MESA+ University of Twente
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Weihua Zhou (promotion date: 2 February 2011)

Proton-conducting solid acid electrolytes based upon MH (PO3H)
(M = Li
+, Na+, K+, Rb+, Cs+, NH4+)

Promotion date: 2. February 2011

Promotor: Prof. dr. ir. Arian Nijmeijer

Assistant promotor: Dr. Henny Bouwmeester

Solid acids, like CsHSO4 en CsH2PO4, are a novel class of anhydrous proton-conducting compounds that can be used as electrolyte in H2/O2 and direct methanol fuel cells. Above the so-called superprotonic phase transition temperature, an increase of proton conductivity occurs by several orders of magnitude.

Protonic conductivity and thermal stability of dihydrogen phosphites are investigated, and found to be comparable to that of widely investigated CsHSO4, showing good stability. This is of prime importance with regard to its potential use as electrolyte in fuel cells.

Methods of heterogeneous and homogeneous doping offer the useful strategy for tuning and optimizing the properties of proton-conducting solid acids.

Was your investigation application oriented?

Especially the second half of the thesis project was. Here, I synthesized and tested various electrolytes and measured the essential performing variables, of direct importance for future use in fuel cells, increasing the proton conductivity and broadening operation window.

Former solid acid electrolytes were developed in America, working at 250 degrees Celsius under high humidity conditions, which are not portable. The phosphite electrolyte family I investigated, perform very well at 150 degrees Celsius and even far below of that, under open ambient conditions. It makes them suitable for portable devices in the future, I believe, especially if one considers the prize of the materials used, being below twenty US dollars per kilo.

In my opinion the electrolytes I used are very promising. Hopefully STW and industrial companies are willing to further optimize their performances.

Did your work lead to some nice publications?

At the end of the second year of my thesis, I was awarded by the Dokiya Foundation, offered by the American Electrochemical Society. This was a reward for excellent research in this field of research. Furthermore I published in Solid State Ionics and in the Journal of Power Sources.

What are your future plans?

Right now, I am working as a post-doc for a new project, in same research group. As a researcher I would like to use my knowledge and skills to push society forward. My parents always encouraged me to do so, with an open mind, not only working in the lab all the time. Working for a small high-tech company, in my opinion, allows me more space to pursue this goal.

What, in your opinion, is important for Mesa+ to stay successful in the future?

The international and multicultural atmosphere is challenging, as are the new buildings and cleanroom and experimental facilities. All is supported by great technicians, willing to share their technical knowledge and expertise.

In building experimental set-ups I was helped a great deal. In using complex, specialized equipment, I was given the opportunity to follow a course from the delivering company.

Also, I did like the annual Mesa+ meetings very much so. In my opinion a meeting like that, especially meant for students, would be a nice completion to that, helping more people to learn from one another, and further strengthening contacts and cooperation.