Electrode Interface Engineering in Lithium–Sulfur Batteries Enabled by a Trifluoroacetamide-Based Electrolyte

Abstract

The passivation caused by the deposition of the insulating discharge final product, lithium sulfide (Li2S), leads to the instability of the cycle and the rapid capacity fading of lithium–sulfur batteries (LSBs), which restricts the development of LSBs. This paper proposes the employment of trifluoroacetamide (TFA) as an electrolyte additive to alleviate the passivation by increasing the solubility of Li2S. The solubilization effect of TFA on Li2S is attributed to intermolecular hydrogen bonds and O–Li bonds. Li2S in the TFA-based electrolyte exhibits a flower-like 3D deposition behavior, which further alleviates the surface passivation of the electrode and impels conversion kinetics. In addition, the LiF-rich solid electrolyte interface layer can effectively defend the Li metal anode and suppress the growth of Li dendrites. Accordingly, the discharge capacity of the TFA-based battery remains at an excellent 681.2 mA h g–1 after 400 cycles with a Coulombic efficiency of 99% at 0.5 C. After the battery stabilizes, the capacity decay is only 0.036% per cycle. Under harsh conditions, such as high rates (2 C) and high sulfur loadings (5.2 mg cm–2) with lean electrolytes and elevated temperatures (60 °C), TFA-containing batteries exhibited more durable and stable cycling. This paper provides new insights into solving practical problems and gives an impetus in cycle stability for LSBs.

Sodium‐Selenium Batteries with Outstanding Rate Capability by Introducing Cubic Mn2O3 Electrocatalyst**

“…Although both composites demonstrate similar redox peak positions, the voltage distance of the reduction and oxidation peaks is much narrower (ΔV Mn 2 O 3 À based ¼ 0:606 V) with Mn 2 O 3 catalyst compared to the absence of Mn 2 O 3 (ΔV Mn 2 O 3 À free ¼ 0:763 V), indicating fast conversion kinetics. [18] Furthermore, the effect of the Mn 2 O 3 electrocatalyst on Na 2 Se conversion was confirmed using the Tafel plot from the CV curves, which derived from the region 1 and 2 (Figure 3b and 3 c). [19] The difference in the activation energy was calculated by Equation 3 (shown in the experiment section) based on the Tafel slopes.…”

“…It is noteworthy that there is no additional redox peak in the selected voltage window, indicating that Mn 2 O 3 particles act as catalysts in the Na−Se battery system. Although both composites demonstrate similar redox peak positions, the voltage distance of the reduction and oxidation peaks is much narrower (Δ$${{{\rm V}}_{{{\rm M}{\rm n}}_{2}{{\rm O}}_{3}-{\rm b}{\rm a}{\rm s}{\rm e}{\rm d}}=0.606\hskip0.17em\hskip0.17em{\rm V}}$$ ) with Mn 2 O 3 catalyst compared to the absence of Mn 2 O 3 (Δ$${{{\rm V}}_{{{\rm M}{\rm n}}_{2}{{\rm O}}_{3}-{\rm f}{\rm r}{\rm e}{\rm e}}=0.763\hskip0.17em\hskip0.17em{\rm V}}$$ ), indicating fast conversion kinetics [18] . Furthermore, the effect of the Mn 2 O 3 electrocatalyst on Na 2 Se conversion was confirmed using the Tafel plot from the CV curves, which derived from the region 1 and 2 (Figure 3b and 3 c) [19] .…”

A review on “Growth mechanisms and optimization strategies for the interface state of solid‐state lithium‐ion batteries”

“…Implementing PTNB@Li, the service life of lithium stripping electroplating was extended to ≈800 h, and lithium dendrites were not formed. [224][225][226][227][228] Rechargeable lithium metal battery with high-energy density is considered as the emerging next-generation energy storage system. In order to realize the application of lithium metal anode in the commercial market, researchers strive to overcome the shortcomings of lithium dendrite growth, volume fluctuation, low mechanical strength, and high interface resistance between electrolyte and electrode.…”

“…Kim and coworkers prepared a flexible hybrid film composed of ionic conductive ceramic LATP, electrochemically inactive PVDFTrFE polymer, and a small amount of ionic liquid electrolyte (ILE) with high lithium content as the composite electrolyte of quasi‐solid lithium battery. Implementing PTNB@Li, the service life of lithium stripping electroplating was extended to ≈800 h, and lithium dendrites were not formed 224–228 …”

Lowered Activation Potential of Lithium Sulfide Cathode Material Aided by Electrolyte Additive

“…Beyond regulating the cathode material, electrolyte additives have also been proven effective in lowering the activation potential of Li 2 S in recent years. − For example, redox mediators help electrons or Li + cross the solid–liquid interface of the Li 2 S/electrolyte in a chemical way instead of via the electrochemical pathway, which has very sluggish kinetics. , As for lithium salt additives or organic co-solvents, the activation potential is greatly reduced due to the promoted Li + conductivity. , Compared with regulating the structure of Li 2 S itself, introducing electrolyte additives seems to be more facile and practical, so the use of electrolyte additives as a strategy to lower the activation potential is attracting attention. From this point of view, we reviewed the research progress on the use of electrolyte additives to reduce the activation potential of Li 2 S in recent years (Figure ).…”