Tag: Sodium-ion batteries

Safe and sustainable batteries focus for new university collaboration

Safe and sustainable batteries focus for new university collaboration

A battery research collaboration focusing on lithium-ion alternatives is starting at MAX IV. The collaboration involving Swedish and Danish universities is a pilot for the new HUB user access mode.

Battery technology is an important Swedish and Nordic research area, something that has been underscored, not least by recent initiatives by the Swedish Government. The challenge of finding new, effective and sustainable lithium-ion battery alternatives is a complex and multifaceted task that requires collaboration between experts in different areas. This need motivated the new Battery pilot HUB, including Chalmers University of Technology, Uppsala University, Lund University, Aarhus University and MAX IV.

We spoke to Aleksandar Matic from Chalmers University of Technology, one of the partners in the newly formed Battery HUB collaboration named BatMAX and Joachim Schnadt, MAX IV Science Director.

“We’re going to study sodium-ion batteries, a promising battery technology for the future. Sodium-ion batteries can store about the same amount of energy as a conventional lithium-ion battery, but have several important advantages. Sodium is more abundant and evenly spread globally as a raw material since it can be extracted from seawater. Sodium-ion batteries are also more sustainable because the cathode materials do not contain cobalt, which is often used in lithium-ion battery cathodes,” says Matic.

Read more on the MAX IV website

Sodium-ion batteries: How doping works

Sodium-ion batteries: How doping works

Sodium-ion batteries still have a number of weaknesses that could be remedied by optimising the battery materials. One possibility is to dope the cathode material with foreign elements. A team from HZB and Humboldt-Universität zu Berlin has now investigated the effects of doping with Scandium and Magnesium. The scientists collected data at the X-ray sources BESSY II, PETRA III, and SOLARIS to get a complete picture and uncovered two competing mechanisms that determine the stability of the cathodes.

Lithium-ion batteries (LIB) have the highest possible energy density per kilogramme, but lithium resources are limited. Sodium, on the other hand, has a virtually unlimited supply and is the second-best option in terms of energy density. Sodium-ion batteries (SIBs) would therefore be a good alternative, especially if the weight of the batteries is not a major concern, for example in stationary energy storage systems.

However, experts are convinced that the capacity of these batteries could be significantly increased by a targeted material design of the cathodes. Cathode materials made of layered transition metal oxides with the elements nickel and manganese (NMO cathodes) are particularly promising. They form host structures in which the sodium ions are stored during discharge and released again during charging. However, there is a risk of chemical reactions which may initially improve the capacity, but ultimately degrade the cathode material through local structural changes. This has the consequence of reducing the lifetime of the sodium-ion batteries.

“But we need high capacity with high stability,” says Dr Katherine Mazzio, who is a member of the joint research group Operando Battery Analysis at HZB and the Humboldt-Universität zu Berlin, headed by Prof Philipp Adelhelm. Spearheaded by PhD student Yongchun Li, they have now investigated how doping with foreign elements affects the NMO cathodes. Different elements were selected as dopants that have similar ionic radii to nickel (Ni 2+), but different valence states: magnesium (Mg 2+) ions or scandium ions (Sc 3+). 

Read more on HZB website

Image: The schematic illustration shows a sodium ion battery: The positive electrode or cathode (left) consists of layered transition metal oxides which form a host structure for sodium ions. The transition metal nickel can be replaced either by magnesium or scandium ions. 

Credit: HZB