Solid-State Battery Electrode Grain Distribution for Electron Conduction
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Solution Overview
Problem
All solid batteries face challenges in achieving optimal electron conduction and capacity due to the limitations of conductive auxiliary agent grain size, where small sizes may not withstand heat during sintering and large sizes increase the ratio required for electron conduction paths, potentially reducing battery capacity.
Innovation Solution
The battery design incorporates a conductive auxiliary agent with a frequency distribution of grain sizes having two peaks between 5 nm and 130 nm, with a cumulative distribution slope of 0.7 or less, allowing for effective electron conduction while maintaining a low ratio of conductive auxiliary agents that do not contribute to capacity, using a combination of small and large grain sizes to achieve good battery operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If small grain size conductive auxiliary agent is used, then electron conduction to each electrode active material is improved, but the conductive auxiliary agent cannot withstand heat during sintering
Solution Approach 1:
The conductive auxiliary agent is segmented into multiple grain size ranges (first range: 5-30 nm for electron conduction, second range: 30-130 nm for heat resistance) rather than using a single grain size, allowing each segment to fulfill different functional requirements simultaneously
Solution Approach 2:
Different regions of the electrode layer have different conductive auxiliary agent grain size distributions - smaller grains (5-30 nm) are distributed near electrode active material particles for electron conduction, while larger grains (30-130 nm) are distributed in other regions for heat resistance, creating local optimization of properties
2Reliability
If large grain size conductive auxiliary agent is used, then electronic conductivity of the electrode layer is improved, but the ratio of conductive auxiliary agent required for electron conduction paths increases, potentially reducing battery capacity
Solution Approach 1:
The conductive auxiliary agent population is segmented into two grain size ranges with different functions: small grains (5-30 nm) form conductive paths to electrode active material, while larger grains (30-130 nm) provide bulk conductivity, allowing efficient electron transport with minimal total conductive auxiliary agent content
Solution Approach 2:
The electrode layer uses a composite structure of conductive auxiliary agents with different grain sizes, combining the advantages of small grains (effective conduction paths) and large grains (bulk conductivity), achieving high electronic conductivity with low overall conductive auxiliary agent ratio
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 configuration ensures good battery operation by maintaining effective electron conduction and suppressing the ratio of conductive auxiliary agents that do not contribute to capacity, thereby achieving high battery characteristics and stability.
Implementation Method 1
electron conduction to each electrode active material becomes good
Implementation Method 2
the conductive auxiliary agent may not be able to withstand heat during sintering
Data Source
AI summary
An all solid battery includes a solid electrolyte layer, and an electrode layer that is provided on each of main faces of the solid electrolyte layer and includes an electrode active material and a conductive auxiliary agent. In a frequency distribution of grain size of the conductive auxiliary agent in a cross section of the electrode layer, two largest peaks, a first peak and a second peak, appear in a range of 5 nm or more and 130 nm or less. In a cumulative distribution of the grain size, a portion appears between the first peak and the second peak where a slope is 0.7 or less (%/nm).