As the world’s population grows, provision of a continuous supply of energy to deliver essential requirements such as food, clean water and healthcare is proving a huge societal challenge. For renewable energy systems, one of the primary challenges is how well we can our capacity to store the energy generated for its subsequent use as electric power. With limited fossil fuel availability and the environmental damage caused by their use, optimising use of current energy sources for more demanding applications, as well as the ability to harness renewable sources such as solar energy, or safe nuclear power, is critical.
Also as modern mobile electrical devices with increased functionality became commonplace, they will need to be powered by batteries providing more energy and hence will need to provide longer battery life as well as power. Energy density in the devices that are used to power larger applications like electric vehicles, whether these are solely powered by batteries or in combination with fuel cells, is also increasingly important.
Neutron scattering techniques, like neutron diffraction, with the ability to probe atomic structure, are the perfect partner to investigate the materials needed for next-generation energy research. Neutrons are particularly suited to this area of investigation as they penetrate large-scale materials easily, which allows the study of complex energy system components in-situ, under the real-world technical conditions they will be applied in.
Lithium-ion batteries are commonly used to power consumer electronic devices, and can also be used to power electric vehicles, solely, or in combination with fuel cells. Understanding how lithium ions are exchanged between electrode materials during the charge/discharge cycle is key to improving the efficiency of these batteries. The best solutions for visualising this process and therefore identifying the innovations required are based on neutrons, as they are scattered by strongly light elements like lithium, unlike X-rays. Neutron diffraction can be used to visualise changes in the crystal structure of electrodes, observing lithium ions moving through the electrodes. Read more.
Longer lasting solar cells
Solar cells convert sunlight into electricity, and have great potential to meet rising energy demands while being environmentally-friendly. Organic solar cells use carbon-containing materials which are currently relatively inefficient, have short lifetimes, and can be expensive compared to other energy sources, such as fossil fuels. One type of organic solar cell incorporates an active layer of thin, electron-rich carbon-containing polymer films which can generate an electric current. However, environmental factors such as heat and light change its structure, in turn damaging performance. Neutron reflectivity and small-angle neutron scattering (SANS) have been used to research these structures and how they change over time, which has led to a 200-fold increase in the stability of solar cells. Read more.
New and better materials
The components of a nuclear reactor must operate in a high-radiation, corrosive environment. To ensure safety, they must be reliable and robust for a given period of time. Some components are vulnerable to stress cracking; caused by a corrosive environment, a susceptible material, and the presence of severe tensile stresses. Neutron diffraction offers a unique tool to study stress in these materials experimentally, as it can measure the changes in distances between atoms in the crystal structure. The results can be used to validate existing models, informing strategies for minimising stress corrosion cracking in the future. Read more.
Another important part of safe nuclear power is the safe disposal of nuclear waste. How oxygen is incorporated into spent uranium oxide fuel affects the radioactive contamination of the environment. X-ray or electron diffraction can hardly detect the oxygen here, as the signal is overwhelmed by the presence of uranium. Neutrons, however, interact only with atomic nuclei, not electrons, so neutron technology is capable of determining the oxygen in the structure of the spent uranium oxide fuel. Read more.
Neutrons and energy, ISIS
Neutrons and energy, ILL