New Proton Conducting Electrolytes

NU 2019-158

INVENTORS

• Sossina Haile*
• Sheel Suketu Sanghvi
• Louis Shen Wang

SHORT DESCRIPTION

This invention introduces Cs₇H(H₂PO₄)₄, a novel proton conducting electrolyte that forms a highly conductive cubic phase (≈10⁻³ S cm⁻¹) at intermediate temperatures (100–150 °C) with exceptional stability in dry atmospheres.

BACKGROUND

The compound Cs₇H(H₂PO₄)₄ addresses the limitations of traditional solid acid electrolytes used in fuel cells by operating at significantly lower temperatures than comparable materials like CsH₂PO₄, and without the need for humidification. This eliminates complex water management and allows for higher Nernst potentials in intermediate temperature electrochemical systems.

ABSTRACT

The disclosed proton conducting electrolytes based on Cs₇H(H₂PO₄)₄ exhibit a superprotonic cubic phase structurally analogous to that of CsH₂PO₄ but with ¼ of the proton sites vacant. Operating efficiently between 100–150 °C, this material not only achieves high conductivity under dry conditions but also offers the ability to extend the temperature range of the superprotonic phase through compositional adjustments. These features present significant potential for improved performance in fuel cells, electrolysis cells, and ammonia electrosynthesis systems.

APPLICATIONS

• Proton conducting electrolyte for fuel cells
  • Enables efficient electrochemical energy conversion at intermediate temperatures.
• Electrolysis cells
  • Facilitates water splitting with simplified water management.
• Ammonia electrosynthesis cells
  • Supports improved process efficiency via stable proton conduction.

ADVANTAGES

• No humidity requirement
  • The high conductivity phase is maintained without external humidification.
• Stable superprotonic phase at 100–150 °C
  • Ensures consistent performance in intermediate temperature applications.
• Extended temperature range for select compositions
  • Samples with x<0.18 can sustain the cubic phase above 150 °C.

PUBLICATIONS

Wang LS et al., Structure and Properties of Cs7(H4PO4)(H2PO4)8: A New Superprotonic Solid Acid Featuring the Unusual Polycation (H4PO4)+. J Am Chem Soc. Nov 12, 2020.

IP STATUS

US Patent issued (12,266,834)