Solid state lithium ion conducting electrochemical cells and methods for forming the cells are described. The electrochemical cells include a composite solid state lithium ion conducting electrolyte separating porous metal supported electrodes. The electrolyte includes a crosslinked oligosiloxane matrix that includes pendant lithium ion chelating functionality that is provided in conjunction with lithium ions and encapsulating lithium ion conducting particles. The solid state electrolyte can extend into the pores of the electrodes to provide high surface area contact and improved electrochemical characteristics.