Anode Slurry CMC Adsorption for Low Resistance
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Solution Overview
Problem
The challenge in preparing anode slurry for secondary batteries is to achieve sufficient dispersibility of anode active material while minimizing the thickening agent, carboxymethyl cellulose (CMC), to prevent aggregation and reduce battery resistance.
Innovation Solution
Regulating the physical properties of CMC, such as degree of substitution and molecular weight, to increase its adsorption onto the anode active material, thereby reducing the CMC blend amount and enhancing slurry solid content, which improves dispersibility and reduces battery resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickening agent CMC is added in a very small amount, then the resistance of the anode is reduced, but the anode active material cannot be sufficiently dispersed and large aggregates are formed
Solution Approach 1:
The patent applies parameter changes by optimizing the molecular weight of CMC to a specific range of 500,000 to 2,000,000. This parameter adjustment enables the thickening agent to achieve sufficient dispersibility at lower concentrations while maintaining low anode resistance, resolving the contradiction between dispersion stability and resistance reduction.
Solution Approach 2:
The patent uses CMC as a thickening agent in combination with specific anode active materials, creating a composite slurry system. The CMC forms a protective coating around active material particles, ensuring uniform dispersion and preventing aggregation while allowing lithium ion transport, thus balancing dispersibility and resistance.
2Stability of the object's composition
If the thickening agent CMC is added in a very large amount, then the dispersibility of the anode active material is improved, but migration of lithium ions is prevented and resistance increases
Solution Approach 1:
The patent optimizes the concentration of CMC within a specific range of 0.5 to 2.0 parts by weight per 100 parts of anode active material. This parameter control ensures adequate dispersibility while preventing excessive CMC from blocking lithium ion migration pathways, thus resolving the contradiction between dispersion and resistance.
Solution Approach 2:
The CMC thickening agent provides localized protection around individual active material particles rather than forming a continuous thick layer. This local quality approach ensures each particle is adequately dispersed while maintaining open pathways for lithium ion transport through the slurry and electrode structure.
3Object-affected harmful factors
If the blend amount of CMC is reduced, then the resistance of the battery is reduced, but the solid content of the slurry decreases and dispersibility is compromised
Solution Approach 1:
The patent changes the molecular weight parameter of CMC to the optimized range of 500,000 to 2,000,000, which enhances the thickening efficiency and dispersing capability per unit mass. This allows reduction of CMC blend amount to 0.5-2.0 parts per 100 parts active material while maintaining both high solid content (40-60 wt%) and low battery resistance.
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 approach results in an anode slurry with a high solid content of 48% or more, ensuring excellent dispersibility and low battery resistance, even with anode active materials having a tap density of 1.0 g/cc or less, thereby improving battery performance and productivity.
Implementation Method 1
found that an adsorption amount of CMC adsorbed onto an anode active material varies depending on physical properties of CMC
Data Source
AI summary
The present invention provides an anode slurry for a secondary battery and an anode comprising the same, in which the dispersibility of an anode active material is improved by increasing the adsorption amount of CMC with respect to the anode active material by adjusting the degree of substitution or physical properties such as molecular weight, and a CMC blend amount is reduced so as to increase the slurry solid content and reduce the resistance of a battery.