Professor Yanglong Hou/Associate Professor Long Zhang AEM Review: The Rise and Development of MOF-based Materials in Metal-Chalcogenide Batteries: Current Status, Challenges and Prospects
【Article Information】
The Rise and Development of MOF-based Materials for Metal-Chalcogenide Batteries: Current Status, Challenges and Prospects
First author: Zhang Long
Corresponding authors: Zhang Long, Hou Yanglong
Unit: University of Science and Technology Beijing, Peking University
【Research Background】
Metal-chalcogenitase batteries (MCBs, negative electrodes: lithium, sodium, potassium; Cathodes: sulfur, selenium, tellurium) are considered candidates for next-generation energy storage systems due to their low cost, high theoretical capacity and environmental friendliness. Unlike the intercalation electrochemical mechanisms of traditional lithium-ion batteries, MCBs involve reversible redox reactions between chalcogenide cathodes and alkali metal ions to achieve energy storage and release. These reactions are not one-step reactions, but complex multi-step, multi-phase and multi-electron reactions accompanied by the formation of a series of intermediates (polysulfides, polyselenides, and polytellurides). Although such a reaction mechanism improves the theoretical capacity of MCBs, it also brings serious problems and challenges that hinder the commercial development of MCBs, mainly including huge volume changes in the charging and discharging process, shuttle effect of soluble intermediates, slow conversion kinetics and uncontrolled negative dendrite growth.
Metal-organic framework materials (MOFs) are a new type of crystalline porous materials with periodic network structure, which have the advantages of high porosity, low density, large specific surface area, regular pore channels, adjustable pore size, and topological diversity, and have been introduced into different parts of MCBs (positive electrode, negative electrode, diaphragm and electrolyte) to overcome the above problems. MOF-based composites and MOF-based derivatives are also further used in MCBs to improve the poor intrinsic conductivity of the original MOFs. The introduction of MOF-based materials plays a crucial role in improving the performance of MCBs. Although the development of MOF-based MCBs has accelerated in recent years, the application of MOF-based materials in MCBs has rarely been systematically and comprehensively sorted out and introduced.
【Article Introduction】
Based on this, Associate Professor Zhang Long of University of Science and Technology Beijing and Professor Hou Yanglong of Peking University published a title entitled "The Rise and Development of MOF-Based Materials for Metal-Chalcogen Batteries: Current Status, Challenges, and" in the international top journal Advanced Energy Materials Prospects". This paper first introduces the structural advantages of MOF-based materials. Secondly, the application of MOF-based materials in the positive and negative electrodes in MCBs is introduced in detail. Then, the application status of MOF-based materials as diaphragm/diaphragm modifiers and electrolyte additives in MCBs was summarized. Each section provides a detailed analysis of the working principle and application advantages of MOF-based materials. Finally, the challenges of MOF-based materials in MCBs are introduced and prospected. This review aims to provide comprehensive research guidelines for relevant researchers and promote the further development of MOF-based materials in MCBs.
Figure 1. Schematic diagram of the application of MOF-based materials to different parts of MCBs
【Key points of this article】
Point 1: Structural advantages of MOF-based materials
MOFs are constructed by linking metal centers (metal ions or clusters) with organic ligands, which results in pore spaces in the structural units of MOFs, and further forms porous structures through periodic combination, resulting in a specific surface area of up to 1000-10000 m2 g-1. What makes MOFs unique compared to other porous materials is the tunability of the pore structure. Since the structure of MOFs is determined by the geometry of metal nodes and the shape size of organic connectants, the selection of different metal nodes and organic connectants makes MOFs have the required pore size and structure to a certain extent. For MCBs, the porous structure and large specific surface area are favorable for MOFs as hosts for electrode active materials. Metal nodes can adsorb intermediates through chemical bonds and provide abundant polar catalytic sites to suppress shuttle effects and accelerate reaction kinetics.
To overcome the problem of inherently poor conductivity of MOFs, the researchers proposed two solutions. The first strategy is to combine MOFs with materials with good conductivity (graphene, carbon nanotubes, etc.) to improve conductivity. The second strategy is to utilize MOFs as self-sacrificing templates for pyrolysis to obtain various derivatives such as porous carbon materials, metal compounds, and metal compounds @ carbon materials, etc. Compared with the original MOFs, MOF-based derivatives can retain the large specific surface area, porous structure and rich active sites of the original MOFs to a large extent, but the conductivity is greatly improved. Therefore, MOF matrix composites and MOF-based derivatives are also widely used to improve the performance of MCBs systems.
