Solid-State Battery Buffer Layers for Porosity-Stable Electrodes
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Solution Overview
Problem
All solid state batteries face issues with increased porosity due to volume changes during charging and discharging, leading to decreased ionic and electronic conductivity, which affects their performance and longevity.
Innovation Solution
The implementation of negative and positive electrode buffer layers with specific compositions and structures, including sulfide-based materials, conductive materials, and binders, to minimize porosity and enhance interlayer adhesion, thereby stabilizing the electrodes during the rolling process and maintaining conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rolling process is used to bond layers in an all solid state battery, then interlayer adhesion is improved, but porosity increases due to volume changes during charging and discharging
Solution Approach 1:
The patent applies a uniaxial pressing process with controlled pressure parameters to densify the electrode structure after layer bonding. This parameter-based approach reduces porosity by compressing the electrode while maintaining the adhesion achieved through the rolling process, thereby resolving the contradiction between interlayer adhesion and porosity control.
2Manufacturing precision
If the solid electrolyte layer is made softer to act as a buffer during charging and discharging, then porosity reduction is improved, but manufacturing precision deteriorates due to difficulty in handling and bonding
Solution Approach 1:
The patent performs preliminary bonding of layers through the rolling process before the electrode undergoes volume changes during charging and discharging. This preliminary action secures the structural integrity and adhesion of layers, allowing the softer solid electrolyte to effectively buffer volume changes without compromising manufacturing handling.
3Reliability
If porosity is reduced through the rolling process, then ionic conductivity is improved, but porosity increases again due to volume changes at the material interface
Solution Approach 1:
The patent applies a uniaxial pressing process as a preliminary densification step before the electrode undergoes operational volume changes. This preliminary action reduces initial porosity and creates a more stable structure that resists porosity increase during charging and discharging, thereby maintaining ionic conductivity and compositional stability.
Solution Approach 2:
The uniaxial pressing process utilizes controlled pressure parameters to densify the electrode structure. By adjusting the pressing pressure and duration, the patent optimizes porosity reduction while maintaining structural stability during subsequent charge-discharge cycles, ensuring consistent 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
This approach reduces electrode porosity and deformation caused by volume changes, improving the battery's performance and life characteristics by maintaining consistent ionic and electronic conductivity.
Implementation Method 1
a solid electrolyte layer (10), a negative electrode (20) configured to include a negative active material layer (27) stacked on a first surface of the solid electrolyte layer (10)
Implementation Method 2
an upper portion of each electrode may act as a buffer during charging and discharging due to the soft solid electrolyte layer to minimize a change in porosity
Data Source
AI summary
An embodiment all solid state battery includes a sulfide-based solid electrolyte layer, a negative electrode comprising a negative active material layer stacked on a first surface of the solid electrolyte layer and a negative buffer layer stacked on a first surface of the negative active material layer, and a positive electrode comprising a positive active material layer stacked on a second surface of the solid electrolyte layer and a positive buffer layer stacked on a second surface of the positive active material layer.