Solid-State Battery Buffer Layers for Low-Porosity Electrodes
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Solution Overview
Problem
Existing all solid state batteries face issues with increased porosity and decreased ionic and electronic conductivity due to volume changes in the electrodes during charging and discharging, which affect battery performance and longevity.
Innovation Solution
The implementation of negative and positive electrode buffer layers made of sulfide-based materials with specific weight percentages of conductive materials and binders, along with surface treatments to enhance interfacial adhesion, minimizes porosity and maximizes conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a rolling process is used to bond layers in an all solid state battery, then internal porosity is reduced, but voids are re-formed due to volume change of active material during charging and discharging
Solution Approach 1:
The electrode is divided into multiple layers: a lower portion formed by adhesion between current collector and material, and an upper portion with soft solid electrolyte layer acting as buffer. This segmentation allows different regions to serve different functions - the lower portion provides structural integrity while the upper portion accommodates volume changes during charging/discharging, preventing void formation.
Solution Approach 2:
The invention changes the mechanical properties parameter of the solid electrolyte layer by making the upper portion soft to act as a buffer during charging and discharging. This parameter change allows the upper portion to minimize porosity changes while the lower portion maintains adhesion, resolving the contradiction between initial porosity reduction and operational void formation.
2Strength
If the lower portion of electrode is formed by adhesion between hard current collector and material, then structural integrity is provided, but porosity increases due to volume change at interface during charging and discharging
Solution Approach 1:
The electrode is segmented into lower and upper portions with distinct functions. The lower portion uses hard current collector adhesion for structural integrity, while the upper portion uses soft solid electrolyte as buffer to accommodate volume changes, preventing porosity increase at the interface during operation.
Solution Approach 2:
Different regions of the electrode are given different mechanical properties - the lower portion has hard adhesion for strength while the upper portion has soft buffering capability. This local quality differentiation allows each region to optimize its function without compromising the other, maintaining both structural integrity and low porosity during operation.
Data Source
AI summary
A method of manufacturing an all solid state battery is disclosed. In one embodiment, the method includes forming a negative electrode including a negative active material layer and a negative buffer layer, forming a sulfide-based solid electrolyte layer on a first surface of the negative electrode, forming a positive electrode including a positive active material layer and a positive buffer layer, and bonding the positive electrode to a second surface of the solid electrolyte layer.