electrolyte, the content of the dynamic metal ion regulating additive is 0.005 wt%-5 wt%. 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 dynamic metal ion regulating additive is 0.1 wt%-2 wt%. For example, 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%.
[0011] As a preferred embodiment of this disclosure, the lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium difluorooxalateborate.
[0012] As a preferred embodiment of this disclosure, the lithium salt content is 5 wt%-25 wt%, based on the total mass of the lithium-ion battery electrolyte. For example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt%.
[0013] As a preferred embodiment of this disclosure, the organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluorocarbonate solvents, and ether solvents.
[0014] In the electrolyte of this disclosure, the dynamic metal ion regulating additive exists primarily in a free state during the initial cycling stage of the battery. Due to the low concentration of transition metal ions inside the battery, its impact on the electrolyte system and lithium-ion transport process is minimal, thus avoiding the impedance increase and ion transport limitation problems caused by traditional strong complexing agents. As the battery cycles, the amount of transition metal ions such as Fe, Mn, and Ni gradually dissolves from the cathode material. The coordinating groups in the dynamic metal ion regulating additive can dynamically coordinate with these transition metal ions, thereby forming a reversible complex structure and regulating their migration and interfacial reaction behavior. This dynamic complex structure can reduce the migration and deposition of transition metal ions to the anode surface, reduce the induced interfacial film rupture and side reactions, thereby inhibiting the continuous decomposition of the electrolyte and the continuous degradation of the interface, ultimately improving the long-cycle performance of the lithium-ion battery.
[0015] In a second aspect, this disclosure provides a lithium-ion battery, including a positive electrode, a negative electrode, a separator, and the lithium-ion battery electrolyte described in the first aspect.
[0016] The technical solution provided in this disclosure has the following advantages compared with the prior art: (1) This disclosure introduces a dynamic metal ion regulation additive and uses the transition metal ions generated during the long-term cycling of the battery as a response signal to achieve dynamic regulation of the transition metal ions, thereby reducing their migration and deposition behavior.
[0017] (2) The dynamic metal ion regulation additive described in this disclosure can form a dynamic complex structure during long-term cycling, which is beneficial to reduce the continuous rupture of the interface film induced by transition metal ions and the occurrence of side reactions, thereby reducing the consumption of active lithium and the growth of interface impedance.
[0018] (3) Compared with traditional strong complexing agent systems, this disclosure regulates the behavior of transition metal ions through dynamic weak coordination, which can reduce the impact on lithium ion transport process while ensuring the metal ion regulation effect, thereby taking into account both cycle performance and rate performance.
[0019] (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
[0020] 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.
[0021] 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.
[0022] 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.
[0023] Unless otherwise specified, all raw materials used in the following embodiments are commercially available products.
[0024] Lithium hexafluorophosphate (LiPF6, CAS No.: 21324-40-3) was purchased from Shenzhen Xinzhoubang Technology Co., Ltd. Ethylene carbonate (EC, CAS No.: 96-49-1) was purchased from Sinopharm Chemical Reagent Co., Ltd. Dimethyl carbonate (DMC, CAS No.: 616-38-6) was purchased from Sinopharm Chemical Reagent Co., Ltd. Ethyl methyl carbonate (EMC, CAS No.: 623-53-0) was purchased from Sinopharm Chemical Reagent Co., Ltd. 4-Aminopyridine (CAS No.: 504-24-5) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Succinic anhydride (CAS No.: 108-30-5) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. 4-Cyanopyridine (CAS No.: 100-48-1) was purchased from Sigma-Aldrich; Nicotinic acid (CAS No.: 59-67-6) was purchased from Sigma-Aldrich; 3-Aminopropyltriethoxysilane (APTES, CAS No.: 919-30-2) was purchased from Sigma-Aldrich; 4-Pyridinecarboxaldehyde (CAS No.: 872-85-5) was purchased from Sigma-Aldrich; 1,3,6-Hexatrionitrile (HTCN, CAS No.: 6298-69-7) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. 18-Crown-6 (CAS No.: 17455-13-9) was purchased from Sigma-Aldrich.
[0025] 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 4-Aminopyridine and succinic anhydride were added to acetonitrile at a molar ratio of 1:1 and stirred at 70 °C for 6 h. After the reaction was completed, the solvent was removed under reduced pressure and the mixture was dried under vacuum for 12 h to obtain a dynamic metal ion regulating additive containing an amide-pyridine structure.
[0028] Preparation Example 2 APTES and 4-pyridinecarboxaldehyde were added to anhydrous ethanol at a molar ratio of 1:1 and refluxed at 80 °C for 8 h. After the reaction was completed, the solvent was removed under reduced pressure, and the mixture was dried under vacuum for 12 h to obtain a dynamic metal ion regulating additive with a silane coordination structure.
[0029] Example 1 A lithium-ion battery electrolyte, based on the total mass of the lithium-ion battery electrolyte, includes a lithium salt (LiPF6: 12 wt%) and a dynamic metal ion regulating additive with an amide-pyridine structure 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 lithium-ion battery electrolyte of this embodiment.
