Deformable Halide Solid Electrolytes for Stable Battery Interfaces
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Solution Overview
Problem
Current solid-state batteries (SSBs) face challenges with mechanical, chemical, and electrochemical compatibility between solid electrolytes (SEs) and electrodes, leading to non-conformal contact, limited power density, and dendrite formation.
Innovation Solution
A Machine Learning (ML)-driven computational workflow is used to design new deformable halide ionic conductors with predicted hardness ≤2.5 GPa, which are computationally characterized for thermodynamic and electrochemical stability, mechanical deformability, and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If rigid solid electrolytes are used to maintain structural integrity, then mechanical stability is improved, but interface contact with electrodes deteriorates leading to non-conformal contact and limited power density
Solution Approach 1:
The patent changes the mechanical parameter of solid electrolytes from rigid to deformable by selecting materials with specific mechanical properties (hardness ≤ 2.5 GPa). This parameter change allows the electrolyte to deform and conform to electrode surfaces, improving interface contact and power density while maintaining sufficient structural integrity for battery operation.
2Adaptability or versatility
If deformable sulfide solid electrolytes are used to improve interface contact, then ease of deformation is improved, but oxidative stability deteriorates limiting battery capacity
Solution Approach 1:
The patent applies local quality by selecting specific halide compounds (chlorides, fluorides) with particular chemical compositions that possess both deformable mechanical properties and high oxidative stability. The local chemical composition (specific halide type and cation combination) determines the dual property profile needed to resolve the contradiction between deformability and oxidative stability.
3Reliability
If oxide solid electrolytes are used to improve oxidative stability, then electrochemical stability is improved, but mechanical deformability deteriorates requiring additional engineering
Solution Approach 1:
The patent changes the material class from traditional oxides to halides (chlorides, fluorides), fundamentally altering the chemical composition parameter. This composition change enables the electrolyte to achieve both high electrochemical stability (comparable to oxides) and sufficient mechanical deformability, eliminating the need for additional engineering strategies like co-sintering or stack pressure.
4Reliability
If protective coatings are applied to sulfide electrolytes to improve oxidative stability, then electrochemical stability is improved, but interface resistance and contact issues aggravate
Solution Approach 1:
The patent extracts the need for protective coatings by selecting halide electrolyte materials that inherently possess both deformability and high oxidative stability. By taking out the coating layer entirely and using a single-material electrolyte system, the patent eliminates the additional interfaces that would otherwise increase resistance and contact issues.
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 new deformable halide ionic conductors exhibit good electrochemical stability against Li metal and high voltage cathodes, ensuring long cycle life and improved interface stability with oxide SEs and cathodes.
Implementation Method 1
halide ionic conductors, particularly chlorides, were raised as a promising class of solid electrolytes. They are ionically conductive
Implementation Method 2
a solid electrolyte forms a point contact with the active material due to its intrinsically rigid nature, thereby inducing sluggish charge transfer and mass transport kinetics at the interface
Data Source
AI summary
A deformable halide-based ionic conductor has one of the following formulas: NaLi3I4, NaLi3Br4, NaLi3Cl4, KLi2F3, Li2HfF6, Li3AgI4, Li3SiB3(ClF3)4, Li3AgBr4, Li2ZnF4 having a trigonal crystal structure with space group R-3, Li3AgCl4, or Li2AgCl3. A catholyte includes a deformable halide-based ionic conductor having one of the following formulas: CsLi2Cl3, wherein the CsLi2Cl3 has an orthorhombic crystal structure, KLi2F3, Li2HfF6, Li3SiB3(ClF3)4, Li3AgBr4, Li2ZnF4, Li3AgCl4, or Li2AgCl3. A solid electrolyte separator includes a deformable halide-based ionic conductor having one of the following formulas: CsLi2Cl3, wherein the CsLi2Cl3 has an orthorhombic crystal structure, NaLi3I4, NaLi3Br4, NaLi3Cl4, KLi2F3, Li2HfF6, Li3AgI4, Li3SiB3(ClF3)4, Li3AgBr4, Li2ZnF4, Li3AgCl4, or Li2AgCl3. A solid state battery includes an anode, a cathode, and a solid electrolyte separator including a deformable halide-based ionic conductor having one of the following formulas: CsLi2Cl3, wherein the CsLi2Cl3 has an orthorhombic crystal structure, NaLi3I4, NaLi3Br4, NaLi3Cl4, KLi2F3, Li2HfF6, Li3AgI4, Li3SiB3(ClF3)4, Li3AgBr4, Li2ZnF4, Li3AgCl4, or Li2AgCl3.