Solid-State Electrolyte Structure Using Volatile Sintering Aids
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Solution Overview
Problem
The adoption of solid-state electrolytes in all-solid-state batteries is hindered by fabrication issues such as voids, gaps, or defects that make the sintered structures vulnerable to Li dendrite penetration, thermal runaway, and explosion, especially at medium-to-high current densities and long durations, due to the decomposition or melting of sintering aids during conventional sintering techniques.
Innovation Solution
The use of volatile sintering aids with high ionic conductivity and low electronic conductivity, which have a melting point less than the sintering temperature of the base material, are incorporated into the solid-state ion-conducting structures using a high-temperature heating pulse to form a dense composite structure, where the sintering aids wet grain boundaries and fill voids, enhancing the relative density and conductivity of the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional sintering techniques are used to form solid-state electrolyte structures, then the base material can be sintered at high temperature, but the sintering aids decompose or melt leading to voids and defects
Solution Approach 1:
The patent changes the key parameter of sintering aid volatility by selecting materials with melting points below the sintering temperature. This parameter change allows the sintering aids to remain stable during the sintering process while still providing their intended function of reducing porosity and improving density of the solid-state electrolyte structure.
Solution Approach 2:
The patent employs composite materials consisting of the base solid-state electrolyte material combined with specifically selected sintering aids. This composite approach allows the sintering aids to enhance the sintering process and fill voids without decomposing, thereby improving both the density and structural integrity of the final product while maintaining stability at sintering temperatures.
2Manufacturing precision
If inorganic filters or sintering aids are used to address fabrication issues, then voids and defects can be reduced, but the prolonged heating causes decomposition and melting of the aids
Solution Approach 1:
The patent addresses this contradiction by changing the thermal stability parameter of the sintering aids. By selecting materials with melting points below the sintering temperature, the aids remain stable throughout the prolonged heating process, preventing decomposition while still achieving the desired density uniformity in the solid-state electrolyte structure.
Solution Approach 2:
The patent employs sintering aids that are designed to be consumed or transformed during the sintering process, but in a controlled manner that prevents harmful decomposition. These aids perform their function of improving density and then remain as stable residual phases, effectively serving as temporary processing aids that do not compromise the final structure.
3Shape
If sintering aids with melting point below sintering temperature are used, then they can wet grain boundaries and fill voids, but they may decompose during prolonged heating
Solution Approach 1:
The patent resolves this contradiction by carefully selecting sintering aids whose melting points are below the sintering temperature but who maintain thermal stability throughout the process. This parameter selection allows the aids to melt and wet grain boundaries effectively, then remain stable during the prolonged heating, preventing decomposition while achieving the desired grain boundary wetting and void filling.
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
This approach results in solid-state ion-conducting structures with higher relative density, ionic conductivity, and lower electronic conductivity compared to conventionally-sintered structures, improving the safety and performance of solid-state batteries by preventing Li dendrite penetration and reducing the risk of thermal runaway.
Implementation Method 1
a melting point of the second material composition being less than the first temperature
Implementation Method 2
the second material composition can wet boundaries of the plurality of grains
Implementation Method 3
subjecting the composite pellet to a high-temperature heating pulse so as to convert the composite pellet into a solid-state ion-conducting structure
Data Source
AI summary
A solid-state ion-conducting structure comprises a plurality of grains formed of a first material composition and a second material composition different from the first material composition. The second material composition can wet boundaries of the grains and/or fill voids between adjacent grains. Each of the material compositions can have an ionic conductivity greater than or equal to 10−4 S/cm. The second material composition may be considered a volatile sintering aid. for example. having a melting point less than a temperature at which the first material composition is sintered. In some embodiments, the solid-state ion-conducting structure can be used as a solid-state electrolyte in a battery.