Enabling Ether Electrolyte for Anode-free Lithium Metal Batteries by Weakening Solvation Power via Asymmetric Dimer Formation, Nano Energy154,112022(2026)
Teklay Mezgebe Hagos, Chen-Wei Hsu, Yosef Nikodimos, Bereket Woldegbreal Taklu, Tripti Agnihotri, Ashok Ranjan, Kassie Nigus Shitaw, Yan Heng Wu, Yu Chun Huang, Zabish Bilew Muche, Steven Suwito, Jyh-Chiang Jiang, Wei-Nien Su*, Bing Joe Hwang*
2026/08/19
Electrolyte engineering is vital in suppressing dendrite growth and enhancing the cycling stability of anode-free lithium metal batteries (AFLMBs). This work introduced the asymmetric dimer formation concept using hydrogen bonding interactions to modulate the solvation power of electrolyte components. This strategy aims to optimize the solvation structure and improve electrolyte stability, thereby enhancing the cycling performance of AFLMBs (Cu||NMC811) even at lower concentrations of electrolytes. An asymmetric dimer electrolyte (2 DEE/3.2 TTE) consisting of the non-solvating 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) with a weakly solvating electrolyte (1,2 diethoxyethane, DEE). Remarkably, the addition of TTE to the electrolyte weakens the interaction of Li+ -DEE, which increases the deshielding effect from −1.05 to −1.03 ppm and the electrolyte solvation energy (ΔGsolv) from −2.41–4.05 kJ/mol. Its weak solvating power encourages the formation of anion-derived and inorganic-rich electrode-electrolyte interfaces. Also, owning to the higher anion association with Li+, the Li+ transference number of the 2 DEE/3.2 TTE electrolyte reaches tLi+ = 0.70, much larger than 2 DEE (tLi+ = 0.58). The designed electrolyte (2 DEE/3.2 TTE) significantly improves the cycling performance of the AFLMB within a 3.6 – 4.3 V voltage range at room temperature. The cell achieves impressive capacity retention of 83% and Coulombic efficiency of 99.70% over 100 cycles, under charge and discharge current densities of 0.2 and 0.5 mA/cm², respectively. The electrolyte design concept offers a promising approach to enhancing the cycling performance of an anode-free lithium metal battery.