Lithium-Titanium Oxide Coated Active Material Particles for Low Resistance
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Solution Overview
Problem
Lithium ion secondary batteries experience a significant decrease in battery capacity during high rate discharge and an increase in resistance with charge-discharge cycles, particularly when using conventional active material particles with surface coatings like Li4Ti5O12, which affects the performance of nonaqueous electrolyte secondary batteries and all-solid-state batteries.
Innovation Solution
The development of active material particles with a composite oxide covering layer containing lithium and titanium atoms, where the molar ratio of lithium to titanium is greater than 1 and 4 or less, is used to suppress the increase in resistance and maintain battery capacity, achieved by applying a coating agent with a specific molar ratio and subsequent heat-treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional active material particles with surface coatings like Li4Ti5O12 are used, then battery capacity is maintained, but resistance increases significantly with charge-discharge cycles
Solution Approach 1:
The patent applies composite materials by creating a surface layer with a specific composite oxide composition (Li2TiO3, Li4TiO4, or LiTiO3) that combines the benefits of lithium ion conductivity with structural stability. This composite oxide coating suppresses resistance increase during charge-discharge cycles while maintaining battery capacity, resolving the contradiction between capacity stability and resistance control.
Solution Approach 2:
The patent changes the compositional parameters of the surface coating by specifying a molar ratio of lithium to titanium atoms greater than 1 and 4 or less, and controlling the thickness between 1-50 nm. These parameter changes optimize the surface layer properties to simultaneously maintain capacity stability and suppress resistance increase, addressing the technical contradiction.
2Reliability
If surface coatings with different composition or structure are applied to active material, then battery performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by modifying only the surface region (1-50 nm thickness) of the active material particles with a specific composite oxide composition, while keeping the bulk material composition unchanged. This localized modification improves battery performance without requiring complete restructuring of the entire material system, thereby limiting the increase in manufacturing complexity.
3Reliability
If surface coating thickness is increased to suppress resistance, then battery capacity stability improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the thickness parameter to a specific range (1-50 nm) that balances capacity stability with manufacturing feasibility. Within this range, the coating is thick enough to suppress resistance increase during cycling but thin enough to allow for practical manufacturing control, resolving the contradiction between reliability improvement and manufacturing precision requirements.
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 effectively inhibits the decrease in battery capacity during high rate discharge and reduces resistance with charge-discharge cycles, enhancing the performance and longevity of nonaqueous electrolyte secondary batteries and all-solid-state batteries.
Implementation Method 1
heat-treating the active material base material covered with the coating agent
Implementation Method 2
the covering layer contains a composite oxide containing lithium atoms and titanium atoms
Implementation Method 3
a substance having a different composition or structure... an oxide having lithium ion conductivity
Data Source
AI summary
An active material particle according to an aspect of the present invention contains an active material base material and a covering layer covering at least a part of a surface of the active material base material, the covering layer contains an oxide containing lithium atoms and titanium atoms, and a molar ratio of a content of the lithium atoms to the titanium atoms in the oxide is more than 1 and 4 or less.