All-solid-state Battery Cover Layer for Ion Conductivity
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Solution Overview
Problem
The existing methods for manufacturing all-solid-state batteries face issues with reduced utilization efficiency of positive electrode active material and ion conductivity due to aggregation of second particles and minute spaces/interfaces in the conductive layer, leading to decreased battery characteristics in both low and high rate charge and discharge.
Innovation Solution
The proposed solution involves a structure where a second solid electrolyte with larger particles is embedded in a cover layer over the positive electrode active material, ensuring uniform ion conduction paths and improved dispersibility, along with a manufacturing method that applies compressive and shearing forces to form the cover layer and embed the second solid electrolyte particles, preventing aggregation and enhancing ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a second solid electrolyte with larger particles is added to improve ion conductivity, then ion conductivity is improved, but aggregation of particles occurs leading to reduced utilization efficiency
Solution Approach 1:
The solid electrolyte is divided into two distinct particle size categories: first particles with smaller average diameter (0.5-5 μm) and second particles with larger average diameter (5-20 μm). This segmentation allows each particle size to fulfill specific functions - smaller particles fill gaps and ensure uniform distribution, while larger particles provide high ion conductivity pathways, thereby resolving the contradiction between improving ion conductivity and preventing aggregation.
Solution Approach 2:
Different regions of the positive electrode layer are designed with different solid electrolyte particle characteristics. The first solid electrolyte (smaller particles) is distributed throughout to ensure uniform coverage and fill interstices, while the second solid electrolyte (larger particles) is concentrated in specific regions to establish high ion conductivity pathways. This local differentiation optimizes both utilization efficiency and ion conductivity simultaneously.
2Manufacturing precision
If a cover layer is formed to prevent aggregation of second particles, then utilization efficiency is improved, but minute spaces and interfaces are created reducing ion conductivity
Solution Approach 1:
The structure implements a nested arrangement where smaller first solid electrolyte particles are embedded within and around the larger second solid electrolyte particles. The smaller particles fill the minute spaces and interfaces between larger particles, creating a hierarchical structure that eliminates voids while maintaining the beneficial effects of particle size differentiation. This nesting resolves the contradiction by ensuring continuous ion conduction pathways without aggregation.
Solution Approach 2:
The positive electrode layer is designed with a controlled porous structure where the interstices between particles are intentionally filled with smaller solid electrolyte particles rather than leaving voids. This creates a dense, interconnected network that prevents aggregation of larger particles while maintaining excellent ion conductivity through the filled porous structure, thereby resolving the contradiction between preventing aggregation and maintaining ion conductivity.
Data Source
AI summary
All-solid-state battery 100 has a structure in which positive electrode current collector 7, positive electrode layer 20 containing positive electrode active material 3, solid electrolyte 1 including a plurality of first particles having a first average particle diameter, and solid electrolyte 2 composed of a plurality of second particles having second average particle diameter larger than the first average particle diameter, solid electrolyte layer 10 containing solid electrolyte 6, negative electrode layer 30 containing negative electrode active material 4 and solid electrolyte 5, and negative electrode current collector 8 are stacked in this order, in which at least a part of solid electrolyte 1 serves as a cover layer 11 covering at least a part of a surface of positive electrode active material 3, and at least one of the plurality of second particles are partially embedded in cover layer 11.