Positive Electrode Composite Particles for Stable Dry-Coated Cathodes
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Solution Overview
Problem
Existing techniques for producing positive active material composite particles for battery electrodes face challenges due to the positive active material's inability to soften like the binder resin, making it difficult to form suitable composite particles for the positive active material mixture layer.
Innovation Solution
The development of positive active material composite particles comprising a positive active material particle, a conductive particle with a smaller diameter, and a binder resin that bonds the conductive particle to the surface of the positive active material particle, ensuring stability during deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the technique of Patent Document 1 is applied to produce positive active material composite particles, then composite particles can be formed through heating, but the positive active material cannot soften like binder resin, making it impossible to obtain suitable composite particles
Solution Approach 1:
The composite particle is segmented into distinct functional components: positive active material particles (core), conductive particles (sub-particles), and binder resin (matrix). This segmentation allows each component to perform its specific function while maintaining overall particle integrity during deposition processes.
Solution Approach 2:
The binder resin acts as an intermediary substance that bonds the positive active material particles and conductive particles together. This mediator enables the formation of stable composite particles without requiring the positive active material itself to soften, resolving the contradiction between manufacturability and suitability.
2Reliability
If conductive particles are placed on the surface of positive active material particles, then electrical conductivity is improved, but the particles may detach during deposition processes
Solution Approach 1:
The conductive particles are preliminarily fixed to the positive active material particle surface through binder resin before the deposition process. This preliminary bonding action ensures that the conductive particles remain in position during subsequent handling and deposition, preventing detachment while maintaining conductivity.
Solution Approach 2:
The physical state of the binder resin is changed through temperature control during the deposition process. By heating to near the glass transition temperature, the binder resin becomes more pliable, allowing for stable bonding of conductive particles while maintaining particle integrity during the deposition process.
3Stability of the object's composition
If binder resin is used to bond particles, then particle stability is improved, but ion transfer between positive active material and electrolyte solution may be hindered
Solution Approach 1:
The binder resin is distributed in a localized, non-uniform manner on the particle surface rather than forming a complete continuous layer. This local quality approach ensures that while the binder provides structural stability, there remain exposed regions of positive active material that can directly contact the electrolyte solution for ion transfer.
Solution Approach 2:
The binder resin forms a porous or discontinuous structure on the particle surface, creating pathways for electrolyte solution to reach the positive active material. This porous configuration maintains particle stability while preserving ion transfer capability through the spaces between binder resin regions.
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 configuration allows for the formation of a stable positive active material mixture layer on the current collecting member, enabling effective ion transfer and maintaining the integrity of the conductive particles during battery operation.
Implementation Method 1
a binder resin located on the surface of the positive active material particle bonding the surface of the positive active material particle and the conductive particle
Implementation Method 2
heating the composite particles obtained in the mixing to temporarily soften the binder resin particles thermally
Data Source
Figure 1~2
Figure 3~4
AI summary
A positive active material composite particle (1) of the present disclosure includes a positive active material particle (2), a conductive particle (3) existing on a surface of the positive active material particle (2) and having a smaller diameter than the positive active material particle (2), and a binder resin (4) bonding the surface of the positive active material particle (2) and the conductive particle (3) on the surface of the positive active material particle (2). A positive electrode sheet (10) of the present disclosure includes a positive active material mixture layer (9) formed on a current collecting member (8) by a dry process using the positive active material composite particle (1).