LLTO Solid Electrolyte Silicon Grain Boundary Conductivity
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Solution Overview
Problem
The low grain boundary conductivity of lithium lanthanum titanate (LLTO) solid electrolytes limits their practical application in lithium ion batteries, as it decreases the overall conductivity below the required levels for commercial use.
Innovation Solution
Introducing amorphous Si or an amorphous Si compound into the grain boundary of LLTO composite solid electrolyte materials, using a wet chemical method with a silicon precursor solution, improves grain boundary conductivity and total conductivity, specifically by adjusting the silicon to LLTO mass ratio between 0.27% to 1.35% and employing sintering at 1100 to 1400°C for 1 to 10 hours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid inorganic electrolyte is used to replace liquid electrolyte, then safety and energy density are improved, but conductivity is extremely low and does not meet commercial requirements
Solution Approach 1:
The patent creates a composite solid electrolyte material by introducing amorphous Si or amorphous Si compound into the grain boundaries of LLTO crystal grains. This composite structure combines the high safety of solid inorganic electrolyte with enhanced conductivity through the Si-containing grain boundary phase, achieving both improved reliability and manufacturing precision.
Solution Approach 2:
The patent applies local quality modification by specifically targeting the grain boundary regions with amorphous Si or Si compound while maintaining the crystal grain structure of LLTO. This localized modification improves conductivity at the grain boundaries without altering the bulk properties, thereby enhancing overall conductivity while preserving the safety benefits of the solid electrolyte.
2Manufacturing precision
If amorphous Si or amorphous Si compound is introduced into grain boundary, then grain boundary conductivity and total conductivity are significantly improved, but synthesis temperature and energy consumption increase
Solution Approach 1:
The patent optimizes the Si content parameter within a specific range (0.27% to 1.35% mass ratio relative to LLTO) to achieve significant conductivity improvement while controlling synthesis temperature. By precisely controlling this compositional parameter, the patent achieves enhanced grain boundary conductivity without requiring excessive energy input or overly high synthesis temperatures.
3Manufacturing precision
If amorphous Si or amorphous Si compound is introduced into grain boundary, then grain boundary conductivity and total conductivity are significantly improved, but production cost increases
Solution Approach 1:
The patent identifies an optimal Si content range (0.27% to 1.35% mass ratio) that achieves significant conductivity improvement while minimizing material costs. This parameter optimization ensures that the conductivity enhancement is achieved at the lowest necessary Si addition, thereby controlling production costs while meeting performance requirements.
Solution Approach 2:
The patent uses amorphous Si or amorphous Si compound as a cost-effective additive in small quantities to dramatically improve the conductivity of the solid electrolyte. The low required amount (0.27% to 1.35% mass ratio) makes this a economically viable approach, using a relatively inexpensive material to achieve high-performance results.
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 significantly enhances the grain boundary and total conductivity of the LLTO composite solid electrolyte material, making it more suitable for high-efficient power lithium ion batteries while reducing synthesis temperature, energy consumption, and production costs.
Implementation Method 1
amorphous Si or an amorphous Si compound exists in a grain boundary between crystal grains (1) of lithium lanthanum titanate, grain boundary conductivity thereof is significantly improved, and therefore, total conductivity is improved
Implementation Method 2
employing sintering at 1100 to 1400°C for 1 to 10 hours
Data Source
AI summary
The invention relates to a lithium lanthanum titanate composite solid electrolyte material containing silicon in which amorphous Si or an amorphous Si compound exist in a grain boundary between crystal grains, and a method of producing the same, and belongs to a field of a lithium ion battery. According to the invention, the amorphous Si or the amorphous Si compound exist in the grain boundary between the crystal grains of the lithium lanthanum titanate. The amorphous Si or the amorphous Si compound are introduced into the grain boundary by employing a wet chemical method. In the wet chemical method, the inexpensive organosilicon compound is used as an additive, and the organosilicon compound is added into the lithium lanthanum titanate solid electrolyte material. Thus, it is possible to synthesize the lithium lanthanum titanate composite solid electrolyte material containing silicon by performing sintering when the ratio of mass of the Si or mass of the Si calculated based on mass of the Si compound to mass of the lithium lanthanum titanate is 0.27% to 1.35%.