Electrode Coating Layer for High-Temperature Battery Insulation
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Solution Overview
Problem
Lithium secondary batteries face high-temperature safety issues due to the shrinkage of polyolefin-based separators, leading to potential short circuits and ignition, which compromises their safety and performance.
Innovation Solution
A coating layer is formed on the electrode active material layer, comprising polymer particles with a zeta potential of 25 mV or more, a dispersant, and a binder such as PVDF, PVA, or starch, which assists or replaces the separator, providing improved electrical insulation and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin-based separator is used to ensure electrical insulation between electrodes, then electrical insulation is improved, but high-temperature safety deteriorates due to shrinkage at elevated temperatures
Solution Approach 1:
The patent changes the material composition parameters of the separator by incorporating inorganic particles (such as alumina, silica, or boehmite) into the polyolefin matrix. This composite structure maintains the electrical insulation properties of polyolefin while the inorganic particles provide thermal stability and prevent shrinkage at high temperatures, thus resolving the contradiction between electrical insulation and high-temperature stability
Solution Approach 2:
The patent creates a composite separator material by combining polyolefin with inorganic particles. The polyolefin provides electrical insulation and flexibility, while the inorganic particles provide thermal stability and dimensional stability at high temperatures. This composite approach allows the separator to simultaneously achieve both electrical insulation and high-temperature resistance, resolving the technical contradiction
2Use of energy by moving object
If the separator is made thinner to increase energy density, then energy density is improved, but safety deteriorates due to increased shrinkage risk and reduced insulation capability
Solution Approach 1:
The patent changes the physical and chemical parameters of the separator material by adding inorganic particles with high thermal stability. This allows the separator to be made thinner while maintaining its structural integrity and insulation properties at high temperatures, thus increasing energy density without compromising safety
Solution Approach 2:
By creating a composite structure with inorganic particles dispersed in the polyolefin matrix, the patent achieves enhanced mechanical strength and thermal stability in a thinner separator. The inorganic particles act as reinforcing agents that prevent shrinkage and maintain insulation properties even at reduced thickness, enabling both high energy density and safety
3Temperature
If a coating layer is formed on the electrode to replace or assist the separator, then high-temperature safety is improved, but device complexity increases
Solution Approach 1:
The patent merges the separator function with the electrode structure by forming a coating layer directly on the electrode surface. This integrated approach combines the electrode and separator into a single composite structure, eliminating the need for a separate standalone separator and reducing overall device complexity while maintaining high-temperature safety
Solution Approach 2:
The coating layer performs multiple functions simultaneously: it serves as both part of the electrode structure and as the separator providing electrical insulation and thermal stability. This multi-functional design eliminates the need for separate components and simplifies the overall battery structure while achieving improved high-temperature safety
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 coating layer enhances high-temperature safety by preventing short circuits, improving lithium ion mobility, and extending the battery's life characteristics, while also ensuring excellent adhesive force and impregnation properties with flame retardant electrolytes.
Implementation Method 1
securing electrical insulation between two electrodes
Implementation Method 2
a dispersant
Data Source
AI summary
An electrode capable of improving high-temperature safety and life characteristic of lithium secondary batteries, and an electrode assembly including the same are provided. The electrode includes an electrode active material layer and a coating layer formed on the electrode active material layer, the coating layer including polymer particles, a dispersant, and a binder, and the binder includes at least one selected from the group consisting of polyvinylidenefluoride (PVDF), polyvinyl alcohol (PVA), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone (PVP), polyethylene (PE), polypropylene, ethylene-propylene-diene polymer, and a sulfonated ethylene-propylene-diene polymer.