Methods and systems are provided for synthesis and deposition of chalcogenides (including Cu₂ZnSnS₄). Binary compounds, such as metal sulfides, can be deposited by alternating exposures of the substrate to a metal cation precursor and a chalcogen anion precursor with purge steps between.

The invention provides a method for producing a molecule capable of undergoing reduction-oxidation when subjected to a voltage potential, the method comprising phosphorylating hydroquinone to create a first intermediate; rearranging the first intermediate to an aryl-bis-(phosphonate) thereby creating a second intermediate comprising phosphorous alkoxy groups; alkylating (e.g., methylating) the second intermediate; converting the alkoxy groups to halides; and substituting the halides to alkyl or aryl groups. Also provided is a system for preventing overcharge in a Lithium-ion battery, the method comprising a mixture of a redox shuttle with electrolyte in the battery such that the shuttle comprises between about 10 and about 20 weight percent of the mixture.