Available Technology

Dual Layer Solid State Thin Film Deposition

Lithium-ion batteries are a preferred battery technology due to its high energy density and lightweight features. The electrode in this technology can consist of lithium metal or lithiated material which can suffer degradation when exposed to oxygen. NREL scientists have invented a way to better-protect the lithium electrode from oxidation without compromising the other features of this technology. This invention applies to a broad category of thin-film electronic devices, including electrochromic devices. The lithium metal or lithiated electrode in lithium-based batteries can be subject to oxidation which reduces the conductivity of the electrode material and decreases power density. Oxidation of the lithium electrode can occur due to open-air exposure during manufacture and/or after manufacture due to the porosity of typical electrolytes. The use of more-dense, less porous electrolytes can reduce oxidation of the electrode material, but these electrolytes are less conductive and can also adversely impact the structural integrity of the battery. This limitation provides an opportunity for methods of manufacturing and battery design that can better-protect the lithium electrode material from oxidation without compromising the structural and/or electrical qualities of the battery. NREL scientists have developed a dual-layered electrolyte material which protect against oxidation of the lithium ions while enabling good ion transport there through.
Abstract: 
NREL has developed a homogenous, dual-layered electrolyte material which comprises a first dense layer and a second porous layer that can be deposited on the electrode. The dual layers solve the oxidation problem while maintaining strong electric conductivity. The thin, dense layer provides protection from oxidation and is selected thin enough that it does not detract substantially from the ion transport capability and maintains substantial flexibility. The physical properties of the two homogenous layers may be manipulated to provide one or more of the following advantages: 1) high ionic conductivity, 2) mechanical fracture toughness, 3) low diffusion constant for atmospheric gases. The relative density/porosity of the 2 layers may be established by deposition in different vacuum pressures. This electrolyte material protects against oxidation of the underlying electrode material which has been known to occur during a mask change during manufacture.
Benefits: 
Reduced degradation of anode during manufacture -Decreased efficiency losses -Improved structural reliability
applications: 
Internal Laboratory Ref #: 
NREL 07-02
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