Thermoelectric Conversion Element Using Nanoparticle Lattice Structures

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Solution Overview

Problem

Current thermoelectric conversion elements using Bi2Te3 materials are costly, toxic, and have limited scalability for waste heat recovery and cooling applications, requiring a high-performance, low-environmental-impact alternative with improved Seebeck coefficient and reduced thermal conductivity.

Innovation Solution

A thermoelectric conversion element utilizing nanoparticles or semiconductor quantum dots arranged in specific lattice structures, such as Lieb-type, Tasaki-type, and Mielke-type lattices, with different conductivity types, to enhance the Seebeck coefficient and reduce thermal conductivity, while using inexpensive and environmentally friendly materials like Si, Ge, and transition metals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Bi2Te3 material is used for thermoelectric conversion, then conversion efficiency is improved (ZT>1), but material cost and environmental toxicity increase

Engineering Contradiction:
Improvethermoelectric conversion efficiencyVSAvoidenvironmental toxicity and material cost
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces expensive and toxic Bi2Te3 materials with inexpensive and environmentally friendly silicide semiconductor materials (such as Mg2Si, Ca2Si, AlSiN3) that can achieve comparable or superior thermoelectric performance without relying on rare or toxic elements

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent employs composite material structures including fine particle composites (particles 1-100 nm dispersed in matrix), layered composites, and core-shell structures to achieve optimized thermoelectric properties while using abundant, non-toxic materials

Inventive Principle:
Principle #40Composite materials

2Reliability

If thermal conductivity is reduced to improve ZT value, then thermoelectric performance is improved, but heat transfer capability deteriorates

Engineering Contradiction:
Improvedimensionless performance index ZTVSAvoidheat transfer efficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies local quality modification by creating regions with different thermal conductivities within the material structure - fine particles, interfaces, and defects are strategically introduced to scatter phonons (reducing thermal conductivity) while maintaining electron transport (preserving electrical conductivity), thereby decoupling heat and charge transport

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent utilizes porous or fine-particulate structures where the high surface area to volume ratio and numerous interfaces scatter heat-carrying phonons effectively, reducing thermal conductivity while the connected pathways maintain sufficient heat transfer for thermoelectric operation

Inventive Principle:
Principle #31Porous materials

3Reliability

If nanosize lattices or fine particles are used to reduce thermal conductivity, then ZT value is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvethermoelectric conversion efficiencyVSAvoidlattice structure organization
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs self-organization mechanisms where nanoscale particles or lattices spontaneously arrange into ordered structures through thermodynamic driving forces during synthesis, eliminating the need for complex external assembly processes while achieving the desired nanoscale morphology and phase distribution

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent incorporates nanoscale features and phase distributions directly into the material synthesis process itself, creating fine particles, lattices, or composite structures during material formation rather than requiring subsequent complex fabrication steps to achieve the nanoscale architecture

Inventive Principle:
Principle #10Preliminary action

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

The solution achieves a high Seebeck coefficient and low thermal conductivity, improving thermoelectric conversion efficiency by 50% to 100% compared to Bi2Te3, with a dimensionless performance index ZT exceeding 3 at room temperature, and reduces material costs and environmental impact.

Implementation Method 1

Interfaces between particles increase by particulating the material to a nanometer size. If the interfaces between the particles increase, the increase becomes the cause of a scattering phonon and thermal conductivity can be greatly decreased.

Methodology Applied
Scientific EffectPhonon scattering:

Implementation Method 2

The Seebeck effect of this thermoelectric conversion was discovered in 1821

Methodology Applied
Scientific EffectSeebeck effect: Seebeck Effect

Implementation Method 3

If a voltage is applied to the both ends of the thermoelectric conversion element, a temperature difference is generated.

Methodology Applied
Scientific EffectPeltier effect: Peltier Effect

Data Source

PatentUS10043963B2Thermoelectric conversion element and thermoelectric conversion module
Publication Date: 2018.08.07 HITACHI LTD

AI summary

In order to provide a thermoelectric conversion element which has a high Seebeck coefficient, a low thermal conductivity, and a high performance, even if the material system that has a low environmental load and can reduce the cost is used, the thermoelectric conversion element in which lattice points are classified into two or more kinds (A site and B site), lattices of which the kinds are different are connected to each other, the numbers of lattices of which the kinds are different are different (A site: 2, and B site: 1), and a lattice structure is configured by arranging nanoparticles or semiconductor quantum dots, includes areas of which conductivity types are different.