Electrode Sheet Particle Coating for Conductivity and Tensile Strength
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Solution Overview
Problem
Existing electrode sheets face a trade-off between conductivity and tensile strength due to the incorporation of conduction aids into binders, leading to insufficient conductivity improvements and reduced tensile strength when the amount of binder is reduced.
Innovation Solution
A manufacturing method involving separate coating of active material particles with binders and conduction aids, where larger particles are coated with conduction aids first, allowing for a larger amount of conduction aid to form conductive pathways without reducing the binder content, thereby improving both conductivity and tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of binder is reduced to prevent conduction aid incorporation, then conductivity improves, but tensile strength decreases
Solution Approach 1:
The patent segments the coating process into two distinct stages: first coating active material particles with binder, then separately coating conduction aid onto the binder-coated particles. This segmentation prevents conduction aid from being incorporated into the binder matrix, allowing sufficient conduction aid to remain exposed for forming conductive pathways while maintaining adequate binder content for tensile strength.
Solution Approach 2:
The patent applies preliminary action by first coating the active material particles with binder, creating a substrate that facilitates subsequent uniform distribution and adhesion of conduction aid. This preliminary coating ensures that conduction aid adheres to the binder-coated surface rather than being absorbed into the binder bulk, resolving the contradiction between conductivity and tensile strength.
2Strength
If a fibrillatable binder is used to improve tensile strength, then tensile strength improves, but conduction aid is more likely to be entangled in the binder
Solution Approach 1:
The patent separates the coating of binder and conduction aid into sequential steps, preventing the conduction aid from being entangled in the binder during fibrillation. By completing the conduction aid coating after binder application, the conduction aid remains on the surface and is not incorporated into the fibrillated binder structure, maintaining both tensile strength and conductivity.
Solution Approach 2:
The patent performs preliminary coating of conduction aid onto binder-coated particles before electrode formation. This ensures that conduction aid is already in place and properly distributed before any fibrillation occurs, preventing entanglement of conduction aid in the binder matrix while still allowing the fibrillatable binder to provide necessary tensile strength.
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 method results in an electrode sheet with enhanced conductivity and tensile strength, maintaining a high energy density as a freestanding sheet without the need for a current collector.
Implementation Method 1
The conduction aid is, for example, carbon black or carbon nanotube, and forms conductive pathways extending between active material particles
Data Source
AI summary
A method for manufacturing an electrode sheet is disclosed. The method may include producing first coated active material particles by mixing first active material particles with at least a binder; producing second coated active material particles by mixing second active material particles with at least a conduction aid; producing an electrode mixture by mixing the first coated active material particles with the second coated active material particles; and forming the electrode mixture into a sheet shape. An average particle diameter of the second active material particles may be larger than an average particle diameter of the first active material particles.