Figure 2. Schematic diagram of the constituent elements and structural characteristics of MOFs
Point 2: MOF-based materials are applied to the positive and negative electrodes in MCBs
MOF-based materials for cathodes, including raw MOFs, MOF-based composites and MOF-based derivatives. For raw MOFs, how factors such as pore size, particle size, shape, size, metal center, and organic ligand affect the performance of MCBs are summarized. For MOF matrix composites, conductive polymers, carbon nanotubes, 3D carbon networks and other conductive materials are introduced. For MOF-based derivatives, porous carbon materials, metal compounds @ carbon materials, and other MOF-based derivative materials such as heterostructures and single metal atoms are introduced. The working mechanism of these materials for the cathode of MCBs is discussed in depth. MOF-based materials not only achieve uniform loading of active materials, but also provide physical confinement, chemisorption and catalytic conversion of soluble intermediates.
MOF-based materials for negative electrodes, including original MOFs, MOF-based composites and MOF-based derivatives. The original MOFs are mainly used as artificial SEI layers due to their limited conductivity, while MOF matrix composites and MOF-based derivatives can be used as artificial SEI layers and metal anode hosts. For MOF-based derivatives, porous carbon materials, metal@carbon materials, and metal compounds@carbon materials are described. The working mechanism of these materials as anodes of MCBs is explored in depth. The regular tunable pore structure or abundant active sites of MOF-based materials can be used as diffusion channels or rich sedimentation sites for metal ions, effectively homogenizing ion deposition, thereby realizing dendrite inhibition and negative protection.
Figure 3. Influence of different factors in MOF-based materials on cathode performance of MCBs
Figure 4. MOF-based materials are used as examples of negative protective layers in MCBs
Point 3: MOF-based materials are used in diaphragms and electrolytes in MCBs
MOF-based materials for diaphragm/diaphragm modifiers in MCBs: According to the different working mechanisms, three types of MOF-based diaphragms are sorted out in detail: MOF-based diaphragm that inhibits the positive shuttle effect, MOF-based diaphragm that regulates the growth of negative dendrite crystals, and MOF-based diaphragm that co-regulates the positive electrode and negative electrode.
MOF-based materials for electrolyte additives in MCBs: According to the physical state of the electrolyte, three types of electrolytes are described in detail: liquid MOF-based electrolytes, solid MOF-based electrolytes, and quasi-solid MOF-based electrolytes.
Figure 5. Example of a MOF-based diaphragm used to regulate both positive and negative electrodes in MCBs
Figure 6. Example of a quasi-solid MOF-based electrolyte
Point 4: Challenges and prospects of MOF-based materials applied to MCBs systems
Although great progress has been made in the application of MOF-based materials to MCBs systems in recent years, there are still blind spots and bottlenecks that need to be solved urgently:
1. The preparation process of MOF-based materials still needs to be improved. Achieving large-scale production of MOFs or MOF-based composites is a prerequisite for the development of MOF-based MCBs. How to prepare highly conductive MOFs remains a challenge. How to prepare more stable MOFs in electrolytes is another challenge. Improving the compatibility between MOF-based diaphragms and electrodes is also an issue that needs to be addressed. The current preparation method cannot completely remove the metal components in the MOF-based derived porous carbon material even after acid leaching, and the porous structure collapses after high-temperature carbonization. Therefore, a more complete preparation process must be explored to solve these problems.
2. The working mechanism of MOF-based materials in MCBs is still not detailed and systematic. For example, some theoretical cognition lacks quantitative results. We know that the pore size and particle size of the original MOFs have a certain effect on the ionic conductance, but the specific quantitative data is not clear. Therefore, it is necessary to further investigate the corresponding quantitative relationships to lay the foundation for the precise design of custom MOFs. In addition, the influence of metal sites on the reaction kinetics of MCBs of MOF-based materials has not been determined, and the optimal metal sites need to be further explored through systematic theoretical calculations.
3. MOF-based materials are currently the most studied in sulfur batteries, while relatively little is studied in other systems (selenium and tellurium batteries), and a complete system has not yet been established. Moreover, most strategies are proposed only for one side of MCBs (positive or negative), and cannot solve the problem of positive and negative poles synchronously, which may affect the further development of MCBs. Therefore, further broader and deeper studies are needed.
