According to the official website of the University of Cambridge, UK, on the 26th, researchers of the university pointed out in the latest issue of Nature that they recently determined that niobium-tungsten oxide has a higher lithium passing speed and can be used to develop batteries that can charge faster. Moreover, the physical structure and chemical behavior of the oxide help them to understand how to build safe and ultra-fast charging batteries.
The battery is mainly composed of three parts: positive pole, negative pole and electrolyte. When the battery is charged, lithium ions flow from the positive electrode and reach the negative electrode through the crystal structure and electrolyte, where they are stored. The faster this process occurs, the faster the battery charges.
When looking for new electrode materials, researchers usually try to make the particles smaller, but it is difficult to manufacture practical batteries containing nanoparticles: the electrolyte will produce more unnecessary chemical reactions, so the battery’s service life is not long, and the manufacturing cost is also high. The niobium tungsten oxide used in the latest research has a hard and open discharge structure, which does not capture the inserted lithium, and the particle size is larger than many other electrode materials.
The first author of the study Kent Griffith, a postdoctoral researcher in the Department of Chemistry at Cambridge University, explained: “Many battery materials are based on the same two or three crystal structures, but these niobium-tungsten oxides are fundamentally different. The oxides are kept open through the oxygen ‘pillar’, so that lithium ions can pass through them in a three-dimensional way, which means that more lithium ions can pass through them, and the speed is faster. The measurement results also show that the speed of lithium ions passing through the oxides is several orders of magnitude higher than in typical electrode materials.”
In addition to high lithium mobility, niobium-tungsten oxide is also easy to manufacture. Griffith said: “Many nanoparticle structures need multiple steps to synthesize, but these oxides are easy to manufacture, and do not need additional chemicals or solvents.”
At present, most of the negative electrodes in lithium-ion batteries are made of graphite, which has high energy density. However, when charged at a high rate, it often forms a thin and long lithium metal fiber called “dendrite”, which will cause a short circuit and cause the battery to catch fire, or even explode.
Griffith said: “In high magnification applications, safety is more important than any other operating environment. These materials and other similar materials are definitely worthy of attention for fast charging applications that require safer graphite substitutes.