"Wane and wax" strategy: Enhanced evolution kinetics of liquid phase Li2S4 to Li2S via mutually embedded CNT sponge/Ni-porous carbon electrocatalysts

Xiaoxiao Liu; Qian Guo; Yu Li; Yue Ma; Xiaotao Ma; Panpan Liu; Donghong Duan; Zhonglin Zhang; Xianxian Zhou; Shibin Liu

doi:10.1016/j.jcis.2023.06.144

"Wane and wax" strategy: Enhanced evolution kinetics of liquid phase Li₂S₄ to Li₂S via mutually embedded CNT sponge/Ni-porous carbon electrocatalysts

J Colloid Interface Sci. 2023 Nov:649:481-491. doi: 10.1016/j.jcis.2023.06.144. Epub 2023 Jun 20.

Authors

Xiaoxiao Liu¹, Qian Guo¹, Yu Li¹, Yue Ma¹, Xiaotao Ma², Panpan Liu³, Donghong Duan¹, Zhonglin Zhang¹, Xianxian Zhou⁴, Shibin Liu¹

Affiliations

¹ College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, PR China.
² Shandong Haihua Group Company Limited, Weifang 262737, PR China.
³ Department of Energy Chemistry and Materials Engineering, Shanxi Institute of Energy, Jinzhong 030600, PR China.
⁴ College of Chemistry, Taiyuan University of Technology, Taiyuan 030024, PR China.

PMID: 37356149
DOI: 10.1016/j.jcis.2023.06.144

Abstract

The lithium-sulfur battery (Li-S) has been considered a promising energy storage system, however, in the practical application of Li-S batteries, considerable challenges remain. One challenge is the low kinetics involved in the conversion of Li₂S₄ to Li₂S. Here, we reveal that highly dispersed Ni nanoparticles play a unique role in the reduction of Li₂S₄. Ni-porous carbon (Ni-PC) decorated in situ on a free-standing carbon nanotube sponge (CNTS/Ni-PC) enriches the current response of liquid phase Li₂S₄ and Li₂S₂ around the cathode more than 8.1 and 5.7 times higher than that of the CNTS blank sample, respectively, greatly boosting the kinetics and decreasing the reaction overpotential of Li₂S₄ reduction (lower Tafel slope and larger current response). Thus, with the same total overpotential, more space is provided for the concentration difference overpotential, allowing the more soluble polysulfide intermediates farther away from the surface of the conductive materials to be reduced based on the "wane and wax" strategy, and significantly improving the sulfur utilization. Consequently, S@CNTS/Ni-PC delivers excellent rate performance (812.4 mAh·g^-1 at 2C) and a remarkable areal capacity of 10.1 mAh·cm^-2. This work provides a viable strategy for designing a target catalyst to enhance the conversion kinetics in the Li₂S₄ reduction process.

Keywords: Carbon nanotube sponge/nickel-porous carbon; Li(2)S(4) conversion kinetics; Lithium-sulfur batteries; Ni nanocatalyst; Polarization.