Solid-State Battery Cathode Interface for Side Reaction Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional solid-state batteries face issues with side reactions between the positive electrode active material and garnet-type oxide during firing, leading to decreased ionic conductivity and reduced utilization rate of the positive electrode active material, particularly when using layered rock salt type structures.
Innovation Solution
The solid-state battery design incorporates a positive electrode layer with a garnet-type oxide having a lower Li concentration in the interface vicinity compared to the particle interior, along with a layered rock salt type positive electrode active material, to suppress side reactions and maintain ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the Li amount in the garnet-type oxide is reduced to suppress side reactions during firing, then the side reaction between positive electrode active material and garnet-type oxide is suppressed, but the ionic conductivity of the garnet-type oxide decreases
Solution Approach 1:
The patent applies local quality by creating a radial concentration gradient of Li within the garnet-type oxide particles, where the Li concentration varies from the particle center to the surface. This allows different regions of the same material to have different compositions: the particle interior maintains higher Li content for ionic conductivity, while the interface vicinity has lower Li content to suppress side reactions with the positive electrode active material.
Solution Approach 2:
The patent changes the chemical composition parameter (Li concentration) of the garnet-type oxide in a controlled manner. By adjusting the Li concentration from 0.05 to 0.65 in the particle interior and 0.05 to 0.35 in the interface vicinity, the patent optimizes the balance between ionic conductivity and side reaction suppression, achieving both low resistance and high utilization rate of the positive electrode active material.
2Stability of the object's composition
If the Li amount in the garnet-type oxide is reduced to prevent Li diffusion into positive electrode active material, then the deterioration of positive electrode active material characteristics is suppressed, but the resistance of the solid-state battery increases
Solution Approach 1:
The patent creates a spatially non-uniform Li distribution within the garnet-type oxide particles, with the particle interior having higher Li concentration (0.05 ≤ x1 ≤ 0.65) to maintain ionic conductivity and the interface vicinity having lower Li concentration (0.05 ≤ x2 ≤ 0.35) to prevent Li diffusion into the positive electrode active material. This local differentiation resolves the contradiction between preventing material deterioration and maintaining low resistance.
Solution Approach 2:
The garnet-type oxide with controlled Li concentration gradient acts as an intermediary layer between the positive electrode active material and the bulk electrolyte. The interface vicinity with lower Li content serves as a protective barrier that mediates the interaction between the electrode material and the electrolyte, preventing harmful Li diffusion while the particle interior with higher Li content maintains ionic conductivity.
3Reliability
If conventional garnet-type oxide with relatively large Li amount is used, then ionic conductivity is maintained, but side reaction occurs during firing and utilization rate of positive electrode active material decreases
Solution Approach 1:
The patent implements local quality by establishing a radial concentration gradient of Li in the garnet-type oxide particles. The particle interior (higher Li: 0.05 ≤ x1 ≤ 0.65) ensures sufficient ionic conductivity, while the interface vicinity (lower Li: 0.05 ≤ x2 ≤ 0.35) minimizes side reactions with the positive electrode active material. This spatial differentiation enables both high ionic conductivity and high utilization rate (≥90%) of the positive electrode active material.
Solution Approach 2:
The patent optimizes the Li concentration parameter x in the garnet-type oxide formula Li6-x-pAxBIIyD1-y-zO12-δ by creating different Li concentrations in different regions. The controlled reduction of Li at the interface (x2 < x1) prevents side reactions that would otherwise occur with conventional uniform high-Li garnet oxides, while maintaining sufficient bulk Li content for 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 effectively reduces side reactions and enhances ionic conductivity, improving the utilization rate of the positive electrode active material and resulting in a low-resistance solid-state battery.
Implementation Method 1
Li was excessively introduced (or diffused) into the positive electrode active material during firing
Implementation Method 2
ionic conductivity of the garnet-type oxide decreases
Data Source
AI summary
A solid-state battery that includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer, in which the positive electrode layer contains a positive electrode active material and an oxide having a garnet-type crystal structure, and a first Li concentration in an interface vicinity with the positive electrode active material in the oxide is lower than a second Li concentration in a particle interior of the oxide.