Abstract
We chose to understand the cyclic instability and rate instability issues in the promising class of Na+ conversion and alloying anodes with Sb2Se3 as a typical example. We employ a synthetic strategy that ensures efficient rGO (reduced graphene oxide) wrapping over Sb2Se3 material. By utilization of the minimum weight of additive (5 wt.% of rGO), we achieved a commendable performance with a reversible capacity of 550 mAh g(-1) at a specific current of 100 mA g(-1) and an impressive rate performance with 100 % capacity retention after high current cycling involving a 2 Ag-1 intermediate current step. The electrochemical galvanostatic intermittent titration technique (GITT) has been employed for the first time to draw a rationale between the enhanced performance and the increased mobility in the rGO wrapped composite (Sb2Se3-rGO) compared to bare Sb2Se3. GITT analysis reveals higher Na+ diffusion coefficients (approx. 30 fold higher) in the case of Sb2Se3-rGO as compared to bare Sb2Se3 throughout the operating voltage window. For Sb2Se3-rGO the diffusion coefficients in the range of 8.0x10(-15) cm(2) s(-1) to 2.2x10(-12) cm(2) s(-1) were observed, while in case of bare Sb2Se3 the diffusion coefficients in the range of 1.6x10(-15) cm(2) s(-1) to 9.4x10(-15) cm(2) s(-1) were observed.