Proton conductors and their applications: A tentative historical overview of the early researches

Abstract

We present here an historical overview of the early researches on proton conductor solids for materials such as fuel cell, battery, electrolyser or H2-sensor. Unexpectedly, the early researches and developments (1960s Gemini orbiter US program, 1967 Ford patent and papers on solid electrolyte battery for electric cars) happened to be a few years before the 1972 ‘The Club of Rome’ report, the first oil crisis in 1973 and certainly the ecological concerns related to global warming. A renewal of research activity then took place in relation with the global warming issues after 1995 and search for the decarbonated energy sources and storage. We discuss here the history of proton conductor research in terms of the communities involved (ion exchange materials, superionic conductors, hydrogen-bonded compounds, electrochromic films, polymer membranes, geology) and the first studied materials, with a comparison between the researches leading to commercial applications and the ones remaining under study. Special attention is paid to the methods of analysis well adapted for the understanding of the space- and time-scale dynamics of proton conductors, namely neutron scattering, frequency dependent conductivity/relaxation and modelling. Some unsolved questions are formalised.