Promoting the Transformation of Li₂S₂ to Li₂S: Significantly Increasing Utilization of Active Materials for High‐Sulfur‐Loading Li–S Batteries

Abstract

Lithium–sulfur (Li–S) batteries with high sulfur loading are urgently required in order to take advantage of their high theoretical energy density. Ether‐based Li–S batteries involve sophisticated multistep solid–liquid–solid–solid electrochemical reaction mechanisms. Recently, studies on Li–S batteries have widely focused on the initial solid (sulfur)–liquid (soluble polysulfide)–solid (Li2S2) conversion reactions, which contribute to the first 50% of the theoretical capacity of the Li–S batteries. Nonetheless, the sluggish kinetics of the solid–solid conversion from solid‐state intermediate product Li2S2 to the final discharge product Li2S (corresponding to the last 50% of the theoretical capacity) leads to the premature end of discharge, resulting in low discharge capacity output and low sulfur utilization. To tackle the aforementioned issue, a catalyst of amorphous cobalt sulfide (CoS3) is proposed to decrease the dissociation energy of Li2S2 and propel the electrochemical transformation of Li2S2 to Li2S. The CoS3 catalyst plays a critical role in improving the sulfur utilization, especially in high‐loading sulfur cathodes (3–10 mg cm−2). Accordingly, the Li2S/Li2S2 ratio in the discharge products increased to 5.60/1 from 1/1.63 with CoS3 catalyst, resulting in a sulfur utilization increase of 20% (335 mAh g−1) compared to the counterpart sulfur electrode without CoS3.

Expediting redox kinetics of sulfur species by atomic‐scale electrocatalysts in lithium–sulfur batteries

“…This strategy is recently coupled with precise surface modification, endowing electrode substrates or functional separators with lithiophilicity and sulfiphilicity to kinetically promote S/Li 2 S precipitation and regulate LiPS transport . Directly blending metal oxides, sulfides, nitrides, and carbide with various carbonaceous hosts has demonstrated considerable merits to mediate sulfur species’ behaviors through chemisorption and/or electrocatalysis mechanisms . Nevertheless, the low surface‐to‐volume ratio of these additives cannot entirely bring active sites to the reaction surface.…”

“…[24][25][26][27][28] Directly blending metal oxides, [29][30][31][32][33] sulfides, [34][35][36] nitrides, [37][38][39] and carbide 40,41 with various carbonaceous hosts has demonstrated considerable merits to mediate sulfur species' behaviors through chemisorption and/or electrocatalysis mechanisms. [42][43][44][45][46] Nevertheless, the low surface-to-volume ratio of these additives cannot entirely bring active sites to the reaction surface. To this line, reducing particle size to nanometer or even to atomic scale has emerged as a promising route to extend reactivity of materials.…”

One‐Step Blade‐Coated Highly Efficient Nonfullerene Organic Solar Cells with a Self‐Assembled Interfacial Layer Enabled by Solvent Vapor Annealing

“…[26] Using this approach, high PCE values >10% were obtained in spin-coated OSCs with a selforganized IL, due to efficient charge extraction. [27][28][29] Unfortunately, OSCs produced via one-step printing method exhibit low PCE that is typically <10%, due to the inability to independently optimize the BHJ morphology and IL formation during drying. [30] For example, optimized phase separation of the BHJ components is often achieved at temperatures >60 C for one-step printed fullerene-based OSCs.…”

“…To the best of our knowledge, the obtained PCE value of >11% is one of the highest values reported to date for one-step printed OSCs featuring a self-assembled IL. [27,30,33] For comparison, two-step doctor-blade printing OSC was also produced with varying PFN thickness, substrate temperature as well as SVA treatment ( Figure S4-6, Table S4-6, Supporting Information). A maximum PCE value of 10.06% was obtained for type-II cells with a J SC of 16.58 mA cm À2 , a FF of 0.64, and a similarly high V OC of 0.94 V. These results demonstrate the attractiveness of SVA in combination with the one-step printing method for R2R manufacturing.…”

Self‐Assembled Monomolecular Layer Modified ZnO for Efficient Inverted Polymer Solar Cells with 11.53% Efficiency

“…These results well match with the reducing R S of the inverted PSCs for performance improvement. [49][50][51] To verify the components and surface chemical states of the ZnO and ZnO-APTES surface, XPS was performed on the relevant films, as shown in Figure 6a. According to the zoomed-in XPS survey spectra and the inserted image of Figure 6a, the N 1s and Si 2p peaks at around 400 eV and 100 eV can be clearly observed from the ITO/ZnO-APTES films.…”