Studies on Sodium Borohydride for Energy Systems

Abstract

This paper describes a process for synthesising a sodium borohydride solution using a two-compartment electrolytic cell with conversion of borate ions to borohydride ions. This occurs in the catholyte to produce the sodium borohydride solution from which the borohydride material may be extracted. The electrolyte carrier may be an aqueous or a non-aqueous solution, namely a room-temperature ionic liquid. Novel permselective membrane separators are considered. The borohydride stepwise hydrolysis is analysed and proposals are advanced to minimise the resulting hydrogen generation. It is disclosed that sodium borohydride may be used for reversible hydrogen storage, for fuel of direct borohydride fuel cells (DBFC), for high power density cells, and for other relevant energy systems with multifunctional applications, namely in spacecraft.