2-Ethylimidazole: a new star in lithium battery electrolytes
In today's era of rapid technological development, the advancement of battery technology is undoubtedly an important driving force for the fields of electronic devices, electric vehicles and even renewable energy storage. Among them, lithium batteries have become mainstream energy storage solutions due to their advantages such as high energy density, long cycle life and low self-discharge rate. However, with the continuous expansion of application scenarios, the performance bottlenecks of traditional lithium batteries have gradually emerged, especially under extreme conditions such as high temperature, low temperature, and high power output, the performance of traditional electrolytes is not satisfactory. Therefore, finding new electrolyte materials has become the focus of scientific researchers.
2-Ethylimidazole (2-Ethylimidazole, referred to as EIM) has made its mark in the field of lithium battery electrolytes in recent years. EIM not only has good chemical stability and electrochemical window, but also can significantly improve the conductivity, interface compatibility and safety of the electrolyte. This article will deeply explore the application potential of 2-ethylimidazole in new lithium battery electrolytes, analyze its advantages and challenges, and look forward to future research directions.
2-Basic Properties of Ethylimidazole
2-Ethylimidazole (EIM) is an organic compound containing an imidazole ring structure, with a molecular formula of C6H10N2. Its molecular weight is 110.15 g/mol, its melting point is 149-151°C and its boiling point is 285°C. EIM has high thermal and chemical stability and can maintain good physical and chemical properties over a wide temperature range. These characteristics make EIM perform well in a variety of application scenarios, especially in the field of lithium battery electrolytes.
1. Molecular structure and chemical properties
The molecular structure of EIM consists of an imidazole ring and an ethyl side chain. The imidazole ring is a five-membered heterocycle containing two nitrogen atoms, conferring excellent coordination capability and electron donor characteristics to EIM. The ethyl side chain increases the hydrophobicity of the molecules, which helps to improve the solubility of EIM in organic solvents. In addition, EIM is also of a certain basic nature and can react with acidic substances to form stable salt compounds. This characteristic allows EIM to act as a buffer in the electrolyte system, adjust the pH value, and prevent the electrolyte from decomposing.
2. Physical properties
In addition to chemical stability, EIM also exhibits excellent physical properties. It is a white crystalline solid at room temperature, has a high melting point and boiling point, and can remain solid or liquid in a wide temperature range. The density of EIM is 1.07 g/cm³ and the dielectric constant is 3.7, which make it very compatible in the electrolyte formulation. In addition, the glass transition temperature (Tg) of EIM is low, about -60°C, which means it can maintain good fluidity in low temperature environments, which is for improving lithium batteries at low temperatures.Performance under temperature conditions is crucial.
3. Electrochemical properties
EIM's electrochemical window is wide, usually between 3.0-5.0 V, which makes it suitable for high voltage lithium battery systems. Research shows that EIM can form a stable solid electrolyte interface (SEI) film on the surface of lithium metal negative electrode, effectively inhibiting the growth of lithium dendrites, thereby improving the safety and cycle life of the battery. In addition, EIM also has a high ion migration number, which can promote the rapid transmission of lithium ions, reduce the polarization phenomenon inside the battery, and thus improve the overall performance of the battery.
Current status of application of 2-ethylimidazole in lithium battery electrolytes
In recent years, with the increasing demand for high-performance lithium batteries, researchers have begun to explore various new electrolyte materials in order to break through the limitations of traditional electrolytes. 2-ethylimidazole (EIM), as a potential electrolyte additive, has shown impressive application prospects in several research projects. The following are the main application status and development trends of EIM in lithium battery electrolytes.
1. As an electrolyte additive
EIM was mainly used as an additive when it was introduced into the lithium battery electrolyte system. Studies have shown that adding EIM in moderation can significantly improve the conductivity and stability of the electrolyte. For example, after adding 1%-5% EIM to the carbonate electrolyte, the ionic conductivity of the electrolyte is increased by about 20%-30%, and the oxidative stability of the electrolyte is also significantly enhanced. This is because EIM can form hydrogen bonds or coordination bonds with anions in the lithium salt, changing the microstructure of the electrolyte, thereby promoting the dissociation and migration of lithium ions.
