3D CNT Negative Electrode Structure for Dendrite-Free High Capacity
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Solution Overview
Problem
Metal negative electrodes with a metal foil and MWCNT layer suffer from low gravimetric and volumetric capacity due to excess metal and limited space utilization, and dendrite growth leads to short circuits.
Innovation Solution
A secondary battery negative electrode with a three-dimensional carbon nanotube current collector and seed particles, eliminating the metal foil and utilizing a sponge-like structure to enhance capacity and prevent dendrite formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal foil and MWCNT layer are used in the negative electrode, then dendrite growth is prevented, but gravimetric capacity and volumetric capacity decrease due to excess metal and limited space utilization
Solution Approach 1:
The invention extracts and removes the metal foil component from the negative electrode structure. Instead of using a metal foil substrate with MWCNT layer, the patent employs only MWCNTs as the active material, eliminating the excess metal that does not contribute to capacity while maintaining dendrite prevention through controlled Li ion transport in the MWCNT network.
Solution Approach 2:
The MWCNTs serve multiple functions simultaneously: they act as the current collector, the active material for Li storage, and the structure that prevents dendrite growth. This multi-functionality eliminates the need for separate metal foil and MWCNT layer components, maximizing space and weight utilization for capacity-enhancing materials.
2Strength
If a metal foil is used as current collector and active material, then structural support is provided, but space utilization and capacity density are reduced
Solution Approach 1:
The invention employs a porous three-dimensional MWCNT network structure that provides structural support while maximizing void space for Li ion insertion and extraction. The porous architecture allows efficient electrolyte penetration and Li ion transport throughout the electrode, achieving both mechanical integrity and high capacity density without requiring dense metal foil.
Solution Approach 2:
The patent transitions from a two-dimensional metal foil structure to a three-dimensional MWCNT network. This dimensional change creates a hierarchical pore structure with interconnected voids at multiple scales, dramatically increasing the volume available for active Li storage while maintaining structural coherence through the 3D carbon framework.
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 increases gravimetric and volumetric capacity while preventing dendrite growth, allowing reversible thickness changes and efficient use of battery space.
Implementation Method 1
a three-dimensional current collector formed of a self-supporting sponge-like structure of carbon nanotubes
Implementation Method 2
by providing the plurality of seed particles that serve as nuclei for plating of Li during charging, the generation of a large dendrite that causes a short circuit between a positive electrode and a negative electrode is prevented
Implementation Method 3
the plurality of seed particles that serve as nuclei for plating of Li during charging
Data Source
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AI summary
To provide a secondary battery negative electrode, which prevents generation of a dendrite and has a high gravimetric capacity and a high volumetric capacity, a secondary battery, and a method of manufacturing a secondary battery negative electrode. A secondary battery negative electrode 13 includes: a second three-dimensional current collector 18 formed of a self-supporting sponge-like structure of second carbon nanotubes 17; a negative electrode active material 19 as a metal active material contained inside the second three-dimensional current collector 18; and a plurality of seed particles 20 contained inside the second three-dimensional current collector 18 and made of a material different from the negative electrode active material 19, and the secondary battery negative electrode 13 does not contain a foil of the metal active material. A secondary battery 10 includes the secondary battery negative electrode 13, and a secondary battery positive electrode 12 whose thickness changes reversibly with charging and discharging and whose thickness decreases during charging and increases during discharging.