A class of materials, recently identified by researchers, could pave the way for rapidly charging batteries that could greatly improve the charging speed of portable devices and even help make technologies such as solar power and electric cars more viable. The research was reported in the journal Nature on Wednesday, and was covered in a report from The Guardian.
Generally, charging speeds for lithium ion batteries are limited by the speed at which lithium ions can move through electrode materials to reach a negatively charged electrode where they are stored. These electrode materials are generally ceramic. Researchers have investigated using smaller particles, since nanoparticles would offer a shorter distance for the lithium ions to move.
“The idea is that if you make the distance the lithium ions have to travel shorter, it should give you higher rate performance,” according to the paper’s first author, Cambridge University Department of Chemistry postdoctoral researcher Dr. Kent Griffith, quoted in an article from Phys.org.
“But it’s difficult to make a practical battery with nanoparticles: you get a lot more unwanted chemical reactions with the electrolyte, so the battery doesn’t last as long, plus it’s expensive to make.”
The materials, niobium tungsten oxides, were first discovered in 1965, and offer a rigid and open structure that allows freer movement for the lithium ions. The particles of the material are also larger than in most other electrode materials. Oxides are propped open by oxygen “pillars,” which allow the lithium ions to move three dimensionally through the space.
According to Griffith:
“Many battery materials are based on the same two or three crystal structures, but these niobium tungsten oxides are fundamentally different. The oxygen pillars, or shear planes, make these materials more rigid than other battery compounds, so that, plus their open structures means that more lithium ions can move through them, and far more quickly.”
The researchers used technology, similar to MRI, to measure the speed of lithium ions moving through the material, and found they were moving hundreds of times faster than their speeds through ceramic electrode materials. It could make it possible to develop smartphones that could fully charge in minutes.
They also note that unlike nanotechnology, the materials are inexpensive and relatively simple to produce.
“These oxides are easy to make and don’t require additional chemicals or solvents,” according to Griffith.
The materials could also boost both electric cars and grid-scale solar energy storage, making two key green technologies immediately more viable and convenient, and potentially speeding their adoption.