Ti-Fluoride Coated Battery Active Material for Low Internal Resistance
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Solution Overview
Problem
Existing methods for manufacturing surface-modified lithium-containing composite oxides for non-aqueous electrolyte secondary batteries fail to inhibit the increase in internal resistance of the batteries during charge and discharge cycles.
Innovation Solution
A surface-modified active material is developed using a lithium-containing composite oxide core with a compound containing trivalent titanium, where the pH of an aqueous solution of fluoride is set between 5.5 and 9.5 for mixing with the core, allowing the compound to adhere and inhibit side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface modification is performed using conventional methods (mixing lithium-containing composite oxide with zirconium compounds and lithium salts), then charge-discharge cycle characteristics are improved, but internal resistance increases
Solution Approach 1:
The patent changes the chemical composition parameters of the surface modification layer by replacing conventional zirconium-based compounds with titanium fluoride compounds (specifically Li2TiF6, LiTiF5, or Li3TiF6). This parameter change in the chemical composition resolves the contradiction by achieving both improved cycle characteristics and suppressed internal resistance increase through the unique properties of trivalent titanium fluoride compounds.
Solution Approach 2:
The patent creates a composite material structure consisting of a lithium-containing composite oxide core (such as LiCoO2, LiMn2O4, or LiNi0.8Co0.1Mn0.1O2) coated with a titanium fluoride compound layer. This composite structure combines the high capacity benefits of the lithium-containing oxide with the protective and conductive benefits of the titanium fluoride surface layer, simultaneously improving cycle life while maintaining low internal resistance.
2Ease of manufacture
If pH of aqueous solution is not controlled within 5.5-9.5, then manufacturing process is simpler, but adhesion of compound to core surface is insufficient
Solution Approach 1:
The patent establishes a specific pH parameter range (5.5-9.5) for the aqueous solution during the surface modification process. This parameter control ensures optimal adhesion of the titanium fluoride compound to the lithium-containing composite oxide core surface, resolving the contradiction by finding the optimal balance between manufacturing simplicity and adhesion quality through controlled pH conditions.
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 reduces the internal resistance of the battery by preventing side reactions and maintaining battery performance.
Implementation Method 1
a compound adhering to a surface of the core
Implementation Method 2
the compound contains trivalent Ti
Implementation Method 3
a step of setting a pH of greater than or equal to 5.5 and less than or equal to 9.5 for an aqueous solution in which a fluoride represented by the general formula M22TiF6
Data Source
AI summary
Provided is an active material that can suppress a rise in the internal resistance of a battery. This active material for nonaqueous electrolyte secondary batteries contains a core that can reversibly store and release Li, and a compound adhered to the surface of the core, and the compound contains trivalent Ti. The compound may be (NH4)2TiF5, for example.