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