Lithium Ion Battery Electrode Binder Coat Edge Adhesion
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Solution Overview
Problem
The existing methods for producing electrodes for lithium ion secondary batteries face issues with peeling and slip-down of the active material at the edge portions, leading to potential short-circuits due to insufficient bonding strength, especially during stress in battery production processes.
Innovation Solution
A method involving the formation of a binder coat layer with varying coating amounts along the collector, including large and small coat amount regions, and the application of granulated particles followed by pressing, which enhances adhesion and prevents peeling and slip-down. Additionally, a cutting step with a large coat amount region at the cutting site further secures the active material layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pressure molding is applied uniformly across the electrode, then the active material layer is formed, but the pressure dissipates at the edge portions causing insufficient bonding strength
Solution Approach 1:
The binder coat layer is designed with spatially varying coating amounts: large coat amount regions at both side edge portions and small coat amount regions at the central portion. This local differentiation ensures that edge portions receive enhanced binder coverage to compensate for pressure dissipation during pressing, thereby maintaining adequate bonding strength without excessive binder in the central region.
2Strength
If the binder coat layer is formed with large coat amount regions at edge portions, then bonding strength is improved, but the coating process becomes more complex
Solution Approach 1:
The binder coat layer is segmented into distinct large coat amount regions at the side edge portions and small coat amount regions at the central portion. This segmentation allows the coating device to apply binder liquid with spatially varying amounts in a systematic manner, achieving differential coverage without requiring overly complex coating mechanisms.
3Manufacturing precision
If the active material layer is pressed uniformly, then the particles are compacted, but edge portions are prone to peeling and particle fall-off
Solution Approach 1:
The binder coat layer is formed on the collector before the active material layer is applied and pressed. The large coat amount regions are pre-positioned at the edge portions where pressing-induced pressure dissipation occurs. This preliminary action ensures that when pressing is applied, the edge portions already have enhanced binder coverage to prevent peeling and particle fall-off.
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
This method effectively suppresses peeling and slip-down of the active material at the edge portions and during cutting, ensuring a stable electrode structure and improved battery performance by maintaining the active material in place, thus preventing short-circuits and enhancing cycle characteristics and production stability.
Implementation Method 1
a binder coat layer through application of a binder liquid containing a binder and a solvent, onto an elongate collector
Implementation Method 2
forming an active material layer through pressing of aggregates of the granulated particles having been supplied onto the binder coat layer
Data Source
Figure 1
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AI summary
A method for producing an electrode for lithium ion secondary batteries proposed herein includes: a step of forming a binder coat layer 16 on a collector 12, with the binder coat layer 16 being formed so as to have a large coat amount region 18A of relatively a large coating amount and a small coat amount region 18B of relatively small coating amount, and the large coat amount region 18A being provided at both side edge portions 16E of the binder coat layer 16; a step of supplying granulated particles containing active material particles and a binder, onto the binder coat layer 16; and a step of forming an active material layer by pressing of aggregates of the granulated particles.