Carbon Nanotube Battery Electrode for Ultra-Fast Charge Retention
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Solution Overview
Problem
Existing secondary batteries do not achieve a sufficient balance between high energy density and high-speed charge-discharge characteristics, with existing technologies falling short in maintaining capacity during ultra-high-speed charging and discharging.
Innovation Solution
An electrode comprising carbon nanotubes and active material particles with an average particle size of 2 to 1000 nm, dispersed in the carbon nanotubes, with a mass ratio of carbon nanotubes to active material particles of 0.1 wt % or more, and without the use of a binder, to form a porous electrode matrix that enhances electron and ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional secondary batteries use traditional electrode structures with binders and larger active material particles, then manufacturing is easier and structure is simpler, but energy density and high-speed charge-discharge characteristics are insufficient
Solution Approach 1:
The patent employs porous carbon nanotubes as the electrode structure, replacing traditional dense electrode materials. The porous structure provides numerous channels for ion transport, significantly enhancing charge-discharge speed while maintaining structural integrity without conventional binders
Solution Approach 2:
The patent creates a composite electrode structure where active material particles are embedded within the carbon nanotube network. This composite approach combines the high conductivity and porous structure of carbon nanotubes with the electrochemical activity of the active material, achieving both high productivity and simplified structure
2Reliability
If the electrode uses a binder to hold active material particles, then structural stability is improved, but electron and ion conductivity deteriorates
Solution Approach 1:
The patent removes the binder component entirely from the electrode structure. Instead of using binders to hold particles together, the carbon nanotubes themselves form a self-supporting three-dimensional network that provides both structural stability and conductive pathways, eliminating the trade-off between stability and conductivity
Solution Approach 2:
The carbon nanotubes serve multiple functions simultaneously: they provide structural support, enable electron transport through their high electrical conductivity, and facilitate ion transport through their porous structure. This multi-functionality replaces the separate roles traditionally filled by binders, conductive additives, and porous substrates
3Ease of manufacture
If active material particles are made larger for easier handling, then manufacturing is simpler, but surface area and reaction efficiency decrease
Solution Approach 1:
The patent employs a bimodal particle size distribution where most active material particles are small (2-100 nm) to maximize surface area and reaction efficiency, while a smaller fraction of larger particles (100-1000 nm) provides structural stability and ease of handling. This local quality variation optimizes both manufacturing and performance
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 electrode achieves an excellent balance between high energy density and high-speed charge-discharge characteristics, retaining capacity of 85% or more of the theoretical capacity, with energy density of 60 Wh/kg or more and power density of 30000 W/kg or more, even at ultra-high C-rates.
Implementation Method 1
The electrode achieves an excellent balance between high energy density and high-speed charge-discharge characteristics... power density of 30000 W/kg or more
Implementation Method 2
ion secondary batteries in which a high energy density is an advantage... energy density of 60 Wh/kg or more
Data Source
AI summary
An electrode for a secondary battery, including carbon nanotubes and active material particles having an average particle size of 2 to 1000 nm supported in a state of being dispersed in the carbon nanotubes, wherein a mass ratio of the carbon nanotubes to a total mass of the active material particles and the carbon nanotubes is 0.1 wt % or more.