Metallic Octahedral CoSe₂ Threaded by N‐Doped Carbon Nanotubes: A Flexible Framework for High‐Performance Potassium‐Ion Batteries

Abstract

Due to the abundant and low‐cost K resources, the exploration of suitable materials for potassium‐ion batteries (KIBs) is advancing as a promising alternative to lithium‐ion batteries. However, the large‐sized and sluggish‐kinetic K ions cause poor battery behavior. This work reports a metallic octahedral CoSe2 threaded by N‐doped carbon nanotubes as a flexible framework for a high‐performance KIBs anode. The metallic property of CoSe2 together with the highly conductive N‐doped carbon nanotubes greatly accelerates the electron transfer and improves the rate performance. The carbon nanotube framework serves as a backbone to inhibit the agglomeration, anchor the active materials, and stabilize the integral structure. Every octahedral CoSe2 particle arranges along the carbon nanotubes in sequence, and the zigzag void space can accommodate the volume expansion during cycling, therefore boosting the cycling stability. Density functional theory is also employed to study the K‐ion intercalation/deintercalation process. This unique structure delivers a high capacity (253 mAh g−1 at 0.2 A g−1 over 100 cycles) and enhanced rate performance (173 mAh g−1 at 2.0 A g−1 over 600 cycles) as an advanced anode material for KIBs.

Effect of Crystal Structures on Electrochemical Performance of Hierarchically Porous CoSe2 Spheres as Anodes for Sodium‐Ion Batteries

“…Typical FESEM images of the o‐CoSe 2 (Figure b,Figure S1a) and c‐CoSe 2 spheres (Figure c, Figure S1b) revealed that the samples still maintain the spherical morphology with a uniform diameter of around 485 nm. The reduced diameter of the o‐CoSe 2 and c‐CoSe 2 spheres is ascribed to annealing effect, which is similar with the reported results . The TEM studies (Figure e,f) of the o‐CoSe 2 and c‐CoSe 2 spheres revealed that such hierarchical porous spheres with a relatively rough surface are constructed by small particles.…”

“…Recently, transition metal sulfides/selenides (MXs), such as MoSe 2 , FeS 2 , CoS 2 , MoS 2 , have been explored as promising anode materials for the SIBs due to their high theoretical capacity and versatile material species . Among them, cobalt diselenide (CoSe 2 ) has received tremendous attention because of its zero bandgap, high theoretical capacity, low cost, and eco‐friendly . Nevertheless, as similar as other MXs, the application of the CoSe 2 is impeded by its poor ion‐diffusion efficiency and large volume expansion during electrochemical reaction process.…”

Nature of FeSe2/N‐C Anode for High Performance Potassium Ion Hybrid Capacitor

“…[29] The reaction mechanism of all these stages of evolution can be expressed by the following equation. Similar phenomena have also been reported in other selenides.…”

“…[27] These series of physical and chemical changes will affect the electrochemical performance. [29][30][31][32] Transition metal dichalcogenides (TMDs) have gained comprehensive attention in the field of energy storage due to their unique electrochemical properties, high electrical conductivity, and high capacity. [29][30][31][32] Transition metal dichalcogenides (TMDs) have gained comprehensive attention in the field of energy storage due to their unique electrochemical properties, high electrical conductivity, and high capacity.…”

Nature of Bimetallic Oxide Sb2MoO6/rGO Anode for High‐Performance Potassium‐Ion Batteries

“…[1][2][3][4][5] Because of the natural abundance of potassium, a similar redox potential of potassium to lithium, and the low cost, potassiumion batteries (KIBs) serve as a promising substitution to LIBs, [6][7][8][9][10][11] especially attractive in the largescale energy storage systems which strive intensively to lower the price to be competitive with other energy storage techniques. [1][2][3][4][5] Because of the natural abundance of potassium, a similar redox potential of potassium to lithium, and the low cost, potassiumion batteries (KIBs) serve as a promising substitution to LIBs, [6][7][8][9][10][11] especially attractive in the largescale energy storage systems which strive intensively to lower the price to be competitive with other energy storage techniques.…”