A novel thermomechanically stable LaF3-CsH5 (PO4)2 composite electrolyte with high proton conductivity at elevated temperatures over 150 °C

A facile strategy is introduced to upgrade thermomechanical stability of the cesium pentahydrogen diphosphate (CPD), which is the most efficient inorganic electrolyte among all solid proton conductors, by constructing P-OH center dot center dot center dot F hydrogen bonds with lanthanum fluoride (LaF3). The optimal combination of the LaF3-CPD composite electrolyte is found to be 1:2 in a molar ratio (LaF3-CPD-2). LaF3-CPD-2 composite maintains robust solid state, even at a temperature up to 200 degrees C, which is 50 degrees C higher than the melting temperature of CPD. Meanwhile, the considerable proton conductivity of CPD is achieved in the LaF3-CPD-2 composite electrolyte due to the synergistic effect of the P-OH center dot center dot center dot F hydrogen bonds and the intrinsic proton conductive property of CPD. Last but not least, the LaF3-CPD-2 composite manifests excellent conductivity durability at 150 degrees C and low humidity condition with sizeable proton conductivity of 0.0262 S cm(-1) after 60h operation, implying that the LaF3-CPD composite could be a promising candidate for intermediate temperature proton conductors. (C) 2018 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.