Nanostructured TiO2 Capacitors for High Energy Density
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Solution Overview
Problem
Current multilayer ceramic capacitors face challenges in achieving high dielectric permittivity and breakdown strength due to the inherent properties of materials like titanium dioxide, which can become semiconducting and exhibit chemical and mechanical incompatibilities with metal electrodes during processing, leading to reduced energy storage capacity.
Innovation Solution
The development of nanostructured titanium dioxide ceramics with a grain size less than 500 nm, sintered in an oxidizing atmosphere to minimize porosity and oxygen vacancies, resulting in high breakdown strength and low dielectric loss, and the use of a multilayered capacitor structure with alternating nanostructured dielectric and electrode layers to enhance energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If titanium dioxide is used as dielectric material, then breakdown strength is improved, but dielectric permittivity deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling grain size (reducing to nanoscale), sintering temperature, and oxygen partial pressure during fabrication. These parameter changes transform TiO2 from a semiconducting state with low permittivity to a high-permittivity dielectric state with enhanced breakdown strength, resolving the contradiction between the two properties.
Solution Approach 2:
The patent uses strong oxidizing conditions (oxygen atmosphere during sintering) to eliminate oxygen vacancies and reduce semiconducting behavior in TiO2. This accelerated oxidation process increases dielectric permittivity while maintaining high breakdown strength, directly addressing the contradiction.
2Volume of moving object
If grain size is reduced to increase energy density, then packaging efficiency is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent employs precise control of sintering temperature and oxygen partial pressure parameters to achieve uniform nanoscale grain size distribution. This parameter control enables reduced grain size for higher energy density while maintaining manufacturing precision through reproducible processing conditions.
Solution Approach 2:
The patent creates a composite microstructure with uniform nanoscale grains and controlled porosity distribution. This composite approach allows simultaneous achievement of high packaging efficiency through reduced grain size and consistent manufacturing quality through uniform microstructural characteristics.
3Volume of moving object
If porosity is increased to accommodate more dielectric layers, then energy density is improved, but breakdown strength deteriorates
Solution Approach 1:
The patent utilizes controlled porous structures where nanoscale porosity is intentionally designed to accommodate more dielectric layers while maintaining high breakdown strength. The key is controlling pore size and distribution at the nanoscale, where pores act as defect-free regions that do not compromise electrical strength.
Solution Approach 2:
The patent applies local quality by creating different microstructural zones: dense regions for electrical strength and controlled porous regions for layer accommodation. This spatial differentiation allows simultaneous achievement of high energy density through increased layer count and high breakdown strength through localized dense structures.
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 achieves a significant increase in energy storage capacity, with some samples demonstrating energy densities over 15J/cm3, surpassing current capacitors by an order of magnitude, while maintaining low dielectric loss and high breakdown strength.
Implementation Method 1
The permittivity (dielectric constant) of the dielectric and its dependence on applied DC voltage
Implementation Method 2
sintered in an oxidizing atmosphere to minimize porosity and oxygen vacancies
Implementation Method 3
sintered in an oxidizing atmosphere to minimize porosity and oxygen vacancies
Data Source
AI summary
A multilayer ceramic capacitor, having a plurality of electrode layers and a plurality of substantially titanium dioxide dielectric layers, wherein each respective titanium dioxide dielectric layer is substantially free of porosity, wherein each respective substantially titanium dioxide dielectric layer is positioned between two respective electrode layers, wherein each respective substantially titanium dioxide dielectric layer has an average grain size of between about 200 and about 400 nanometers, wherein each respective substantially titanium dioxide dielectric layer has maximum particle size of less than about 500 nanometers. Typically, each respective substantially titanium dioxide dielectric layer further includes at least one dopant selected from the group including P, V, Nb, Ta, Mo, W, and combinations thereof, and the included dopant is typically present in amounts of less than about 0.01 atomic percent.