Sulfur confinement into highly porous banana peduncle-derived carbon for high-rate performance lithium‑sulfur battery

Abstract

In this work, we introduce a facile route to synthesize an eco-friendly and inexpensive cathode host material to address the critical challenges of insulating sulfur, polysulfide shutting, and volume changes for lithium‑sulfur batteries (LSBs). The cathode uses banana peduncle, a biomass as a carbon precursor, to enhance the specific surface area and porosity after chemical activation. The two approaches (with/without the outer layer and with/without activation) have been compared to substantiate the role of banana skin and activation in boosting the performance of LSB. The carbon‑sulfur composite prepared with a sulfur loading of 75 % yields a significantly high initial discharge capacity of 1498 mA h g−1 at 0.1C, which remains stable with a very minimal capacity decay for the subsequent 100 charge-discharge cycles. Even at a high current rate (2C), the electrode shows a remarkable discharge capacity of 1076 mA h g−1, reflecting the efficacy of the as-fabricated cathode for LSB for high current applications. Further, the cycling performance is corroborated with high aerial sulfur loading (4 mg cm−2) to investigate the commercial feasibility. This confirms the advantage of the highly porous cathode matrix (surface area: 3148.42 m2 g−1 and pore volume: 2.51 cm3 g−1) in confining the lithium polysulfides and the volume expansion during charge-discharge cycles. To the best of our knowledge, this is the first-time banana peduncle has been used as a source of electrode material, and the present approach may pave the path for developing a green and sustainable, low-cost, highly porous carbon made from waste material as a sulfur host for high-performance LSB.