All Solid Battery Grain Diameter Control for Short Prevention
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Solution Overview
Problem
Existing all solid batteries with oxide-based solid electrolytes face challenges in reducing thickness to enhance response characteristics while maintaining surface roughness and preventing shorts, as larger grain diameters can lead to degraded surface roughness and short circuits.
Innovation Solution
The development of an all solid battery with a phosphoric acid salt-based solid electrolyte layer, where the D50% grain diameter is 0.5 μm or less and the D90% grain diameter is 3 μm or less, and a manufacturing method involving a multilayer structure with specific firing conditions to achieve these grain diameters, ensuring optimal surface roughness and preventing shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the thickness of the oxide-based solid electrolyte is reduced to secure desired response characteristic, then the response characteristic is improved, but the surface roughness is degraded and short circuits occur
Solution Approach 1:
The patent changes the grain diameter parameter of the solid electrolyte from conventional larger sizes to specifically 0.5 μm or less (with D90% at 3 μm or less). This parameter change allows the electrolyte layer to be made thinner while maintaining surface smoothness, thereby improving response characteristic without causing short circuits.
Solution Approach 2:
The patent applies local quality control by specifically controlling the grain size distribution within the solid electrolyte layer. By ensuring that the majority of grains (D50%) are 0.5 μm or less and 90% of grains (D90%) are 3 μm or less, the surface maintains local smoothness even when the overall layer thickness is reduced, preventing short circuits while improving response.
2Shape
If the grain diameter of solid electrolyte is reduced to maintain surface roughness, then the surface roughness is maintained, but the manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent specifies precise parameter ranges for grain diameter (D50% ≤ 0.5 μm, D90% ≤ 3 μm) that balance surface roughness requirements with manufacturing feasibility. These parameter changes provide clear manufacturing targets that are stringent enough to ensure surface quality but practical enough to achieve through conventional ceramic processing techniques.
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 suppresses the occurrence of shorts and maintains high ionic conductivity, enhancing the performance and reliability of the all solid battery by controlling the grain diameter of the solid electrolyte layer.
Implementation Method 1
firing the multilayer structure, wherein a D50% grain diameter of the phosphoric acid salt-based solid electrolyte grains is 0.3 μm or less and a D90% grain diameter of the phosphoric acid salt-based solid electrolyte grains is 2 μm or less, wherein a firing condition of the firing is adjusted so that a D50% grain diameter of crystal grains of solid electrolyte in a solid electrolyte layer to be formed in the firing from the green sheet is 0.5 μm or less and a D90% grain diameter of the crystal grains is 3 μm or less
Data Source
AI summary
An all solid battery includes: a solid electrolyte layer including phosphoric acid salt-based solid electrolyte; a first electrode that is formed on a first main face of the solid electrolyte layer; and a second electrode that is formed on a second main face of the solid electrolyte layer, wherein a D50% grain diameter of crystal grains of the phosphoric acid salt-based solid electrolyte is 0.5 μm or less, wherein a D90% grain diameter of the crystal grains is 3 μm or less.