Gas Sensor Electrode with Ceramic Particles for Low-Temperature Activity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing porous electrodes for gas sensors, formed using vanishable solid materials, face challenges such as difficulty in particle size control, pore size variations, and poor compatibility with solvents and binders, leading to inconsistent oxygen pumping performance and increased electrode resistance, which hinders low-temperature activity.
Innovation Solution
The electrodes are designed with a combination of noble metal particles and ceramic particles, where second ceramic particles are added to retard the growth of first ceramic particles during sintering, maintaining the three-phase interface and pore structure, and improving compatibility with solvents and binders, resulting in stable electrode resistance reduction and enhanced low-temperature activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If porous electrodes are formed by adding vanishable solid material (such as theobromine or carbon) into electrode paste and sintering, then the three-phase interface between electrodes, solid electrolyte body and air increases for improvement of oxygen pumping performance, but particle size control of the vanishable solid material becomes difficult and pore size variations occur
Solution Approach 1:
The patent introduces a specific vanishable solid material (organic compound particles with controlled size distribution) as an intermediary that decomposes during sintering to create pores. The key is controlling the particle size distribution of this intermediary material to ensure uniform pore formation. The organic compound acts as a mediator between the electrode paste components and the final porous structure, allowing precise control over pore characteristics while maintaining oxygen pumping performance.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the particle size distribution of the vanishable solid material within specific ranges (0.1-10 μm average diameter, with most particles between 0.5-5 μm). By adjusting these physical parameters of the organic compound particles and controlling the sintering temperature profile (heating rate, holding temperature, and time), the patent achieves consistent pore size and distribution, resolving the manufacturing precision issue while maintaining reliability.
2Reliability
If theobromine is used as the vanishable solid material, then pores are formed in the electrodes, but the theobromine has poor compatibility with solvent and binder so that variations in the thickness of the electrodes occur due to deterioration of leveling
Solution Approach 1:
The patent uses organic compound particles that are designed to be completely decomposed and removed during the sintering process. These temporary structures (the organic particles) serve their purpose by creating pores, then vanish completely, leaving no residual impact on electrode thickness or performance. This approach replaces problematic materials like theobromine with more compatible organic compounds that decompose cleanly.
Solution Approach 2:
The patent changes the chemical and physical parameters of the vanishable solid material by selecting organic compounds with specific properties: particle size 0.1-10 μm, good compatibility with electrode paste solvents and binders, and controlled decomposition characteristics. These parameter changes ensure uniform dispersion in the paste, proper leveling during application, and consistent pore formation after sintering, thereby maintaining both electrode thickness uniformity and oxygen pumping performance.
3Reliability
If pores are formed in the electrodes by vanishing of the vanishable solid material at 600 to 800° C., then oxygen pumping performance improves, but some of the pores are destroyed during the process of temperature rise to a final firing temperature (about 1000 to 1500° C.) so that variations in the pore size occur
Solution Approach 1:
The patent applies preliminary action by carefully designing the sintering temperature profile with controlled heating rates and holding periods. The temperature is raised gradually through the decomposition range (600-800°C) where the organic material vanishes, allowing pores to form before further heating. The heating rate is controlled to prevent pore collapse, and a holding period is maintained at the peak temperature to stabilize the pore structure before cooling. This preliminary and controlled thermal treatment preserves pore integrity throughout the sintering process.
4Reliability
If the amount of three-phase interface of the electrodes of the oxygen pumping cell is increased to achieve improved low-temperature activity, then oxygen pumping performance improves, but electrode resistance reduction becomes difficult due to variations in pore size and electrode thickness
Solution Approach 1:
The patent systematically controls multiple parameters: organic compound particle size (0.1-10 μm, predominantly 0.5-5 μm), sintering temperature profile (heating rate, holding temperature and time), and electrode paste composition. These parameter changes work together to produce electrodes with uniform pore size, consistent thickness, and stable three-phase interface area. The result is reduced electrode resistance and improved low-temperature activity, as the controlled pore structure ensures reliable oxygen pumping performance without the variations that previously hindered resistance reduction.
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 effectively reduces electrode resistance and improves oxygen pumping performance while maintaining a stable pore structure and adhesion, achieving better low-temperature activity in gas sensors.
Implementation Method 1
the organic compound particles which have an average diameter of 0.1 to 10 μm and a most frequent diameter of 0.5 to 5 μm... during the process of temperature rise to a final firing temperature (about 1000 to 1500° C.)
Implementation Method 2
sintering the resulting paste... during the process of temperature rise to a final firing temperature (about 1000 to 1500° C.)
Implementation Method 3
there also occurs variations in the thickness of the electrodes due to deterioration of leveling (flatness) during the application of the electrode paste
Data Source
AI summary
Provided are: an electrode for a gas sensor formed as a porous electrode so as to stably allow reduction in electrode resistance for excellent low-temperature activity; and a gas sensor. The electrode (108, 110) for the gas sensor is adapted for use on a surface of a solid electrolyte body (109), which is predominantly formed of zirconia, and contains particles (2) of a noble metal or an alloy thereof, first ceramic particles (4) of stabilized zirconia or partially stabilized zirconia and second ceramic particles (6) of one or more selected from the group consisting of Al2O3, MgO, La2O3, spinel, zircon, mullite and cordierite, wherein the second ceramic particles are contained in an amount smaller than that of the first ceramic particles.