Boracite Lithium-Ion Conductor for Safe High-Conductivity Electrolytes
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Solution Overview
Problem
Current solid-state lithium-ion conductors face challenges with safety concerns, limited ionic conductivity, and high costs due to the use of rare-earth elements or noble metals, which restrict their application in electric vehicles and grid-based energy storage.
Innovation Solution
A solid-state ion conductor with a boracite-type structure, represented by the compound Li4+xB7O12+0.5xX1aX21−a, where X1 is a pseudohalogen and X2 is a halogen, offering high ionic conductivity and stability, and can be synthesized using a solid-state synthesis method with precursor compounds and heat-treating or mechanochemical milling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfide solid-state electrolytes are used to provide greater lithium conductivity, then ionic conductivity is improved, but safety concerns arise due to reaction with air or water to evolve hydrogen sulfide
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating halogen atoms (F, Cl, Br, I) into the boracite-type crystal structure at specific lattice positions. This parameter change transforms the electrolyte from reactive sulfide-based materials to stable halide-containing materials, achieving high ionic conductivity (≥10⁻⁴ mS/cm at 300K) while eliminating hydrogen sulfide evolution and improving stability in air and water.
Solution Approach 2:
The patent creates composite solid-state electrolyte materials by combining lithium-containing precursors with boron oxide and halogen-containing compounds to form a new class of halide-containing boracite-type compounds. This composite approach integrates the high ionic conductivity benefits of sulfides with the stability benefits of oxides and halides, achieving both high performance and safety.
2Object-affected harmful factors
If oxide solid-state electrolytes are used to provide reduced toxicity and stability in air, then safety is improved, but ionic conductivity is limited
Solution Approach 1:
The patent modifies the oxide structure by incorporating halogen atoms at specific crystallographic positions within the boracite-type structure. This parameter change increases lithium ion mobility pathways while maintaining the stable oxide framework, achieving ionic conductivity of ≥10⁻⁴ mS/cm at 300K, which is significantly higher than conventional oxide electrolytes like LLZO.
3Stability of the object's composition
If conventional solid-state electrolytes are used, then stability is achieved, but sintering temperature is high, increasing manufacturing complexity
Solution Approach 1:
The incorporation of halogen atoms into the boracite-type structure creates weaker bonding characteristics that allow the material to be sintered at lower temperatures (below 900°C) while maintaining structural stability. This parameter change in chemical composition reduces the activation energy required for sintering, making manufacturing more accessible.
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-state ion conductor achieves ionic conductivity of up to 10 mS/cm at 300 K, is kinetically stable with lithium transition metal oxides and lithium metal, and has a lower sintering temperature, making it suitable for solid-state batteries with reduced costs and improved performance.
Implementation Method 1
The solid-state ion conductor achieves ionic conductivity of up to 10 mS/cm at 300 K
Implementation Method 2
can be synthesized using a solid-state synthesis method with precursor compounds and heat-treating or mechanochemical milling
Data Source
AI summary
A solid-state ion conductor includes a compound of Formula (I):Li4+xB7O12+0.5xX1aX21−a Formula (I)wherein, in Formula (I), 0≤x≤1; X1 is a pseudohalogen; X2 is a halogen; and 0<a≤1.