LLZO Solid Electrolyte With Sb Coating for Low-Resistance Interfaces
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Solution Overview
Problem
LLZO-based solid state batteries face issues with high interface resistance, low critical current density, and poor lithium metal wettability, leading to limited performance and safety concerns due to dendrite formation.
Innovation Solution
A dense Li7La3Zr2O12 membrane with a thin antimony coating is used, combined with a Li-Sb alloy at the interface, to enhance wettability and reduce resistance, allowing for high current densities and improved cycling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin antimony coating is applied to LLZO to improve wettability and reduce interface resistance, then the interface resistance decreases, but the thickness becomes unsuitable for commercial battery cells
Solution Approach 1:
The patent applies composite materials by combining LLZO solid electrolyte with a thin antimony coating layer (5-20 nm) to create an interface that exhibits both low resistance and appropriate thickness for commercial batteries. The composite structure leverages the high ionic conductivity of LLZO and the wetting properties of antimony to achieve optimal performance.
Solution Approach 2:
The patent changes the thickness parameter of the antimony coating to a specific range (5-20 nm) that is thin enough to provide good wettability and low interface resistance but thick enough to be suitable for commercial battery applications. This precise parameter control resolves the contradiction between thinness for performance and adequate thickness for commercial viability.
2Use of energy by moving object
If LLZO is used as solid electrolyte to achieve high Li-ion conductivity, then energy density improves, but poor wettability by lithium metal leads to high interface resistance and dendrite formation
Solution Approach 1:
The patent introduces a thin antimony coating layer as an intermediary between the LLZO solid electrolyte and lithium metal anode. This intermediate layer improves wettability and reduces interface resistance, preventing direct contact between LLZO and lithium metal, thereby reducing dendrite formation while maintaining high Li-ion conductivity through the LLZO bulk.
3Stability of the object's composition
If conventional LLZO SSE is used to maintain structural stability, then reliability improves, but performance at elevated temperatures and high current densities remains limited
Solution Approach 1:
The patent creates a composite structure where the thermally stable LLZO bulk provides structural stability while the antimony coating layer enhances performance at elevated temperatures by maintaining low interface resistance and good wettability. The composite design allows each material to contribute its advantageous properties.
Solution Approach 2:
The patent applies local quality by providing the antimony coating specifically at the interface regions where temperature effects and current density effects are most pronounced. This localized treatment enhances performance at elevated temperatures and high current densities without requiring changes to the bulk LLZO structure, thereby maintaining structural stability while improving operational reliability.
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 solution achieves low interface resistance and high critical current density, enabling fast charging and extended battery life with a reduced thickness, suitable for commercial applications.
Implementation Method 1
the poor LLZO wettability by lithium metal, which leads to a relatively high Li/LLZO interface resistance
Implementation Method 2
a high Li-ion conductivity of up to 1 mS.cm -1
Data Source
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AI summary
The present invention relates to a solid state electrolyte (SSE) comprising a dense membrane comprising LLZO having a thickness equal to or lower than 100 µm and a Sb-comprising coating layer having a thickness between 1 and 20 nm provided on a surface of the dense membrane, the dense membrane having a density equal to or higher than 90 % of the theoretical density of the membrane, wherein the surface of dense membrane onto which the coating layer is provided is substantially free of Li2CO3, wherein the SSE comprises a first Li-Sb alloy at the interface of the Sb-comprising coating layer and the LLZO-comprising dense membrane, wherein the thicknesses are as calculated from SEM images of the SSE. The invention further relates to a solid state battery (SSB) comprising the SSE and to methods of producing the SSE and the SSB.