N‐Doped Carbon‐Coated Mixed‐Phase SnS–SnS2 Anode with Carbon Nanofibers Skeleton for Improving Dual‐Ion Battery in Concentrated Electrolyte

Abstract

Metal sulfides exhibit great potential for anode material due to the lamellar structure. However, the intrinsic low conductivity and large volume expansion result in poor cycle stability. Herein, a porous hierarchical structure (SnS–SnS2)–NC–CF anode material composed of carbon nanofibers skeleton and N‐doped carbon is designed, and a full dual‐ion battery based on the anode is constructed, coupled with natural graphite and high‐concentration electrolyte (6 M LiTFSI + 5% vinylene carbonate). The graphite/(SnS‐SnS2)–NC–CF dual‐ion battery shows a high initial discharge specific capacity up to 154.3 mAh g−1 at a current density of 100 mA g−1 in a working voltage window of 1.0–4.0 V. Also, the battery obtains a considerable capacity of 67.1 mAh g−1 at the high current density of 1000 mA g−1 and achieves an excellent cycling performance up to 2000 cycles with remarkable Coulombic efficiency near 100%. In addition, the battery exhibits a low self‐discharge of 1.83% h−1 and superior fast charge performance. Furthermore, the results of the X‐ray diffraction and scanning electron microscope characterizations further demonstrate good reversibility and stability. Consequently, this work provides a feasible strategy for the design of a high performance dual‐ion battery energy storage device.