Thin Ceramic Coated Separator for High-Energy Batteries
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Solution Overview
Problem
Current separators for lithium high energy batteries are not adequately thin, light, or safe, with existing materials having limitations in thermal stability, conductivity, and safety features, leading to potential short circuits and energy density issues.
Innovation Solution
A thin, lightweight separator is developed using a nonwoven substrate with a porous inorganic ceramic coating, featuring a thickness of less than 35 μm and a weight of less than 50 g/m², achieved by applying a ceramic coating to a polymeric web with specific production parameters and using small pyrogenic silica particles for high porosity and integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a porous organic polymer film separator is used, then ion permeability is achieved, but thermal stability is insufficient (below 150°C)
Solution Approach 1:
The patent employs a composite structure consisting of a porous organic polymer film substrate combined with an inorganic ceramic coating layer. The organic substrate provides ion permeability and flexibility, while the inorganic coating layer contributes high thermal stability and chemical resistance, thereby resolving the contradiction between achieving ion permeability and maintaining thermal stability.
2Volume of moving object
If the separator thickness is reduced to increase energy density, then manufacturing precision becomes difficult to maintain without flaws
Solution Approach 1:
The patent utilizes a porous inorganic ceramic coating with controlled pore structure that can be applied as a thin layer while maintaining structural integrity and ion conductivity. The porous nature allows the coating to achieve sufficient thickness for manufacturing precision even when the overall separator thickness is reduced to below 100 μm, preventing flaws and ensuring uniformity.
3Temperature
If inorganic composite materials are used to improve thermal stability, then the separator becomes more complex and difficult to produce without flaws
Solution Approach 1:
The patent applies the inorganic ceramic material specifically as a coating layer on the organic substrate rather than using it as the bulk material. This localized application provides thermal stability only where needed (at the surfaces exposed to electrolyte and electrodes) while keeping the overall structure simple and manufacturable through conventional coating processes.
4Weight of moving object
If the separator weight is reduced to increase specific energy, then mechanical strength and safety are compromised
Solution Approach 1:
The composite structure combines lightweight organic polymer fibers in a nonwoven mat format with a thin inorganic ceramic coating. The organic substrate provides low weight and flexibility, while the inorganic coating adds mechanical strength and thermal stability, achieving weight reduction without compromising strength or safety.
5Ease of operation
If polyolefin separators are used to achieve flexibility, then they are attacked by lithium and lithiated graphite over time
Solution Approach 1:
The patent uses a composite where the organic polymer substrate maintains flexibility and ion permeability, while the inorganic ceramic coating layer provides chemical resistance to lithium and lithiated graphite. This protective coating prevents direct contact and chemical attack on the organic substrate, ensuring long-term stability while preserving flexibility.
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 separator provides enhanced safety, high energy density, and efficient ion conductivity while preventing short circuits and meltdown, making it suitable for high energy batteries with improved manufacturing efficiency and safety.
Implementation Method 1
The separator is a thin porous electronically insulating material possessing high ion permeability
Implementation Method 2
using small pyrogenic silica particles for high porosity and integrity
Data Source
AI summary
The present invention relates to electrical separators, especially for use in lithium high energy batteries, and to a process for making them.Separators for use in lithium high energy batteries have to have a very low weight and a very low thickness. It has been found that, surprisingly, such separators having a weight of less than 50 g/m2 and a thickness of less than 35 μm are preparable by applying a ceramic coating to a polymeric web less than 30 μm in thickness, these separators being very useful in lithium high energy batteries when pyrogenic oxides of the elements Al, Si and/or Zr are used as a particulate pore-forming component.