|Rechargeable AA batteries being charged. / Photo by: art_photo_sib via Shutterstock|
While fast-charging batteries are becoming more common among smartphones, the technology remains a challenge in other devices, such as electric cars and grid-scale storage used for solar power. Scientists at the University of Cambridge identified a new class of materials to support fast-charging in many battery models.
The new materials are called niobium tungsten oxides, compounds that increase the charging rate in a typical battery cycle. Aside from that, the scientists found the chemical and structural behavior of the materials are good in producing super-fast charging batteries, without the significant risk typically found in the standard components.
A battery has three main parts: a positive electrode, a negative electrode, and an electrolyte. When a battery is charging, the lithium ions are taken out from the positive electrode. These pass through the crystal structure and electrolyte of the battery until they reach the negative electrode where they are stored. If the ions can move faster, it means the battery can be charged quicker.
“We’re always looking for materials with high-rate battery performance, which would result in a much faster charge and could also deliver high power output,” said Dr. Kent Griffith, first author of the study.
The scientists tried to make the particles of the electrode smaller so the lithium ions would travel faster. However, unwanted chemical reactions can occur with the electrolyte, resulting in batteries having a shorter lifespan.
Instead of making the components smaller, they used the niobium tungsten oxides that have an open structure which does not trap the inserted lithium. The new materials have larger particle sizes than electrodes, but the complex atomic arrangements exhibit unique properties that help transport the ions faster.
The new materials have pillars of oxygen that allow the ions to pass through them in three dimensions. The oxygen pillars also make the materials more rigid compared to other battery components, increasing the speed of the moving ions.
At the moment, batteries made from these oxides have limited applications due to its lower cell voltage compared with some electrode materials. Still, the scientists are improving the new materials for compatibility, efficiency, and safety.