Semi-Ionic C-F bond enabling fluorinated carbons rechargeable as Li-ion batteries cathodes

Pengyu Chen; Wei Liu; Hao Wang; Yao Jiang; Xiaobin Niu; Liping Wang

doi:10.1016/j.jcis.2023.06.108

Semi-Ionic C-F bond enabling fluorinated carbons rechargeable as Li-ion batteries cathodes

J Colloid Interface Sci. 2023 Nov:649:255-263. doi: 10.1016/j.jcis.2023.06.108. Epub 2023 Jun 19.

Authors

Pengyu Chen¹, Wei Liu¹, Hao Wang¹, Yao Jiang², Xiaobin Niu³, Liping Wang⁴

Affiliations

¹ School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, China.
² 21C Innovation Laboratory, Contemporary Amperex Technology Ltd. (21C LAB), Ningde 352100, Fujian, China.
³ School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, China. Electronic address: xbniu@uestc.edu.cn.
⁴ School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, China. Electronic address: lipingwang@uestc.edu.cn.

PMID: 37348345
DOI: 10.1016/j.jcis.2023.06.108

Abstract

Fluorinated carbon (CF_x) cathodes possess the highest theoretical energy density among lithium primary batteries. However, achieving reversibility in CF_x remains a significant challenge. This work employs a high-voltage sulfolane electrolyte and achieves a highly reversible CF_x cathodes in lithium-ion batteries (LIBs) via fine modification of the C-F bond character. The improved reversibility of CF_x originates from the semi-ionic CF_x phase, with a superior bond length and weaker bond energy than a covalent bond. This characteristic significantly mitigates the challenges encountered during the charging process. We screen and identify the fluorinated graphene CF_1.12 as a suitable cathode, providing an appropriate fluorine content and sufficient semi-ionic C-F bonds for rechargeable LIBs. This fluorinated graphene CF_1.12 exhibits an initial discharge specific capacity of 814 mAh g^-1 and a reversible discharge specific capacity of 350 mAh g^-1. This work provides a new clue for chemical bond regulation studies and provides insights into stimulating reversibility of primary-cell cathodes.

Keywords: Fluorinated carbons; Lithium-ion secondary batteries; Semi-ionic C-F bonds; Sulfolane-based electrolyte.