Lithium Titanate Composite Sintering Phase Stability
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Solution Overview
Problem
During sintering, lithium titanate (LTO) and lithium lanthanum titanium oxide (LLTO) based all-solid-state batteries react to form inactive phases, reducing the effectiveness and functionality of the battery due to the formation of lithium, titanium, and oxygen phases, which diminishes the active LTO and LLTO phases, leading to non-functional electrodes.
Innovation Solution
Incorporating a solid lithium compound, such as Li2O, in the range of 0.5% to 10% by weight, either as a mixture or coating on LTO and LLTO, to suppress the formation of inactive phases during sintering, thereby maintaining the original active phases and enhancing the electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If sintering is performed at elevated temperatures to densify the battery components, then the body density is improved and internal pores are reduced, but the active LTO and LLTO phases react to form inactive phases, reducing the functional capacity
Solution Approach 1:
A lithium compound coating is applied to the surface of LTO particles to act as an intermediary layer that prevents direct reaction between LTO and LLTO during sintering, thereby maintaining the active phases while still allowing densification to occur
Solution Approach 2:
The sintering process parameters are optimized to balance densification with phase stability, and a lithium compound coating is applied to modify the surface properties of LTO particles to prevent unwanted reactions at sintering temperatures
2Reliability
If LTO and LLTO are sintered together to form a composite structure, then the electrochemical performance is improved, but the formation of inactive phases such as Li2La2Ti3O10, Li2TiO3, and Li2Ti3O7 reduces the amount of active material
Solution Approach 1:
The lithium compound coating serves as a protective intermediary that allows the LTO-LLTO composite structure to form for improved electrochemical performance while preventing the formation of inactive phases that would reduce active material content
3Productivity
If the sintering temperature is increased to enhance densification, then the manufacturing efficiency is improved, but the reaction between LTO and LLTO accelerates, forming more inactive phases
Solution Approach 1:
The lithium compound coating enables higher sintering temperatures to be used for improved manufacturing efficiency by acting as a protective barrier that maintains phase composition stability even at elevated temperatures
Solution Approach 2:
The lithium compound coating is applied to LTO particles before sintering to pre-establish protection against phase reactions, allowing the sintering process to proceed at higher temperatures without forming inactive phases
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 addition of the lithium compound effectively reduces the formation of inactive phases, ensuring the retention of active phases post-sintering, resulting in a functional and high-capacity all-solid-state battery with improved energy density and stability.
Implementation Method 1
a solid lithium compound configured to suppress formation of inactive phases during sintering
Implementation Method 2
sintering, a process which involves heating a compacted monolithic body of powder for a period of time during which the body densities and the internal pores are greatly reduced or eliminated
Data Source
AI summary
A pre-sintered all-solid-state battery comprises a powdered lithium titanate (LTO), a powdered lithium lanthanum titanium oxide (LLTO), and a solid lithium compound configured to suppress formation of inactive phases during sintering. The solid lithium compound is about 0.5% to 10% by weight of the pre-sintered all-solid-state battery.