From monitoring our heart rate and generating renewable energy to keeping astronauts safe in space, a number of novel applications for carbon nanotubes have emerged in recent months.
Academic and industrial interest around carbon nanotubes (CNTs) continues to increase, owing to their exceptional strength, stiffness and electronic properties.
Over the years, this interest has mainly focused on creating products that are both stronger and lighter, for example, in the sporting goods sector, but recently many ‘quirkier’ applications are beginning to appear.
Carbon nanotubes are already used in sporting goods such as tennis racquets. Image: Steven Pisano/Flickr
At Embry-Riddle Aeronautical University in Prescott, Arizona, for example, researchers are currently working with NASA on new types of nano sensors to keep astronauts safer in space.
The Embry-Riddle team – along with colleagues at LUNA Innovations, a fibre-optics sensing company based in Virginia, US – have focused on developing and refining smart material sensors that can be used to detect stress or damage in critical structures using a particular class of CNT called ‘buckypaper’.
The next step in nanotechnology | George Tulevski. Video: TED
With buckypaper, layers of nanotubes can be loosely bonded to form a paper-like thin sheet, effectively creating a layer of thousands of tiny sensors. These sensor sheets could improve the safety of future space travel via NASA’s inflatable space habitats’ – pressurised structures capable of supporting life in outer space – by detecting potentially damaging micrometeroroids and orbital debris (MMOD).
CNTs coated on a large flexible membrane on an inflatable habitat, for instance, could accurately monitor strain and pinpoint impact from nearby MMODs.
Energy storage is absolutely crucial in today’s world. More than just the batteries in our remote controls, more even than our mobile phones and laptops; advancements in energy storage could solve the issues with renewable power, preserving energy generated at times of low demand.
Advances in lithium-ion batteries have dominated the headlines in this area of late, but a variety of developments across the field of electrode materials could become game changers.
1. In the beginning, there were metals
The Daniell cell, an early battery from 1836 using a zinc electrode. Image: Daderot
Early batteries used metallic electrodes, such as zinc, iron, platinum, and lead. The Daniell cell, invented by British chemist John Frederic Daniell and the historical basis for the volt measurement, used a zinc electrode just like the early batteries produced by scientists such as Alessandro Volta and William Cruickshank.
Alterations elsewhere in the Daniell cell substantially improved its performance compared with existing battery technology and it became the industry standard.
2. From acid to alkaline
Waldemar Jungner: the Swedish scientist who developed the first Nickel-Cadmium battery. Image: Svenska dagbladets årsbok 1924
Another major development in electrode materials came with the first alkaline battery, developed by Waldemar Jungner using nickel (Ni) and cadmium (Cd). Jungner had experimented with iron instead of cadmium but found it considerably less successful.
The Ni–Cd battery had far greater energy density than the other rechargeable batteries at the time, although it was also considerably more expensive.
3. Smaller, lighter, better, faster
Organic materials for microbattery electrodes are tested on coin cells. Image: Mikko Raskinen
Want your electronic devices to be even smaller and lighter? Researchers from Aalto University, Finland, are working on improving the efficiency of microbatteries by fabricating electrochemically active organic lithium electrode thin films.
The team use lithium terephthalate, a recently found anode material for a lithium-ion battery, and prepare it with a combined atomic/molecular layer deposition technique.
4. There’s more to life than lithium
50-70% of the world’s known lithium reserves are in Salar de Uyuni, Bolivia. Image: Anouchka Unel
Lithium-ion batteries have dominated the rechargeable market since their emergence in the 1990′s. However, the rarity of material means that, increasingly, research and development is focused elsewhere.
Researchers at Stanford University, USA, believe they have created a sodium ion battery with the same storage capacity as lithium but at 80% less cost. The battery uses sodium salt for the cathode and phosphorous for the anode.
5. Back to the start
Advances are also being made in the electrode materials used in artificial photosynthesis. Video: TEDx Talks
Hematite and other cheap, plentiful metals are being used to create photocatalytic electrode materials by a team of scientists from Tianjin University, China. The approach, that combines nanotechnology with chemical doping, can produce a photocurrent more than five times higher than current approaches to artificial photosynthesis.
You can read an interview with the recipient of SCI’s 2017 Castner Medal, who delivered the lecture Developments in Electrodes and Electrochemical Cell Design, here.