Ph. D. THESIS DEFENSE
Name: Mr. Neeraj Pal
Research Supervisor: Prof. Aninda Jiban Bhattacharyya
Title: “Exploring Scalable Materials Strategies for Practical Metal-Sulfur Batteries”
Date & Time: Friday, 31st October 2025 at 11:30 a.m.
Venue: Microsoft Teams
Teams Link: SSCU: Ph. D. Thesis Defense by Mr. Neeraj Pal on Friday, 31st October 2025 at 11.30 a.m. through Microsoft teams | Meeting-Join | Microsoft Teams
Abstract:
Lithium-ion batteries (LIBs) dominate the market of portable electronic devices and currently serve as the stand-alone power source for electric vehicles.1,2 LiBs are approaching their theoretical energy density limit, necessitating the development of alternative battery chemistries.3,4 Metal-sulfur batteries are an important class of high-energy-density batteries under the domain of post-Li-ion battery systems. This thesis proposes strategies for the development of practical metal-sulfur batteries, focusing on monovalent (Li) and bivalent (Zn) sulfur battery systems. The practical implementation of metal-sulfur batteries is hindered by several critical challenges, such as the polysulfide shuttle effect, sluggish redox kinetics, volume expansion, and overoxidation of metal sulfide in aqueous electrolyte.5,6
We have added commercially available carbon modified with polar transition metal oxide to the sulfur host to effectively immobilize and mediate lithium polysulfide conversion to lithium sulfide. We systematically investigated the catalytic activity of titanium diselenide (TiSe2) towards the sulfur redox kinetics, namely, the reduction reaction (SRR) and sulfur evolution reaction (SER). Subsequently, we employed TiSe2 as an electrocatalyst additive in the sulfur cathode. These cathodes were evaluated under practically relevant conditions in coin and pouch cell formats, including high sulfur loadings and lean electrolyte environments.
In aqueous electrolytes, the free protons lead to hydrogen evolution reaction and the oxidation of ZnS to zinc sulfate (ZnSO4).7 To suppress the water activity, we have developed a hybrid electrolyte. The hybrid electrolyte enables the reversible deposition and dissolution of Zn-ions. We characterized the electrochemical conversion of S to ZnS using in-situ spectroscopy/diffraction methods. The performance of the Zn-S battery was assessed in both coin and pouch cell configurations. The volume expansion of the S-cathode and challenges associated with the Zn-metal anode are addressed by developing an anode-free battery, utilizing carbon-coated ZnS nanoparticles as cathode material. Further, we probe the role of ZnI2 in enabling the reversible deposition and dissolution of Zn2+ ions on the Cu-current collector.
Overall, our work provides insights into scalable materials and design strategies for advancing practical metal–sulfur batteries and highlights the importance of performance evaluation under realistic conditions, particularly using pouch cell configurations that better reflect commercial feasibility compared to conventional coin cells.
References:
(1) Kim, T.; Song, W.; Son, D. Y.; Ono, L. K.; Qi, Y. Lithium-Ion Batteries: Outlook on Present, Future, and Hybridized Technologies. J. Mater. Chem. A. 2019, 7, 2942–2964.
(2) Kim, U. H.; Lee, S. B.; Park, N. Y.; Kim, S. J.; Yoon, C. S.; Sun, Y. K. High-Energy-Density Li-Ion Battery Reaching Full Charge in 12 Min. ACS Energy Lett 2022, 7 (11), 3880–3888.
(3) Choi, J. W.; Aurbach, D. Promise and Reality of Post-Lithium-Ion Batteries with High Energy Densities. Nat Rev Mater 2016, 1, 16013.
(4) Zhou, G.; Chen, H.; Cui, Y. Formulating Energy Density for Designing Practical Lithium–Sulfur Batteries. Nat Energy 2022, 7 (4), 312–319.
(5) Manthiram, A.; Fu, Y.; Chung, S. H.; Zu, C.; Su, Y. S. Rechargeable Lithium-Sulfur Batteries. Chem. Review 2014, 10 (23), 11751–11787.
(6) Liu, J.; Ye, C.; Wu, H.; Jaroniec, M.; Qiao, S. Z. 2D Mesoporous Zincophilic Sieve for High-Rate Sulfur-Based Aqueous Zinc Batteries. J Am Chem Soc 2023, 145 (9), 5384–5392.
(7) Yang, M.; Yan, Z.; Xiao, J.; Xin, W.; Zhang, L.; Peng, H.; Geng, Y.; Li, J.; Wang, Y.; Liu, L.; Zhu, Z. Boosting Cathode Activity and Anode Stability of Zn-S Batteries in Aqueous Media Through Cosolvent-Catalyst Synergy. Angew. Chem. 2022, 16 (42), e202212666
(8) Bhattacharyya, A. J., Pal, N. 2025 “An electrode active material and its preparations thereof” Indian Application number: 202541034477.
(9) Pal, N.; Bhattacharyya, A. J., J. Phys. Chem. C 2023, 127 (12), 5713– 5719