Halogen-Substituted Solid Electrolyte for Moisture-Stable Lithium-Air Cells
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Solution Overview
Problem
Existing solid electrolytes fail to maintain good ionic conductivity, even after exposure to a strong base such as lithium hydroxide, and maintain good ionic conductivity after exposure to moisture. Existing solid electrolytes have low stability and conductivity under such conditions. Existing solid electrolytes have low stability against moisture and strong bases like lithium hydroxide, and the ionic conductivity under strongly basic conditions, like in lithium-air batteries, is reduced.
Innovation Solution
A solid electrolyte comprising a compound represented by Formula 1: Li x M1 2-y M2 y (PO 4-z X z ) 3, where M1 is hafnium or titanium, M2 is a monovalent to hexavalent element, and X is a halogen or pseudohalogens, with specific stoichiometric ratios, is introduced to enhance stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid electrolytes are used in lithium-air batteries, then the battery structure is simple, but the ionic conductivity is reduced under strongly basic conditions like lithium hydroxide
Solution Approach 1:
The patent employs composite solid electrolyte materials combining multiple metal elements (M1, M2, M3) with specific oxidation states in a phosphate-based structure Li x M1 2-y M2 y M3 z (PO 4-z X z ) 3. This composite approach creates synergistic effects where different metal elements contribute to both structural stability and ionic conductivity, resolving the contradiction between maintaining simple battery structure and achieving reliable ionic conductivity under basic conditions.
Solution Approach 2:
The patent systematically varies compositional parameters including the stoichiometric coefficients x, y, z, the oxidation states of metal elements, and the halogen substitution level to optimize performance. By adjusting these parameters within specific ranges, the electrolyte achieves enhanced ionic conductivity and stability under basic conditions while maintaining a manageable structural framework.
2Reliability
If conventional solid electrolytes are used, then manufacturing is simple, but stability against moisture and strong bases is insufficient
Solution Approach 1:
The patent introduces local quality variations through selective substitution of oxygen atoms with halogen atoms (X = F, Cl, Br, I) at specific positions in the phosphate structure, and through non-uniform distribution of different metal elements (M1, M2, M3) with varying oxidation states. This local modification enhances chemical stability against moisture and bases at critical sites while maintaining overall manufacturability through a systematic compositional framework.
Solution Approach 2:
The patent optimizes manufacturing feasibility by defining specific parameter ranges for compositional variables (x, y, z ratios, metal element combinations, halogen substitution levels) that simultaneously achieve enhanced stability and reasonable manufacturing complexity. These parameter specifications guide the synthesis process to produce stable electrolytes without excessive process complexity.
3Stability of the object's composition
If existing solid electrolytes are used in lithium-air batteries, then the battery design is straightforward, but phase stability is poor under discharge conditions
Solution Approach 1:
The patent employs composite solid electrolyte materials combining multiple metal elements (M1, M2, M3) with specific oxidation states in a phosphate-based structure Li x M1 2-y M2 y M3 z (PO 4-z X z ) 3. This composite approach creates synergistic effects where different metal elements contribute to both structural stability and ionic conductivity, resolving the contradiction between maintaining simple battery structure and achieving reliable ionic conductivity under basic conditions.
Solution Approach 2:
The patent systematically varies compositional parameters including the stoichiometric coefficients x, y, z, the oxidation states of metal elements, and the halogen substitution level to optimize performance. By adjusting these parameters within specific ranges, the electrolyte achieves enhanced ionic conductivity and stability under basic conditions while maintaining a manageable structural framework.
4Reliability
If conventional electrolytes are used, then internal resistance is high, but improving conductivity requires complex material composition
Solution Approach 1:
The patent optimizes ionic conductivity by systematically adjusting compositional parameters including lithium content (x), metal element ratios (y, z), oxidation states of M1, M2, and M3, and halogen substitution levels. These parameter optimizations enhance ionic conductivity while maintaining a systematic material framework that avoids excessive complexity.
Solution Approach 2:
The patent employs composite solid electrolyte materials combining multiple metal elements (M1, M2, M3) with specific oxidation states in a phosphate-based structure Li x M1 2-y M2 y M3 z (PO 4-z X z ) 3. This composite approach creates synergistic effects where different metal elements contribute to both structural stability and ionic conductivity, resolving the contradiction between maintaining simple battery structure and achieving reliable ionic conductivity under basic conditions.
Data Source
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AI summary
The present invention relates to SOLID ELECTROLYTE, PREPARATION METHOD THEREOF, LITHIUM-AIR BATTERY INCLUDING THE SAME, AND ELECTROCHEMICAL DEVICE INCLUDING THE SAME. A solid electrolyte including: a compound represented by Formula 1, Formula 1 LixM12-yM2y(PO4-zXz)3 wherein, in Formula 1, M1 is a tetravalent element, M2 is a monovalent element, a divalent element, a trivalent element, a tetravalent element, a pentavalent element, a hexavalent element, or a combination thereof, X is a halogen atom, a pseudohalogen, or a combination thereof, 0<x<8, 0≤y<1, and 0<z<4.