Lithium-Sulfur Batteries

Lithium-Sulfur Batteries

Lithium sulfur rechargeable battery is potentially low cost and high energy storage chemistry, because sulfur is an abundant element, and can be mined at low cost. However, LiS chemistry has many challenges due to the polysulfides dissolution, and inhomogeneous lithium metal deposition during charge and discharge process. We aim to address these challenges through design, synthesis and formulation of new electrolytes, and electrode engineering. 

Projects

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Amphiphilic Electrolyte Approach
(a) molecular structure of fluorocarbon ethylene oxides with different chain length denotated as F8EO4 and F4EO2 respectively. (b) schematic diagram to show solvation mechanism of LiTFSI with HFE in the electrolyte and formation of micelle complex structure.
(a) molecular structure of fluorocarbon ethylene oxides with different chain length denotated as F8EO4 and F4EO2 respectively. (b) schematic diagram to show solvation mechanism of LiTFSI with HFE in the electrolyte and formation of micelle complex structure. 
Electrochemical performance of Li-S cells with 0.5M LiTFSI in F4EO2/TTE electrolyte: (a) voltage profiles for 1:5 F4EO2/TTE volume ratio; (b) coulombic efficiency comparison of various electrolytes; (c) cycling stability comparison of various electrolytes.
Electrochemical performance of Li-S cells with 0.5M LiTFSI in F4EO2/TTE electrolyte: (a) voltage profiles for 1:5 F4EO2/TTE volume ratio; (b) coulombic efficiency comparison of various electrolytes; (c) cycling stability comparison of various electrolytes.

References

Zhao, Y. Z.;  Fang, C.;  Zhang, G. Z.;  Hubble, D.;  Nallapaneni, A.;  Zhu, C. H.;  Zhao, Z. W.;  Liu, Z. M.;  Lau, J.;  Fu, Y. B.; Liu, G., A Micelle Electrolyte Enabled by Fluorinated Ether Additives for Polysulfide Suppression and Li Metal Stabilization in Li-S Battery. Front. Chem. 2020, 8, 9.

Ai, G.;  Wang, Z. H.;  Dai, Y. L.;  Mao, W. F.;  Zhao, H.;  Fu, Y. B.;  En, Y. F.;  Battaglia, V.; Liu, G., Improving the over-all performance of Li-S batteries via electrolyte optimization with consideration of loading condition. Electrochim. Acta 2016, 218, 1-7.

Biomimetic Electrode Design

The structure of the ant-nest network is famous for the smart spatial design with abundant storage space and multi interconnected channels between storage sites, which allows for efficient and fast transportation of food.

  • Facilitate fast lithium ion transport
  •  Retain polysulfide dissolution
  • Assist polysulfide precipitation

This image shows the ant-nest netweok of electrode designs, showing lithium ions going in and out of the charged and discharged slate.

References

Ai, G.;  Dai, Y. L.;  Mao, W. F.;  Zhao, H.;  Fu, Y. B.;  Song, X. Y.;  En, Y. F.;  Battaglia, V. S.;  Srinivasan, V.; Liu, G., Biomimetic Ant-Nest Electrode Structures for High Sulfur Ratio Lithium-Sulfur Batteries. Nano Letters 2016, 16 (9), 5365-5372.

Active Binder

Polysulfide shuttling has been the primary cause of failure in lithium-sulfur (Li-S) battery cycling. In this work, an unexpected outcome of Li-S battery research shows that a substitution reaction between polysulfides and binders greatly immobilizes the shuttling polysulfides. The substitution reaction is verified by UV-visible spectra and X-ray photoelectron spectra. The immobilization of polysulfide is in situ monitored by synchrotron based sulfur K-edge X-ray absorption spectra. The resulting electrodes exhibite initial capacity up to 20.4 mAh/cm2, corresponding to 1199.1 mAh/g based on a micron-sulfur mass loading of 17.0 mg/cm2. Furthermore, nano-size sulfur adoption promotes an extra high capacity of 33.7 mAh/cm2, which is one of the highest areal capacity reported. The promoted performance is benefited from the controlled shuttle factor by nucleophilic substitution reaction. The nucleophilic substitution strategy demonstrated here for Li-S battery is of great significance and very promising for scale up production.

This image shows the chemical formulas, their structures in carrageenan, and graphs of the visual effects over 24 hours.
The polymers with chemical leaving groups can react with polysulfide. (A) Molecular structures of PVS and natural product of carrageenan and their replacement reactions with polysulfide to form immobilized polysulfides on the polymer backbones. (B) Visual effects of the polysulfide solution exposed to different binders over 24 hrs. (C,D,E) The time-lapsed UV-vis absorbance of in situ UV-vis spectra of PVS, PVDF and carrageenan in 3 mmol/L Li polysulfide in DOL/DME solution. (F) UV-vis absorbance changes with time of the three polymer binders.

References

Ling, M.;  Zhang, L.;  Zheng, T. Y.;  Feng, J.;  Guo, J. H.;  Mai, L. Q.; Liu, G., Nucleophilic substitution between polysulfides and binders unexpectedly stabilizing lithium sulfur battery. Nano Energy 2017, 38, 82-90.

Featured Publications

Zhao, Yangzhi, Chen Fang, , Guangzhao Zhang, Dion Hubble, Asritha Nallapaneni, Chenhui Zhu, Zhuowen Zhao, Zhimeng Liu, Jonathan Lau, Yanbao Fu, and Gao Liu."A Micelle Electrolyte Enabled by Fluorinated Ether Additives for Polysulfide Suppression and Li Metal Stabilization in Li-S Battery."Frontiers in Chemistry 8 (2020). DOI
Ling, Min, Liang Zhang, Tianyue Zheng, Jun Feng, Jinghua Guo, Liqiang Mai, and Gao Liu."Nucleophilic substitution between polysulfides and binders unexpectedly stabilizing lithium sulfur battery."Nano Energy 38 (2017) 82 - 90. DOI
Ai, Guo, Zhihui Wang, Yiling Dai, Wenfeng Mao, Hui Zhao, Yanbao Fu, Yunfei En, Vincent S. Battaglia, and Gao Liu."Improving the over-all performance of Li-S batteries via electrolyte optimization with consideration of loading condition."Electrochimica Acta 218 (2016) 1 - 7. DOI
Ai, Guo, Yiling Dai, Wenfeng Mao, Hui Zhao, Yanbao Fu, Xiangyun Song, Yunfei En, Vincent S. Battaglia, Venkat Srinivasan, and Gao Liu."Biomimetic Ant-Nest Electrode Structures for High Sulfur Ratio Lithium–Sulfur Batteries."Nano Letters 16.9 (2016) 5365 - 5372. DOI