Cyclic Voltammetry in Lithium–Sulfur Batteries—Challenges and Opportunities

Abstract

Lithium–sulfur batteries (LSBs) have attracted tremendous interest due to their high theoretical energy density and the earth‐abundant sulfur feedstock. Multifarious characterization techniques have been applied to investigate the electrochemical mechanisms and the structure–property relationships in LSBs. Among them, cyclic voltammetry (CV), a basic electrochemical tool, can provide indispensable thermodynamic and kinetics information of the redox processes. However, the CV analysis in most LSB studies is sketchy—providing some well‐known information while ignoring some specific features. To fulfill the versatile role of CV and thus spur further breakthroughs on LSBs, the electrochemical reactions and challenges are first described, followed by the work principles and experimental setup of LSBs for the CV technique. Then, various protocols for specific research purposes in LSBs are summarized, particularly on the performance evaluation of sulfur cathodes. Ending with challenges and the outlook of the CV technique in the LSB study, the Review provides a timely summary and thus can be a guidance for future studies on batteries.

Optimizing Redox Reactions in Aprotic Lithium–Sulfur Batteries

“…So far, CV is an effective electrochemical technique extensively adopted to determine the redox couples and investigate electrochemical kinetics process. [ 50 ] In early studies, combined with the rotating‐ring disk electrode (RRDE), the three‐electrode system facilitates the basic mechanism analysis of the electrochemical process in different solvents including dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran, and 1,3‐dioxolane (DOL)/dimethoxymethane (DME). [ 51 ]…”

“…Reproduced with permission. [ 50 ] Copyright 2019, Wiley‐VCH. d) Elucidation of the catalytic effects of the asymmetric cell‐S.…”

Enhancement in Electrochemical Performance of Lithium‐Sulfur Cells through Sulfur Encapsulation in Hollow Carbon Nanospheres Coated with Ultra‐Thin Aluminum Fluoride Layer

“…Figure ‐a shows the CV curves of the S@HCS@AlF 3 electrode for the first three cycles. The cathodic peak located at higher voltage (2.2‐2.3 V) corresponds to the reduction process of S 8 to soluble high‐order polysulfides (Li 2 S n , 3≤ x ≤8), while the second cathodic peak at lower voltage (1.9‐2.0 V) is attributed to the formation of insoluble low‐order polysulfides (Li 2 S 2 /Li 2 S) . There are no peaks observed associated with Li insertion in the AlF 3 coating.…”

ZnO quantum dot-modified rGO with enhanced electrochemical performance for lithium–sulfur batteries

“…This means a lower charge transfer barrier of the conversion of S 8 to Li 2 S n in rGO@ZnO QDs/S. 60 Moreover, with a much sharper second reduction peak, the reaction kinetics of Li 2 S n to Li 2 S 2 /Li 2 S is enhanced by rGO@ZnO QDs. Also, the oxidation peaks emerged with a negative shi during the ve cycles for rGO@ZnO QDs, while no such phenomenon occurred for rGO@ZnO/S.…”