Structural Studies of Electrochemical Interfaces with Liquid Electrolytes Using Neutron Reflectometry: Experimental Aspects

With ever more increasing use of electrochemical-energy storage devices, in particular, lithium power sources, there is a call for the development of special-purpose approaches to studying the processes that take place in these devices (including those at buried charge interfaces) during their operation. The use of neutron reflectometry in studies of electrochemical interfaces enables us to determine, at a new level, the effects that the initial parameters of the electrode surface, external conditions, electrolyte composition, overvoltage, current density, and other parameters have on their evolution. The high penetrating power of neutrons enables the study of complex systems that closely model actual storage devices in terms of operating conditions. This work addresses current issues concerning the development of methods of neutron reflectometry in the specular-reflection mode for investigating model planar interfaces between solid electrodes and liquid electrolytes. These include ensuring the possibilities of contrast-variation experiments involving isotopic substitution in the electrolyte and enhancing the sensitivity of the method to probing the structure of thin layers formed on the electrode surface. The adaptation of neutron-reflectometry experiments to study the structures of electrochemical interfaces is presented by the example of the GRAINS reflectometer at the IBR-2 reactor, Joint Institute for Nuclear Research, Dubna, Russia.