In addition, EIM can improve interfacial compatibility between the electrolyte and the electrode material. Experimental results show that in the electrolyte containing EIM, the surface morphology of the positive electrode material is more uniform, the utilization rate of active substances is higher, and the charging and discharging efficiency of the battery is also improved. Especially for high-nickel ternary cathode materials (such as NCM811), the addition of EIM can effectively suppress the occurrence of side reactions and extend the cycle life of the battery.
2. As a functional solvent
In addition to being an additive, EIM can also be used directly as a functional solvent, replacing traditional carbonate solvents. Compared with traditional solvents, EIM has lower viscosity and higher flash point, and can maintain good fluidity over a wider temperature range, especially suitable for lithium batteries in high temperature environments. Studies have shown that EIM-based electrolytes can maintain high ionic conductivity and stability under high temperature conditions above 60°C, while traditional carbonate electrolytes often suffer performance degradation due to decomposition at this temperature.
In addition, EIM has better wetting properties, which can better wet the electrode material and reduce the contact resistance between the electrode and the electrolyte. This is particularly important for improving the battery's rate performance and low temperature performance. The experimental results show that EIM is usedThe lithium battery as a solvent can still maintain a capacity retention rate of more than 80% in a low temperature environment of -20°C, while the capacity retention rate of traditional electrolyte batteries is only about 50%.
3. As a solid electrolyte component
With the rapid development of solid-state lithium battery technology, the application of EIM in solid-state electrolytes has also attracted widespread attention. As an organic small molecule, EIM has high flexibility and good film formation. It can form composite materials with inorganic solid electrolytes (such as LiPON, LLZO, etc.), improving the mechanical strength and ionic conductivity of the solid electrolyte. Research shows that by mixing EIM with inorganic solid electrolytes, a composite solid electrolyte with high ionic conductivity and good mechanical properties can be prepared, which is suitable for all-solid lithium batteries.
In addition, EIM can also be combined with polymer electrolytes (such as PEO, PVDF, etc.) to form a quasi-solid electrolyte. This type of electrolyte not only has high ionic conductivity, but also has good flexibility and processability, and can maintain stable electrochemical properties under large deformation. Experimental results show that EIM-based quasi-solid electrolytes can still maintain good conductivity and interface stability under extreme conditions such as bending and folding, and are suitable for lithium batteries in flexible electronic devices and wearable devices.
2-Advantages of ethylimidazole in lithium battery electrolytes
2-ethylimidazole (EIM) has attracted widespread attention in the field of lithium battery electrolytes mainly because it shows significant advantages in many aspects. The advantages of EIM will be discussed in detail from three aspects: electrochemical performance, safety and cost-effectiveness.
1. Excellent electrochemical performance
The application of EIM in lithium battery electrolytes has greatly improved the electrochemical performance of batteries, which is specifically reflected in the following aspects:
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Wide electrochemical window: The electrochemical window of EIM is wide, usually between 3.0-5.0 V, and can be suitable for high-voltage lithium battery systems. This makes EIM an ideal electrolyte additive for high voltage positive electrode materials (such as NCM811, NCA, etc.), helping to increase the energy density of the battery.
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High ionic conductivity: EIM can form hydrogen bonds or coordination bonds with anions in lithium salts, change the microstructure of the electrolyte, and promote the dissociation and migration of lithium ions. Research shows that the ionic conductivity of electrolytes containing EIM is 20%-30% higher than that of traditional electrolytes, thereby reducing the polarization phenomenon inside the battery and improving the overall performance of the battery.
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Good interface compatibility: EIM can form a stable solid electrolyte interface (SEI) film on the electrode surface, effectively inhibiting the occurrence of side reactions, especially lithium dendrites.Grow. This not only improves the safety of the battery, but also extends the cycle life of the battery. Experimental results show that electrolytes containing EIM can keep the battery at a high capacity retention rate after thousands of cycles.
