Two dimensional layered Co_0.85Se nanosheets as a high-capacity anode for lithium-ion batteries

Abstract

In recent years, two-dimensional (2D) layered transitional metal chalcogenides (TMCs) have received much attention as promising electrode materials in energy storage. Although recent reports on 2D TMC nanostructures have demonstrated promising electrochemical performances, the major scientific challenge is to develop a viable synthesis process to produce layered structures of chalcogenides (Co, Ni or Fe based TMCs) as anode materials. In this work, we propose the synthesis of layered Co0.85Se nanosheets in a solution based method by using a 2D oriented attachment strategy. The as-prepared Co0.85Se nanosheets exhibit specific capacities as high as 675 mA h g(-1) at 100 mA g(-1). When the current densities were further increased to 200, 500 and 1000 mA g(-1), the reversible capacities can still reach up to 645, 574 and 493 mA h g(-1) with excellent cycling life of 95, 85 and 73%, respectively. Li-ion storage performance of layered Co0.85Se nanosheets is higher than that of Co0.85Se microspheres as well as cobalt sulfide. The superior electrochemical performance of Co0.85Se nanosheets is attributed to their 2D layered structure which enhances electrical conductivity and improves diffusion pathways of the Li-ion within the host material. The synthesis method described in this work serves as a general route for the design and preparation of other 2D layered TMCs.

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

“…[37] The strong cathodic peak at 1.27 V can be ascribed to the formation of Li x CoSe and solid electrolyte interface (SEI) films. [38] The broad peak at 0.63 V corresponds to the conversion reaction of Li x CoSe to Li 2 Se and metallic Co. [39] Correspondingly, the anodic peaks at 1.28 and 2.1 V are associated with the oxidation…”

Nontopotactic Reaction in Highly Reversible Sodium Storage of Ultrathin Co9Se8/rGO Hybrid Nanosheets

“…Raman spectrum in Figure b shows a typical characteristic of cobalt selenide with a sharp peak around 665.7 cm −1 and another two weak peaks at 512.8 and 461.8 cm −1 . The sharp peak around 191.4 cm −1 corresponds to the Raman active Se−Se stretching vibrational modes in the cubic structure . In addition, there are another two prominent peaks around 1350 and 1580 cm −1 , which can be attributed to the local defects and disorder induced D band and sp 2 graphite G band originated from rGO, respectively .…”

“…Figure a and Figure S4a,b (see the Supporting Information) show the cyclic voltammetry (CV) for Co 9 Se 8 /rGO CS50, CS20, and CS70 electrodes at a scan rate of 0.1 mV s −1 with a cut‐off voltage range of 0–3.0 V versus Na/Na + at room temperature, respectively. During the first sodiation process, a sharp and intense cathodic peak around 0.89 V for CS50 can be related with the conversion reaction as well as the formation of irreversible solid electrolyte interphase (SEI) in the first cycle . This peak is shifted to 0.63 V (CS20) and 0.94 V (CS70) due to different Co 9 Se 8 contents (see Figure S4, Supporting Information).…”

Electrospun CoSe@N-doped carbon nanofibers with highly capacitive Li storage

“…Recently, CoSe x , GeSe 2 , SnSe 2 and VSe 2 have shown excellent electrochemical performance as anode materials for LIBs [9][10][11] . In particular, cobalt selenides (CoSe x ) have been extensively studied in the energy storage device [12][13][14][15] . However, large volume changes in the charge/discharge process lead to pulverization of electrode materials and the subsequent detachment from the current collector, resulting in rapid capacity degradation.…”