Strain Engineering of a MXene/CNT Hierarchical Porous Hollow Microsphere Electrocatalyst for a High-Efficiency Lithium Polysulfide Conversion Process

Xin Wang; Dan Luo; Jiayi Wang; Zhenghao Sun; Guoliang Cui; Yuxuan Chen; Tong Wang; Lirong Zheng; Yan Zhao; Lingling Shui; Guofu Zhou; Krzysztof Kempa; Yongguang Zhang; Zhongwei Chen

doi:10.1002/anie.202011493

Strain Engineering of a MXene/CNT Hierarchical Porous Hollow Microsphere Electrocatalyst for a High-Efficiency Lithium Polysulfide Conversion Process

Angew Chem Int Ed Engl. 2021 Feb 1;60(5):2371-2378. doi: 10.1002/anie.202011493. Epub 2021 Jan 4.

Authors

Xin Wang¹, Dan Luo², Jiayi Wang^{1

3

4}, Zhenghao Sun³, Guoliang Cui^{1

3}, Yuxuan Chen¹, Tong Wang³, Lirong Zheng⁵, Yan Zhao³, Lingling Shui⁴, Guofu Zhou¹, Krzysztof Kempa^{1

6}, Yongguang Zhang^{1

3}, Zhongwei Chen²

Affiliations

¹ South China Academy of Advanced Optoelectronics & International Academy of Optoelectronics at Zhaoqing, South China Normal University, Guangzhou, 510006, China.
² Department of Chemical Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
³ School of Materials Science and Engineering, Hebei University of Technology, Tianjin, 300130, China.
⁴ School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, China.
⁵ Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China.
⁶ Department of Physics, Boston College, Chestnut Hill, MA, 02467, USA.

PMID: 33398902
DOI: 10.1002/anie.202011493

Abstract

Tensile-strained Mxene/carbon nanotube (CNT) porous microspheres were developed as an electrocatalyst for the lithium polysulfide (LiPS) redox reaction. The internal stress on the surface results in lattice distortion with expanding Ti-Ti bonds, endowing the Mxene nanosheet with abundant active sites and regulating the d-band center of Ti atoms upshifted closer to the Fermi level, leading to strengthened LiPS adsorbability and accelerated catalytic conversion. The macroporous framework offers uniformed sulfur distribution, potent sulfur immobilization, and large surface area. The composite interwoven by CNT tentacle enhances conductivity and prevents the restacking of Mxene sheets. This combination of tensile strain effect and hierarchical architecture design results in smooth and favorable trapping-diffusion-conversion of LiPS on the interface. The Li-S battery exhibits an initial capacity of 1451 mAh g^-1 at 0.2 C, rate capability up to 8 C, and prolonged cycle life.

Keywords: Li-S batteries; Mxene nanosheets; electrochemical performance; porous hollow microspheres; strain engineering.