Electrode mixture, battery, and method for producing electrode
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high charge-discharge efficiency due to issues with grain-boundary resistance in oxide solid electrolytes and degradation caused by resin materials in sulfide solid electrolytes, which affect adhesion and dispersibility in electrode mixtures.
Innovation Solution
An electrode mixture incorporating a sulfide solid electrolyte and a carbon-containing material, where the carbon intensity ratio to sulfur intensity, determined by Auger electron spectroscopy, is within the range of 0.2 to 1, enhancing adhesion and dispersibility, and a method for producing this mixture by preparing a slurry with the sulfide solid electrolyte and carbon-containing material, ensuring appropriate distribution and minimizing resin material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If resin materials are used in sulfide solid electrolytes to improve adhesion, then adhesion is enhanced, but charge-discharge efficiency decreases due to degradation
Solution Approach 1:
The patent removes resin materials from the sulfide solid electrolyte composition entirely, replacing them with a carbon-containing material coating on sulfide solid electrolyte particles. This extraction eliminates the degradation issue while maintaining adhesion through the carbon coating layer that provides binding between particles without the harmful effects of resin materials.
Solution Approach 2:
The patent changes the chemical composition parameter by controlling the carbon-to-sulfur intensity ratio (C/S) from Auger electron spectroscopy to be within 0.03 to 0.3. This parameter control ensures optimal carbon coating thickness that provides sufficient adhesion while preventing excessive carbon accumulation that would hinder ionic conductivity and charge-discharge efficiency.
2Stability of the object's composition
If oxide solid electrolytes are used to maintain battery structure, then structural stability is improved, but grain-boundary resistance increases reducing efficiency
Solution Approach 1:
The patent transitions from oxide solid electrolytes to sulfide solid electrolytes, changing the chemical composition parameter. Sulfide solid electrolytes inherently exhibit lower grain-boundary resistance compared to oxide solid electrolytes, thereby improving charge-discharge efficiency while maintaining structural stability through the controlled carbon coating that prevents particle aggregation.
3Strength
If carbon-containing material is added to sulfide solid electrolyte to improve adhesion, then adhesion and dispersibility are enhanced, but excessive carbon accumulation reduces ionic conductivity
Solution Approach 1:
The patent precisely controls the carbon-containing material content by specifying the C/S intensity ratio from Auger electron spectroscopy between 0.03 and 0.3. This parameter control ensures the carbon coating is sufficient to provide adhesion and prevent aggregation but not excessive to block ionic conduction pathways in the sulfide solid electrolyte.
Solution Approach 2:
The carbon-containing material is applied as a surface coating on sulfide solid electrolyte particles rather than bulk mixing. This local application ensures carbon is present where needed for adhesion at particle surfaces and interfaces, while the interior of the sulfide solid electrolyte particles remains free of excessive carbon that would impede ionic conductivity.
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
The approach increases charge-discharge efficiency and maintains suitable battery properties by optimizing the distribution of the carbon-containing material on the sulfide solid electrolyte surfaces, reducing aggregation and enhancing ionic and electron conductivity.
Implementation Method 1
an intensity ratio C/S determined from a spectrum obtained by analyzing the electrode mixture by Auger electron spectroscopy
Data Source
AI summary
An electrode mixture includes a sulfide solid electrolyte and a carbon-containing material having contact with the sulfide solid electrolyte. An intensity ratio C/S determined from a spectrum obtained by analyzing the electrode mixture by Auger electron spectroscopy satisfies 0.2≤C/S≤1, where C is an intensity of a peak in the spectrum which corresponds to carbon included in the carbon-containing material, and S is an intensity of a peak in the spectrum which corresponds to sulfur included in the sulfide solid electrolyte.