In Situ Formation of Co₉S₈/N‐C Hollow Nanospheres by Pyrolysis and Sulfurization of ZIF‐67 for High‐Performance Lithium‐Ion Batteries

Abstract

Co S is considered a promising candidate as the anode material in lithium-ion batteries (LIBs) because of its remarkable electrical conductivity, high theoretical capacity, and low cost. However, the practical application of Co S is greatly restricted because of its poor cycling stability and rate performance, which result mainly from the large volume expansion and dissolution of the polysulfide intermediates during the charge/discharge process. In this report, Co S embedded in N-rich carbon hollow spheres are successfully designed and synthesized through an in situ pyrolysis and sulfurization process, employing the well-known ZIF-67 as the precursor and ethanethiol as the sulfur source. Co S nanoparticles embedded in the N-rich hollow carbon shell exhibit excellent lithium storage properties at a high charge/discharge rate. A discharge capacity of 784 mAh g is obtained upon battery testing at a current density of 1 C (544 mA g ). Even upon cycling at a current density of 4 C, the as-prepared Co S /N-C can still deliver a discharge capacity of 518 mAh g . The excellent battery performance can be attributed to the hollow structure as well as the N-rich carbon encapsulation. Moreover, this metal-organic framework sulfurization route also shows good generality for the synthesis of other metal sulfide-carbon composites such as ZnS/N-C and Cu S/C.

Heterostructure CoS/NC@MoS2Hollow Spheres for High‐Performance Hydrogen Evolution Reactions and Lithium‐ION Batteries

“…ZIF‐67 hollow spheres were synthesized according to our previous report . Briefly, 20 mmol of CoSO 4 ⋅ 7H 2 O and 160 mmol of 2‐methylimidazole were dissolved in 400 mL absolute methanol, respectively.…”

Bimetallic Sulfide Co9S8/N‐C@MoS2Dodecahedral Heterogeneous Nanocages for Boosted Li/K Storage

“…In Figure 4a, in the first sweep, the peak at 1.40 V corresponds to the intercalation of Li ions into MoS 2 layer and further reduction of Li x MoS 2 [15] . The strong peak at approximately 1.13 V can be described to the reduction of Co 9 S 8 to metallic Co by listed reaction: Co 9 S 8 + 16 Li + + 16 e À $ 9 Co + 8 Li 2 S. [16] The cathodic peak at 0.65 V can be attributable to the decomposition of electrolyte, the formation of a solid electrolyte interface (SEI) layer and the reduction of MoS 2 to metallic Mo. [17] In Figure 4a, the anodic peak at 2.01 V are indexed to the oxidization of metallic Co.…”

Electrochemical Energy Conversion and Storage with Zeolitic Imidazolate Framework Derived Materials: A Perspective

“…ZIF‐67‐derived porous/hollow nano/microstructures significantly improved lithium storage properties due to their enlarged contact area with the electrolyte, reduced diffusion path for Li + ions and sufficient void space to release stress . In addition, the derived carbonaceous skeletons both improved electron conductivity and enhanced structural stability ,,…”

“…The fabrication of ZIF‐67 derived cobalt chalcogenides usually involves multi‐step synthetic procedures ,,. Lou's group designed a facile two‐step diffusion‐controlled method to prepare unique ZIF‐67 derived CoS 2 hierarchical hollow prisms .…”