Researchers from University of Cambridge identified a group of material named niobium tungsten oxides, which can potentially charge batteries in real-time
Conventional standard batteries are made of three components, which include a positive electrode, a negative electrode and an electrolyte. Battery is charged by lithium ions, which are extracted from the positive electrode and move through the crystal structure and electrolyte to the negative electrode, where they are stored. Recent study published in journal Nature in July 2018, reported that utilization of new materials with a complex crystalline structure can help lithium ions to move through them at rates that exceed conventional electrode materials.
Although these materials, known as niobium tungsten oxides, do not result in higher energy densities when used under typical cycling rates, they come into their own for fast charging applications, the study said. “Many battery materials are based on the same two or three crystal structures, but these niobium tungsten oxides are fundamentally different,” said Kent Griffith, a postdoctoral researcher in Cambridge’s Department of Chemistry and the paper’s first author.
The oxides are operated by ‘pillars’ of oxygen, which enables lithium ions to move through them in three dimensions. Researchers measured the movement of lithium ions through the oxides using Pulsed Field Gradient (PFG) nuclear magnetic resonance (NMR) spectroscopy. It was found that, they moved at rate several orders of magnitude higher than typical electrode materials.
Negative electrodes in current lithium-ion batteries are made of graphite, which has a high energy density, but when charged at high rates, tends to form spindly lithium metal fibers known as dendrites, which can create a short-circuit and cause the batteries to catch fire and possibly explode. Furthermore, niobium tungsten oxides have high lithium transport rates and they are simple to make. Moreover, these materials have applications in two major clean technologies such as electric cars and grid-scale storage for solar power.