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Excellent low-temperature performance: EIM has a low glass transition temperature (Tg) and can maintain good fluidity in low-temperature environments. This is crucial to improving the performance of lithium batteries under low temperature conditions. Studies have shown that lithium batteries using EIM as solvent can still maintain a capacity retention rate of more than 80% in a low temperature environment of -20°C, while the capacity retention rate of traditional electrolyte batteries is only about 50%.
2. Significantly improved safety
The safety of lithium batteries has always been the focus of industry attention, especially in electric vehicles and energy storage systems. The safety of batteries directly affects the reliability and service life of the entire system. The application of EIM in lithium battery electrolytes has significantly improved the safety of the battery, which is specifically manifested as:
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Inhibit the growth of lithium dendrites: EIM can form a stable SEI film on the surface of the lithium metal negative electrode, effectively inhibiting the growth of lithium dendrites. Lithium dendrites are one of the main causes of battery short circuit and thermal runaway, so the addition of EIM can significantly reduce the risk of safety accidents in batteries.
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Improving Thermal Stability: EIM has high thermal stability and chemical stability, and can maintain good physical and chemical properties over a wide temperature range. This allows the electrolyte containing EIM to maintain stable electrochemical properties under high temperature environments, avoiding the safety hazards caused by the decomposition of traditional electrolytes at high temperatures.
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Reduce volatility and flammability: Compared with traditional carbonate solvents, EIM has lower volatility and higher flash point, and is less prone to combustion and explosion. This makes the application of EIM in electrolytes greatly reduces the safety risks of batteries under high temperature or overcharge conditions.
3. Significant cost-effective
In addition to its advantages in electrochemical performance and safety, EIM also performs excellent in cost-effectiveness. Specifically reflected in the following aspects:
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Easy to obtain raw materials: The synthesis process of EIM is relatively simple, with a wide range of raw materials and a low price. Compared with some complex organic electrolyte additives, EIM has obvious cost advantages and is suitable for large-scale industrial production.
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Small amount and good effect: EIM as an efficient electric power supplyDetection additives can significantly improve the performance of the electrolyte by adding a small amount. This not only reduces material costs, but also reduces the complexity of the production process and improves production efficiency.
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Extend battery life: EIM can effectively suppress the occurrence of side reactions and extend the battery's cycle life. This means that maintenance and replacement costs will be greatly reduced throughout the battery life, thereby improving the economics of the battery.
2-Challenges and Coping Strategies of Ethylimidazole in Lithium Battery Electrolyte
Although 2-ethylimidazole (EIM) shows many advantages in lithium battery electrolytes, it still faces some challenges in practical application. In order to fully realize the potential of EIM, researchers need to propose effective response strategies to these issues. Here are several major challenges and solutions faced by EIM in lithium battery electrolytes.
1. Solubility issues
EIM has good chemical stability and electrochemical properties, but its solubility in some organic solvents is low, especially when crystallization is easily precipitated at high concentrations. This not only affects the uniformity and stability of the electrolyte, but may also lead to local current unevenness in the battery, which in turn affects the performance of the battery.
Coping strategies:
- Optimize solvent system: By selecting the appropriate co-solvent, the solubility of EIM can be effectively improved. Studies have shown that adding a small amount of high-polar solvents (such as DMC, EC) or low-polar solvents (such as FEC, VC) can significantly improve the solubility of EIM in the electrolyte. In addition, it is also possible to consider using an ionic liquid as a co-solvent to further improve the solubility of EIM and the stability of the electrolyte.
- Adjust the concentration of EIM: Reasonably control the amount of EIM added according to different application scenarios. Generally speaking, the amount of EIM should not be too high, and it is usually more suitable between 1% and 5%. Excessive concentrations not only increase the risk of precipitation of EIM, but may also affect other performance indicators of the electrolyte, such as viscosity and ionic conductivity.