4. A unified standardized test protocol should be established in MOF-based MCBs. Many current reports claim that the excellent electrochemical performance of MCBs can be achieved through their strategies. However, differences between different reported electrochemical test methods and test conditions greatly interfere with fair comparisons. The lack of a unified standardized test protocol has become an obstacle to current research and even future commercialization of MOF-based MCBs. Therefore, it is necessary to develop reasonable and uniform test standards. In addition, target values for key parameters such as specific capacity, cycle life, and coulombic efficiency should be set to facilitate the study of MCBs towards commercial applications.
5. The electrochemical test conditions should be more similar to the actual application. This means that the test needs to be carried out under more severe conditions, such as increasing the mass load of the active material, reducing the use of electrolyte, and increasing the current density. In addition, the assembly and testing of whole cells (such as pouch cells) should be introduced as a necessary performance evaluation method to promote the further development of MOF-based MCBs.
Although there are still many challenges in the application of MOF-based materials in MCBs, outstanding research results continue to emerge. It is believed that with the continuous innovation of research ideas, the deepening of mechanism research and the continuous maturity of experimental conditions, MOF-based MCBs, energy storage systems with broad application prospects, will eventually achieve commercial application.
【Article Link】
The Rise and Development of MOF-Based Materials for Metal-Chalcogen Batteries: Current Status, Challenges, and Prospects https://onlinelibrary.wiley.com/doi/10.1002/aenm.202204378
【Corresponding Author Profile】
Zhang Long
Associate Professor, University of Science and Technology Beijing
He joined the School of Materials Science and Engineering, University of Science and Technology Beijing in 2021 and is currently an associate professor. Mainly engaged in the development of new energy storage materials and device design research, including high-performance metal-sulfur batteries, safe and stable alkali metal anodes, high-safety aqueous ion batteries, etc. He has presided over the National Natural Science Foundation of China Youth Project, the State Key Laboratory of New Metal Materials Open Project, the Central University Basic Research Business Fund Project, and the Postdoctoral Innovation Talent Support Program. In Adv. Energy Mater., Adv. Funct. Mater., ACS Nano, Nano Energy., J. Mater. Chem. A, Small, Chem. Commun., eScience and other international journals have published more than 20 academic papers. He serves as the Theme Consultant Editorial Board Member of Batteries, the Young Editorial Board Member of eScience, and the Adv. Energy Mater., Adv. Funct. Mater, Small, New J. Chem., reviewer of domestic and foreign academic journals such as Materials Review.
Hou Yanglong
Distinguished Professor of Liberal Arts at Peking University
Fellow of the Royal Society of Chemistry (FRSC), Chief Scientist of the National Key Research and Development Program of Nanotechnology, Director of the Beijing Key Laboratory of Magnetoelectric Functional Materials and Devices. Mainly engaged in the controlled synthesis of multifunctional magnetic materials and new energy materials and their application exploration in the field of nano-biomedicine and energy. The general preparation method of monodisperse magnetic nanomaterials was developed, and the application of magnetic nanoparticles in the diagnosis and treatment of major diseases such as tumors was explored. Several nanostructured hybrid materials are designed and prepared for high-performance lithium battery electrodes. So far, he has published more than 200 academic papers, cited more than 26,000 times, and H factor 89.
16 patents have been applied for, and 12 have been authorized. In 2019, he won the second prize of National Natural Science Award. He won the National Innovation Competition Award, Beijing Mao Yisheng Youth Science and Technology Award, and the Chinese Chemical Society-Royal Society of Chemistry Youth Chemistry Award. He has been funded by the National Science Foundation for Outstanding Young Scholars, and has been selected as a leading talent of the Ministry of Education, a leading talent of scientific and technological innovation of the 10,000 people plan, an outstanding talent of the Ministry of Education in the new century, a national outstanding scientific and technological worker and a Cited Scientist of Clarivate and Anco (at the beginning of 2018). He has given more than 80 invited presentations at international and various bilateral conferences. He is presiding over the National Key R&D Program, the National Natural Science Foundation of China's major scientific research instrument development, key projects, etc. He is currently the Associate Editor of Rare Metals, Adv. Sci., Adv. Healthc. Mater., Adv. Ther., Sci. China Mater. and other journal consultants/editorial board members, director / deputy secretary-general of the Chinese Chemical Society, etc.
【Introduction of the research group】
Professor Hou Yanglong's research group website:
http://nbm.coe.pku.edu.cn/Home.html
Associate Professor Zhang Long's personal homepage:
http://mse.ustb.edu.cn/shiziduiwu/shiziduiwu/cailiaoxuexi/2021-09-30/255.html