Protective coatings for negative electrodes
AssigneePolyPlus Battery Company
InventorsSteven J. Visco, May-Ying Chu
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Abstract
Disclosed is an alkali metal negative electrode having a protective layer. Specifically, the disclosed negative electrode includes a glassy or amorphous surface protective layer which conducts alkali metal ions but effectively blocks the alkali metal in the electrode from direct contact with the ambient. The protective layer has improved smoothness and reduced internal stress in comparison to prior protective layers such as those formed by sputtering. In a specific embodiment, the protective layer is formed on the lithium metal electrode surface by a plasma assisted deposition technique.
Claims38
A negative electrode comprising:
- an alkali metal layer having a first surface;
- and
- a glassy or amorphous protective layer coating the first surface and forming a substantially impervious layer which protects the alkali metal, which protective layer has a surface roughness of no greater than about 500 angstroms r.m.s. deviation;
- wherein the protective layer conducts alkali metal ions.
A negative electrode comprising:
- an alkali metal layer having a first surface;
- and
- a glassy or amorphous protective layer coating the first surface and forming a substantially impervious layer which protects the alkali metal, which protective layer has a variable composition which gradually varies from a first composition to a second composition over a distance of about 50 angstroms in the direction from the first surface of the alkaline metal to an opposite surface on the protective layer;
- wherein the protective layer conducts alkali metal ions.
A negative electrode having an alkaline metal and a glassy amorphous protective layer coating a first surface of the alkali metal wherein the negative electrode is fabricated by a method comprising:
- introducing the alkali metal into a reaction chamber;
- introducing precursors of the protective layer into the reaction chamber;
- generating a plasma with the precursors;
- and
- conducting a reaction involving the precursors to form the glassy amorphous layer on the alkali metal.
A battery cell comprising:
- a) a positive electrode comprising a mixture of
- i) an electrochemically active material, and
- ii) an electronically conductive material,
- the mixture having between about 10% and about 100% of the electrochemically active material accessible to electrons and ionic charge carriers;
- b) a current collector electrically connected to the positive electrode;
- c) a negative electrode including
- i) a metal or metal ion, and
- ii) a protective layer on an electrolyte facing surface of the negative electrode;
- and
- d) an electrolyte separator;
- wherein electrochemically active material is selected from the group consisting of elemental sulfur, sulfides of the metal, polysulfides of the metal, and combinations thereof.
Dependencies are inferred from the claim text.