Rational design of NiCo2S4@MoS2 ball-in-ball heterostructure nanospheres for advanced lithium-sulfur batteries

• Published in: Electrochimica acta Vol. 383; p. 138268
• Main Authors: Yan, Lei, Zhang, Zexian, Yu, Fang, Wang, Jinxing, Mei, Tao, Wang, Xianbao
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2021; Elsevier BV
• Subjects: Ball-in-ball NiCo2S4@MoS2; Charging; Chemisorption; Discharge; Heterojunction; Heterojunctions; Heterostructures; Lithium sulfur batteries; Low conductivity; Molybdenum disulfide; Nanospheres; Polysulfides; Redox reactions; Sulfur content; Superior rate performance; Synergistic chemisorption; Three dimensional flow; Superior rate performance; Lithium-sulfur batteries; Ball-in-ball NiCo2S4@MoS2; Synergistic chemisorption; Heterojunction
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2021.138268

lNiCo2S4@MoS2 heterojunction structures is constructed to improve electrical conductivity.lThe flower-like ball-in-ball structure provides larger specific surface area and active sites.lA solid ball inside the ball-in-ball structure prevents the formation of the "dead sulfur".lThe composite maintains a capacity of 593.6 mAh g−1 after 500 cycles at 2 C. Lithium sulfur battery has a theoretical specific capacity of up to 1600 mA h g−1, which has a significant prospect. However, the shuttle effect of polysulfide, the low conductivity of sulfur and the serious volume change during charging and discharging process hinder the commercial application of lithium-sulfur batteries (LSBs). Here, the flower-like ball-in-ball NiCo2S4@MoS2 heterojunction composites were fabricated as the effective sulfur host in LSBs, which exhibited high specific capacity and durable cyclic life. The NiCo2S4 made up ball-in-ball structure offering more chemisorption sites to limit lithium polysulfide (LiPS) dissolution, and the MoS2 nanosheets grow in the surface of NiCo2S4 sphere to form three dimensional flower structure for accelerating the kinetics of LSBs redox reaction. Additionally, the specific hollow structure also availably alleviated the volume change during charging and discharging. Based on these merits, the NiCo2S4@MoS2 electrode with a sulfur content of 74% possessed an initial specific capacity of 1118 mAh g−1 at 0.1 C, and still had a reversible capacity of 865 mAh g−1 after 300 cycles. Even at a high rate of 5 C, the capacity of 467 mAh g−1 could still be achieved after 500 cycles. The flower-like ball-in-ball structure of NiCo2S4@MoS2 was prepared as the sulfur main body to inhibit the “shuttle effect”, improving the utilization rate of sulfur. And MoS2 catalyzed the transformation of LiPS, thus enhancing the stability of the lithium-sulfur battery. [Display omitted]