Dry Electrode Film Processing to Prevent Micronization and Cracks
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Solution Overview
Problem
The manufacturing of dry electrodes for electrochemical devices faces challenges such as micronization of active materials and degradation of mechanical properties due to high-shear mixing processes, leading to issues like pinholes, cracks, and reduced flexibility and strength.
Innovation Solution
A dry manufacturing process using a binder resin with crystallinity of 10% or less, involving steps like kneading and pulverization, to produce a dry electrode film with improved tensile strength and flexibility, and porosity of 20-50 vol%, without the use of solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high-shear mixing process is used to manufacture dry electrode, then binder fibrilization is achieved, but active material is micronized and mechanical properties are degraded
Solution Approach 1:
The patent changes the shear rate parameter from high to low during the mixing process. By controlling the shear rate to be low, the patent prevents excessive fibrilization of the binder and micronization of the active material, thereby maintaining mechanical properties and particle size integrity while still achieving sufficient mixing and electrode formation.
2Strength
If high-shear mixing is applied to fibrilize binder, then binder fibrilization is improved, but flexibility of free-standing film is degraded
Solution Approach 1:
The patent adjusts the shear rate parameter to a low level, which controls the degree of binder fibrilization. This moderate fibrilization achieves sufficient binding strength while preserving the flexibility of the free-standing film, avoiding the excessive fibrilization that would occur with high-shear mixing and subsequent fiber cutting.
3Reliability
If conventional drying apparatus is used to remove solvent, then solvent evaporation is controlled, but manufacturing cost and time are increased
Solution Approach 1:
The patent extracts and eliminates the solvent from the electrode mixture formulation. By using a solvent-free system, the patent removes the need for expensive and time-consuming drying apparatus and processes, while still achieving uniform electrode formation through the low-shear mixing process that prevents powder floating and ensures homogeneous distribution of components.
4Ease of manufacture
If solvent is used in electrode mixture, then flowability and dispersion are improved, but pinholes and cracks are generated during drying
Solution Approach 1:
The patent removes the solvent from the electrode mixture system. By using a solvent-free formulation with low-shear mixing, the patent achieves uniform distribution of active material, conductive material, and binder without the formation of pinholes or cracks that occur during solvent evaporation, while still maintaining adequate flowability for electrode formation.
Data Source
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AI summary
Disclosed is a method for manufacturing a dry electrode. The method allows determination of the micro-fibrilization degree of a binder resin from the crystallinity of the binder resin. Based on this, the processing conditions of mixed powder for electrode or an electrode film may be controlled. In this manner, it is possible to check and control the processing conditions easily and efficiently. In addition, the method for manufacturing a dry electrode includes a kneading step using a kneader under a low speed and high temperature and pulverization step. Therefore, there is no problem of blocking of a flow path caused by aggregation of the ingredients, which is favorable to mass production.