Recipe For Making Batteries: Add A Dash Of Salt

"Researchers have found that using salt crystals as a template to grow thin sheets of conductive metal oxides make the materials turn out larger and more chemically pure. The secret to making bigger and purer energy storage materials? Just add salt, as an international team of researchers have found. Their findings, reported in Nature Communications, suggest that this method may help in creating an aluminum-ion battery that could store more charge than the best lithium-ion batteries found in laptops and mobile devices today. The team of researchers from Drexel University in the US and Huazhong University of Science and Technology (HUST) and Tsinghua University in China has shown that using salt crystals as a template to grow thin sheets of conductive metal oxides make the materials turn out larger and more chemically pure. These qualities make them better suited for gathering ions and storing energy. In an energy storage device—a battery or a capacitor, for example—energy is contained in the chemical transfer of ions from an electrolyte solution to thin layers of conductive materials. As these devices evolve, they become smaller and more capable of holding an electric charge for longer periods of time without needing a recharge. The reason for their improvement is that researchers are fabricating materials that are better equipped, structurally and chemically, for collecting and releasing ions. In theory, the best materials for the job should be thin sheets of metal oxides, because their chemical structure and high surface area makes it easy for ions to attach, which is how energy storage occurs. But the metal oxide sheets that have been fabricated in labs thus far have fallen well short of their theoretical capabilities. According to study co-author Zhou Jun, a professor at HUST’s Wuhan National Laboratory for Optoelectronics, the problem lies in the production process which often leaves trace chemical residue that contaminate the material and prevent ions from bonding to it. In addition, the materials made in this way are often just a few square micrometers in size. “The challenge of producing a metal oxide that reaches theoretical performance values is that the methods for making it inherently limit its size and often foul its chemical purity, which makes it fall short of predicted energy storage performance,” said Zhou."