Multidirectional Binder Fiberization in Lithium Battery Electrodes
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Solution Overview
Problem
The durability of lithium secondary battery electrodes is insufficient due to reduced bonding force between electrode active material, electrically conductive material, and binder, particularly in dry manufacturing methods where fiberization of the binder is limited to specific directions, affecting the electrode's lifetime and performance.
Innovation Solution
An electrode with a binder fiberized in multiple directions is developed, achieved through a method involving mixing at low temperature, primary fiberization, grinding, and secondary fiberization, which enhances the bonding force and durability by ensuring even distribution of the binder across the active layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If binder is fiberized only in machine direction through conventional rolling, then manufacturing process is simple, but bonding force between particles is insufficient and electrode durability is reduced
Solution Approach 1:
The patent applies multidirectional fiberization by introducing a transverse rolling step in addition to the conventional machine direction rolling. This transforms the unidirectional fiberization process into a bidirectional process, creating binder fibers oriented in both machine direction (MD) and transverse direction (TD), thereby significantly improving bonding force between particles throughout the electrode structure.
2Reliability
If binder is fiberized in multiple directions, then electrode durability and bonding force are improved, but manufacturing process complexity increases
Solution Approach 1:
The fiberization process is segmented into distinct sequential steps: first rolling in machine direction, then rolling in transverse direction. This segmentation allows each rolling operation to be optimized independently while achieving cumulative benefit of multidirectional fiberization, improving electrode durability without requiring a completely new complex process.
3Duration of action of stationary object
If conventional unidirectional fiberization is used, then manufacturing cost is low, but electrode lifetime is reduced due to insufficient bonding
Solution Approach 1:
The patent performs preliminary fiberization in machine direction first, creating an initial binder fiber network that provides basic bonding. This preliminary action is followed by transverse rolling that further develops the fiber structure, ensuring adequate bonding force is established before electrode completion, thereby extending electrode lifetime.
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 significantly improves the tensile strength and durability of the electrode in both machine and transverse directions, leading to enhanced performance and longevity of the lithium secondary battery.
Implementation Method 1
When a binder such as polytetrafluoroethylene (PTFE) is pressed, fiberization proceeds centering on the surface in contact with the roll. This fiberization is done in the moving direction of the roll (Machine Direction, MD direction) and is mostly formed in the binder located on the surface of the electrode.
Data Source
AI summary
An electrode for a lithium secondary battery. The electrode includes an active layer. The active layer includes an electrode active material, an electrically conductive material, and a binder. The binder is fiberized in multiple directions.