Electrode Assembly Thickness Control for NP Ratio Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges in preventing localized NP ratio imbalances due to sliding regions in electrode assemblies, leading to potential lithium precipitation and safety issues like short circuits, which existing technologies struggle to manage effectively.
Innovation Solution
The electrode assembly design includes specific thickness ratios and notching predetermined lines for positive and negative electrodes, ensuring that the thickness ratios at specific face-to-face positions satisfy predetermined conditions to prevent NP ratio reversal, and a standardized method for managing electrode sliding standards is implemented to maintain balanced NP ratios during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrode mixture slurry is applied to the electrode current collector, then the electrode mixture layer is formed, but the slurry flows down due to fluidity creating a sliding region with thickness variation
Solution Approach 1:
The patent applies a release agent to the electrode current collector before applying the electrode mixture slurry. This preliminary action prevents the slurry from flowing down by reducing adhesion between the slurry and the current collector, thereby eliminating the sliding region and ensuring uniform thickness distribution.
2Reliability
If the sliding region is not controlled, then the NP ratio becomes imbalanced locally, but controlling it requires complex measurement and management
Solution Approach 1:
The patent extracts and removes the sliding region by applying a release agent before slurry application. This eliminates the source of NP ratio imbalance without requiring complex measurement and management systems, as the harmful sliding phenomenon is prevented at its origin.
3Object-affected harmful factors
If the electrode mixture layer thickness varies in the sliding region, then lithium precipitation occurs, but preventing it requires standardized management methods
Solution Approach 1:
The patent applies a release agent to the electrode current collector before applying the electrode mixture slurry. This preliminary action prevents the slurry from flowing down by reducing adhesion between the slurry and the current collector, thereby eliminating the sliding region and ensuring uniform thickness distribution.
Data Source
AI summary
An electrode assembly including a negative electrode including a sliding region, wherein a first negative electrode thickness ratio of the thickness TN1 of the negative electrode mixture layer at the first face-to-face position where the negative electrode faces the lower end part of the positive electrode, to the thickness TNC of the negative electrode mixture layer at the center part of the negative electrode, and a first positive electrode thickness ratio of the thickness TP1 of the positive electrode mixture layer at the lower end part of the positive electrode, to the thickness TPC of the positive electrode mixture layer at the center part of the positive electrode satisfy the disclosed Condition 1 below. When the disclosed Condition 1 is satisfied, the risk of local NP ratio reversal in the sliding region can be effectively prevented.