Defect-riched prussian blue analogues with superior adsorption-catalysis toward lithium polysulfides for high performance lithium-sulfur batteries

Abstract

Lithium‑sulfur batteries (LiS) garner significant interest within the energy storage industry, because of their exceptional theoretical energy density coupled with employment of environmental materials. Nevertheless, the broader implementation of LiS batteries faces challenges, primarily due to the lithium polysulfide (LiPSs) shuttle effect and the sluggish conversion kinetics associated with LiPSs. In this work, we introduce a reduction-induced dissolution process to fabricate a mesoporous CoFePB rich in crystal defects via a facile solvothermal method. The experimental results indicate that the abundance of crystal defects originate from the phase transition from Co3[FeIII(CN)6]2 to Co2[FeII(CN)6]. The subsequent adsorption tests and electrochemical evaluations have shown that the defect-rich CoFePB possesses enhanced LiPSs absorption capacity and improved cycling performance in contrast to the pristine CoFePB, which is primarily ascribed to proliferation of active sites emerging as a result of the crystal defects. Consequently, the D-CoFePB-S cathode demonstrates remarkable rate performance with 583 mAh g−1 at a substantial 5C current rate, superior long-term stability with capacity retention of 64.3 % over 2000 cycles at current rate of 2C and outstanding areal capacity of 4.9 mAh cm−2 at 0.1C, even under a substantial sulfur loading of 5.0 mg cm−2.