Thanks Asterix for giving the link to one of these two stories.
With the race on to develop grid scale storage in an economical way, many researchers are turning to sodium-Ion batteries
The following are two press releases and articles about current research at two universities.
Led by the inventor of the lithium-ion battery, a team of researchers in the Cockrell School of Engineering at The University of Texas at Austin has identified a new safe and sustainable cathode material for low-cost sodium-ion batteries.
During the past five years, sodium-ion batteries have emerged as a promising new type of rechargeable battery and an alternative to lithium-ion batteries because sodium, better known as the main element of salt, is abundant and inexpensive. In contrast, lithium-ion batteries are limited by high production costs and availability of lithium.
If researchers can figure out how to improve the performance and safety of sodium-ion batteries enough to widely commercialize them, then they could one day be used for wind and solar energy storage and to power electric vehicles.
To that end, professor John Goodenough, the inventor of the lithium-ion battery, and his team have identified a new cathode material made of the nontoxic and inexpensive mineral eldfellite, presenting a significant advancement in the race to develop a commercially viable sodium-ion battery. The researchers reported their findings Aug. 27 in the journal Energy & Environmental Science.
“At the core of this discovery is a basic structure for the material that we hope will encourage researchers to come up with better materials for the further development of sodium-ion batteries,” said Preetam Singh, a postdoctoral fellow and researcher in Goodenough’s lab.
Sodium-ion batteries work just like lithium-ion batteries. During the discharge, sodium ions travel from the anode to the cathode, while electrons pass to the cathode through an external circuit. The electrons can then be used to perform electrical work.
Although sodium-ion batteries hold tremendous potential, there are obstacles to advancing the technology including issues related to performance, weight and instability of materials. The team’s proposed cathode material addresses instability. Its structure consists of fixed sodium and iron layers that allow for sodium to be inserted and removed while retaining the integrity of the structure.
One challenge the team is currently working through is that their cathode would result in a battery that is less energy dense than today’s lithium-ion batteries. The UT Austin cathode achieved a specific capacity (the amount of charge it can accommodate per gram of material) that is only two-thirds of that of the lithium-ion battery.
“There are many more possibilities for this material, and we plan to continue our research. ” Singh said. “We believe our cathode material provides a good baseline structure for the development of new materials that could eventually make the sodium-ion battery a commercial reality.”
The UT Austin team’s sodium-ion cathode research received support from the Robert A. Welch Foundation.
Sodium-ion batteries are potential power technology of future
September 22, 2015
WEST LAFAYETTE, Ind. – The high cost and scarcity of lithium are driving research to develop alternatives to lithium-ion batteries, especially to meet future needs in energy storage, say researchers from Purdue University in an article about a potential replacement.
Sodium-ion batteries represent a possible alternative, in large part because of sodium’s low cost and natural abundance. However, critical advances are needed for sodium-ion technology to fulfill its promise, said Vilas Pol, an associate professor of chemical engineering.
The article appeared earlier this month in Current Opinion in Chemical Engineering. The article was authored by Pol and doctoral students Arthur Dysart and Jialiang Tang.
Lithium-ion batteries are used widely in products from consumer electronics to electric vehicles. However, the need for alternatives is being driven by new and expanding applications including batteries to store power from sources such as solar and wind energy for use on the power grid.
“If everybody wants to start using lithium-ion batteries for multiple purposes, we don’t have enough lithium on the planet to sustain that, so we have to find alternatives,” Pol said.
Researchers are working to replace lithium-ion batteries’ standard internal components with functioning sodium counterparts.
Batteries have two electrodes, called an anode and a cathode. The anodes in most of today’s lithium-ion batteries are made of thin layers of stacked graphene called graphite. In lithium-ion batteries, lithium ions can easily fit between graphene layers due to their small size. In sodium-ion batteries, sodium ions cannot pass between the graphitic layers reversibly due to their larger size and bulkier nature. The sodium ions go inside the graphitic layers during charging but do not come back during discharging process.
On the cathode side, new materials have to be developed to replace lithium-containing materials. One option is to replace lithium cobalt oxide cathodes with sodium cobalt oxide cathodes.
One drawback to sodium-ion batteries is that they are slightly heavier than lithium-ion batteries. However, their low cost and abundant nature compared to lithium-ion batteries may outweigh this concern.
“The main advantage of sodium-ion batteries is the potential financial benefit,” Dysart said. “Lithium is a very scarce element in the world. We could actually experience a lithium shortage in coming years.”
Pol added: “Sodium is more abundant and a thousand times cheaper than lithium. It’s even in seawater.”
He is leading research at Purdue to improve sodium-ion batteries by using a variety of tailored carbons and their combinations with sodium-alloying materials such as tin and antimony to potentially double the capacity of the anodes, making possible smaller anodes and reducing the size and weight of the batteries.
The challenge with sodium-alloying materials is the great volumetric expansion effect once sodium ions form a high-energy chemical bond.
“It will expand more than 300 percent, and then it shrinks when the battery is discharged as the sodium is taken out,” said Pol, also an associate professor of materials engineering. “This great degree of expansion and contraction will cause the anode to fail over time, so we are working on alternative materials breathing architectures to mitigate the expansion.”
Tang said, “Perhaps we can confine the expansion locally, similar to breathing lungs. When we breathe our lungs expand and contract quite a bit, but we don’t expand.”
The sodium alloying materials in combination with carbon could bring higher performance anodes that overcome limitations in conventional carbon anodes.
Writer: Emil Venere, 765-494-4709, email@example.com
Source: Vilas G. Pol, 765-494-0044, firstname.lastname@example.org
Advancement in sodium-ion rechargeable batteries
Jialiang Tang, Arthur D Dysart and Vilas G Pol
School of Chemical Engineering, Purdue University
Corresponding author: Pol, Vilas G (email@example.com)*
With growing importance of high-performance and increasingly-portable energy storage, it is important that we consider sustainable solutions to global energy storage demand. Sodium-ion batteries (SIBs) are the highly regarded alternative to lithium-ion batteries, proposed due to its great sustainability without sacrifice in electrochemical performance. Layered oxide with tertiary or greater transition metals have shown to give the greatest performance among reported cathode materials. Promising anodes are composites of sodium alloying metals and carbon, but further work should be done to reduce the adverse effects of volume expansion. Finally, preliminary studies upon electrolyte formulation, inspired by the analogous chemistries of lithium-ion batteries, have laid the foundation for more complex studies. While already established at a remarkable speed, research in SIBs is still maturing with much progress still left to be explored.