Composite Electrolyte for Garnet Battery Grain Boundary Resistance
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Solution Overview
Problem
Existing battery technologies using garnet-type ion conductive oxides face challenges in achieving low temperature sintering without sufficient interface sintering between crystal grains, leading to high crystal grain boundary resistance and poor lithium ion conduction properties.
Innovation Solution
A composite electrolyte system is introduced, comprising a crystalline lithium composite metal oxide with specific compositional substitutions and an amorphous second electrolyte, creating a concentration gradient that reduces grain boundary resistance and enhances lithium ion conduction, even at low firing temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If low temperature firing is performed using garnet-type ion conductive oxide, then energy consumption is reduced, but crystal grain boundary resistance increases and lithium ion conduction property deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the garnet-type oxide by substituting specific elements (Al for La, Nb for Zr) at controlled ratios. This compositional parameter change enables the material to achieve good sintering and low grain boundary resistance at lower firing temperatures, resolving the contradiction between energy consumption and lithium ion conduction property.
Solution Approach 2:
The invention creates a composite electrolyte system combining crystalline garnet-type oxide with specific substitution patterns. The multi-element substitution strategy (Al, Nb, Ta) creates a composite structure that maintains cubic phase stability and achieves effective grain boundary sintering at reduced temperatures, improving both energy efficiency and ion conduction.
2Ease of manufacture
If low temperature firing is performed using garnet-type ion conductive oxide, then production cost is reduced, but interface sintering between crystal grains is insufficient
Solution Approach 1:
By adjusting the substitution ratios (0.05 ≤ x ≤ 0.20 for Al substitution, 0.05 ≤ y ≤ 0.20 for Nb substitution), the invention optimizes the material's sintering characteristics. This parameter control enables sufficient interface sintering at lower temperatures, reducing production costs while maintaining manufacturing precision.
Solution Approach 2:
The invention applies local quality enhancement by concentrating substitution elements at grain boundaries. The Al and Nb substitutions preferentially locate at interface regions, improving local sintering quality and grain boundary conductivity without requiring high overall processing temperatures.
3Stability of the object's composition
If conventional garnet-type oxide is used, then material stability is maintained, but grain boundary resistance remains high
Solution Approach 1:
The invention modifies the compositional parameters within the garnet structure by substituting Al at La sites and Nb at Zr sites. These controlled parameter changes maintain the overall cubic garnet phase stability while specifically targeting grain boundary properties, achieving low grain boundary resistance without sacrificing material stability.
Solution Approach 2:
The invention creates a substituted composite garnet structure combining multiple elements (Li, La, Al, Zr, Nb, Ta, O). This composite approach maintains the stable garnet framework while introducing beneficial substitutional elements that reduce grain boundary resistance and enhance lithium ion conduction pathways.
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 composite electrolyte system significantly decreases grain boundary resistance and improves lithium ion conduction, stabilizing the crystal structure and enhancing the battery's charge-discharge characteristics and capacity.
Implementation Method 1
the concentration gradient of the metal element occurs between the crystalline first electrolyte and the amorphous second electrolyte
Implementation Method 2
the stabilization of the crystal (cubic crystal) in the first electrolyte is promoted
Implementation Method 3
an interface between crystal grains is not sufficiently sintered
Data Source
AI summary
An electrolyte includes a first electrolyte, in which an element constituting a crystalline lithium composite metal oxide represented by the following compositional formula (1) is substituted with a first metal element having a crystal radius of 78 pm or more, and an amorphous second electrolyte, which contains Li and a second metal element contained in the first electrolyte other than Li.(Li7−3x+yGax)(La3−yCay)Zr2O12 (1)(In the formula (1), x and y satisfy the following formulae: 0.1≤x≤0.6 and 0.0<y≤0.3).