Electrode Assembly Conductive Coating Spacing and Merging
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Solution Overview
Problem
Existing lithium secondary battery electrode assemblies face issues with increased thickness and resistance due to conductive material coating layers, which also lead to separation of negative electrode active materials and decreased productivity during manufacturing.
Innovation Solution
An electrode assembly with a conductive material coating layer spaced apart from the negative electrode tabs, applied only to the central portion of the negative electrode, minimizing thickness increase and resistance, and a method involving a single application of conductive material slurry before lamination to prevent separation and enhance control over the coating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive material coating layer is formed on the negative electrode to inhibit side reactions, then side reactions are suppressed, but the electrode assembly thickness increases and resistance increases
Solution Approach 1:
The conductive material coating layer is applied selectively to specific regions of the negative electrode where side reactions predominantly occur, rather than uniformly across the entire electrode surface. This localized coating approach provides side reaction inhibition precisely where needed while minimizing the overall thickness increase and resistance added to the electrode assembly.
2Reliability
If a two-step coating process is used to apply both negative electrode active material slurry and conductive material slurry, then a conductive material coating layer can be formed, but productivity decreases due to multiple coating steps and active material separation occurs during conveying
Solution Approach 1:
The patent combines the application of negative electrode active material slurry and conductive material slurry into a single simultaneous coating step. The conductive material is mixed with the negative electrode active material slurry before application, allowing both materials to be deposited together in one operation. This eliminates the need for separate coating steps and prevents active material separation during conveying, thereby maintaining coating quality while significantly improving manufacturing productivity.
3Productivity
If conductive material slurry is applied to negative electrode active material slurry during the same drying step, then productivity is improved, but the negative electrode active material separates and the conductive material coating layer cannot be controlled
Solution Approach 1:
The patent creates a composite slurry mixture containing both negative electrode active material and conductive material in specific proportions. This composite material maintains the integrity of both components during the coating and drying process, preventing separation while enabling precise control over the final conductive material coating layer composition and distribution. The composite nature ensures uniform behavior during processing while achieving the desired functional properties.
Data Source
AI summary
The present disclosure is directed to preventing generation of side reactions at a negative electrode, inhibiting an increase in resistance, and improving productivity. An electrode assembly is provided including: a negative electrode including a negative electrode current collector having a negative electrode tab at one end, and a negative electrode active material layer formed on a surface thereof; a positive electrode including a positive electrode current collector having a positive electrode tab at one end, and a positive electrode active material layer formed on a surface thereof; and a separator interposed between the positive and negative electrodes, and including a coating layer containing a conductive material and a polymer binder on the top surface of the negative electrode active material layer, wherein the coating layer is spaced apart from the top end, where the negative electrode tab is formed, and the bottom end by a predetermined distance.