Compositions and methods for protection of active metal anodes and polymer electrolytes
Electrochemical structures with a protective interlayer for prevention of deleterious reactions between an active metal electrode and polymer electrolytes, and methods for their fabrication. The structures may be incorporated in battery cells. The interlayer is capable of protecting an active metal anode and a polymer electrolyte from deleterious reaction with one another while providing a high level of ionic conductivity to enhance performance of a battery cell in which the structure is incorporated. The interlayer has a high ionic conductivity, at least 10 −7 S/cm, generally at least 10 −6 S/cm, and as high as 10 −3 S/cm or higher. The interlayer may be composed, in whole or in part, of active metal nitrides, active metal phosphides or active metal halides. These materials may be applied preformed, or they may be formed in situ by conversion of applied precursors on contact with the active metal anode material.
1. A method of fabricating an electrochemical device component structure, the method comprising:
applying a layer consisting of a protective interlayer precursor selected from the group consisting of Cu 3 N metal phosphides, Cu 3 N, red phosphorus, phosphines, borazine (B 3 N 3 H 6 ), and triazine (C 3 N 3 H 3 ) on a polymer electrolyte; and
applying an active metal selected from the group consisting of alkali metals, alkaline earth metals and alloys thereof to the layer of precursor on the polymer electrolyte;
whereby the precursor is converted to a reaction product formed by contact of the active metal with the precursor such that a protective interlayer conductive to ions of the active metal is formed in situ between the active metal and the polymer electrolyte.
2. The method of claim 1 , wherein the active metal comprises an anode.
3. The method of claim 2 , further comprising applying a current collector on a surface of the active metal anode opposite that in contact with the protective interlayer.
4. The method of claim 1 , wherein the active metal is an alkali metal or alloy thereof.
5. The method of claim 4 , wherein the active metal is lithium or a lithium alloy.
6. The method of claim 1 , wherein the precursor is red phosphorus, the active metal is lithium, and the protective interlayer formed in situ on reaction with the active metal is Li 3 P.
7. The method of claim 6 , wherein the precursor and active metal are applied by evaporation.
8. The method of claim 1 , wherein the precursor is Cu 3 N, the active metal is lithium, and the protective interlayer formed in situ on reaction with the active metal is Li 3 N.