Coal tar pitch-based carbon composited Sb2Se3 microrod anode toward superior sodium storage performance

Abstract

Antimony selenide (Sb2Se3) with low cost and high theoretical capacity has been explored as a potential alternative anode for sodium ion batteries. However, the large volumetric variation and sluggish dynamics of Sb2Se3 lead to unsatisfactory long-term cycling life and inferior rate performance. In order to resolve these issues, we proposed a fabrication of Sb2Se3 coated by N-doped carbon derived from coal tar pitch (CTP) by a facile solvothermal method followed by annealing process. The reasonable content of CTP can accommodate the volume expansion, hinder the pulverization and accelerate the charge transfer of Sb2Se3 upon the cycling process. As a result, the Sb2Se3/CTP6 electrode exhibits superior long cycling property with desodiation/sodiation of 129.2(130.6) mAh g−1 after 400 cycles at high current density of 5 A g−1 and outstanding rate performance. The XPS spectrum tests verify the decomposition of Sb2Se3 during the cycling in the first time and demonstrate the CTP can effectively enhance the structural stability of Sb2Se3. The ex-situ XRD is also utilized to reveal the Na+ storage mechanism and phase transition. This work offers a new modification for enhancing the structural stability of alloy-type anode materials.