Electrolyte Membrane with Perpendicular Carbon Nanotube Channels
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Solution Overview
Problem
Current lithium-ion batteries face limitations in achieving both high power and high energy density due to low ionic conductivity and kinetic factors, with existing methods like fluorination having drawbacks such as short-circuit risks and structural damage to carbon nanotubes.
Innovation Solution
A method for manufacturing an electrolyte membrane with carbon nanotubes, where the second end of the nanotubes is fixed with a holding layer and coated with a polymer matrix, ensuring regular spacing and orientation perpendicular to the membrane surfaces, and an ion-conductive, electrically insulating layer is applied to prevent short circuits and enhance conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorination is used to make CNT walls electrically insulating, then short-circuit prevention is improved, but CNT structure is damaged and sp2 hybridization is destroyed
Solution Approach 1:
The CNT surface modification is segmented into two distinct approaches: fluorination for single-walled CNTs and coating with polymer matrix for multi-walled CNTs. This segmentation allows each type of CNT to be treated with the most appropriate method, preserving the structural integrity of multi-walled CNTs while still achieving electrical insulation where needed.
Solution Approach 2:
Different surface treatment methods are applied to different types of CNTs based on their specific properties. Single-walled CNTs receive fluorination treatment while multi-walled CNTs are coated with polymer matrix, creating local quality variations that optimize both electrical insulation and structural preservation for each CNT type.
2Ease of manufacture
If CNT carpet is grown and space between CNTs is filled with polymer, then membrane formation is achieved, but CNT arrangement control becomes difficult
Solution Approach 1:
The CNT carpet is grown on a substrate with controlled arrangement before the polymer matrix is formed. This preliminary action establishes the desired CNT orientation and spacing in advance, allowing the subsequent polymer filling to proceed without disrupting the precise CNT arrangement.
Solution Approach 2:
The substrate acts as an intermediary that facilitates controlled CNT growth with specific orientation and spacing. The substrate provides a template that guides CNT arrangement, and this intermediate structure is later removed or integrated into the final membrane, preserving the controlled CNT configuration.
3Quantity of substance
If ionic liquid electrolyte is used, then high energy density is achieved, but spontaneous self-organization causes density fluctuations and reduced ionic conductivity
Solution Approach 1:
The membrane utilizes the porous structure formed by the CNT carpet to confine the ionic liquid electrolyte. The pores provide a structured environment that limits the spontaneous self-organization of ionic liquid molecules, reducing density fluctuations while maintaining high energy density and improving ionic conductivity through the confined pathways.
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 membrane achieves significantly improved ionic conductivity and mechanical stability, leading to a higher power delivery capacity by maintaining the arrangement of carbon nanotubes and preventing short circuits, while the insulating layer ensures safety against overheating.
Implementation Method 1
forming a holding layer of a first polymeric material on the second end of the carbon nanotubes, whereby the second end of the carbon nanotubes is covered and held by the holding layer
Implementation Method 2
forming, between the holding layer and the substrate, a polymer matrix made of a second polymer material, so as to coat at least the central part of the carbon nanotubes
Implementation Method 3
covering the second end of the carbon nanotubes by an ion-conductive and electrically insulating element
Implementation Method 4
covering the second end of the carbon nanotubes by an ion-conductive and electrically insulating element
Implementation Method 5
the carbon nanotubes forming channels within the membrane electrolyte, the channels being oriented perpendicular to the first surface and to the second surface
Data Source
Figure 1a~2c
Figure 3a~4f
Figure 5a~6f
AI summary
A method comprising the following steps: a) providing a substrate covered by a mat of carbon nanotubes (50), fixed to the substrate by a first end, b) forming a retaining layer, of a first polymer material, on a second end of the carbon nanotubes (50), c) forming, between the retaining layer and the substrate, a polymer matrix (120) of a second polymer material, d) when the first polymer material is not ionically conductive and electrically insulating, removing the retaining layer and then covering the second end of the carbon nanotubes (50) with an ionically conductive and electrically insulating element (140), e) removing the substrate, to obtain an electrolyte membrane (100), having two main faces, the carbon nanotubes (50) forming channels, oriented perpendicular to the two main faces, and preferably being regularly spaced.