Metal valence state-regulated Li bond chemistry for efficient lithium–sulfur battery catalysis: A case study of cupric and cuprous oxides (Open Access)--颗粒学报PARTICUOLOGY

Metal valence state-regulated Li bond chemistry for efficient lithium–sulfur battery catalysis: A case study of cupric and cuprous oxides (Open Access)

Hao-Bo Zhang^a, Bo-Bo Zou^a, Xian Zhong^a, Xin-He Liu^a, Kai-Xi You^a, Xinyan Liu^{a b *}, Hong-Jie Peng^a *

a Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 611731, China
b Key Laboratory of Quantum Physics and Photonic Quantum Information, Ministry of Education, University of Electronic Science and Technology of China, Chengdu, 611731, China

10.1016/j.partic.2025.03.004

Volume 100, May 2025, Pages 95-102

Received 10 February 2025, Revised 7 March 2025, Accepted 7 March 2025, Available online 15 March 2025, Version of Record 25 March 2025.

E-mail: xinyanl@uestc.edu.cn; hjpeng@uestc.edu.cn

Highlights

• Regulatory mechanism of (poly)sulfide–oxide interactions by Cu valence states was systematically unraveled.

• Cu²⁺ with a higher valence state was identified to indirectly regulate the Li bond strength with O²⁻.

• CuO with stronger Li bonds exhibited higher catalytic activity for the sulfur reduction reactions than Cu₂O.

• CuO-based catalytic layer further improved Li–S battery performance at kinetically limited conditions.

Abstract

Valence state is identified as a key property of transition metal-based catalysts in conventional heterogeneous catalysis research. For a specific monometal element, however, the regulatory role of valence state has seldom explored in emerging energy catalytic applications such as rechargeable lithium–sulfur batteries suffering from sluggish sulfur cathode conversion kinetics. In this study, two monometal oxides with distinct valence states, cupric oxide (CuO) and cuprous oxide (Cu₂O), were investigated, revealing valence-state-dependent interactions between oxides and sulfur species, as well as the modulated sulfur reduction reaction (SRR) kinetics. In addition to the inherent Cu²⁺-enabled surface (poly)thiosulfate redox, divalent Cu²⁺ and monovalent Cu⁺ were found to steer the oxygen reactivity and so indirectly tune the lithium bond strength that dictates the surface chemisorption of lithium (poly)sulfides. The stronger interactions between CuO and sulfur species promoted SRR conversion kinetics, enabling enhanced lithium–sulfur battery performance under kinetically demanding conditions such as high-rate capability at 2 C with a moderate sulfur loading of 1.3 mg cm⁻² and cycling stability for over 110 cycles at a high sulfur loading of 4.8 mg cm⁻². This work is expected to expand the scope of metal-valence-state effect on heterogeneous catalysis and offer an unconventional “indirect” way to regulate lithium-bond chemistry for battery research.

Graphical abstract

Keywords

Lithium–sulfur battery; Oxide; Valence state; Sulfur reduction reactions; Lithium bond chemistry

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