A method for producing a sulfide solid electrolyte includes: preparing a uniform solution that includes at least elemental lithium (Li), elemental tin (Sn), elemental phosphorus (P), and elemental sulfur (S) in an organic solvent; removing the organic solvent from the uniform solution to obtain a precursor; and heat-treating the precursor to obtain a sulfide solid electrolyte.

A method for synthesizing an alkali metal-based phosphorous compound includes contacting an elemental alkali metal with elemental phosphorous to create a mixture and applying a pressure of less than 20 gigapascals to the mixture for forming the alkali metal-based phosphorous compound.

A proton-exchange-membrane fuel cell bipolar plate includes a metal substrate having a bulk portion and a surface portion including an anticorrosive, conductive binary phosphide material having a formula (I):
A.sub.xP.sub.y  (I),
where A is an alkali metal, alkaline earth metal, transition metal, post-transition metal, or metalloid, x, y is each a number independently selected from 1 to 15, and the binary phosphide material is configured to impart anticorrosive and conductive properties to the metal substrate.

A method for synthesizing an alkali metal-based phosphorous compound includes contacting an elemental alkali metal with elemental phosphorous to create a mixture and applying a pressure of less than 20 gigapascals to the mixture for forming the alkali metal-based phosphorous compound.

A proton-exchange-membrane fuel cell bipolar plate includes a metal substrate having a bulk portion and a surface portion including an anticorrosive, conductive binary phosphide material having a formula (I):

A.sub.xP.sub.y(I),

where A is an alkali metal, alkaline earth metal, transition metal, post-transition metal, or metalloid, x, y is each a number independently selected from 1 to 15, and the binary phosphide material is configured to impart anticorrosive and conductive properties to the metal substrate.

A method of synthesizing soluble polyphosphides by conversion of red phosphorous using alkali metal compounds and organic solvents is presented. A reaction between an alkali metal alkoxy compound or alkali metal alkyl thiolate compound, such as potassium ethoxide, and shelf stable red phosphorus generated soluble polyphosphides in a variety of organic solvents with the .sup.31P NMR spectrum being used to detect the species of polyphosphides produced.

A method of generating soluble polyphosphides using solution chemistry is presented. A reaction between potassium ethoxide and shelf stable red phosphorus generated soluble polyphosphides in a variety of organic solvents with the .sup.31P NMR spectrum being used to detect the species of polyphosphides produced.

A method of generating soluble polyphosphides using solution chemistry is presented. A reaction between potassium ethoxide in THF/DME and shelf stable red phosphorus generated soluble polyphosphides in a variety of organic solvents with the .sup.31P NMR spectrum being used to detect the species of polyphosphides produced.

A method of generating soluble polyphosphides using solution chemistry is presented. A reaction between an alkali metal alkoxy compound or alkali metal alkyl thiolate compound and shelf stable red phosphorus generated soluble polyphosphides in a variety of organic solvents with the .sup.31P NMR spectrum being used to detect the species of polyphosphides produced.

A method of synthesizing soluble polyphosphides using shelf-stable reagents and common organic solvents is presented. A reaction between an alkali metal alkoxy compound or alkali metal alkyl thiolate compound and shelf stable red phosphorus generated soluble polyphosphides in a variety of organic solvents with the .sup.31P NMR spectrum being used to detect the species of polyphosphides produced.