Hierarchical Copper Nanofoam Anode for High-Areal-Capacity Li-Ion Cells
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Solution Overview
Problem
Existing techniques for manufacturing dealloyed nanoporous copper are limited by small size and poor mechanical properties due to the use of metal powders, hindering practical applications in advanced electrodes for energy devices.
Innovation Solution
A pack-cementation process using copper foil to create a copper-aluminum alloy precursor, followed by dealloying, results in a hierarchical microporous or nanoporous copper structure with improved mechanical properties and large surface area, suitable for use as an anode in lithium-ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal powders are used to create precursor alloy, then nanoporous copper can be manufactured, but the resulting structure has small size and poor mechanical properties
Solution Approach 1:
The invention changes the physical state parameter of the copper from powder to foil form. This parameter change fundamentally alters the mechanical properties while enabling nanoporous structure formation through dealloying. The foil-based approach maintains structural integrity and mechanical strength that powder-based methods cannot achieve.
Solution Approach 2:
The invention creates a composite structure by forming an aluminum-copper alloy precursor where aluminum is distributed within the copper foil matrix. This composite precursor structure enables controlled dealloying to form nanoporous copper while maintaining mechanical strength through the hierarchical micro-nano structure.
2Device complexity
If traditional graphite anode is used, then battery structure is simple, but areal capacity is low
Solution Approach 1:
The invention employs porous copper foam with hierarchical micro-nano structure as the anode substrate. The porous structure provides extremely high surface area and active sites for lithium ion insertion, achieving four-fold higher areal capacity compared to traditional graphite anodes while maintaining structural simplicity.
Solution Approach 2:
The invention transitions from the layered two-dimensional structure of graphite to a three-dimensional hierarchical porous network. This dimensional change from 2D to 3D structure dramatically increases the available surface area and lithium ion accommodation capacity within the same areal footprint.
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 hierarchical structure achieves a four-fold higher areal capacity and stable performance up to 20 cycles compared to traditional graphite anodes, effectively addressing the limitations of previous methods.
Implementation Method 1
The pack cementation process uses copper foil instead of copper powder... The pack cementation can contain the mixed powder pack of one or more metal powders, filler, and halide salt activator... The pack cementation temperature can be varied from about 400 degrees Celsius to about 900 degrees Celsius in order to form the aluminum-copper precursor alloy foil.
Implementation Method 2
The alloy precursor can be reacted in a dealloying solution (HCl)... The dealloying solution can be about a 0.01 molar to about 20 molar hydrochloric acid (HCl) solution at about 20 degrees Celsius to about 100 degrees Celsius... aluminum can be replaced with another element that possesses greater corrosiveness than copper.
Data Source
AI summary
A facile method is based on a pack-cementation process using large-area copper foil instead of copper powder. By controlling a pack-cementation time and an amount of alloying element (e.g., aluminum), a hierarchical microporous or nanoporous copper can be created. When coated with tin active material, the hierarchical microporous or nanoporous copper can be used as an advanced lithium-ion battery anode. A coin-cell test exhibited a four-fold higher areal capacity (e.g., 7.4 milliamp-hours per square centimeter without any performance degradation up to 20 cycles) as compared to a traditional graphite anode.