Recycling two wastes for constructing vanadium nitride/vanadium trioxide dual-decorated carbonfiber interlayer and...

Reasonably constructing functional interlayers and sulfur host materials to synergistically suppress the shuttle effect of lithium polysulfides (LiPSs) and enhance reaction kinetics is key to effectively improve electrochemical performance of lithium‑sulfur (LiS) batteries. Herein, two wastes including cotton masks and coffee shells are recycled to prepare the polar vanadium nitride (VN)/vanadium trioxide (V₂O₃) co-decorated carbon fiber functional interlayer and biological porous carbon via facile liquid-phase impregnation and pyrolysis approaches. The functional interlayer as a physical barrier to suppress the dissolution and shutting of the LiPSs, whilst providing an interconnected highly conductive network for boosting electronic transmission. Especially, the V₂O₃ and VN particles exhibit strong synergistic adsorption capacity of the LiPSs by a density functional theory calculation due to the abundant empty 3d orbitals of vanadium atoms and strong polarity of nitrogen/oxygen atoms. Additionally, the redox conversion of the LiPSs is also synchronously accelerated by the conductive VN. So, the functional interlayer endows the biological porous carbon‑sulfur composite cathode materials with good electrochemical performances. The initial discharge capacity is 1018.3 mAh g^-1 at 0.2C, whilst 802.5 mAh g^-1 can be maintained after 200 cycles. After 500 cycles at 2.0C, the discharge capacity of 540.1 mAh g^-1 is also obtained. Even with the high sulfur content of 80 wt% and 90 wt%, the relatively good electrochemical performances are also achieved.