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From China:The process Engineering Institute and others developed single-atom tin/carbon composites

Anode material is a key factor in determining the capacity of lithium-ion batteries. Recently, process engineering, Chinese Academy of Sciences institute of clean fuel conversion research energy catalytic and porous materials research associate professor Wang Yanhong cooperation with changsha institute professor chenhan, anode materials in lithium ion battery tin base important progress in research and innovation to combine with one atom structure tin compound preparation with nano carbon ball, The development of single-atom sn/carbon composite anode materials with high magnification and long cycle stability is of great significance to the development of sn based anode materials for lithium ion batteries. The study was published in Chemical Engineering Journal.  

In recent years, monatomic composite materials have been used in catalysis, energy storage and other fields. Monatomic composite materials are used as anode materials of sodium/potassium ion batteries, which can improve the dynamic behavior of materials, inhibit the volume change in the cycle process, and improve the electrochemical performance of materials. Tin-based materials have high lithium storage capacity, but the formation of Li-Sn alloy in the process of lithium lithium changes the lattice structure of materials, resulting in huge volume expansion, which affects the electrochemical performance of materials, hindering the commercial application of tin-based anode materials in lithium ion batteries. Tin-based monatomic composites prepared by monatomic tin and carbon nanospheres are expected to solve the problems of large volume change and poor electrochemical performance of lithium ion battery anode materials.  

The research group of Energy Catalysis and Porous Materials of fuel Clean Conversion Research Department is devoted to the research of anode materials for lithium ion batteries, and has won many invention patents. Based on the previous work, the researchers used the electrostatic interaction between Sn2+ and phenolic hydroxyl groups in phenolic resin to achieve the metal cation in the phenolic resin skeleton structure of the atomic level limited encapsulation, and then obtained single-atom tin/carbon composites. In the complete lithium state, each tin atom tends to adsorb 3 lithium ions, and one step desorption reaction is achieved in the process of delithium, showing a unique lithium storage mechanism. Compared with the conventional tin-based anode materials obtained by multi-step dealloying reaction, the desorption/lithium intercalation process of tin single atom shows faster dynamic behavior, different electrochemical reaction characteristics, and more outstanding electrochemical performance. The single-atom sn/CARBON composite has a capacity retention rate of 78.5% (281 mAh g-1) and a capacity loss rate of 0.0031%/ week after 7000 weeks of cycling at 1000 mA G-1 current density, while the capacity decay rate of the sn/carbon composite is 0 after 7000 weeks of cycling under the same condition.  

The preparation of single-atom sn/C composites promotes the commercial application of sn matrix composites, and provides important research value for the application of long-cycle lithium ion batteries in the field of energy storage, and further advances the comprehensive understanding and understanding of the electrochemical behavior of alloyed anode materials in lithium ion batteries. The work was supported by the National Natural Science Foundation of China and the 2020 Li Ka-shing Foundation Interdisciplinary Research Fund.  

Paper Link & NBSP;

 

Figure 1. (a) Schematic diagram of preparation process of SASn/C composites, (b) SEM images of precursor 3-AF/Sn and (C) SASn/C, (D-G) EDS Mapping of SASn/C materials, (H) HAADF-STEM images of SPHERICAL aberration correction of SASn/C materials & NBSP;

Figure 2. XPS (A) Sn 3D, (b) O 1S spectra of CNS and SASn/C materials, (C-D) FT-IR spectra, Sn K-Edge XANES spectra of SASn/C materials and fitting results of (F) R space, (g) K space and (h) wavelet transform. (I) Schematic diagram of Sn atom coordination environment in SASn/C material & NBSP;

Figure 3. Cycling properties of single-atom sn-carbon composites & NBSP;



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