An electrolyte composition is described. The electrolyte composition includes at least one ionic compound; at least one polar solvent; at least one polymerizable material; at least one nanoparticle based viscosity modifier; at least one chain transfer agent; and at least one initiator. Also described are electrochromic articles and devices including an electrolyte layer including an electrolyte composition. Methods of assembling an electrochromic article are also included.