Doped Argyrodite Solid Electrolyte for Conductivity and Stability
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Solution Overview
Problem
Conventional solid-state batteries with argyrodite sulfide electrolytes face challenges with inferior ionic conductivity and electrochemical stability compared to liquid electrolytes, which limits their performance in energy storage and discharge applications.
Innovation Solution
The development of phosphorus-site doped and off-stoichiometric argyrodite-based compositions, specifically Li6PS5Cl with excess chlorine, which includes dopants like Sn, Si, Zr, Ti, Sb, Bi, V, or Ta, to enhance ionic conductivity and chemical stability, forming a solid-state electrolyte with improved lithium ion diffusivity and thermodynamic stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional argyrodite sulfide electrolytes are used in solid-state batteries, then the battery structure is simplified and safety is improved, but ionic conductivity and electrochemical stability deteriorate compared to liquid electrolytes
Solution Approach 1:
The patent modifies the chemical composition parameters of the argyrodite sulfide electrolyte by introducing P-site dopants (elements from Groups 13-16) and adjusting the stoichiometric ratios of Li, P, S, and Cl. This changes the physical and chemical properties of the electrolyte to achieve both high ionic conductivity (>1 mS/cm at 25°C) and electrochemical stability, resolving the contradiction between safety and ionic conductivity
Solution Approach 2:
The patent creates a composite solid-state electrolyte material by doping phosphorus sites with multiple candidate elements (Al, Ga, In, Sn, Si, Ge, Ge, Sb, Bi, V, Nb, Ta) in controlled amounts (0.01-0.5 moles per mole of LPSC). This composite approach combines the structural stability of argyrodite with the enhanced ionic conductivity provided by dopant elements, simultaneously improving safety and ionic conductivity
2Reliability
If conventional argyrodite sulfide electrolytes are used in solid-state batteries, then the battery structure is simplified and safety is improved, but electrochemical stability deteriorates compared to liquid electrolytes
Solution Approach 1:
The patent adjusts the compositional parameters by controlling the doping amount (0.01-0.5 moles of dopant per mole of LPSC) and maintaining specific stoichiometric ratios in the Li6-xP1-yAyS5-zCl1+z composition. This parameter optimization enhances electrochemical stability while preserving the safety advantages of solid-state electrolytes
3Quantity of substance
If P-site dopants with larger ionic radius are introduced, then ionic conductivity is enhanced, but structural stability may deteriorate
Solution Approach 1:
The patent introduces P-site dopants with larger ionic radii (Al³⁺: 0.39nm, Ga³⁺: 0.47nm, In³⁺: 0.80nm, Sn⁴⁺: 0.69nm, Si⁴⁺: 0.26nm, Ge⁴⁺: 0.53nm, Sb³⁺: 0.76nm, Bi³⁺: 1.03nm, V⁵⁺: 0.54nm, Nb⁵⁺: 0.64nm, Ta⁵⁺: 0.64nm) at controlled concentrations (0.01-0.5 moles per mole of LPSC). This local substitution creates favorable conditions for lithium ion transport while the limited doping amount prevents excessive lattice distortion, thus enhancing ionic conductivity while maintaining structural stability
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 and off-stoichiometric argyrodite compositions exhibit lithium ion diffusivity comparable to the parent compound with improved thermodynamic stability, leading to enhanced safety, power density, and energy density in all-solid-state batteries, suitable for electric vehicles and other applications, while reducing greenhouse gas emissions.
Implementation Method 1
lithium ion diffusivity comparable to the parent compound
Implementation Method 2
high ionic conductivity with adequate chemical and electrochemical stability
Data Source
AI summary
Aspects of the disclosure relate to solid state electrolytes which include a composition of Li6PS5Cl having a dopant substituted, in part, for phosphorus (P-site dopant) and an excess molar amount of Cl (i.e., doped, off-stoichiometric compositions). The P-site dopant can be selected among Groups 4, 5, 14, or 15 of the periodic table of elements and has an ionic radius greater than phosphorus (P). Such solid state electrolytes can be used in all solid-state batteries and configured for use in electric vehicles.