Battery and capacitor electrode technologies available in the industry today, are struggling to keep up with rapidly advancing applications that require high power and energy density such as electric vehicles, solar cells and telecommunications systems. One of the leading solutions to this problem are CNT-based films, exhibiting excellent conductivity with potentially moderate costs, yet current methods for their formation are both complicated and expensive or hamper the qualities of the material, causing conductivity reduction. A new technology developed by a group of researchers from the Weizmann Institute of Science is simple and potentially cost-effective, preserves the high electrical qualities of the original CNTs and can be easily used to form large surfaces. This technology involves a simple assembly method of organic nanocrystal combined with carbon nanotubes (ONC)/(CNT) to form self-supporting hybrid films with conductivities as high as 5.78 S/m, and excellent thermal stability (of up to ~300 < face=Calibri>°C). The characteristics of the films enable their use as porous electrodes, with easily adjustable pore sizes. These films can then be straightforwardly incorporated into existing platforms such as solar cells, batteries and super capacitors, improving their energy and power density capabilities. Successful incorporation of electrodes into perovskite solar cells has already been demonstrated to improve its efficiency and photo-stability and promising preliminary results were recently demonstrated for the utilization of ONC porous electrodes as separators in super-capacitors.
Porous electrodes in:
- Perovskite solar cells
- Improved batteries (e.g., for electric vehicles).
Other potential applications:
- CNT dispersion method
- Chemical sensors
- Water treatment and separation films
- Conductive colorant and optoelectronics systems
- Polymer/CNT composites
- Electromagnetic shielding and microwave absorption.
Excellent characteristics for porous electrode applications:
- Tunable CNT content
- High thermal stability (~300 < face=Calibri>°C)
- Excellent conductivity (5.8 ± 0.5 S/m)
- Straightforward and low-cost production
- Highly controllable pore structure and density, enabling different porous electrode applications.
A team of researchers led by Prof. Rybtchinski used readily available, hydrophobic perylene diimide (PDIs) derivatives as the base component for the production of organic nanocrystals (ONCs). The PDIs were mixed and bath-sonicated with either single-wall or multi-wall CNTs, in an aqueous medium, to produce film dispersions with different CNT/ONC ratios. Similarly, CNT/PDI films can be obtained from organic media dispersions. The researchers were able to achieve homogenous dispersion of the CNTs in the ONCs, with CNT content ranging from ~3-8 %wt to >60 %wt. Characterization of the nanocomposite showed excellent thermal stability up to 300 °C, along with high electrical conductance of 5.8 S/m even with a CNT content as low as 3% concentration. This dispersion and fabrication technology was used for the production of self-supporting films that can be incorporated into different systems as was demonstrated for multi-layered perovskite solar cells to which a CNT/ONC film was integrated, serving as an electrode.
Figure 1. Cross-sectional SEM image of solar cells with a) standard gold electrode and b) hybrid membrane ONC/CNT electrode. Scale bars are 500 nm. c) Schematic presentation of CsPbBr3 perovskite solar cell architecture.