Ion-Conductive Separator Coating for Battery Micro-Short Suppression
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Solution Overview
Problem
Lithium secondary batteries face issues with micro-short circuits due to metal columns growing through the pores of the separator, leading to reduced lifetime and safety concerns, especially with lithium metal batteries which have higher reactivity compared to carbon-based materials.
Innovation Solution
A separator with a substrate and coating layer having selectively filled pores using an ion conductive polymer, such as a fluorine-based ionomer, to prevent metal column growth from the negative electrode towards the positive electrode, while maintaining ionic conductivity similar to an open pore structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the separator has open pores to ensure lithium ion conduction, then ionic conductivity is improved, but metal columns can grow through the pores causing micro-short circuits
Solution Approach 1:
The separator is designed with non-uniform pore distribution: the first region (facing negative electrode) has pores filled with ion conductive polymer to prevent metal column growth, while the second region (facing positive electrode) maintains open pores for efficient lithium ion conduction. This local differentiation resolves the contradiction by providing both protection and conductivity in appropriate locations.
Solution Approach 2:
An ion conductive polymer is introduced as an intermediary material to fill the pores in the first region. This polymer acts as a mediator that allows lithium ion transport while physically blocking metal column growth, thus resolving the contradiction between maintaining ionic conductivity and preventing micro-short circuits.
2Reliability
If the pores are filled to prevent metal column growth, then reliability is improved, but lithium ion conduction is hindered
Solution Approach 1:
The separator differentiates pore filling by region: the first region has filled pores for reliability, while the second region has open pores for ion conduction. This spatial differentiation allows the system to achieve both protection and conductivity simultaneously.
Solution Approach 2:
The separator is divided into two distinct regions with different pore structures. The first region (near negative electrode) is segmented as a protective barrier with filled pores, while the second region (near positive electrode) is segmented as a conduction pathway with open pores, allowing each region to optimize its function.
3Reliability
If a coating layer is added to the separator to enhance protection, then reliability is improved, but device complexity increases
Solution Approach 1:
The separator is segmented into distinct functional regions: a substrate layer providing mechanical support, a coating layer with inorganic particles for thermal stability, and two functional regions with different pore filling states. This segmentation allows each layer to perform its specific function while maintaining overall system reliability.
Solution Approach 2:
The separator employs a composite structure combining organic substrate material with inorganic particles in the coating layer, and ion conductive polymer in the filled pores. This composite approach enhances protection through material synergies while managing structural complexity through functional integration.
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 solution effectively inhibits micro-short circuits, improves the lifetime of lithium secondary batteries, and secures output characteristics by ensuring lithium ion conduction without compromising thermal or mechanical stability.
Implementation Method 1
an ion conductive polymer which selectively fills either one of all of the first pores and all of the second pores
Data Source
AI summary
The present disclosure relates to a separator for lithium secondary battery, a method for manufacturing same, and a lithium secondary battery including the same.Specifically, in one embodiment of the present disclosure, by filling the pores of the separator, the present invention physically inhibits the metal column capable of growing on the surface of the negative electrode from moving toward the positive electrode, inhibits a micro-short circuit of the lithium secondary battery, and ultimately improves the lifetime of the lithium secondary battery.In addition, by controlling the type of filling the pores of the separator and the type of the polymer filling it, the output characteristics of the lithium secondary battery are secured and improved.