Binder-free cobalt sulfide@carbon nanofibers composite films as cathode for rechargeable aluminum-ion batteries

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2021-04, Vol.409, p.128235, Article 128235
• Main Authors: Zhuang, Ruiyuan, Huang, Zengliang, Wang, Sixian, Qiao, Jia, Wu, Jian-Chun, Yang, Jianhong
• Format: Article
• Language: English
• Subjects: Aluminum-ion batteries; Binder-free cathode; Cobalt sulfides; Electrochemical performance; Energy-storage mechanisms
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.128235

•CoS2@CNFs films have been synthesized as a novel binder-free cathode for AIBs.•3D network CNFs with CoS2 nanoparticles uniform distribution contribute to the excellent electrochemical performance.•New substance of AlCo2S4 is discovered during discharge/charge process.•Ex situ XRD, XPS and DFT are performed to reveal the charge-storage mechanism. Rechargeable aluminum ion battery (AIB) is considered to be a promising next-generation battery system that can meet future needs for the large scale energy storage, because of its high energy density and low-cost. For the development of long life AIBs, the most urgent challenge is to explore suitable cathode and understand the exact Al charge/discharge mechanism. Herein, a novel binder-free cathode material, CoS2@carbon nanofibers, was synthetized by electrospinning and annealing process. As a result, a specific capacity of ~80 mAh g−1 was maintained after 500 cycles under a current density of 200 mA g−1, which was higher than that of AIBs using a normal CoS2 cathode with binder. Significantly, even at a high current density of 500 mA g−1, the battery can still retain 74 mAh g−1 after 1200 cycles. Furthermore, its working mechanism was explored in combination with ex-situ XRD, XPS and first-principles calculations, which revealed that the reversible conversion reaction of CoS2/AlCo2S4. The novel binder-free CoS2@Carbon nanofibers cathodes are meaningful for the further design of binder-free AIBs with low-cost and long cycling life.