Cathode Slurry Composition to Prevent Gelation in Li-Ion Batteries
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Solution Overview
Problem
Existing methods for preparing cathode slurry for lithium secondary batteries fail to adequately prevent gelation and crosslinking, leading to increased internal resistance and reduced lifespan due to residual dispersion medium and phase instability in the cathode active material layer.
Innovation Solution
Incorporating a multivalent carboxylic acid compound and its salt into the cathode slurry at a specific content range, along with a fluorine binder resin, to inhibit gelation and crosslinking, and reduce the dispersion medium's presence in the cathode active material layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If acid is added to the cathode slurry to adjust alkali content and prevent gelation, then gelation is suppressed, but a large amount of dispersion medium remains in the cathode active material layer after drying, causing degradation in life-span characteristics and increased internal resistance
Solution Approach 1:
The patent changes the chemical parameter by using a multivalent carboxylic acid compound (with 2-5 carboxyl groups) instead of conventional single-carboxylic acids. This structural parameter change enables the acid to effectively neutralize alkali components and prevent gelation while maintaining proper slurry properties that allow for adequate dispersion medium removal, thus improving life-span characteristics without sacrificing gelation prevention.
Solution Approach 2:
The patent employs a composite approach by using a multivalent carboxylic acid compound with multiple carboxyl groups (2-5 groups) in a specific quantity range (0.01-0.05 parts by weight per 100 parts of lithium metal oxide particles). This composite chemical structure provides enhanced alkali neutralization capability while maintaining slurry processability, resolving the contradiction between gelation prevention and life-span performance.
2Stability of the object's composition
If acid is added to the cathode slurry to adjust alkali content and prevent gelation, then gelation is suppressed, but internal resistance of the secondary battery increases
Solution Approach 1:
The patent modifies the chemical parameter by introducing a multivalent carboxylic acid compound with 2-5 carboxyl groups, which provides superior alkali neutralization efficiency. This parameter change allows for effective gelation prevention at lower acid dosages (0.01-0.05 parts by weight per 100 parts of lithium metal oxide particles), thereby minimizing the residual acid content and its harmful effects on internal resistance while maintaining gelation suppression.
Solution Approach 2:
The patent uses a multivalent carboxylic acid compound that effectively replicates and enhances the alkali-neutralizing function of conventional acids while avoiding their drawbacks. The multiple carboxyl groups in the compound provide amplified neutralization capability, allowing for precise control of alkali content without excessive acid addition, thus preventing both gelation and internal resistance increase.
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 solution results in improved coating properties, phase stability, and reduced internal resistance, enhancing the lifespan characteristics of the lithium secondary battery.
Implementation Method 1
In order to prevent gelation of the cathode slurry, a method of adjusting an alkali component by adding an acid to the cathode slurry has been proposed
Implementation Method 2
crosslinking of the binder and gelation of the cathode slurry may be progressed by an alkaline component (e.g., Li+)
Implementation Method 3
crosslinking of the binder and gelation of the cathode slurry may be progressed by an alkaline component (e.g., Li+)
Implementation Method 4
a large amount of the dispersion medium remains in the cathode active material layer after drying
Data Source
AI summary
A cathode slurry for a lithium secondary battery according to exemplary embodiments may include a cathode active material including lithium metal oxide particles, a binder, a dispersion medium, and at least one of a multivalent carboxylic acid compound and a salt of the multivalent carboxylic acid compound. A total amount of the multivalent carboxylic acid compound and the salt of the multivalent carboxylic acid compound in the cathode slurry may be 0.01 to 0.05 wt. parts based on 100 wt. parts of the lithium metal oxide particles.