[0031] Example 2 A lithium-ion battery electrolyte differs from Example 1 in that the content of the dynamic metal ion regulating additive is 0.2 wt%. The rest is the same as in Example 1.
[0032] Example 3 A lithium-ion battery electrolyte differs from Example 1 in that the content of the dynamic metal ion regulating additive is 1 wt%. The rest is the same as in Example 1.
[0033] Example 4 A lithium-ion battery electrolyte differs from Example 1 in that the dynamic metal ion regulation additive is replaced with 4-cyanopyridine. Otherwise, it is the same as Example 1.
[0034] Example 5 A lithium-ion battery electrolyte differs from Example 1 in that the dynamic metal ion regulation additive is replaced with nicotinic acid. Otherwise, it is the same as Example 1.
[0035] Example 6 A lithium-ion battery electrolyte differs from Example 1 in that the dynamic metal ion regulating additive is replaced with the silane-coordination-structured dynamic metal ion regulating additive prepared in Preparation Example 2. Otherwise, it is the same as Example 1.
[0036] Comparative Example 1 A lithium-ion battery electrolyte differs from Example 1 in that it does not contain a dynamic metal ion regulation additive. Otherwise, it is the same as Example 1.
[0037] Comparative Example 2 A lithium-ion battery electrolyte differs from Example 1 in that the dynamic metal ion regulation additive is replaced with HTCN. Otherwise, it is the same as Example 1.
[0038] Comparative Example 3 A lithium-ion battery electrolyte differs from Example 1 in that the dynamic metal ion regulation additive is replaced with 18-crown-6. Otherwise, it is the same as Example 1.
[0039] Comparative Example 4 A lithium-ion battery electrolyte differs from Example 1 in that the dynamic metal ion regulation additive is replaced with 4-aminopyridine. 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 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 used, except that the electrolyte in Example 1 was replaced with the electrolytes 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 electrolyte in Example 1 was replaced with the electrolytes prepared in Comparative Examples 1-4.
[0044] Test case The 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: Transition Metal Ion Migration Test The Fe ion concentration in the electrolyte after battery cycling was tested using ICP-OES.
[0046] Test conditions: 45 ℃, 300 cycles at 1 C, electrolyte collected after battery disassembly.
[0047] The results are shown in Table 1. As can be seen from Table 1, the Fe dissolution concentration in the system of this embodiment is significantly lower than that in the comparative system, indicating that the dynamic metal ion regulating additive of this embodiment can effectively reduce the migration behavior of transition metal ions.
[0048] Table 1 Fe ion migration test
[0049] 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 1000 cycles.
[0050] The results are shown in Table 2. As can be seen from Table 2, the embodiments of this disclosure have better cycle stability.
[0051] Table 2 Room temperature cycling performance test
[0052] 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 500 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.
[0053] 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.
[0054] Table 3 High-Temperature Cycling Performance Test
[0055] Test Example 4: Electrochemical Impedance Testing AC impedance was measured 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 1000 cycles.
[0056] 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.
[0057] Table 4 Impedance Change Test
[0058] 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.
[0059] 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. A lithium-ion battery electrolyte, characterized in that, The lithium-ion battery electrolyte includes lithium salt, organic solvent, and dynamic metal ion regulating additive; the dynamic metal ion regulating additive includes a coordinating group, which includes one or more of pyridyl, nitrile, amide, carboxyl, β-diketone, ether, and crown ether.
2. The lithium-ion battery electrolyte according to claim 1, characterized in that, The dynamic metal ion regulating additive includes one or more of the following: amide-pyridine structure, nitrile-pyridine structure, carboxyl-pyridine structure, and silane-containing coordination structure.
3. The lithium-ion battery electrolyte according to claim 2, characterized in that, The dynamic metal ion regulating additive includes an amide-pyridine structure.
4. The lithium-ion battery electrolyte according to claim 3, characterized in that, The dynamic metal ion regulating additive is obtained by reacting 4-aminopyridine with succinic anhydride.
5. The lithium-ion battery electrolyte according to any one of claims 1 to 4, characterized in that, Based on the total mass of the lithium-ion battery electrolyte, the content of the dynamic metal ion regulating additive is 0.005 wt%-5 wt%.
6. The lithium-ion battery electrolyte according to claim 5, characterized in that, Based on the total mass of the lithium-ion battery electrolyte, the content of the dynamic metal ion regulating additive is 0.1 wt%-2 wt%.
7. The lithium-ion battery electrolyte according to claim 1, 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 lithium-ion battery electrolyte according to claim 7, characterized in that, Based on the total mass of the lithium-ion battery electrolyte, the lithium salt content is 5 wt%-25 wt%.
9. The lithium-ion battery electrolyte according to claim 1, 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 lithium-ion battery electrolyte as described in any one of claims 1 to 9.