benefit of an artificial SEI in early stages of cycling,
a cathode approach with mechanically rather than melt-infiltrated
sulfur was chosen. Furthermore, an aqueous slurry was utilized to
establish an environmentally friendly and energy-efficient preparation
route, which is depicted in detail in a previous study.2 (link) In brief, sulfur (99.5%, Alfa Aesar) and Ketjenblack
EC 600-JD (Akzo Nobel) were ball-milled at 500 rpm for 15 min in a
mass ratio of 5:4. Subsequently, aqueous carboxymethyl cellulose solution
(3.7 wt % CMC, Walocel CRT 2000 PA, Dow Wolff) and styrene-butadiene
rubber solution (40.4 wt % SBR, JSR TRD 102A, JSR Micro) were added
to the ball-milled powder. After stirring, a well-dispersed slurry
was achieved, which was doctor-bladed on carbon-coated aluminum foil
(22 μm) and dried at ambient conditions. Finally, a cathode
with 50:40:10 wt % S/KB/CMC-SBR (CMC/SBR 1:2) and approximately 1.0
mg(S)/cm2 results.
The synthesis of magnesium
hexafluoroisopropyloxy borate (Mg[B(hfip)4]2) was executed according to previous studies,54 (link) and the salt was thoroughly dried at elevated temperatures
from RT to 60 °C for 15 h in vacuum (0.1 Pa) before use. Subsequently,
1 mmol Mg[B(hfip)4]2 was dissolved in 5 mL of
dimethoxyethane (G1, monoglyme, 99.5%, <10 ppm H2O,
Acros Organics), stirred over night, and purified with a PTFE syringe
filter to result in a 0.2 M electrolyte.