Electrode Assembly Bare Surface Design for Nail Penetration Safety
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Solution Overview
Problem
Lithium-ion batteries face safety issues due to unpredictable abuses, particularly nail penetration, which can cause internal short circuits, thermal runaway, and potential harm, as existing solutions like extended foils and conductive particles may lead to short-circuit heating and combustion.
Innovation Solution
An electrode assembly design where the first current collector has a bare surface facing a conductive surface on the second current collector, preventing electron flow and embedding conductive particles and edge burrs to reduce the risk of internal short circuits during mechanical abuse, ensuring quick discharge and enhanced safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extended aluminum foil and copper foil are applied on the electrode tails to enable quick short-circuit discharge during nail penetration, then battery safety against thermal runaway is improved, but conductive particles fill the empty foil area and cause short-circuit heating and combustion under formation pressure
Solution Approach 1:
The patent applies different surface treatments to different regions of the current collector. The first surface (facing the separator) is kept bare without electrode active material, while the second surface has conductive material. This local differentiation prevents conductive particles from causing harmful effects while maintaining the safety function of quick discharge during abuse.
Solution Approach 2:
The bare first surface of the current collector acts as an intermediary layer between the separator and the conductive material on the second surface. This intermediate bare surface prevents conductive particles and edge burrs from directly contacting and penetrating the separator, thereby eliminating the harmful effect of short-circuit heating while allowing the conductive material to provide safety discharge function.
2Reliability
If extended aluminum foil and copper foil are applied to surround the electrode assembly for one turn to enable quick discharge, then battery safety is improved, but edge burr area of the empty foil area is more likely to penetrate the separator causing short circuit
Solution Approach 1:
The patent creates a local quality difference where the first surface of the current collector is bare while the second surface has conductive material. This ensures that the edge burr areas, which are part of the first surface facing the separator, do not have conductive material that could facilitate penetration and short circuiting.
Solution Approach 2:
The bare first surface of the current collector serves as a protective intermediary between the separator and potential edge burrs. By having no conductive material on this surface, edge burrs cannot directly contact the separator through conductive pathways, thus preventing short circuit while maintaining the safety function.
3Quantity of substance
If conductive particles are used to fill the empty foil area, then the empty foil area is occupied, but conductive particles penetrate the separator under large pressure causing short-circuit heating
Solution Approach 1:
The patent extracts the conductive material from the first surface (the side facing the separator) and places it only on the second surface. This extraction eliminates the harmful effect of conductive particles penetrating the separator while still utilizing the empty foil area for its intended safety function of quick discharge during abuse conditions.
Solution Approach 2:
The patent implements local quality by having conductive material only on the second surface of the current collector while keeping the first surface bare. This spatial differentiation allows the empty foil area to be utilized for safety functions without the harmful effect of conductive particles causing short-circuit heating through separator penetration.
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 design effectively prevents explosions and ignitions by ensuring mechanical abuse resistance, reduces the likelihood of separator damage, and embeds conductive particles and edge burrs, thereby improving the safety and reliability of lithium-ion batteries.
Implementation Method 1
the conductive material also hinders the edge burr of the current collector from penetrating the separator, so that an effect that the separator is not easily broken is caused
Implementation Method 2
the first current collector and the second current collector may quickly form a short circuit, so that the internal power of the electrode assembly is discharged, thereby preventing the battery from exploding and igniting
Data Source
AI summary
The present application provides an electrode assembly comprising a first electrode comprising a first current collector and a second electrode comprising a second current collector, wherein the first current collector comprises a first surface, the second current collector comprises a second surface, the first surface faces the second surface, and the second surface is provided with a conductive material. It is an object of the present application to provide an electrode assembly for improving short-circuit defects existing in the electrode assembly while ensuring resistance to mechanical abuse. The present application further provides a battery.