Amorphous Cobalt Selenite Nanoparticles Decorated on a Graphitic Carbon Hollow Shell for High-Rate and Ultralong Cycle Life Lithium-Ion Batteries

Abstract

Transition metal compounds with complex compositions forming heterointerfaces during cycling are under development on account of their excellent electrochemical properties. Herein, a new synthesis strategy is successfully developed for uniquely structured hollow carbon nanospheres comprising amorphous CoSeO x nanoparticles. A drop-and-dry infiltration method is applied to synthesize metal salt-infiltrated hollow carbon nanospheres, which are then posttreated with a metalloid Se under inert conditions to form CoSe2–C hollow nanospheres. Partial oxidation of these nanospheres under a 350 °C air atmosphere produces amorphous CoSeO x –C hollow nanospheres. The synthesis of amorphous metal selenite using conductive carbon is being reported here for the first time. Moreover, the conversion mechanism of amorphous CoSeO x is studied systemically via ex situ X-ray photoelectron spectroscopy, transmission electron microscopy, and electrochemical analyses. The amorphous characteristics and heterostructure formation and the graphitic carbon with a good electric conductivity contribute to the good electrochemical kinetic performance and ultrastable cyclic stability of CoSeO x –C. CoSeO x –C shows remarkable long-term cycle performance (799 mA h g–1 for the 3000th cycle at a high current density of 5.0 A g–1) as well as remarkable rate capability (691 mA h g–1) even at 30 A g–1.

Electrochemical properties of yolk‐shell structured cobalt hydroxy chloride‐carbon composite as an anode for lithium‐ion batteries

“…The capacity retention difference between CoOHCl@C and CoOHCl proves that the hollow carbon structure effectively restrains the pulverization of the active material during repeated cycling, as hollow carbon acts as both a conducting material and a frame for maintaining the morphology during the repeated discharge and charge processes. 25,32 While the difference between CoOHCl@C and CoClHy-C verifies that yolk-shell structure and heterojunction structure are effective for ameliorating cycle stability. The cycle performances at a low current density of 0.5 A g À1 in Figure S4b corroborate that the yolk-shell structured carbon composite improves cycle performance.…”

“…The hollow carbon, generated binding energies of 283.8, 284.4, and 285.6 eV, which correspond to C═C sp 2 , CC sp 3 , and CO bonding, respectively (Figure 2C). 25 The large peak area of CC sp 3 implies that the hollow carbon mainly consists of graphitic carbon. The CoO peak at 531.4 eV is generated from cobalt oxide, and the CoOH peak at 532.0 eV is due to cobalt hydroxy chloride (Figure 2D).…”

Investigation of the potassium‐ion storage mechanism of nickel selenide materials and rational design of nickel selenide‐C yolk‐shell structure for enhancing electrochemical properties

“…40 The C 1s spectrum could be fitted to several peaks at 284.0, 284.6, 285.6, and 288.5 eV, which were assigned to C═C, C C,C O, and O C═O bonds, respectively, as displayed in Figure 6C. 41,42 Furthermore, in the Raman spectrum of NiSe x @C, the two peaks located at 1354 and 1602 cm À1 corresponded to the D band (related to disordered characteristics) and G band (related to graphitic characteristics), respectively, as shown in Figure 6D. [43][44][45][46] The I D /I G ratio (0.99) suggested that the carbon in the carbon nanospheres was partially graphitized by post-treatment at 700 C. 47,48 The thermogravimetric (TG) curves of NiSe x @C and bare NiSe x are represented in Figure S7.…”

Double‐shell and yolk‐shell structured ZnSe ‐carbon nanospheres as anode materials for high‐performance potassium‐ion batteries

“…b can be between 0.5 and 1, which determines the tendency of diffusion-controlled behaviors (b = 0.5) to capacitive behaviors (b = 1). [57][58][59] Figure 9B,D showed b values for the anodic peak1 and cathodic peak2, 0.84/0.89 for d-ZnSe@HC and 0.84/0.87 for y-ZnSe@HC. Based on Equation ( 4), the ratio of the capacitive contribution (k 1 v) can be analyzed, as shown in Figure 9E,F.…”