Ultrafine Co0.85Se nanocrystals dispersed in 3D CNT network as a flexible free-standing anode for high-performance lithium-ion battery. (23rd June 2021) - Li, Huapeng
Abstract : A flexible free-standing film electrode with high pseudocapacitive contribution and strengthened cyclic stability was successfully prepared. Abstract : Cobalt selenides have drawn much attention in the field of rechargeable batteries owing to their considerable capacity. However, when applied to lithium-ion batteries (LIBs), their electrochemical performances are usually restrained by the limited active sites exploring the electrolyte. In this work, ultrafine Co0.85 Se nanocrystals with an average size of about 17 nm were applied to offer a feasible solution. The smallest grain size of Co0.85 Se ever applied to LIBs showed its advantage in ensuring more Li + active sites. Furthermore, a surface coating strategy was introduced to suppress the aggregations of Co0.85 Se nanocrystals, and carbon nanotubes (CNTs) helped to create a 3D hierarchical porous network, which could greatly facilitate the infiltration of electrolyte and improve the electronic conductivity as well. Due to the intertwined CNTs, the as-prepared composites also exhibited great flexibility. When tested in the half cells of LIBs, they demonstrated excellent rate capabilities of 797, 824, 830, 776, 687 and 548 mA h g −1 at 0.1, 0.2, 0.5, 1, 2, 5 A g −1, respectively, and the outstanding cyclic performance of 1582 mA h g −1 after 80 cycles at 0.2 A g −1 . Furthermore, full cells were assembled and they exhibited excellent rate and cyclic performances. With the extraordinary electrochemical performances, the flexible free-standing anode showed potential uses for next-generation wearable devices.