Current Collector Coating for Rapid Battery Charging
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Solution Overview
Problem
Conventional lithium secondary batteries face issues with rapid charge/discharge characteristics due to high internal resistance, leading to decreased battery capacity retention rates, especially when high current is applied, and there is a need to minimize the use of conductive particles to enhance energy density.
Innovation Solution
A method of producing a current collector for electrochemical elements using a coating liquid comprising a binder, carbon particles, and an organic solvent, where the binder includes polysaccharides and organic acids, applied to a metal foil to form a coating layer that reduces internal resistance, allowing for rapid charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high current is applied to charge/discharge electrochemical elements, then charge/discharge speed is improved, but internal resistance increases causing large decrease in capacity retention rate
Solution Approach 1:
The invention changes the chemical composition parameters of the coating layer by selecting specific polysaccharide binders (with defined molecular weights and degrees of substitution) and organic acid crosslinking agents, which modifies the electrical and mechanical properties of the current collector to reduce internal resistance and improve capacity retention during high-rate charge/discharge cycles
Solution Approach 2:
The invention creates a composite coating layer by combining polysaccharide-based polymers with organic acid crosslinking agents and conductive carbon particles on the metal foil surface, forming a multi-component system that simultaneously provides structural integrity, electrical conductivity, and adhesion to reduce internal resistance
2Reliability
If electrically conductive particles are added to electrode mixtures to improve electrical conductivity, then internal resistance decreases, but energy density decreases due to increased amount of conductive particles
Solution Approach 1:
The invention concentrates conductive carbon particles specifically in the coating layer on the current collector surface, providing localized electrical conductivity enhancement at the electrode-current collector interface without requiring bulk addition of conductive particles to the electrode mixture, thereby maintaining energy density
Solution Approach 2:
The coating layer acts as an intermediary between the metal foil current collector and the electrode mixture, providing a conductive pathway that reduces contact resistance and improves overall electrical conductivity without requiring conductive particles throughout the entire electrode structure
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 enables lithium secondary batteries to maintain high capacity retention rates even under high charge/discharge currents by reducing internal resistance and impedance, while minimizing the use of conductive particles, thus improving energy density.
Implementation Method 1
a step for removing the organic solvent and forming a coating layer on the metal foil
Data Source
AI summary
An object of the present invention is to provide a method of producing a current collector for an electrochemical element that enable rapid charging and discharging with low internal resistance. The method of producing a current collector for an electrochemical element in the present invention has a step for coating a coating liquid onto a metal foil, the coating liquid containing at least one substance selected from the group consisting of methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl ethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl starch, hydroxypropyl starch, dextrin, pullulan, dextran, guar gum and hydroxypropyl guar gum; an organic acid having valence of two or more or a derivative thereof, carbon particles and an organic solvent, followed by removing the organic solvent and forming a coating layer on the metal foil.