Garnet Solid Electrolyte Doping for High Ionic Conductivity
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Solution Overview
Problem
Lithium batteries with liquid electrolytes face issues such as decomposition at high voltages, leakage, fire risk, and dendrite formation, while solid-state lithium batteries require a solid ion conductor with high lithium ion conductivity and chemical stability to overcome these limitations.
Innovation Solution
A solid ion conductor is developed using a garnet-type oxide represented by Formula L5+x+2y(Dy,E3-y)(Mez,M2-z)Od, where L, D, E, Me, and M are specific cations, and B2O3 is added to improve ionic conductivity without altering the crystal structure, achieving enhanced lithium ion conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a garnet-type oxide (e.g., Li5La3M2O12) is used as a solid ion conductor, then chemical stability and wide potential window are improved, but lithium ionic conductivity deteriorates (approximately 10^-6 S/cm at 25°C)
Solution Approach 1:
The patent modifies the chemical composition parameters of the garnet-type oxide by introducing dopants (Ta, Nb, W, Mo, V) at specific sites (M1 or M2) and adjusting the stoichiometry (Li5+xLa3M2O12 where x=0.01-0.20). This parameter optimization increases lithium ionic conductivity from 10^-6 S/cm to above 10^-4 S/cm at 25°C while preserving the garnet crystal structure and chemical stability
Solution Approach 2:
The patent creates a composite solid ion conductor by combining garnet-type oxide with other materials (such as Li3PO4, Li2SiO3, or amorphous layers) to form a composite electrolyte structure. This composite approach enhances ionic conductivity through synergistic effects while maintaining the chemical stability of the garnet base material
2Ease of manufacture
If liquid electrolyte is used in lithium battery, then ease of manufacture is improved, but safety deteriorates (high risk of leakage, fire, and explosion)
Solution Approach 1:
The patent replaces the liquid electrolyte system with a solid-state garnet-type oxide electrolyte system. This substitution eliminates the safety hazards of liquid electrolytes (leakage, fire, explosion) while maintaining ionic conduction functionality through the solid oxide material's intrinsic lithium ion conductivity
Solution Approach 2:
The patent changes the physical state parameter of the electrolyte from liquid to solid, and optimizes the ionic conductivity parameter of the solid oxide to exceed 10^-4 S/cm at 25°C, thereby achieving safety improvement without sacrificing essential electrochemical performance
3Ease of manufacture
If liquid electrolyte is used in lithium battery, then ease of manufacture is improved, but reliability deteriorates (decomposition at voltage of 2.5 V or more)
Solution Approach 1:
The patent changes the electrochemical stability window parameter by using solid oxide electrolyte with stability exceeding 4.0 V (compared to 2.5 V for liquid electrolytes), enabling high-voltage operation and improving overall battery voltage stability and reliability
4Ease of manufacture
If liquid electrolyte is used in lithium battery, then ease of manufacture is improved, but harmful factors worsen (support formation of dendrites)
Solution Approach 1:
The patent replaces liquid electrolyte with solid-state oxide electrolyte, which physically prevents dendrite formation through its rigid structure and controlled ion transport pathways, eliminating this harmful effect while maintaining manufacturing feasibility
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 solid ion conductor exhibits improved ionic conductivity and stability, reducing interface resistance and enhancing energy efficiency in all-solid-state lithium batteries, while maintaining thermal stability and preventing dendrite formation.
Implementation Method 1
B2O3 is added to improve ionic conductivity without altering the crystal structure, achieving enhanced lithium ion conductivity and stability
Implementation Method 2
The solid ion conductor exhibits improved ionic conductivity and stability, reducing interface resistance
Data Source
AI summary
A solid ion conductor including a garnet oxide represented by Formula 1:L5+x+2y(Dy,E3-y)(Mez,M2-z)Od Formula 1whereinL is at least one of a monovalent cation or a divalent cation,D is a monovalent cation,E is a trivalent cation,Me and M are each independently a trivalent, tetravalent, pentavalent, or a hexavalent cation,0<x+2y≦3, 0≦y≦0.5, 0≦z<2, and 0<d≦12,wherein O is partially or totally substituted with at least one of a pentavalent anion, a hexavalent anion, or a heptavalent anion; andB2O3.