First Author: Zhong Hao
Corresponding authors: Ma Guozheng, Xu Weiqin, Lin Xiaoming
Correspondence unit: South China Normal University, Guangdong Second Normal University
【Background】
Zeolite imidazolate backbone material derivatives (ZIFs) and their derivatives have the characteristics of structural design and chemical composition control, and have been gradually applied to the field of secondary batteries. The success of ZIFs derivatives in anode materials for lithium-ion and sodium-ion batteries has received widespread attention. Potassium-ion batteries have been rapidly developed in recent years as an alternative to lithium-ion batteries and sodium-ion batteries. Previous studies have summarized the research progress of organometallic frameworks (MOFs) in potassium-ion batteries and the application of ZIFs in secondary batteries, but there are few systematic evaluations of ZIF derivatives in potassium-ion batteries.
【Key issues to be solved】
In this paper, we summarize the relevant work in recent years, and systematically expound the synthesis strategy of ZIF derivatives, the potassium storage mechanism of ZIF derivatives, and the applications of ZIF-derived porous carbon materials, alloy materials, metal selenides, metal sulfides, metal phosphide and metal telluride in the anode of potassium-ion batteries. On the basis of the above summary and analysis, the future development and innovation of ZIF derivatives in potassium-ion battery anode are proposed, and it is hoped that this paper can provide some guidance for the development of ZIF derivatives in the anode material of potassium-ion battery.
[Analysis of Research Ideas]
In this paper, combined with the relevant work published in recent years, the specific preparation methods of different types of ZIF derivatives are summarized, and some structural parameters of the materials are provided. Combined with in-situ or ex situ characterization, the potassium storage mechanism of three types of ZIF derivatives was illustrated by the potassium storage schematic diagram system. At the same time, according to the different types of ZIF derivatives, the electrochemical parameters of six ZIF derivatives on potassium-ion batteries were summarized, and the applications of various materials in potassium-ion batteries were summarized, which provided a reference for future research directions.
【Graphic Introduction】
Fig.1 Application and mechanism of ZIF derivatives in potassium-ion battery anodes
Fig.2 Preparation methods and strategies of various ZIF derivatives
Point 1. The diversification of preparation methods for ZIF derivatives and ZIF composites has laid a solid foundation for the design and application of ZIF-based potassium-ion battery electrodes. By adjusting the types of metal ions, relying on the flexibility of organic ligands and the characteristics of target materials, the targeted design of synthesis strategies can greatly achieve the optimization of the structure and function of the target products.
Fig.3 Mechanism of potassium storage in intercalation reaction
Point 2. ZIF-derived porous carbon has a stable carbon backbone, large surface area and porosity to accommodate the volume changes brought about by the adsorption/insertion of K+ process, and at the same time, more surface-active sites are introduced by heteroatom (N) doping, and the layer spacing is expanded to accelerate K+ transport. Pyridine-N contains lone pairs of electrons, which can adsorb K+ and provide more active sites, so the design and preparation of ZIF-derived carbon materials with high pyridinium-N content is the key.
Fig.4. Mechanism of potassium storage in alloy reaction
Point 3. The alloying reaction makes the alloy type anode have great potential, but the volume expansion problem of potassium-ion batteries using alloy type electrodes as long cycle life still needs to be solved. We hope to study the charge and discharge of alloy materials by in-situ and operando characterization methods, and obtain accurate and detailed potassium storage mechanisms, so as to carry out targeted structural design.
Fig.5. Mechanism of potassium storage in conversion reaction
Point 4. The potassium storage of ZIF-derived metal selenides, metal sulfides, and metal phosphide is achieved by a multi-electron conversion reaction between the original metal selenide, metal sulfide, and metal selenide phases and the final metal phase, which is usually accompanied by the formation of K2Se, K2S, and K3P. In situ or ex situ characterization methods can be used to identify the new phases generated during the charge-discharge process, so as to explain the potassium storage mechanism of transition metal selenide.
Fig.6 Application of ZIF-derived porous carbon in potassium-ion batteries
Point 5. Compared with traditional carbon-based materials, ZIF-derived porous carbon has a unique structure and the following advantages: i) Controllable porosity: ZIFs have an adjustable microporous structure, which is conducive to promoting electrolyte permeation and K+ rapid and efficient embedding/ejection, thereby improving the rate performance of the battery. ii) High specific surface area: ZIFs have a large comparative area, which can provide more active sites, improve the pseudocapacitance effect, and thus increase the potassium storage capacity. iii) Structure manipulation and doping: By selecting different organic ligands and metal centers, and controlling the calcination temperature, ZIF can be customized to form different kinds of N and defects, thereby achieving excellent electrochemical performance.
Fig.7. Application of ZIF-derived alloy materials in potassium-ion batteries
Point 6. The introduction of ZIF's strong and stable carbon skeleton through nanostructure engineering can effectively alleviate the volume change of alloy materials and achieve appropriate size control. Compared with the original alloy material, the ZIF-derived alloy material has a more stable electrode structure, higher capacity, better contact with the electrolyte, and more stable long-cycle performance.
Fig.8. Application of ZIF-derived metal selenide in potassium-ion batteries
Takeaway 7. ZIF-derived metal selenide has a special chemical composition and rich structure, which contributes to: i) improving the structural stability of the electrode and preventing the breakage of the active substance; ii) improve the ionic conductivity of the overall structure and promote K+ diffusion; iii) improve the contact between the active substance and the electrolyte; iv) Realize the design of chemical composition diversification, and design binary or ternary metal selenides.
Fig.9 Application of ZIF-derived metal sulfides in potassium-ion batteries
Point 8. Similar to ZIF-derived metal selenides, ZIF-derived metal sulfides have: i) a stable rigid structure that ensures the stability of metal sulfides in the event of electrochemical reactions; ii) the carbon skeleton has high ionic and electronic conductivity, which can speed up the reaction; iii) The presence of synergies and heterostructures may achieve unexpected electrochemical properties. At the same time, most ZIF-derived metal sulfides have a voltage plateau at around 1 V, which facilitates the realization of full-cell applications.
Fig.10 Application of ZIF-derived metal phosphide in potassium-ion batteries
Point 9. Embedding metal phosphide into a porous N-doped carbon framework composed of ZIF is one of the most effective methods for the practical utilization of metal phosphide. Through the rational design of ZIF-derived metal phosphides, electrode fragmentation and aggregation caused by repeated chemical reaction processes involving K+ can be effectively alleviated, thereby promoting the conversion or alloying reaction. In addition, the N-doped carbon backbone formed by annealing can significantly improve the electronic conductivity and cycling stability. ZIF-derived metal phosphide has a superior potassium storage capacity compared to conventional metal phosphides.
Fig.11 Summary of ZIF derivatives as materials for potassium-ion batteries
【Significance Analysis】
In this paper, the synthesis strategy of ZIF derivatives is summarized, the three potassium storage mechanisms of ZIF derivatives are expounded, and the application of six ZIF derivatives in potassium-ion batteries is summarized and analyzed, which provides guidance for the development of more reasonable and diversified ZIF derivatives as anode materials for potassium-ion batteries in the future, and provides a feasible scheme for the early commercialization of ZIF derivatives as anode materials for potassium-ion batteries.
【Original link】
https://doi.org/10.1016/j.mtener.2024.101625
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