Interfacial Electrochemical Lithiation and Dissolution Mechanisms at a Sulfurized Polyacrylonitrile Cathode Surface

Dacheng Kuai; Shen Wang; Saul Perez-Beltran; Sicen Yu; Gerard A Real; Ping Liu; Perla B Balbuena

doi:10.1021/acsenergylett.3c02757

Interfacial Electrochemical Lithiation and Dissolution Mechanisms at a Sulfurized Polyacrylonitrile Cathode Surface

ACS Energy Lett. 2024 Feb 5;9(3):810-818. doi: 10.1021/acsenergylett.3c02757. eCollection 2024 Mar 8.

Authors

Dacheng Kuai^{1

2}, Shen Wang³, Saul Perez-Beltran¹, Sicen Yu³, Gerard A Real¹, Ping Liu^{3

4}, Perla B Balbuena^{1

2

5}

Affiliations

¹ Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States.
² Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States.
³ Department of Nanoengineering, University of California, San Diego, La Jolla, California 92093, United States.
⁴ Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, United States.
⁵ Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States.

Abstract

Advances in sulfurized-polyacrylonitrile (SPAN)-based cathode materials promise safer and more efficient lithium-sulfur (Li-S) battery performance. To elucidate electrolyte-cathode interfacial electrochemistry and polysulfide (PS) dissolution, we emulate discharge SPAN reactions via ab initio molecular dynamics (AIMD) simulations. Plausible structures and their lithiation profiles are cross-validated via Raman/IR spectroscopy and density functional theory (DFT). Lithium bis(fluorosulfonyl)imide (LiFSI) plays versatile roles in the Li-SPAN cell electrochemistry, primarily as the major source in forming the cathode-electrolyte interphase (CEI), further verified via X-ray photoelectron spectroscopy and AIMD. Besides being a charge carrier and CEI composer, LiFSI mediates the PS generation processes in SPAN electrochemical lithiation. Analysis of AIMD trajectories during progressive lithiation reveals that, compared to carbonates, ether solvents enable stronger solvation and chemical stabilization for both salt and SPAN structures. Differentiated CEI formation and electrochemical lithiation decomposition pathways and products are profoundly associated with the intrinsic nature of lithium bonding with oxygen and sulfur.