Positive Electrode Slurry Composition for Uniform Coating Flow
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Solution Overview
Problem
Conventional slurry compositions for lithium-sulfur secondary batteries suffer from low thixotropy, leading to inadequate flowability and non-uniform formation of the positive electrode active material layer during the coating process, which affects the charging/discharging performance of the battery.
Innovation Solution
A slurry composition for lithium secondary batteries is developed, comprising lithiated carboxymethyl cellulose (LiCMC) as a thickening agent and LiCMC to which an aminobenzoic acid group is bonded (LiCMC-ABA) as an additive, enhancing the slurry's thixotropy and flowability to accommodate varying coating speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional slurry composition is used for lithium-sulfur secondary battery, then the battery can be manufactured, but the slurry has low thixotropy resulting in inadequate flowability and non-uniform formation of positive electrode active material layer
Solution Approach 1:
The patent modifies the chemical composition parameters of the slurry by introducing specific additives (carboxymethyl cellulose and its derivatives) to change the rheological properties. This alters the thixotropy index from low to high, enabling the slurry to maintain stability during storage while achieving uniform coating during the coating process through shear thinning effects.
Solution Approach 2:
The patent creates a composite slurry system by combining multiple components: sulfur-carbon composite particles, binder materials (carboxymethyl cellulose and its derivatives), and other additives. This composite formulation works synergistically to achieve both high thixotropy for stability and appropriate flowability for uniform coating.
2Ease of operation
If dispersion agent and/or rheology modifier are added to improve flowability, then the slurry becomes more flowable, but the charging/discharging performance is weakened
Solution Approach 1:
The patent uses carboxymethyl cellulose and its derivatives as intermediary substances that serve dual functions: they act as rheology modifiers to improve slurry flowability while simultaneously serving as binders that maintain electrode structural integrity. This intermediary role allows improvement of processing properties without compromising electrochemical performance.
Solution Approach 2:
The patent carefully controls the concentration parameters of the additive components within specific ranges (0.1-5 wt% of total slurry weight) to optimize the balance between flowability improvement and performance maintenance. By adjusting these parameters, the slurry achieves adequate flowability without excessive additive content that would harm charging/discharging performance.
3Stability of the object's composition
If carboxymethyl cellulose-based material is used as binder, then the slurry gains stable and flexible properties, but the thixotropy remains low causing non-uniform spreading at variable coating speeds
Solution Approach 1:
The patent creates a composite binder system by combining carboxymethyl cellulose with its derivatives (such as carboxymethyl starch or other modified cellulose materials). This composite binder provides both the stability and flexibility needed for electrode structural integrity while introducing thixotropic properties that enable uniform spreading at variable coating speeds.
Solution Approach 2:
The patent introduces dynamic rheological properties to the slurry through the binder composition, making it thixotropic. This means the slurry viscosity dynamically adjusts during coating: it remains stable at rest for uniform composition, then becomes more flowable under shear stress during coating to ensure uniform spreading, and returns to stable state after coating.
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 improved slurry composition allows for the formation of a uniform positive electrode active material layer, enhancing the charging/discharging performance of the lithium secondary battery.
Implementation Method 1
the conventional slurry for positive electrode for lithium-sulfur secondary battery had low thixotropy, so sufficient flowability was not ensured when applying the slurry for positive electrode to the solution coating process
Data Source
AI summary
The present disclosure relates to a slurry composition for a positive electrode for a lithium secondary battery, and a positive electrode and a lithium secondary battery including the same, and more particularly, when manufacturing the positive electrode for the lithium secondary battery including slurry coating process, it is possible to increase the processability during the manufacture of the positive electrode for the lithium secondary battery, by manufacturing the positive electrode using a slurry composition for positive electrode with thixotropy that can secure flowability to an extent that can respond flexibly to changes in the coating speed of the slurry.