3D Electrode with Electron Directing Members for Silicon Anodes
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Solution Overview
Problem
Lithium-ion batteries using carbon-based electrodes suffer from low energy density and rapid capacity fade due to the volume expansion of silicon active materials, leading to electrode delamination and increased internal resistance.
Innovation Solution
A three-dimensional electrode structure with electron directing members extending from the current collector, comprising vertically aligned graphene sheets and carbon nanotubes, which maintain conductive pathways and restrain active material expansion, enhancing lithium ion storage and battery durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is added to active materials to increase theoretical lithium storage capacity, then energy density is improved, but rapid capacity fade and poor cycle life occur due to volume expansion
Solution Approach 1:
The electrode is divided into multiple thin sheets (first sheet and second sheet of electron directing material) separated by spacers, creating a segmented structure that accommodates volume expansion of silicon while maintaining structural integrity and preventing delamination
Solution Approach 2:
Electron directing members are strategically positioned at specific locations within the electrode structure to provide localized electron pathways, ensuring continuous electrical conductivity in regions where active material expansion occurs
2Quantity of substance
If silicon active materials are used to increase lithium storage, then energy density is improved, but particle cracking and pulverization occur due to volume expansion
Solution Approach 1:
The flexible electrode structure with multiple sheets and spacers is designed in advance to accommodate and cushion the volume expansion of silicon particles during lithium insertion, preventing particle cracking and pulverization before they occur
3Ease of manufacture
If conventional two dimensional electrode structure is used, then manufacturing is simple, but electron flow pathways are insufficient leading to increased internal resistance
Solution Approach 1:
The electrode structure transitions from a conventional two-dimensional planar configuration to a three-dimensional architecture with vertically stacked sheets and electron directing members, creating multiple electron pathways that reduce internal resistance while maintaining manufacturing feasibility
4Quantity of substance
If electrode thickness increases to accommodate active material, then lithium storage capacity is improved, but electron transport distance increases leading to higher internal resistance
Solution Approach 1:
The thick electrode is segmented into multiple thin sheets separated by spacers, reducing the distance electrons must travel through active material while maintaining high lithium storage capacity through the distributed arrangement of electron directing members
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 three-dimensional electrode structure increases lithium ion storage capacity, slows the increase of internal resistance, and extends battery life by maintaining conductive pathways and reducing issues related to active material expansion, such as particle cracking and pulverization.
Implementation Method 1
growing nanotubes at predetermined points on a first sheet of electron directing material
Implementation Method 2
depositing magnetic particles along the second sheet
Implementation Method 3
applying a magnetic field to the magnetic particles to rotate the first sheet, the second sheet and the nanotubes ninety degrees to form an electron directing structure
Data Source
AI summary
A method of making a three dimensional electrode having an active material layered between a current collector and a separator includes growing nanotubes at predetermined points on a first sheet of electron directing material, wherein the electron directing material is highly conductive and chemically inert; aligning the nanotubes in a direction perpendicular to the first sheet; functionalizing a distal end of each nanotube; bonding a second sheet of electron directing material to the functionalized distal end of each nanotube; depositing magnetic particles along the second sheet; applying a magnetic field to the magnetic particles to rotate the first sheet, the second sheet and the nanotubes ninety degrees to form an electron directing structure; and attaching the electron directing structure on a surface of the current collector with a polymer binder. The electron directing structure is configured to direct electron flow along a layered direction of the three dimensional electrode.