The chemical composition of anion-derived SEI.

An international research team led by Professor Tang Wei from the School of Chemical Engineering and Technology at Xi'an Jiaotong University (XJTU) has developed a wide-temperature-adaptive electrolyte (WTAE) through precise regulation of solid electrolyte interphase (SEI) chemistry. This was achieved in collaboration with Professor Wu Yuping of Southeast University, Associate Professor Gao Xiangwen of Shanghai Jiao Tong University, Researcher Li Yong from Shanghai Institute of Space Power-Sources, and Professor Stefano Passerini of Karlsruhe Institute of Technology.

By constructing localized high-concentration electrolytes that shift the lithium-ion solvation structure from solvent-dominated to anion-dominated, they promoted anion decomposition to form an inorganic-rich SEI layer (containing LiF and other components) on lithium metal anodes.

Electrochemical tests, theoretical simulations, interface characterization, and in-situ optical observations collectively demonstrate that this LiF-enriched SEI significantly enhances Li⁺ diffusion through the interphase, accelerates Li⁺ desolvation at the SEI/electrode interface, improves lithium metal anode kinetics, and effectively suppresses lithium dendrite growth at low temperatures.

The developed electrolyte enables a 5.8 Ah pouch cell to operate across a wide temperature range (-40 to 60 C), achieving 503.3 Wh kg⁻¹ energy density with 260 cycles at 25 C, and 339 Wh kg⁻¹ discharge energy density at -40 C.

This breakthrough highlights the critical role of SEI chemistry understanding and provides an effective strategy for designing wide-temperature electrolytes, offering significant guidance for advancing high-energy-density lithium metal batteries (LMBs) toward commercialization.

The work, titled Wide temperature 500 Wh kg⁻¹ lithium metal pouch cells, has been published in Angewandte Chemie International Edition, demonstrating a crucial advancement in broadening the operational temperature range for next-generation energy storage systems.