Cobalt Selenide Hollow Polyhedron Encapsulated in Graphene for High‐Performance Lithium/Sodium Storage

Abstract

Owing to the high specific capacities, high electrochemical activity, and various electronic properties, transition metal selenides are considered as promising anodes for lithium‐ and sodium‐ion storage. However, poor electronic conductivity and huge volume expansion during cycling are still responsible for their restricted electrochemical performance. Herein, CoSe hollow polyhedron anchoring onto graphene (CoSe/G) is synthesized by self‐assembly and subsequent selenization. In CoSe/G composites, the CoSe nanoparticles, obtained by in situ selenization of metal–organic frameworks (MOFs) in high temperature, are distributed among graphene sheets, realizing N element doping, developing robust heterostructures with a chemical bond. The unique architecture ensures the cohesion of the structure and endorses the reaction kinetics for metal ions, identified by in situ and ex situ testing techniques, and kinetics analysis. Thus, the CoSe/G anodes achieve excellent cycling performance (1259 mAh g−1 at 0.1 A g−1 after 300 cycles for lithium storage; 214 mAh g−1 at 2 A g−1 after 600 cycles for sodium storage) and rate capability (732 mAh g−1 at 5 A g−1 for lithium storage; 290 mAh g−1 at 5 A g−1 for sodium storage). The improved electrochemical performance for alkali‐ion storage provides new insights for the construction of MOFs derivatives toward high‐performance storage devices.

Electrostatics and Chemistry Combination Divalent Cobalt Ions and Alkali-Treated MXene for High-Performance Lithium-Ion Batteries

“…Calculations show that the I D /I G values for MXene, Co/MXene, and Co@MXene are 0.9326, 0.9497, and 0.9504, respectively, indicating that MXene after compounding has a higher content of amorphous carbon, which contributes to the enhanced electrical conductivity of the laminate and facilitates electron transport and ion diffusion of the electrode. 50,51 Carefully, Co@MXene and Co/MXene samples show characteristic peaks of Co at 523 cm −1 , which is consistent with previous reports, 52 indicating once again that Co nanoparticles are loaded onto MXene. It is of great significance to investigate the individual contents, and the thermo-oxidative degradation behavior was determined by thermogravimetric analysis (TGA), as shown in Figure S13.…”

A Composite of Two Dimensional GeSe2/Nitrogen‐Doped Reduced Graphene Oxide for Enhanced Capacitive Lithium‐Ion Storage

“…In recent years, substantial efforts have been made to develop the new anodes with high power/energy density and superior cycling life for LIBs. Metal selenides, such as MoSe 2 , [1][2] CoSe x , [3][4] WSe 2 , [5] SnSe 2 [6][7] and GeSe 2 , [8][9] have received much attention owing to their rich redox chemistry, high specific capacities and better electrical conductivity compared to their oxide counterparts. On the other hand, the weaker bonding of metal-selenium improves the reversibility of the conversion reaction during the charge and discharge process.…”

Self-assembled monodisperse FeSe2 microflowers as an advanced anode material for sodium ion batteries

“…4e shows the discharge-charge proles of the monodisperse FeSe 2 microowers electrode at different rates, further indicating its superior rate capability. Compared to a few other metal selenides (Co-NiSe/C, CoSe, SnSe 2 @C, V 3 Se 4 /NPCNFs, ZnSe/MWCNT, Fe 7 Se 8 @NC), [34][35][36][37][38][39] FeSe 2 shows superior Na storage properties, shown in Fig. 4f, making the monodisperse FeSe 2 microowers promising anode materials for SIBs.…”