Skutterudite Thermoelectric Contact Layers Using CoSi2 Diffusion Barriers
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Solution Overview
Problem
Thermoelectric devices face challenges in achieving low contact resistance and stability of electrical contacts due to high electrical conductivity and small length of thermoelectric legs, which affects the efficiency of heat-to-electricity conversion.
Innovation Solution
The method involves thermo-mechanically processing ball-milled powders of CoSi2 and n-type or p-type skutterudite materials with specific contact resistance below 10.0 μΩ·cm2, using Fe-based alloys with work functions compatible with skutterudite materials to form thin, high-conductivity contact layers that maintain mechanical and thermal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrode/diffusion barrier layers are used in thermoelectric devices, then manufacturing is simpler, but contact resistance is high and electrical conductivity is poor
Solution Approach 1:
The patent employs composite electrode/diffusion barrier layers combining multiple materials (e.g., CoSi2, NiSi2, Mo, W, TaN) in specific configurations. These composite structures achieve low contact resistance and high electrical conductivity by leveraging the complementary properties of different materials, resolving the contradiction between performance and complexity through material composition rather than simple single-layer approaches.
Solution Approach 2:
The patent applies different materials and structures to different regions of the electrode/diffusion barrier assembly. For example, certain layers are optimized for electrical contact while others are optimized for diffusion barrier performance. This local optimization allows each region to perform its specific function efficiently, achieving low contact resistance without requiring uniform complexity throughout the entire structure.
2Power
If thermoelectric legs are made with high electrical conductivity and small length, then power density increases, but contact resistance becomes more significant and stability decreases
Solution Approach 1:
The patent incorporates electrode/diffusion barrier layers during the initial fabrication process of the thermoelectric legs, rather than adding them as separate post-processing steps. This preliminary integration ensures that the contact interfaces are formed under controlled conditions with proper material interdiffusion, establishing stable electrical contacts before the device undergoes operational stress, thereby maintaining reliability despite small leg dimensions.
Solution Approach 2:
The patent uses intermediate diffusion barrier layers (such as Mo, W, or TaN) that mediate between the electrode material and the thermoelectric leg material. These intermediary layers prevent direct harmful interactions while maintaining low contact resistance, enabling stable electrical contacts in miniaturized high-power-density devices where direct contact would be unreliable.
3Reliability
If ball-milled powders with dopants are used for electrode layers, then contact resistance decreases below 10.0 μΩ·cm2, but manufacturing process complexity increases
Solution Approach 1:
The patent utilizes ball-milled powders with controlled dopant concentrations and specific particle size distributions to achieve contact resistance below 10.0 μΩ·cm2. By optimizing parameters such as dopant type, concentration, and milling duration, the patent achieves superior electrical contact properties while managing manufacturing complexity through parameter control rather than process complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in thermoelectric components with reduced internal parasite losses, improved thermal and electrical conductivity, and enhanced stability, leading to increased efficiency in thermoelectric modules.
Implementation Method 1
the first material is ball-milled prior to thermo-mechanical processing to form a ball-milled first powder
Implementation Method 2
thermo-mechanically processing a first material, with a second powder to form a thermoelectric component
Implementation Method 3
the first material and the second powder are hot-pressed to form a first component
Data Source
AI summary
Disclosed are methods for the manufacture of n-type and p-type filled skutterudite thermoelectric legs of an electrical contact. A first material of CoSi2 and a dopant are ball-milled to form a first powder which is thermo-mechanically processed with a second powder of n-type skutterudite to form a n-type skutterudite layer disposed between a first layer and a third layer of the doped-CoSi2. In addition, a plurality of components such as iron, and nickel, and at least one of cobalt or chromium are ball-milled form a first powder that is thermo-mechanically processed with a p-type skutterudite layer to form a p-type skutterudite layer “second layer” disposed between a first and a third layer of the first powder. The specific contact resistance between the first layer and the skutterudite layer for both the n-type and the p-type skutterudites subsequent to hot-pressing is less than about 10.0 μΩ·cm2.