All-Solid Battery Electrode Composition for Capacity and Short-Circuit Balance
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Solution Overview
Problem
All-solid batteries using oxide-based solid electrolytes face challenges in achieving high capacity and conductivity while avoiding short-circuit defects and poor yield, particularly due to issues with conductive auxiliary agents and electrode layer configurations.
Innovation Solution
The use of fibrous conductive auxiliary agents with specific diameter and area ratios, combined with a phosphoric acid salt-based oxide solid electrolyte and olivine-type crystal structure electrode active materials, in a configuration that balances conductivity and electrode material content within the battery layers, ensuring sufficient thickness of the solid electrolyte layer to prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the area ratio of conductive auxiliary agent is increased to improve conductivity, then electrical conductivity is improved, but the area ratio of electrode active material decreases leading to reduced battery capacity
Solution Approach 1:
The patent optimizes the area ratio parameter of conductive auxiliary agent to a specific range (0.5-10%) to achieve the best balance between conductivity and capacity. This parameter optimization resolves the contradiction by finding the optimal point where conductivity is sufficient without excessively reducing the active material content.
2Reliability
If the thickness of solid electrolyte layer is increased to prevent short-circuit defects, then reliability is improved, but the overall battery size and volume increase
Solution Approach 1:
The patent sets the solid electrolyte layer thickness within a specific range (5-20 μm) to prevent short circuits while minimizing volume increase. This parameter optimization ensures sufficient mechanical strength and insulation properties without making the battery excessively large.
3Reliability
If the average diameter of conductive auxiliary agent is reduced to improve dispersion and conductivity, then electrical conductivity is improved, but manufacturing precision and control become more difficult
Solution Approach 1:
The patent specifies the average diameter of conductive auxiliary agent within a precise range (2-150 nm) to achieve optimal dispersion and conductivity while maintaining manufacturability. This parameter control balances the need for fine dimensions with the practical limitations of manufacturing precision.
Data Source
AI summary
An all solid battery includes a solid electrolyte layer, and electrode layers that are provided on both main faces of the solid electrolyte layer and include an electrode active material and a fibrous conductive auxiliary agent. In cross sections of the electrode layers, an average diameter of the conductive auxiliary agent is 2 nm or more and 150 nm or less, an area ratio occupied by the conductive auxiliary agent is 0.5% or more and 5.0% or less, and an area ratio occupied by the electrode active material is 28% or more and less than 80%. A thickness of the solid electrolyte layer is 5 μm or more and 20 μm or less.