LiNbO3 Coated Active Material Powder Pore Control
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Solution Overview
Problem
Lithium ion secondary batteries using active material powders with uneven coating layer thickness exhibit high reaction resistance due to the slow drying rate of the alkoxide solution and impurities in the coating layer, leading to inefficient lithium ion conductivity.
Innovation Solution
The active material powder is produced with a controlled coating process where the alkoxide solution is dried at 100°C or higher and exposed to a humidified inert gas atmosphere for four hours or longer, reducing the V1/V2 ratio of pores to 0.185 or less, thereby minimizing coating layer unevenness and improving alkoxide purity, which decreases reaction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the alkoxide solution is dried at a low temperature to maintain coating layer integrity, then the coating layer remains intact, but the drying rate is slow and the thickness becomes uneven
Solution Approach 1:
The patent changes the drying temperature parameter from conventional low temperature to 100°C or higher, which dramatically increases the drying rate while maintaining coating layer integrity through the controlled atmosphere and timing of the process
Solution Approach 2:
The patent applies a surfactant to the alkoxide solution before drying to prevent premature aggregation and ensure uniform distribution, then proceeds with high-temperature drying to achieve both speed and uniformity
2Productivity
If the alkoxide solution is dried quickly at high temperature to increase productivity, then the drying rate increases, but impurities remain in the coating layer and reaction resistance increases
Solution Approach 1:
The patent performs preliminary purification by exposing the coated particles to a humidified inert gas atmosphere for four hours or longer before drying, which removes impurities and promotes complete hydrolysis of the alkoxide, ensuring low reaction resistance even after rapid high-temperature drying
Solution Approach 2:
The patent uses a humidified inert gas atmosphere (such as nitrogen or carbon dioxide) during the hydrolysis promotion step to prevent contamination and control the chemical environment, ensuring pure coating layer formation without introducing harmful impurities
3Reliability
If the hydrolysis time is extended to improve coating layer purity, then the alkoxide purity increases, but the production time increases
Solution Approach 1:
The patent changes the hydrolysis conditions by using a humidified inert gas atmosphere at controlled humidity and temperature, which accelerates the hydrolysis reaction rate and allows complete hydrolysis to be achieved in four hours or longer rather than extended periods
Solution Approach 2:
The patent replaces conventional prolonged hydrolysis methods with a controlled gas-phase hydrolysis process using humidified inert gas, which provides more uniform moisture distribution and faster hydrolysis kinetics, reducing the required time while maintaining high purity
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 a lithium ion secondary battery with reduced reaction resistance and coating layer unevenness, enhancing lithium ion conductivity and overall battery performance.
Implementation Method 1
drying the alkoxide solution attached to the surface of the active material particle with a fluidized bed granulating-coating machine, the intake-gas temperature of the fluidized bed granulating-coating machine being 100° C. or higher
Implementation Method 2
promoting hydrolysis of the alkoxide compound by exposing the powder to a humidified inert gas atmosphere
Data Source
AI summary
An active material powder includes an active material particle, and a coating layer. The coating layer contains LiNbO3 and has pores. When a total volume of pores having a diameter of 2 nm to 7 nm and a total volume of pores having a diameter of 2 nm to 200 nm are respectively represented by V1 and V2, V1/V2 is 0.185 or less. In addition, a method of producing an active material powder includes: obtaining, with a fluidized bed granulating-coating machine, a powder including an active material particle to which an alkoxide compound is attached; and promoting hydrolysis of the alkoxide compound by exposing the powder to a humidified inert gas atmosphere. An intake-gas temperature of the fluidized bed granulating-coating machine is 100° C. or higher. A time during which the powder is exposed to the humidified inert gas atmosphere is four hours or longer.