Conductive-Coated Battery Separator for Lithium Dendrite Interception
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Solution Overview
Problem
Lithium dendrites growing during battery charge and discharge cycles can penetrate the separator, leading to battery short circuits, fires, and explosions, as existing coatings only delay penetration without alleviating short circuits.
Innovation Solution
A battery separator with a conductive coating on one side and an insulating base film, featuring a conductivity of 102-106 S/m, intercepts lithium dendrites and creates a low-current micro-short circuit to delay catastrophic accidents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a thinner separator is used to increase energy density, then productivity and energy density are improved, but the reliability deteriorates due to increased risk of separator penetration by lithium dendrites
Solution Approach 1:
The patent applies composite materials by combining a base film with a conductive coating layer containing conductive materials (such as metal oxides or carbon-based materials) and insulating materials. This composite structure provides both the thin profile needed for high energy density and the enhanced dendrite resistance required for reliability, resolving the contradiction between thickness and penetration resistance.
Solution Approach 2:
The conductive coating is applied locally on one or both surfaces of the base film, creating local quality enhancement at the critical interface where dendrites contact the separator. This localized treatment provides targeted protection without requiring the entire separator to be thicker, maintaining high energy density while improving reliability at the penetration risk points.
2Reliability
If existing insulating coatings are applied to prevent dendrite penetration, then separator protection is improved, but the harmful effect worsens because short circuits still occur without warning
Solution Approach 1:
The conductive coating provides electrical feedback by creating a measurable current signal when lithium dendrites contact it. This feedback mechanism allows the battery management system to detect dendrite penetration early and trigger warnings or shutdown protocols before catastrophic short circuits occur, transforming the harmful effect into a detectable signal that enables preventive action.
Solution Approach 2:
The conductive coating acts as an intermediary layer between the base film and the dendrites. It provides a conductive pathway that allows electrical signal transmission for detection while still serving as a physical barrier that delays or prevents complete penetration to the cathode, thereby reducing short circuit severity while maintaining protection.
3Reliability
If a conductive coating with high electrical conductivity is applied to intercept dendrites, then reliability is improved by creating micro-short circuits, but the harmful effect worsens due to increased electrical conductivity potentially causing safety issues
Solution Approach 1:
The patent carefully controls the electrical conductivity parameter of the coating by selecting appropriate conductive materials and optimizing their concentration and distribution. The conductivity is tuned to a specific range that enables dendrite interception and micro-short circuit formation for detection purposes, while remaining low enough to prevent hazardous current flows, thus resolving the contradiction between interception capability and 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 conductive coating intercepts lithium dendrites, creating a controlled micro-short circuit to provide additional time for warning, reducing the risk of serious accidents and damage.
Implementation Method 1
a material of the coating includes a conductive material and an insulating material... the coating side is conductive... a low-current micro-short circuit is created by the conductive coating
Data Source
AI summary
Disclosed are a battery separator and a preparation method therefor, as well as a secondary battery and an electric device, relating to the field of batteries. The battery separator includes a base film and a coating, wherein the coating is disposed on a surface of the base film that faces the cathode of a battery. The coating comprises both a conductive material and an insulating material. When applied in a lithium battery, the separator functions such that, if lithium dendrites grow through the uncoated side of the base film, the coating intercepts the dendrites before they make direct contact with the cathode. This structure prevents a direct short circuit between the anode and cathode. Instead, a low-current micro-short circuit is formed through the coating, which effectively delays the onset of serious failure or thermal events. As a result, the separator improves the safety and operational reliability of the lithium battery.