Sb-Coated LLZO Solid Electrolyte for Low-Resistance Lithium Interfaces
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Solution Overview
Problem
LLZO-based solid state batteries face issues with high interface resistance, low critical current density, and limited performance due to poor wettability by lithium metal, leading to dendrite formation and insufficient performance in commercial applications.
Innovation Solution
A dense Li7La3Zr2O12 (LLZO) membrane with a thin antimony (Sb) coating is used, forming a Li—Sb alloy at the interface, which is prepared by heating and deposition methods to achieve a clean surface and uniform interface, reducing impurities like Li2CO3 and enhancing conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin antimony coating is applied to LLZO to reduce interface resistance, then interface resistance decreases, but the thickness becomes unsuitable for commercial battery cells
Solution Approach 1:
The patent changes the chemical composition and structure of the electrolyte material itself by doping LLZO with Al, Ta, and Nb to create a composite garnet structure. This modifies the intrinsic properties of the bulk electrolyte to achieve lower interface resistance without requiring thinning, thus maintaining suitable thickness for commercial batteries while improving interfacial performance
Solution Approach 2:
The patent creates a composite material system combining multiple doped garnet phases (Al-doped, Ta-doped, Nb-doped LLZO) to achieve synergistic effects. The composite structure provides both the mechanical stability of thick electrolytes and the low interface resistance typically achieved only with thin coatings, resolving the contradiction between thickness and interface performance
2Temperature
If conventional LLZO is used to maintain thermal stability, then thermal stability is improved, but wettability by lithium metal deteriorates leading to high interface resistance
Solution Approach 1:
The patent applies local quality modification by introducing specific dopants (Al, Ta, Nb) at controlled concentrations within the garnet structure. These dopants create local compositional variations that enhance lithium ion conductivity and improve wettability at the lithium metal interface, while the overall bulk structure maintains the thermal stability characteristic of LLZO
Solution Approach 2:
The patent modifies the chemical parameters of LLZO through multi-element doping to change the electronic and ionic properties. The doping alters the band structure and defect chemistry locally at the interface region, improving lithium metal wettability and reducing interface resistance while preserving the high-temperature stability of the parent LLZO structure
3Strength
If LLZO thickness is increased for commercial applications, then mechanical stability is improved, but performance at elevated temperatures deteriorates
Solution Approach 1:
The patent constructs a composite garnet electrolyte combining multiple doped phases (Al-LLZO, Ta-LLZO, Nb-LLZO) in a synergistic arrangement. This composite structure provides enhanced mechanical strength from the thick configuration while the specific dopant combinations maintain high ionic conductivity and electrochemical stability at elevated temperatures, resolving the trade-off between mechanical and thermal performance
4Ease of manufacture
If conventional LLZO is used to maintain low cost, then manufacturing cost is reduced, but critical current density remains low leading to limited fast charging capability
Solution Approach 1:
The patent optimizes the compositional parameters of LLZO through controlled doping with Al, Ta, and Nb at specific ratios. These parameter changes enhance the bulk ionic conductivity and interfacial properties, enabling higher critical current density for fast charging applications. The doping levels are carefully controlled to balance performance improvement with manufacturing complexity and cost
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 results in a low interface resistance and high critical current density, enabling fast charging and extended cycling life, even at elevated temperatures, with a significantly improved performance compared to existing LLZO-based SSEs.
Implementation Method 1
heating and deposition methods to achieve a clean surface and uniform interface, reducing impurities like Li2CO3
Implementation Method 2
heating and deposition methods to achieve a clean surface and uniform interface
Implementation Method 3
forming a Li—Sb alloy at the interface, which is prepared by heating and deposition methods
Data Source
AI summary
A solid state electrolyte (SSE) including a dense membrane including LLZO having a thickness equal to or lower than 100 μm and a Sb-including 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-including coating layer and the LLZO-including dense membrane, wherein the thicknesses are as calculated from SEM images of the SSE. Also, a solid state battery (SSB) including the SSE and to methods of producing the SSE and the SSB.