Dry Electrode Mixture Sheet with Fibrous Binder for High Rupture Strength
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Solution Overview
Problem
The existing methods for manufacturing electrodes in non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, face issues with uneven binder distribution due to solvent drying and the use of large shear forces, which degrade formability and rupture strength of the electrode mixture sheets.
Innovation Solution
A method involving the use of a fibrous binder produced by applying a shear force to particulate binder particles with a median diameter of 5 to 100 μm, mixed with active material to form an electrode mixture sheet with a rupture peripheral speed ratio of 8 or more, eliminating the need for solvent drying and reducing the impact of shear forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slurry including a binder dissolved in a solvent is used in producing an electrode, then adhesiveness by the binder is achieved, but the solvent must be dried requiring additional steps and equipment
Solution Approach 1:
The invention extracts and eliminates the solvent component from the electrode manufacturing process. By using a dry mixture of particulate binder and active material without any solvent, the patent removes the need for drying steps and equipment while maintaining binding functionality through the particulate binder's mechanical interlocking and adhesion properties.
Solution Approach 2:
The invention replaces the chemical bonding mechanism (dissolved binder forming adhesive matrix) with a mechanical bonding mechanism (particulate binder providing friction and interlocking). The particulate binder particles create mechanical interlocking between active material particles, substituting the chemical adhesive action with physical mechanical bonds.
2Stability of the object's composition
If a large shear force is applied to the electrode mixture for treatment in a long time to accelerate fibrillation of the binder, then mixing is improved, but the formability of the electrode mixture sheet deteriorates and rupture strength is significantly lowered
Solution Approach 1:
The invention changes the physical parameters of the binder from requiring extensive fibrillation (long treatment time, large shear force) to using particulate binder with optimal size distribution (median diameter 5 to 100 μm). This parameter change allows adequate mixing and binding performance without subjecting the electrode mixture to prolonged high shear forces, thereby preserving sheet formability and rupture strength.
3Reliability
If the binder is dissolved in a solvent to allow the binder to exhibit binding property, then adhesiveness is achieved, but labor saving in the step and equipment is difficult
Solution Approach 1:
The invention extracts and eliminates the solvent from the electrode manufacturing process. By using a dry mixture of particulate binder and active material without any solvent, the patent removes the need for drying steps and equipment while maintaining binding functionality through the particulate binder's mechanical interlocking and adhesion properties.
4Manufacturing precision
If binder migration occurs during drying of the coating film, then the binder distributes unevenly in the thickness direction, but this cannot be prevented without drying
Solution Approach 1:
The invention extracts and eliminates the drying step by using a solvent-free particulate binder system. Without solvent evaporation and drying, there is no binder migration to cause non-uniform distribution. The particulate binder maintains uniform distribution throughout the electrode mixture and coating film thickness without requiring any drying process.
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 approach results in an electrode mixture sheet with improved formability and high rupture strength, enhancing the production of electrodes with better electron conductivity and appearance.
Implementation Method 1
a fibrous binder, wherein in forming the electrode mixture into a sheet, a rupture peripheral speed ratio is 8 or more
Data Source
AI summary
According to this method for producing an electrode, a fibrous binder is produced by fibrillating a particulate binder, which has a volume-based median diameter of from 5 to 100 μm, by means of the application of a shear force, and an electrode mixture is produced by mixing the fibrous binder with an active material, said electrode mixture having a solid content concentration of substantially 100%. It is preferable that the fibrillation is carried out so that the breaking peripheral velocity ratio of the electrode mixture is 8 or more. In addition, an electrode mixture sheet is produced by shaping the electrode mixture into a sheet form by rolling, and the electrode mixture sheet is subsequently bonded to a core material.