Deciphering fundamental mechanism of different-type diluents on manipulating interfacial chemistry toward lithium metal anode

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 490; p. 151812
• Main Authors: Liu, Zhenfang, Guo, Weiqian, Tan, Jin, Yan, Hanbing, Bao, Chenguang, Tian, Yao, Liu, Qi, Li, Baohua
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.06.2024
• Subjects: Dendrite Li; High concentration electrolyte; Interfacial chemistry; Li anode; Li metal battery; Li metal battery; Dendrite Li; High concentration electrolyte; Interfacial chemistry; Li anode
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2024.151812

[Display omitted] •Effects of different-type diluents on manipulating solvation chemistry are highlighted.•An evolutive solvation structure and interfacial model are also presented.•Diverse behaviors for Li depositions and corresponding interfacial chemsitry are compared.•The full cells based high-voltage cathode with different systems are also explored. The growth of dendrites on lithium metal anode is troublesome because it induces irreversible capacity loss and safety hazards. Formulating localized high-concentration electrolytes (LHCEs) is an alternative solution to satisfy these challenges. However, the role of diluents in tailoring interfacial chemistry remains to be explicated. Herein, we decipher the direct relationship between different-type diluents and Li-coordinated solvation at the molecular scale. Compare to hydrofluoroethers (HFE), the “active” difluoro ethylene carbonate (DFEC) delivers a pronounced interaction with Li+ and 1, 2-dimethoxyethane (DME) molecule, resulting in a compressed but more accumulated aggregates (AGGs) solvation shell, assisting in the expected chemical nature of SEI with defluorination of DFEC. Consequently, DFEC-based LHCEs (D-LHCEs) realize a record-long lifespan over 3000 h with dendrite-free at 1 mA cm−2 and outstanding dendrite tolerance even under 3 mA cm−2 in symmetric cells. The assembled full cells with D-LHCEs outperform a superior capacity retention of ∼86.83 % with average CE of ∼99.42 % after 500 cycles at 0.5C and the remarkable cycling performance even under harsh conditions (including pouch cells or with controlled N/P of 1.8) in 4.45 V-level Li||LiCoO2 cells. This work highlights the decisive role of diluents in pursuing high-efficiency electrolytes for high-energy Li metal batteries.