Polymorph interface strategy presents avenues for kinetics-enhanced and dendrite-free lithium sulfur batteries

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-10, Vol.498, p.155856, Article 155856
• Main Authors: Cai, Lucheng, Ying, Hangjun, He, Chaowei, Huang, Pengfei, Han, Qizhen, Xu, Zuojie, Liu, Shenwen, Zheng, Haonan, Zhou, Yijing, Wang, Mengya, Han, Wei-Qiang
• Format: Article
• Language: English
• Subjects: CoSe2 compounds; Electrocatalysis; Lithium-sulfur batteries; Polymorph interfaces; Separator modification
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.155856

Nitrogen (N)-doped carbon-confined cobalt selenide (CoSe2) anchored on bacterial cellulose derived carbon fibers (denoted as CNF-NC/CoSe2) were prepared, and different crystalline phases of CoSe2 were obtained. Mix-phase CoSe2 with unique polymorph interface showcases excellent adsorptive and catalytic capacity to LiPSs and uniform lithium deposition. The shuttle effects have been effectively suppressed, promoting the conversion of LiPSs and ultimately resulting in enhanced performance. [Display omitted] •CNF-NC/CoSe2 with different crystalline phases CoSe2 were prepared.•The polymorph interface exhibits strong confinement and catalysis to LiPSs.•The CNF-NC/CoSe2-500 modified separator enables improvement to Li-S batteries.•The CNF-NC/CoSe2-500 can serve to protect the lithium metal anode. Shuttle effect and slow kinetic property are the challenges for the practical application of lithium-sulfur (Li-S) batteries. As an effective strategy, the polymorph effect is applied to rationally design multifunctional catalysts. Herein, the unique polymorph interface was constructed by different CoSe2 crystalline phases, and the systematic investigation on the sulfur cathodes and lithium anode is reported. Carbon nanofiber (CNF) derived from bacterial cellulose (BC) is used as a scaffold for disperse CoSe2 catalysts to construct electrically conductive highways. According to the experimental and calculation results, orthorhombic CoSe2 exhibits superior adsorption capacity and catalytic activity towards LiPSs, while cubic CoSe2 shows better electronic conductivity. Mixed phase CoSe2 not only balances the advantages of both, but also showcases impressive performance due to its unique polymorph interface structure. Besides, uniform lithium deposition can be also achieved. Consequently, the modified separators endow Li-S batteries with a high reversible discharge capacity (700 cycles at 1 C with only 0.063 % capacity decay per cycle) and excellent rate performance (702 mAh g−1 is maintained at 5 C). The pouch cell with separator modifications on both sides was assembled and exhibits a high discharge capacity. This work provides a polymorph interface strategy for the rational design of catalysts.