Fuel cells

Researchers at Tokyo Institute of Technology and Tohoku University have reported hexagonal perovskite-related oxides with exceptionally high proton conductivity and thermal stability. 

The team explained that these materials' unique crystal structure and large number of oxygen vacancies enable full hydration and high proton diffusion, making them ideal candidates as electrolytes for next-generation protonic ceramic fuel cells that can operate at intermediate temperatures without degradation.

Protonic ceramic fuel cells (PCFCs) have attracted much attention lately. These devices do not operate via the conduction of oxide ions (O²⁻) but light protons (H⁺) with smaller valence. A key feature of PCFCs is their ability to function at low and intermediate temperatures in the range of 50–500 °C. However, PCFCs based on perovskite electrolytes reported thus far suffer from low proton conductivity at low and intermediate temperatures.

A research team, led by Professor Masamoto Yashima from Tokyo Institute of Technology (Tokyo Tech), in collaboration with High Energy Accelerator Research Organization (KEK), has set out to address this limitation of perovskite-based proton conductors. 

Researchers from Japan's Shibaura Institute of Technology and National Institute for Materials Science have developed a method to grow single-crystal perovskite hydrides, enabling accurate hydride conductivity measurements.

Perovskite hydrides, whose molecular structure contains hydrogen anions (H−), attract special attention because of their hydrogen-derived properties and many believe they can be useful for hydrogen storage technologies such as fuel cells and next-generation batteries, as well as energy-saving superconducting cables. However, measuring their intrinsic hydride-ion conductivity is difficult. In their recent study, the researchers addressed this issue using a novel laser deposition technique in an H-radical atmosphere. Using this approach, they grew thin-film single crystals of two different perovskite hydrides and characterized their hydride-ion conductivity. 

Researchers from Huazhong University of Science and Technology, Tohoku University, Lanzhou University, Tsinghua University and Georgia Institute of Technology have reported on a new method to enhance the electrochemical surface area (ECSA) in a calcium-doped perovskite, La_0.6Ca_0.4MnO₃ (LCMO64), which could help in overcoming a common bottleneck in the application of perovskite oxides as electrocatalysts in hydrogen fuel cells.

Perovskite oxides have potential for use in various fields thanks to their interesting and diverse properties. Their high intrinsic activities also position them as a promising alternative to noble metal catalysts for efficiently catalyzing the oxygen reduction reaction (ORR). However, their application is still hampered by their poor electrical conductivity and low specific surface area.

Researchers at the Tokyo Institute of Technology (Tokyo Tech), in collaboration with Tohoku University, Australian Nuclear Science and Technology Organization (ANSTO) and the High Energy Accelerator Research Organization (KEK), recently investigated a promising material for next-generation electrochemical devices: hexagonal perovskite-related oxide Ba₇Nb_3.8Mo_1.2O_20.1. The team unveiled the material's unique ion-transport mechanisms, that could pave the way for better dual-ion conductors.

Clean energy technologies are the cornerstone of sustainable societies, and solid-oxide fuel cells (SOFCs) and proton ceramic fuel cells (PCFCs) are among the most promising types of electrochemical devices for green power generation. These devices, however, still face challenges that hinder their development and adoption.

Tokyo Institute of Technology researchers have shown that donor doping into a mother material with disordered intrinsic oxygen vacancies, instead of the widely used strategy of acceptor doping into a material without oxygen vacancies, can greatly enhance the conductivity and stability of perovskite-type proton conductors at intermediate and low temperatures of 250–400 ℃, (e.g. 10 mS/cm at 320 ℃). This approach provides a new design direction for proton conductors for fuel cells and electrolysis cells.

Protonic ceramic (or proton conducting) fuel/electrolysis cells (PCFCs/PCECs) are a strong contender for future sustainable energy technologies. These devices can directly convert chemical energy into electricity and vice versa with zero emissions at low or intermediate temperatures, making them an attractive option for many emerging applications such as next-generation distributed power sources. In addition, unlike other types of fuel cells and electrolysers, the PCFCs/PCECs do not require precious metal catalysts or expensive, heat-resistant alloys.

A Department of Energy (DoE) project, lead by University of Michigan's Prof. Zetian Mi, is using perovskites to develop high efficiency, low cost, and ultrastable production of green hydrogen fuels directly from sunlight and water.

The new method to achieve clean hydrogen through solar water splitting offers a promising path to achieving net-zero carbon emissions. The University of Michigan research team aims to stabilize perovskite-based solar cells to produce highly-efficient, low-cost, ultrastable green hydrogen fuel.

Solid oxide fuel cells, or SOFCs, are a type of electrochemical device that generates electricity using hydrogen as fuel, with the only 'waste' product being water. 

To potentially accelerate the development of more efficient SOFCs, a research team from Kyushu University, Yamagata University and Kyushu Synchrotron Light Research Center has uncovered the chemical innerworkings of a perovskite-based electrolyte developed for SOFCs. The team combined synchrotron radiation analysis, large-scale simulations, machine learning, and thermogravimetric analysis, to uncover the active site of where hydrogen atoms are introduced within the perovskite lattice in its process to produce energy. 

Researchers from Japan's Tsukuba University have found that ultraviolet light can modulate oxide ion transport in a perovskite crystal at room temperature.

The performance of battery and fuel cell electrolytes depends on the motions of electrons and ions within the electrolyte. Modulating the motion of oxide ions within the electrolyte could enhance future battery and fuel cell functionality by increasing the efficiency of the energy storage and output. Use of light to modulate the motions of ions - which expands the source of possible energy inputs - has only been demonstrated thus far for small ions such as protons. Overcoming this limitation of attainable ion motions is something the researchers in this study aimed to address.

A joint research team that includes researchers from the Institute of Solid State Chemistry and Mechanochemistry (the Ural Branch of the Russian Academy of Sciences), the Donostia International Physics Centre and the HSE Tikhonov Moscow Institute of Electronics and Mathematics has studied the characteristics of cubic double perovskite oxides.

To date, experimental measurements of the minerals' characteristics have not corresponded to the results of theoretical modeling. In this new work, the researchers set out to better understand this disparity. The data obtained could allow the improvement of low-temperature fuel cell technologies'one of the main alternatives to current sources of electricity.