Development of operando XRD coin cells for lithium-sulfur batteries
Yu-Chuan Chien, Ashok S. Menon, William R. Brant, Daniel Brandell, Matthew J. Lacey
Department of Chemistry – Ångström Laboratory, Uppsala University Box 538, SE-751 21 Uppsala, SWEDEN
yuchuan.chien@kemi.uu.se
Motivation
The lithium-sulfur system is considered a promising energy storage technology due to the high theoretical energy density (2500 Wh kg-1) and abundance of sulfur [1]. Several works [2–7] on operando X-ray diffraction (XRD) of the Li-S system have been published; however, their cell setups were not optimal considering the excessive electrolyte [8], non-uniform stack pressure and electronic contact [9]. This work aims for a cell design that satisfies these criteria in order to obtain operando XRD data from a Li-S cell optimized towards practical requirements.
Experimental design
Li S/C on Al
Proof of concept Preliminary result
Future work
References
[1] S. Urbonaite, et al., Adv. Energy Mater. 5 (2015) [2] J. Nelson, et al., J. Am. Chem. Soc. 134 (2012) [3] N.A. Cañas, et al., J. Power Sources 226 (2013) [4] S. Waluś, et al., Chem. Commun. 49 (2013)
[5] M. a. Lowe, et al., RSC Adv. 4 (2014)
[6] J. Kulisch, et al., Phys. Chem. Chem. Phys. 16 (2014)
Find a substitute for the Kapton window so that the background can be reduced with the removal of the pouch
Complement structural information with electrochemical properties through ‘online’ electrochemical characterization techniques, e.g. Intermittent Current Interruption (ICI) method [11]
Refine the diffraction data to extract phase fraction and crystallite size
Acknowledgement
Be Be
Dectris Mythen 1K strip detector X-ray source
(Cu K
α) Kapton® tape
Stainless steel coin cell casing with 5-mm drilled holes
At the moment, the coin cell is then sealed in a modified pouch bag due to the imperfect sealing
of the coin cell.
Lithium-sulfur system
Li S embedded in C
Li+
e-
+ -
Overall reaction:
S + 2Li → Li2S
Typical potential profile of Li-S cells 1
2
Proposed reaction route[10]
S
8→ Li
2S
8Li
2S ← (Li
2S
2) ← Li
2S
4↓ Li
2S
6↓
1st plateau 2nd plateau
Solid state
Dissolved in electrolyte
Research questions:
How are the dissolution and precipitation processes
affected by operational parameters?
How is the reaction
influenced by the structure of the C-matrix and other cell components?
The cell showed typical potential
profile of Li-S cells with 10 µL mgS-1 electrolyte at cycling rate C/50
The large overpotential of the 1st discharge resulted from the high S-loading (4.9 mg cm-2)
β-S was detected after the 1st charge (75th hour) in agreement with [4]
Li2S only showed up as diffuse peaks
The pouch contributed significantly to the background
discharge
Diffractometer:
STOE STADI P in transmission setup
charge
The authors thank Swedish Energy Agency for financial support through Sulfur Technology Advanced Research Concept (Y.C.) and Swedish Foundation for Strategic Research for funding
(A.M.).
Broad peaks around 21° and 23 ° were contributed from the modified pouch
[7] J. Conder, et al., Nat. Energy 2 (2017) [8] M.J. Lacey, ChemElectroChem (2017)
[9] O.J. Borkiewicz, et al., J. Phys. Chem. Lett. 6 (2015) [10] M. Wild, et al., Energy Environ. Sci. 8 (2015)
[11] M.J. Lacey, ChemElectroChem 4 (2017)
