Complex Metal Halide Electrolytes With Sublimation Purification
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Solution Overview
Problem
Current solid electrolyte materials for solid-state lithium batteries face challenges such as high synthesis temperatures, brittleness, safety concerns, and limited ionic conductivity, particularly in oxide, halide, and sulfide materials, which hinder their mass production and application in lithium metal anodes.
Innovation Solution
A method for forming a solid ion conductive material using a complex metal halide with a dopant like ammonium, involving a reaction mixture of ammonium halides and metal compounds, followed by a solid-state reaction and sublimation process to produce a material with improved purity and ion conductivity, suitable for forming electrolytes and electrodes in lithium batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-energy ball milling-based solid-state synthesis methods are used for halide electrolytes, then room-temperature ionic conductivity above 1 mS/cm is achieved, but synthesis challenges for mass production and high cost occur due to expensive binary halide reactants and high-temperature annealing
Solution Approach 1:
The patent changes the synthesis parameters by using a solution-based approach instead of solid-state ball milling, and by employing a different temperature regime (lower synthesis temperature with subsequent annealing) to achieve the same ionic conductivity target while improving manufacturability
Solution Approach 2:
The patent introduces an intermediary step by using a solution precursor method where reactants are dissolved and mixed in solution before crystallization, serving as a mediator between the starting materials and the final solid electrolyte product, thereby avoiding direct high-energy mechanical processing
2Stability of the object's composition
If high-temperature synthesis above 1000-1200°C is used for oxide-based materials, then good chemical and electrochemical stability is achieved, but brittleness and limited ionic conductivity up to 1.0 mS/cm occur
Solution Approach 1:
The patent employs composite material strategies by creating complex metal halide structures with multiple cations (e.g., Li, Na, K combined with Al, Ga, In) that synergistically provide both stability and high ionic conductivity, overcoming the limitations of simple oxide materials
Solution Approach 2:
The patent changes the chemical composition parameters by transitioning from oxide to halide-based complex metal structures, and optimizes the cation ratios to achieve enhanced ionic conductivity while maintaining stability through compositional design rather than relying solely on high-temperature synthesis
3Reliability
If sulfide materials are used to achieve high ionic conductivity up to 25 mS/cm, then mechanical softness and deformability are obtained, but poor electrochemical stability and safety concerns occur due to risk of releasing toxic H2S gas
Solution Approach 1:
The patent converts the harmful sulfide chemistry into beneficial halide chemistry, where the halide ions provide similar high ionic conductivity mechanisms without the toxic H2S release problem, effectively transforming a harmful material class into a safe alternative while preserving the desired performance
Solution Approach 2:
The patent adopts halide materials that are safer and more stable than sulfides, accepting that while sulfides offer higher conductivity, the safety risks make halides the preferable choice for practical applications where safety outweighs marginal conductivity differences
4Manufacturing precision
If complex metal halide with ammonium dopant is synthesized through solution-based method, then enhanced purity and bulk ion conductivity are achieved, but additional processing steps are required
Solution Approach 1:
The patent performs preliminary action by dissolving and mixing all reactants in solution before crystallization, pre-establishing the correct stoichiometric ratios and homogeneous distribution of dopants, which simplifies subsequent processing and ensures high purity without requiring extensive additional purification steps
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 process enables the production of solid ion conductive materials with enhanced purity, bulk ion conductivity, and electrochemical stability, facilitating the development of cost-effective and efficient solid-state lithium batteries with improved safety and performance.
Implementation Method 1
a reaction mixture of ammonium halides and metal compounds, followed by a solid-state reaction
Implementation Method 2
followed by a solid-state reaction and sublimation process to produce a material with improved purity and ion conductivity
Data Source
AI summary
A solid ion conductive material can include a complex metal halide. The complex metal halide can include at least one alkali metal element. In an embodiment, the solid ion conductive material including the complex metal halide can be a single crystal. In another embodiment, the ion conductive material including the complex metal halide can be a crystalline material having a particular crystallographic orientation. A solid electrolyte can include the ion conductive material including the complex metal halide.