Nitrogen-Doped Carbon Coated WS2 Nanosheets as Anode for High-Performance Sodium-Ion Batteries.

Yong Liu,Fengzhang Ren,Wanhong Zhang,Bok H Kim,Xianfu Wang,Chao Wang,Haichao Wang,Huijie Wei,Fei Wang,Chenglin Yan

doi:10.3389/fchem.2018.00236

Abstract

Due to the cost-effectiveness of sodium source, sodium-ion batteries (SIBs) have attracted considerable attention. However, SIBs still have some challenges in competing with lithium-ion batteries for practical applications. Particularly, the high rate capability and cycling stability are posing big problems for SIBs. Here, nitrogen-doped carbon-coated WS2 nanosheets (WS2/NC) were successfully synthesized by a high-temperature solution method, followed by carbonization of polypyrrole. When used as anode electrodes for SIBs, WS2/NC composite exhibited high-rate capacity at 386 and 238.1 mAh g−1 at 50 and 2,000 mA g−1, respectively. Furthermore, even after 400 cycle, the composite electrode could still deliver a capacity of ~180.1 mAh g−1 at 1,000 mA g−1, corresponding to a capacity loss of 0.09% per cycle. The excellent electrochemical performance could be attributed to the synergistic effect of the highly conductive nature of the nitrogen-doped carbon-coating and WS2 nanosheets. Results showed that the WS2/NC nanosheets are promising electrode materials for SIBs application.

Highlights

Nowadays, lithium ion batteries (LIBs) have become the most widely used energy storage devices for many applications ranging from high performance portable electronics and electrical vehicles to sustainable energy smart grids
The asprepared WS2/NC sample exhibits the similar XRD pattern as the as-prepared WS2, indicating the phase of the WS2 remains unchanged after the N-doped carbon coating
The structure can buffer the volume change during the repeated sodiation/desodiation processes and maintain the structural stability of WS2 nanosheets, which is beneficial for the rate capability and cycle stability (Li et al, 2017)

Summary

Introduction

Lithium ion batteries (LIBs) have become the most widely used energy storage devices for many applications ranging from high performance portable electronics and electrical vehicles to sustainable energy smart grids. The advantages of LIBs include high energy density, long life span, and so on (Armand and Tarascon, 2008; Yang et al, 2011; Lu et al, 2017; Wu et al, 2017; Xu et al, 2017; Geng et al, 2018; Wang et al, 2018; Zhang et al, 2018) These large-scale applications may be gradually hindered due to insufficient lithium resource and its uneven distribution in the Earth’s crust (Hou et al, 2017a; Fu et al, 2018). Graphite is well-known for being not suitable to host sodium ions since sodium seldom forms stable intercalation compounds with graphite (Komaba et al, 2011; Tian et al, 2017)

Methods

Results

Conclusion