Solid-state lithium ion electrolytes of metal lithium chloride derivative compounds having a crystal morphology in the P21/c space group are provided as materials for conducting lithium ions. An activation energy of the lithium aluminum chloride derivative compounds is from 0.15 to 0.40 eV and conductivities are from 0.01 to 3 mS/cm at 300K. Compounds of specific formulae are provided and methods to alter the materials with inclusion of aliovalent ions shown. Lithium batteries containing the composite lithium ion electrolytes and electrodes containing the lithium aluminum chloride derivative compounds are also provided.