Lithium-Titanate Gas Adsorption Control via Dew Point
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Solution Overview
Problem
Lithium titanate powders used in lithium-ion secondary batteries tend to adsorb gases such as moisture and carbon dioxide during the manufacturing process, leading to instability and safety concerns, as these gases can react with the electrolyte or cause electrode reactions, and existing methods do not effectively prevent gas adsorption while maintaining high specific surface area for better battery characteristics.
Innovation Solution
A manufacturing method involving heat treatment at 600°C or above, followed by cooling and reheat treatment up to 700°C with controlled dew point at −30°C or below, to minimize gas adsorption, resulting in a lithium-titanium complex oxide with low water and carbon dioxide generation, thereby enhancing safety and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium titanate powder is manufactured with high specific surface area to improve battery rate characteristics, then electrical characteristics are improved, but gas adsorption increases leading to stability and safety issues
Solution Approach 1:
The patent applies parameter changes by controlling the dew point of the atmosphere during heat treatment to -30°C or lower. This specific parameter change in the manufacturing process reduces gas adsorption on the lithium titanate powder surface while maintaining high specific surface area, thereby improving battery stability without sacrificing electrical characteristics
Solution Approach 2:
The patent creates an inert environment by controlling the atmosphere during heat treatment to have a dew point of -30°C or lower. This inert atmospheric condition prevents gas adsorption on the powder surface while allowing the material to maintain its high specific surface area structure, resolving the contradiction between reliability and harmful gas adsorption
2Reliability
If lithium titanate powder is manufactured with high specific surface area to improve battery rate characteristics, then electrical characteristics are improved, but the amount of solvent required for electrode coating solution increases
Solution Approach 1:
The patent changes the atmospheric parameter (dew point) during heat treatment to -30°C or lower, which reduces gas adsorption on the powder. This parameter change decreases the amount of solvent needed for electrode coating solution preparation while maintaining the high specific surface area required for good rate characteristics
Solution Approach 2:
The patent performs preliminary gas adsorption prevention during the heat treatment process by controlling the atmosphere dew point. This preliminary action reduces gas adsorption before electrode coating, thereby reducing the subsequent solvent requirement while maintaining high specific surface area for good electrical characteristics
3Ease of manufacture
If conventional heat treatment is used to manufacture lithium titanate, then manufacturing process is simple, but gas adsorption occurs leading to safety concerns
Solution Approach 1:
The patent modifies the heat treatment parameter by controlling the atmosphere dew point to -30°C or lower. This simple parameter change prevents gas adsorption during manufacturing while maintaining process simplicity, avoiding complex additional steps
Solution Approach 2:
The patent makes the heat treatment process self-protective by controlling the atmosphere dew point during the existing heat treatment. The process itself prevents gas adsorption without requiring separate protection steps, maintaining simplicity while eliminating safety concerns
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 method produces lithium-titanium complex oxide with reduced gas adsorption, allowing for finer particles and improved electrical characteristics, reducing the need for solvent in electrode coating solutions and ensuring higher safety and stability in lithium-ion secondary batteries.
Implementation Method 1
heat treatment at 600°C or above, followed by cooling and reheat treatment up to 700°C with controlled dew point at −30°C or below, to minimize gas adsorption
Data Source
AI summary
A lithium-titanium complex oxide whose total water generation amount and total carbon dioxide generation amount measured by thermal decomposition GC-MS are preferably 1500 wt ppm or less and 2000 wt ppm or less, respectively, is obtained by subjecting a mixture of titanium compound and lithium compound to a heat treatment at 600° C. or above, cooling the obtained reaction product to 50° C. or below, and then subjecting the cooled reaction product to a reheat treatment involving heating to the maximum temperature of 300 to 700° C. and then cooling, wherein the dew point of the ambience of the reheat treatment is controlled at −30° C. or below at a temperature of 200° C. or above.