2. Interface compatibility issues
Although EIM can form a stable SEI film on the electrode surface, in some cases, there are still certain problems with the interface compatibility between the EIM and the electrode material. For example, EIM may react sideways with certain high-nickel ternary positive electrode materials, resulting in poor passivation layers on the electrode surface, affecting the battery charge and discharge efficiency and cycle life.
Coping strategies:
- Develop new electrode materials: By improving the surface structure of the electrode material or introducing a functional coating, the interface compatibility between the EIM and the electrode material can be effectively improved. For example, using nanoscale positive electrode materials or coating a thin layer of conductive polymer (such as PEDOT-PSS) on its surface can reduce the side reaction between EIM and the electrode material and improve the overall performance of the battery.
- Optimize electrolyte formula: Interface compatibility between EIM and electrode material can be improved by adjusting other components in the electrolyte. For example, adding an appropriate amount of fluorocarbonate additives (such as FEC, FEMC) can enhance the interaction between EIM and the electrode material, promote the formation of SEI films, and reduce the occurrence of side reactions.
3. Long-term stability issues
EIM has high thermal and chemical stability, but during long-term use, there may still be certain decomposition or aging phenomena, especially under high temperature or high voltage conditions. This will not only affect the performance of the battery, but may also lead to safety issues.
Coping strategies:
- Introduce antioxidants: By adding an appropriate amount of antioxidants (such as BHT, THF) to the electrolyte, it can effectively inhibit the decomposition and aging of EIM and extend the service life of the battery. Studies have shown that adding 0.1%-0.5% antioxidants can significantly improve the stability of electrolytes containing EIM under high temperature conditions and reduce the capacity attenuation of the battery.
- Optimize battery packaging technology: By improving the battery packaging technology, it can effectively prevent the impact of the external environment on EIM and extend the battery's service life. For example, using aluminum-plastic film or ceramic separator with better sealing can reduce the invasion of oxygen and moisture, prevent EIM from reacting with oxygen in the air, thereby improving the long-term stability of the battery.
4. Cost and large-scale production issues
Although EIM's raw materials are easy to obtain and the synthesis process is relatively simple, in large-scale industrial production, they still face problems of cost and output. Especially for some high-end applications (such as electric vehicles and energy storage systems), the production cost and supply capacity of EIM will become the key factors that restrict its widespread use.
Coping strategies:
- Optimize synthesis process: By improving the synthesis process of EIM, production costs can be reduced and output can be increased. For example, using a continuous flow reactor instead of a traditional batch reactor can achieve efficient synthesis and large-scale production of EIM. In addition, it can also be optimized by optimizing reaction conditions (such as temperature, pressure, urging, etc.) and further improve the yield and purity of EIM.
- Build supply chain cooperation: Establish close cooperative relationships with upstream suppliers to ensure stable supply of EIM. At the same time, the production cost of EIM can be reduced through joint research and development and technology transfer, and promoted its widespread application in lithium battery electrolytes.
Future development direction and prospect
2-ethylimidazole (EIM) has broad application prospects in lithium battery electrolytes, but there are still many directions worthy of in-depth research. In the future, scientific researchers can further explore the application potential of EIM from the following aspects and promote the development of lithium battery technology.
1. Development of new electrolyte systems
With the continuous expansion of lithium battery application scenarios, traditional electrolytes have been unable to meet the growing performance needs. Therefore, the development of new electrolyte systems has become a hot topic in current research. As a multifunctional organic compound, EIM can play an important role in different types of electrolyte systems. Future research can focus on the following directions:
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High voltage electrolyte: With the widespread application of high-voltage positive electrode materials (such as NCM811, NCA, etc.), it is particularly urgent to develop electrolytes suitable for high-voltage lithium batteries. EIM has a broad electrochemical window, which can effectively inhibit the oxidation and decomposition of positive electrode materials, and is expected to become an ideal additive for high-voltage electrolytes.
