Proton conductivity of (NH4)2TiP4O13-based material for intermediate temperature fuel cells

A new proton-conductive electrolyte of (NH4)(2)TiP4O13 was synthesized for intermediate temperature fuel cells. Structure of the resultant electrolyte was studied by X-ray diffraction and its ionic conductivities was obtained from AC impedance spectroscopy. Partial decomposition of (NH4)(2)TiP4O13 occurred by annealing at 300 degreesC under a dry argon atmosphere, resulting in the formation of TiP2O7, and after annealing its proton conductivity was evaluated to be about 5 mS cm(-1) at 300 degreesC under the same dry argon atmosphere. Electrolyte of (NH4)(2)SiP4O13 was prepared for comparison. In contrast to (NH4)(2)TiP4O13, it is stable under a dry Ar atmosphere at 300 degreesC, and its proton conductivity was 0.6 mS cm(-1). These results indicate that partial decomposition of (NH4)(2)TiP4O13 to TiP2O7 should be responsible for high proton conductivity. (C) 2003 Elsevier B.V. All rights reserved.