Nickel-Based Cathode Material Slurry Gelation Prevention
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Solution Overview
Problem
Lithium secondary battery cathode slurries often experience gelation due to the strong basicity of nickel-based active materials, leading to increased viscosity and instability during preparation, which existing methods fail to adequately address.
Innovation Solution
A composite cathode active material is prepared by mixing a nickel-based oxide with an organic acid and an organic solvent, which neutralizes basic components and reduces water content, preventing gelation and enhancing slurry stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-based active material is mixed with fluorine-based binder to prepare slurry, then high energy capacity is achieved, but gelation occurs due to strong basicity causing increased viscosity and instability
Solution Approach 1:
An organic acid (such as acetic acid, formic acid, or citric acid) is introduced as an intermediary substance to neutralize the strong basicity of the nickel-based active material. This mediator prevents the direct harmful interaction between the base and fluorine-based binder, eliminating gelation while preserving high energy capacity
Solution Approach 2:
The pH parameter of the slurry is adjusted by adding organic acid to reduce basicity from strongly basic conditions to a more neutral state. This parameter change prevents the chemical reactions that cause gelation, maintaining slurry stability without compromising the energy capacity of the nickel-based material
2Quantity of substance
If excess base is used in preparing nickel-based active material, then high energy capacity is achieved, but slurry basicity increases causing gelation and viscosity increase
Solution Approach 1:
Organic acid serves as a mediator that counteracts the excess base in the slurry without requiring re-preparation of the active material. This allows the high energy capacity material to be used while enabling easy slurry preparation through simple acid addition
Solution Approach 2:
The excess base, which originally caused harmful gelation, is converted into a benefit by using it as a target for neutralization. The strong basicity that caused manufacturing difficulties is transformed into a controlled parameter that can be easily adjusted with organic acid, turning a manufacturing obstacle into a manageable aspect of the process
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 composite cathode active material suppresses gelation, allowing for the production of stable electrode slurries and lithium batteries with improved high rate discharge characteristics and capacity.
Implementation Method 1
the cathode active material reacts with the acid in the organic solvent, thereby neutralizing the basic components (Li2O, LiOH, etc.) remaining in the cathode active material
Implementation Method 2
the water generated from the acid-base reaction forms an azeotrope with the organic solvent which are then evaporated and removed together
Implementation Method 3
the lithium ions bond to the anions of the acid to form complex compounds
Data Source
AI summary
Composite cathode active materials comprising a composite oxide and an acid treated with an organic solvent are provided. The composite cathode active materials are prepared by treating mixtures of nickel-based composite oxides and organic acids with organic solvents. The active materials suppress gelation of the electrode slurries for a long period of time, even when the active materials are mixed with fluorine-based polymers, by decreasing the basicity of the slurries and the amount of lithium present on the surfaces of the active materials. As a result, electrode slurries having high stability can be prepared. Cathodes and lithium batteries comprising the slurries have excellent charge-discharge characteristics, including high capacity and excellent high rate discharge characteristics.