On nanoscale structure of planar electrochemical interfaces metal/liquid lithium ion electrolyte by neutron reflectometry

The sensitivity of the method of specular neutron reflectometry was studied with respect to the nanoscale structure of planar electrochemical interfaces in which a metal anode (copper) was in contact with an aprotic liquid lithium ion electrolyte (lithium perchlorate in propylene carbonate). The structure of the lithium enriched layers formed on the working electrode including solid electrolyte interphase and next depositions was analyzed in terms of the scattering length density depth profiles obtained from the modelling of the reflectivity curves. The preferable choice of fully deuterated electrolyte for better analysis of the structural features of such layers was experimentally proven. From the comparison of the profiles obtained for interfaces with fully deuterated and fully protonated electrolytes the porosity of the deposited layer was estimated. A principal change in the interface profile evolution was observed when non-electroactive additive (TBA+) is present in the electrolyte.