CNT Pulp Network for Thick Cathode Layers
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Solution Overview
Problem
Rechargeable energy storage devices, such as lithium-ion batteries and super-capacitors, face limitations due to the use of carbon black as conductive additives, which restricts the thickness of cathode active material layers and compromises mechanical stability, leading to reduced volumetric and gravimetric capacity.
Innovation Solution
A carbon nanotube (CNT) pulp network with a binder and active material is used to form a structure that enables electron transport and ion storage, allowing for thicker, more flexible, and mechanically robust energy storage devices by achieving percolation threshold at lower concentrations of CNTs compared to carbon black.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon black is used as conductive additive to achieve electrical conductivity, then electron transport is enabled, but the cathode active material layer thickness is limited and mechanical stability deteriorates
Solution Approach 1:
The patent changes the physical and chemical parameters of the conductive additive from carbon black (zero-dimensional particles) to carbon nanotubes (one-dimensional structures). This parameter change enables the conductive network to form at lower concentrations, allowing thicker active material layers while maintaining electrical conductivity and mechanical stability.
Solution Approach 2:
The patent creates a composite structure where carbon nanotubes are integrated with the active material particles, forming a synergistic network. The CNTs provide both electrical conductivity and mechanical reinforcement, enabling the cathode to achieve higher thickness without compromising structural integrity or electrical performance.
2Reliability
If carbon black concentration is increased to achieve needed electrical conductivity in thicker layers, then electron transport improves, but mechanical stability deteriorates due to mud-cracking
Solution Approach 1:
The patent changes the dimensional parameters and aspect ratio of the conductive additive from isotropic carbon black particles to anisotropic carbon nanotubes with high aspect ratios. This parameter change allows the formation of efficient conductive networks at much lower concentrations (0.1-5 wt%), eliminating the need for high concentrations that cause mechanical instability and mud-cracking.
Solution Approach 2:
The carbon nanotubes act as an intermediary structure that simultaneously provides electrical conductivity and mechanical reinforcement. Unlike carbon black which only provides conductivity, the CNTs serve as a dual-function mediator that bridges the electrical and mechanical requirements, preventing mud-cracking while enabling electron transport.
3Reliability
If multiple thin layers are used to achieve needed capacity, then electrical conductivity is maintained, but volumetric and gravimetric capacity are reduced due to additional separators and current collectors
Solution Approach 1:
The patent changes the concentration parameter of the conductive additive to enable single-layer or fewer-layer configurations. By using CNTs at optimized concentrations, the cathode can be made thicker while maintaining conductivity, thereby reducing the number of layers, separators, and current collectors needed, which directly increases volumetric and gravimetric capacity.
4Reliability
If multiple thin layers are used to maintain electrical conductivity, then electron transport is ensured, but device weight increases due to additional components
Solution Approach 1:
The patent optimizes the concentration and distribution parameters of carbon nanotubes to enable thicker active material layers with fewer layers overall. This parameter optimization reduces the total number of separators and current collectors required, thereby reducing the overall device weight while maintaining the necessary electrical conductivity for electron transport.
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 CNT pulp network enhances electrical conductivity and mechanical strength, enabling thicker cathode layers, improved battery flexibility, and increased energy storage capacity while reducing the need for conductive additives, thus overcoming the limitations of carbon black.
Implementation Method 1
the CNT pulp being provided in an amount sufficient to permit electron transport throughout the structure
Implementation Method 2
a binder material dispersed within the CNT pulp network
Implementation Method 3
an active material distributed throughout the body for ion storage
Implementation Method 4
curing the dispersion to form a structure having a CNT pulp network formed therein
Data Source
AI summary
Provided herein are products and methods for making structures having a body defined by a carbon nanotube (CNT) pulp network having a long-range connectivity exceeding a percolation threshold of the structure to permit electron transport throughout the structure, an active material dispersed within the body, and a binder material binding the active material to the CNT pulp network within the body.