of 10
Supplemental Materials for:
Promoting
Reversibility of Multielectron Redox in
Alkali-Rich Sulfide Cathodes through
Cryomilling
Seong Shik Kim,
David N. Agyeman-Budu,
Joshua J. Zak,
Andrew Dawson,
Qizhang Yan,
§
Miguel Cában-Acevedo,
Kamila M.
Wiaderek,
Andrey A. Yakovenko,
Yiyi Yao,
Ahamed Irshad,
Sri R. Narayan,
Jian Luo,
§
Johanna Nelson Weker,
Sarah H. Tolbert,
and Kimberly A. See
,
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena,
California 91125, United States
Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo
Park, California 94025, United States
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles,
California 90095, United States
§
Department of NanoEngineering, University of California San Diego, La Jolla, California
92093, United States
Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
Department of Chemistry and Loker Hydrocarbon Research Institute, University of Southern
California, Los Angeles, California 90089-1661, United States
E-mail: ksee@caltech.edu
S2
Figure S1:
Williamson-Hall analysis of XRD peaks of as-prepared LiNaFeS
2
and cryomilled
LiNaFeS
2
. Calculated crystallite size decreases from 1.47 nm to 0.56 nm upon cryomilling, while
microstrain increases from 29800 to 425500.
Figure S2:
TEM image of as-prepared LiNaFeS
2
. Regions of fringes are observed throughout
the particle suggesting high crystallinity.
S3
Figure S3:
TEM image of cryomilled LiNaFeS
2
. Fewer crystalline domains are observed, which
only exist in the bulk. The surface of the particle appears amorphous.
S4
Figure S4:
FFT of background carbon. The absence of a broad ring suggests that the broad ring
observed in the FFT of the edge of cryomilled particle cannot be explained by carbon supporta
lone.
Figure S5:
Galvanostatic cycling and corresponding dQ/dV plots of as-prepared LiNaFeS
2
to
different upper voltage cutoffs 2.5 V and 2.8 V. Both upper cutoffs exhibit the same peak in the
dQ/dV plots of cycle 2.
S5
Figure S6:
Cycle 13 GITT of (a) as-prepared LiNaFeS
2
and (b) cryomilled LiNaFeS
2
. As-prepared
LiNaFeS
2
continues to show higher overpotentials above 2.5 V.
Figure S7:
Intermittent EIS during cycle 1 at different states of charge. While high-frequency x-
intercepts and the size of semicircles are similar, cryomilled LiNaFeS
2
always shows shorter tails,
suggesting lower mass transfer resistance.
S6