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Low-temperature electrolytes: In cold areas or low-temperature environments, the performance of lithium batteries is often limited. EIM has a low glass transition temperature (Tg) that maintains good fluidity under low temperature conditions, helping to develop high-performance electrolytes suitable for low temperature environments. Future research can further optimize the synergistic effect of EIM and other low-temperature additives and improve the low-temperature performance of electrolytes.
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Solid-state electrolyte: Solid-state lithium batteries are considered to be an important development direction for the next generation of lithium batteries, with higher safety and energy density. As an organic small molecule, EIM has good flexibility and film formation, and can form composite materials with inorganic solid electrolytes or polymer electrolytes, thereby enhancing the mechanical strength and ionic conductivity of the solid electrolytes. Future research can explore more application possibilities of EIM in solid-state electrolytes and promote the commercialization of all-solid-state lithium batteries.
2. Interface engineering and material modification
Interface problems are one of the key factors affecting the performance of lithium batteries. EIM can form a stable SEI film on the electrode surface, effectively suppressing the occurrence of side reactions, but its interface compatibility with the electrode material still needs to be improved.One-step optimization. Future research can focus on the following directions:
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Interface Modification: By introducing a functionalized coating or modification layer on the electrode surface, the interface compatibility between the EIM and the electrode material can be further improved. For example, using nanoscale positive electrode materials or coating a thin layer of conductive polymer (such as PEDOT-PSS) on its surface can reduce the side reaction between EIM and the electrode material and improve the overall performance of the battery.
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Material Modification: By modifying the electrode material, the interaction with EIM can be enhanced and the formation of SEI film can be promoted. For example, using doping and coating can improve the surface activity and stability of the electrode material, reduce the decomposition of EIM on the electrode surface, and extend the cycle life of the battery.
3. Design of multifunctional electrolyte additives
In order to further improve the comprehensive performance of lithium batteries, future electrolyte additives must not only have a single function, but also have multiple synergistic effects. As a versatile organic compound, EIM has demonstrated excellent conductivity, interface compatibility and safety in electrolytes. Future research can further explore the synergy between EIM and other additives to design composite electrolyte additives with multiple functions. For example, combining EIM with fluorocarbonate additives (such as FEC, FEMC) can simultaneously improve the conductivity and interface stability of the electrolyte; combining EIM with antioxidants (such as BHT, THF) can simultaneously improve the thermal stability of the electrolyte; combining EIM with antioxidants (such as BHT, THF) can simultaneously improve the thermal stability of the electrolyte. and long-term stability.
4. Promotion of industrial production
Although EIM has shown many advantages in the laboratory, it still faces some challenges in large-scale industrial production. Future research needs to focus on the following aspects:
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Optimize synthesis process: By improving the synthesis process of EIM, production costs can be reduced and output can be increased. For example, using a continuous flow reactor instead of a traditional batch reactor can achieve efficient synthesis and large-scale production of EIM. In addition, the yield and purity of EIM can be further improved by optimizing reaction conditions (such as temperature, pressure, catalyst, etc.).
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Build supply chain cooperation: Establish close cooperative relationships with upstream suppliers to ensure stable supply of EIM. At the same time, the production cost of EIM can be reduced through joint research and development and technology transfer, and promoted its widespread application in lithium battery electrolytes.
Conclusion
2-ethylimidazole (EIM) as a novel electrolyteMaterials have shown huge application potential in the field of lithium batteries. It can not only significantly improve the electrochemical performance, safety and cost-effectiveness of batteries, but also have broad application prospects in emerging fields such as high voltage, low temperature and solid-state lithium batteries. However, EIM still faces some challenges in practical applications, such as solubility, interface compatibility and long-term stability. In the future, scientific researchers need to further optimize the performance of EIM through multidisciplinary cross-disciplinary research, solve the bottleneck problems in their applications, and promote the continuous innovation and development of lithium battery technology.
In short, the emergence of EIM has brought new opportunities and challenges to the field of lithium battery electrolytes. We have reason to believe that with the deepening of research, EIM will surely play a more important role in future lithium battery technology, helping global energy transformation and sustainable development.
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