PEO/LAGP hybrid solid polymer electrolytes for ambient temperature lithium batteries by solvent-free, “one pot” preparation

Here, we report hybrid solid polymer electrolytes (HSPE) obtained by rapid, truly solvent-free, thus scalable preparation process. HSPE composition is very simple: a LiTFSI added poly(ethylene oxide) (PEO) polymer matrix encompassing NASICON-type Li1.5Al0.5Ge1.5(PO4)3 (LAGP) super Li+ ion conducting ceramic. Homogeneous, self-standing, mechanically robust solid electrolyte films are obtained by simply mixing in “one pot” and hot pressing the solid mixture of dry powders at moderate temperature. Noteworthy, unlike several other super ionic conductors used for composite electrolytes, LAGP is relatively stable in air atmosphere and can be processed in a dry-room, which is more favorable, cheap and scalable than Ar-filled dry glove box for industrial fabrication of safe lithium batteries. The proper, homogeneous mixing of LAGP powder, PEO and LiTFSI leads to HSPE with interesting electrochemical behavior in lab-scale lithium cells, especially under high current regimes, and even at ambient temperature. HSPE-based cells outperform the PEO-LiTFSI-based counterpart, in terms of specific capacity output (about 70% of the theoretical value retained at very high 2C rate), limited fading and excellent Coulombic efficiency (>99.5%) even at low rate. Interfacial stability issues remain to be solved, chiefly linked to the reactivity of LAGP in contact with lithium metal, but results here proposed represent a step further toward truly all-solid-state batteries conceived for high energy/power technologies, assuring safety and performance in a wide range of operating conditions.