NASICON Solid-State Battery Electrolyte for Low-Temperature Co-Sintering
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Solution Overview
Problem
The formation of oxide-based solid electrolyte batteries with a NASICON-type crystal structure faces challenges such as cracks, delamination, and segregation due to deviations in sintering behavior between the solid electrolyte and internal electrodes, leading to poor co-sinterability and reliability, especially at higher firing temperatures.
Innovation Solution
An all-solid battery design featuring a solid electrolyte with a NASICON-type crystal structure and specific compositional formula (Li1+x+2y+aAyM′xM″2-x-yP3O12+c) is used, where 'A' is a divalent metal element, 'M′' is a trivalent metal, and 'M″' is a quadrivalent transition metal, along with internal electrodes, to improve co-sinterability while maintaining an appropriate firing temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the firing temperature is increased to improve sintering, then the sintering behavior of the solid electrolyte and internal electrodes becomes more uniform, but segregation and density imbalance occur more remarkably
Solution Approach 1:
The patent modifies the chemical composition parameters of the solid electrolyte by introducing specific dopants (Al, Ga, In, Y, or La) at controlled concentrations (0.01-0.5 mol ratio) to adjust the sintering characteristics. This compositional parameter change enables the solid electrolyte to achieve adequate sintering at lower temperatures, preventing the segregation and density imbalance that occur at high temperatures while maintaining composition uniformity.
Solution Approach 2:
The patent creates a composite solid electrolyte system by combining the base NASICON-type material (Li1+xMxM''2-xPO4) with dopant elements (Al, Ga, In, Y, or La). This composite approach modifies the sintering behavior to achieve better co-sinterability with internal electrodes at reduced temperatures, avoiding the harmful effects of high-temperature processing while maintaining structural integrity.
2Manufacturing precision
If the firing temperature is increased to ensure complete sintering, then the density of the solid electrolyte layer improves, but cracks and delamination are more likely to occur
Solution Approach 1:
The patent changes the sintering temperature parameter from conventional high temperatures to a reduced range (900-1100°C) by modifying the solid electrolyte composition with dopants. This parameter change achieves adequate density without the thermal stress that causes cracks and delamination, thereby improving reliability while maintaining manufacturing precision.
Solution Approach 2:
The dopant elements (Al, Ga, In, Y, or La) act as intermediaries that facilitate sintering at lower temperatures by modifying the diffusion characteristics and reducing the sintering activation energy. This intermediary作用 enables density improvement without reaching the high temperatures that cause structural damage.
3Strength
If the firing temperature is increased to improve co-sinterability, then the bonding between solid electrolyte and internal electrodes strengthens, but mutual diffusion reaction causes segregation
Solution Approach 1:
The patent modifies the chemical composition of the solid electrolyte by adding dopants (Al, Ga, In, Y, or La) at controlled levels (0.01-0.5 mol ratio), which changes the sintering temperature parameter to a lower range. This parameter change achieves adequate bonding strength through enhanced interfacial reactions at moderate temperatures, preventing the segregation that occurs at high temperatures.
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 enhances the co-sinterability of the solid electrolyte and internal electrodes, reducing porosity and maintaining a suitable firing temperature range, thereby improving the battery's characteristics and reliability.
Implementation Method 1
An oxide-based solid electrolyte containing a NASICON-type crystal structure is formed, for example, by a sintering process in order to obtain desired characteristics
Implementation Method 2
due to the mutual diffusion reaction during the co-firing, segregation of some substance between the solid electrolyte layer and the internal electrode and imbalance in density occur
Data Source
AI summary
An all solid battery is characterized by including a solid electrolyte layer of which a main component is an oxide-based solid electrolyte having a NASICON type crystal structure which has a compositional formula of Li1+x+2y+aAyM′xM″2-x-yP3O12+c, in which “A” is a divalent metal element, “M′” is a trivalent metal element, “M″” is a quadrivalent transition metal, and satisfies 0<a<1.4, a first internal electrode which is provided on a first main face of the solid electrolyte layer and includes an electrode active material, and a second internal electrode which is provided on a second main face of the solid electrolyte layer and includes an electrode active material.