Constructing Hollow Ni_0.2Co_0.8S@rGO Composites at Low Temperature Conditions as Anode Material for Lithium‐Ion batteries

Abstract

Due to their high theoretical capacities, metal sulfides have been considered as promising electrode materials for lithium‐ion batteries (LIBs). Heavy‐duty applications of metal sulfides for LIBs, however, are still restricted by the unavoidable volume change, resulting in poor rate capability and cycling stability. In this work, a Ni−Co‐ZIF derived Ni0.2Co0.8S hollow nanocage@reduced graphene oxide (Ni0.2Co0.8S@rGO) composite was fabricated through facile self‐assembly followed by freeze‐drying. The highly porous architecture of Ni0.2Co0.8S hollow nanocages wrapped by flexible reduced graphene oxide (rGO) is shown to not only validly inhibit the huge volume expansion during repeated charge/discharge cycling, but also accelerate lithium‐ion and electron transport through the 3D rGO network. The as‐obtained Ni0.2Co0.8S@rGO exhibits excellent electrochemical performance with a high specific capacity of 1585 mA h g−1 after 250 cycles at a current density of 1 A g−1. It is shown that the increasing reversible capacity during cycling can be attributed to the electrochemical activation of porous Ni0.2Co0.8S‐2.5@rGO, the pseudocapacitive behavior, and the highly reversible formation/decomposition of the solid electrolyte interface layer during lithiation/de‐lithiation. The sulfidation and reduction syntheses were operated at a relative low temperature of 90 °C, which is beneficial to inherit the unique morphology of precursor.

Enhanced High-Rate Capability and Long Cycle Stability of FeS@NCG Nanofibers for Sodium-Ion Battery Anodes

“…In Figure c, a linear relationship between the square root of the scan rate (v 1/2 ) and the peak current (I p ) can be confirmed. The Na + diffusion coefficient was obtained using the Randles–Sevcik formula: , …”

Understanding the High‐Performance Anode Material of CoC2O4⋅2 H2O Microrods Wrapped by Reduced Graphene Oxide for Lithium‐Ion and Sodium‐Ion Batteries

“…In particular, reduced graphene oxide (rGO) is considered to be a promising carbonaceous material owing to its unique chemical stability, high flexibility, and large surface area. [18] Metal oxalates can be synthesized through the hydrothermal method, [19] solvothermal reaction, [20] microwave-assisted solution approach, [21] the sol-gel method, [22] and the reverse-micellar route. [23] In this work, CoC 2 O 4 •2 H 2 O is modified with graphene oxide, and CoC 2 O 4 •2 H 2 O and CoC 2 O 4 •2 H 2 O/rGO are prepared by a facile solvothermal and hydrothermal method, respectively.…”