Doped Lithium Argyrodite Electrolytes for Stable High-Ion Conduction
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Solution Overview
Problem
Solid-state lithium batteries face challenges due to poor ionic conductivity, mechanical instability, high precursor costs, and interfacial degradation of argyrodite-type materials, which hinder their large-scale adoption.
Innovation Solution
Doping lithium argyrodite with metal oxides and adjusting halide concentrations to enhance ionic conductivity and stability, while using inert atmospheres to prevent degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If argyrodite-type solid electrolytes are used in solid-state lithium batteries, then safety and thermal stability are improved, but ionic conductivity is poor compared to liquid electrolytes
Solution Approach 1:
The patent modifies the chemical composition parameters of argyrodite-type solid electrolytes by doping with metal oxides (Fe2O3, NiO, CuO, ZnO, Co3O4, Mn3O4) and adjusting halide concentrations. These parameter changes optimize the ionic conductivity while maintaining the safety and thermal stability advantages of solid electrolytes, achieving ionic conductivity greater than 2.0 mS cm−1 at 20°C.
Solution Approach 2:
The patent creates composite solid electrolyte materials by combining argyrodite-type base materials with metal oxide dopants. This composite approach integrates the safety and stability of argyrodite with the enhanced ionic conductivity provided by metal oxide additions, resolving the contradiction between safety and ionic conductivity.
2Reliability
If argyrodite-type solid electrolytes are used, then flammability is reduced, but mechanical stability is poor
Solution Approach 1:
The patent adjusts compositional parameters including metal oxide content (0.05 ≤ a ≤ 0.5) and halide concentration (0.05 ≤ b ≤ 0.5) to simultaneously improve mechanical stability and maintain low flammability. The doping process strengthens the crystal structure while preserving the inherent fire-resistant properties of solid electrolytes.
3Quantity of substance
If doped lithium argyrodite is synthesized, then ionic conductivity is improved, but precursor costs increase
Solution Approach 1:
The patent employs metal oxides (Fe2O3, NiO, CuO, ZnO, Co3O4, Mn3O4) as dopants that are relatively inexpensive and widely available. These metal oxide precursors provide cost-effective doping solutions compared to other potential additives, enabling high ionic conductivity while controlling manufacturing costs.
Solution Approach 2:
The patent optimizes the doping concentration parameters (0.05 ≤ a ≤ 0.5 for metal oxide content) to achieve the minimum effective doping level that provides >2.0 mS cm−1 ionic conductivity. This parameter optimization avoids excessive precursor usage while maintaining performance, thereby reducing costs.
4Power
If lithium argyrodite is used as solid electrolyte, then power density is increased, but interfacial degradation occurs
Solution Approach 1:
The patent employs inert atmosphere processing during synthesis and handling to prevent interfacial degradation of lithium argyrodite. This inert environment protection maintains the stability of the solid electrolyte interfaces while preserving the high power density characteristics, enabling sustained performance without degradation.
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 doped lithium argyrodite exhibits improved ionic conductivity (greater than 2.0 mS cm−1) and reduced electronic conductivity (less than 4×10−9 S cm−1), addressing interfacial issues and reducing precursor costs.
Implementation Method 1
When a solid-state lithium battery is charged, lithium ions move from the cathode to the anode via diffusion through the solid electrolyte
Implementation Method 2
During discharging, lithium ions move from the anode to the cathode via diffusion through the solid electrolyte
Implementation Method 3
heating the pellet, membrane, or film to form the solid-state electrolyte
Data Source
AI summary
A solid-state electrolyte material includes doped lithium argyrodite of formula of Li6-2a-bMaTCh5-a-bOaX1+b; where 0<a≤0.5; 0<b≤0.5, M is Zn, Mg, Ca, Sr, Be or a combination of any two or more thereof; T is P, As, Sb, or a combination of any two or more thereof; Ch is S, Se, or a combination thereof; and X is F, Cl, Br, I, or a combination of any two or more thereof.