Room‐Temperature Solid‐State Polymer Electrolyte in Li‐LiFePO<sub>4</sub>, Li‐S and Li‐O<sub>2</sub> Batteries
Vittorio Marangon, Luca Minnetti, Edoardo Barcaro, Jusef Hassoun
Abstract
Abstract A solid polymer electrolyte has been developed and employed in lithium‐metal batteries of relevant interest. The material includes crystalline poly(ethylene glycol)dimethyl ether (PEGDME), LiTFSI and LiNO 3 salts, and a SiO 2 ceramic filler. The electrolyte shows ionic conductivity more than 10 −4 S cm −1 at room temperature and approaching 10 −3 S cm −1 at 60 °C, a Li + ‐transference number exceeding 0.3, electrochemical stability from 0 to 4.4 V vs. Li + /Li, lithium stripping/deposition overvoltage below 0.08 V, and electrode/electrolyte interphase resistance of 400 Ω. Thermogravimetry indicates that the electrolyte stands up to 200 °C without significant weight loss, while FTIR spectroscopy suggests that the LiTFSI conducting salt dissolves in the polymer. The electrolyte is used in solid‐state cells with various cathodes, including LiFePO 4 olivine exploiting the Li‐insertion, sulfur–carbon composite operating through Li conversion, and an oxygen electrode in which reduction and evolution reactions (i. e., ORR/OER) evolve on a carbon‐coated gas diffusion layer (GDL). The cells operate reversibly at room temperature with a capacity of 140 mA h g −1 at 3.4 V for LiFePO 4 , 400 mA h g −1 at 2 V for sulfur electrode, and 500 mA h g −1 at 2.5 V for oxygen. The results suggest that the electrolyte could be applied in room‐temperature solid polymer cells.