( Invited ) Solid Electrolyte Interfaces (SEI) at Low Temperatures: Key Challenges, Design Strategies and Mechanistic Understanding

Lithium-ion batteries (LIBs) suffer severe performance loss at low temperatures due to inefficient solid electrolyte interphase (SEI) layers, with critical challenges including elevated charge-transfer resistance hindering reaction kinetics, lithium plating from impaired ion intercalation, 1 and ion-blocking LiF-rich SEI structures limiting Li⁺ diffusion. Conventional electrolytes (e.g., EC-based) degrade through solidification and poor solvation behavior below 0°C, exacerbating interfacial incompatibility and reducing ionic conductivity, while electrode polarization and electrolyte phase separation lead to dramatic energy/power density losses. These issues collectively drive irreversible capacity loss, accelerated aging, and safety hazards such as thermal runaway during low-temperature cycling or storage. Our research team at Purdue University has developed a pioneering lithium-ion battery testing system capable of simulating ultralow lunar temperatures down to -175°C, enabling rigorous performance evaluation 2 in extreme environments such as polar regions and space missions. By employing a cyclopentyl methyl ether-based electrolyte, Li₄Ti₅O₁₂||Li cells achieved reversible operation at -100°C, setting unprecedented benchmarks 3 for low-temperature discharge capacities critical for aerospace applications. Parallel breakthroughs include niobium tungsten oxides (NbWO) electrodes paired with tailored electrolytes, which enable stable cycling 4 at -100°C (75 mAh g⁻¹) and extend operational limits to -120°C in pouch cells, alongside a tetrahydrofuran-derived localized high-concentration electrolyte 5 that stabilizes lithium-metal anodes through inorganic-rich SEI formation, retaining 75% capacity at -20°C and 64% at -40°C while sustaining charge-discharge functionality at -60°C. Further innovations involve a ternary 6 fluorinated electrolyte (LiFSI in FEC/FEMC/NONA) with a -135°C freezing point and optimized solvation structures, delivering 61% capacity retention at -50°C via LiF-rich cathode interfaces. A non-polar dipropyl ether-based electrolyte that prioritizes anion-derived decomposition to form robust cathode interphases, 1 maintaining 74% capacity after 150 cycles in high-voltage Li||NCM811 cells at 25°C, enabling significant performance at low temperatures. Most recently, our Integrated Photovoltaic and Battery (IntPB) system facilitates simultaneous extreme-temperature testing (-105°C to +80°C) of polycrystalline silicon photovoltaics 7 and NbWO-based batteries, demonstrating reversible cycling with charge-discharge capacities within 10% of PV-generated energy, thereby bridging energy harvesting and storage technologies for mission-critical environments. This presentation will explore SEI at low temperatures, addressing key challenges, design strategies (electrolyte engineering, tailored solvation structures), and mechanistic insights derived from our years of experimental and computational research. References Z. Li, H. Rao, R. Atwi, B. M. Sivakumar, B. Gwalani, S. Gray, K. S. Han, T. A. Ajantiwalay, V. Murugesan, N. N. Rajput, V. G. Pol. Non-polar ether-based electrolyte solutions for stable high-voltage non-aqueous lithium metal batteries. Nature Communications 14, 868 (2023). C. M. Jamison, S. Kim, H. V. Ramasamy, T. E. Adams, V. G. Pol. Lithium-ion battery testing capable of simulating ultralow lunar temperatures. Energy Technology 2022, 2200799 (2022). H. V. Ramasamy, S. Kim, E. Adams, H. Rao, V. G. Pol. Novel cyclopentyl methyl ether electrolyte solvent with unique solvation structure for room and ultralow temperature (−40 °C) lithium-ion battery cycling. Chemical Communications 58, 5124–5127 (2022). S. Kim, Y. Zhang, H. Wang, T. E. Adams, V. G. Pol. Enabling extreme low-temperature (≤−100 °C) battery cycling with niobium tungsten oxides electrode and tailored electrolytes. Small 2306438 (2024). S. Kim, V. G. Pol. Tailored solvation and interface structures by tetrahydrofuran-derived electrolyte facilitates ultra-low temperature lithium metal battery operations. ChemSusChem 16, e202202143 (2023). E. Adams, M. Parekh, D. Gribble, T. Adams, V. G. Pol. Novel ternary fluorinated electrolyte’s enhanced interfacial kinetics enables ultra-low temperature performance of lithium-ion batteries. Sustainable Energy & Fuels 7, 3122–3133 (2023). E. Adams, A. Camacho, E. Mammana, S. Kim, T. E. Adams, V. G. Pol. Efficient photovoltaics integrated with innovative Li-ion batteries for extreme (+80 °C to −105 °C) temperature operations. Scientific Reports 15, 10190 (2025).