Garnet Ceramic Sheet With Lithium Gradient for Stable Solid Electrolytes
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Solution Overview
Problem
Conventional lithium secondary batteries using flammable liquid electrolytes pose safety risks, and all-solid secondary batteries with garnet-type oxide solid electrolytes face challenges in atmospheric stability and ionic conductivity.
Innovation Solution
A garnet-type oxide-based ceramic sheet with controlled lithium concentration and multimodal particle size distribution is prepared through a two-stage sintering process, incorporating doping elements to enhance atmospheric stability and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If garnet-type oxide solid electrolyte is used in all-solid secondary batteries, then safety is improved by replacing flammable liquid electrolytes, but atmospheric stability deteriorates due to reaction with moisture and carbon dioxide forming impurity phases
Solution Approach 1:
The patent applies local quality by creating a surface layer with different lithium content than the deep layer. The surface layer has lower lithium content (Li6.20-La3Zr2O12 composition) compared to the deep layer (Li6.33-La3Zr2O12 composition), making the surface layer specifically resistant to atmospheric reactions while the interior maintains high ionic conductivity. This localized compositional differentiation resolves the contradiction between atmospheric stability and ionic conductivity.
Solution Approach 2:
The patent creates a composite structure with two distinct layers: a surface layer with reduced lithium content for atmospheric stability and a deep layer with stoichiometric lithium content for ionic conductivity. This composite material approach allows the electrolyte to simultaneously achieve both atmospheric stability and high ionic conductivity by combining materials with complementary properties in a layered architecture.
2Reliability
If lithium content is increased to improve ionic conductivity, then lithium ion conductivity is improved, but atmospheric stability deteriorates due to increased reaction with moisture forming Li2CO3 impurity phases
Solution Approach 1:
The patent applies local quality by creating a surface layer with different lithium content than the deep layer. The surface layer has lower lithium content (Li6.20-La3Zr2O12 composition) compared to the deep layer (Li6.33-La3Zr2O12 composition), making the surface layer specifically resistant to atmospheric reactions while the interior maintains high ionic conductivity. This localized compositional differentiation resolves the contradiction between atmospheric stability and ionic conductivity.
3Reliability
If surface lithium content is high, then ionic conductivity is improved, but impurity phase formation increases when exposed to atmospheric moisture and carbon dioxide
Solution Approach 1:
The patent applies local quality by creating a surface layer with different lithium content than the deep layer. The surface layer has lower lithium content (Li6.20-La3Zr2O12 composition) compared to the deep layer (Li6.33-La3Zr2O12 composition), making the surface layer specifically resistant to atmospheric reactions while the interior maintains high ionic conductivity. This localized compositional differentiation resolves the contradiction between atmospheric stability and ionic conductivity.
Solution Approach 2:
The patent converts the potential harm of lithium reaction with atmospheric CO2 and moisture into a benefit by deliberately creating a surface layer with controlled lower lithium content. This surface layer acts as a protective barrier that reacts preferentially or resists atmospheric reactions, protecting the high-lithium-content interior from degradation. The controlled impurity formation at the surface prevents deeper penetration and maintains overall battery performance.
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 ceramic sheet exhibits high lithium ion conductivity and improved atmospheric stability, reducing impurity phase formation and maintaining ionic conductivity, suitable for use in all-solid batteries and green technology applications.
Implementation Method 1
producing a sintered body by sintering the oxide molded body
Data Source
Figure 1(a)~1(c)
Figure 2(i)(a)~2(ii)
Figure 3(i)(a)~3(ii)
AI summary
The present disclosure provides a ceramic sheet, a method for preparing same, and an all-solid secondary battery comprising same. According to the present disclosure, provided is a garnet-type oxide-based ceramic sheet that contains a garnet-type oxide and comprises a surface layer and a deep layer, wherein the average lithium content in garnet-type oxide particles in the surface layer is greater than the average lithium content in garnet-type oxide particles in the deep layer, and the ratio of the average lithium content in the garnet-type oxide in the surface layer to the average lithium content in the garnet-type oxide in the deep layer is greater than 1 and less than 1.014.