Bismuth Sulfide-Carbon Nanotube Composite As a High Capacity Anode for K-Ion Batteries

K-ion batteries (KIBs) have attracted attention as a promising alternative to commercial Li-ion batteries (LIBs) because of their low cost, earth abundance, and low redox potential (Li: -3.04 V and K: -2.93 V vs. standard hydrogen electrode), along with the similar chemical properties between K and Li. [1] KIBs also possess an electrical energy storage mechanism similar to LIBs, which has accelerated the development of KIBs.[2] To date, alloys of group 14 or 15 elements in the periodic table, as defined by their corresponding alloying reactions, have been considered as potential candidates for high-capacity anodes in KIBs.[3] In the previously reported LIB and sodium-ion battery (SIB) system, bismuth sulfide (Bi 2 S 3 ) was considered a potential electrode material for high capacity and low-cost electrode materials; however, their development is still infancy. In addition, to the best of our knowledge, K-storage capability in Bi 2 S 3 has not yet been reported. In this presentation, we synthesize nanostructured Bi 2 S 3 carbon nanotube (CNT) composites and investigate their possible electrochemical K-ion storage behaviors in KIBs for the first time. [4] A combination of experimental and first-principles calculations was used to investigate the overall K-storage mechanism of Bi 2 S 3 . The CNT matrix in this composite anode not only provides electronic conductivity but also decreases the absolute stress/strain, and accommodates a period of large volume changes during the potassiation–depotassiation process. Compared to Bi 2 S 3 , the Bi 2 S 3 -CNT composite electrode delivered much higher discharge–charge capacity of and 750 mA h g -1 and good cycling stability. It should be noted that the CNT encapsulants provided a strong buffer effect that mitigated the large volume changes and pulverizations of Bi 2 S 3 particles upon cycling, and enabled more efficient electronic conduction of the whole electrode during cycling. The XRD, SEM, TEM and EIS results clearly demonstrate the superior structural stability of the Bi 2 S 3 -CNT composite and its enhanced electrochemical K-storage performance. Reference s : [1] J.-Y. Hwang, S.-T. Myung, Y.-K. Sun, Adv. Funct. Mater., 2 (2018) 182938. [2] K. Kubota, M. Dahbi, T. Hosaka, H. Kumakura, S. Komaba, Chem. Rec., 18 (2018) 459-479. [3] W. Zhang, W. K. Pang, V. Sencadas and Z. Guo, Joule, 2 (2018) 1534-1547. [4] J.-Y. Hwang, R. Kumar, H. M. Kim, M. H. Alfaruqi, J. Kim, Y.-K. Sun, RSC Adv., 10 (2020) 6536–6539.