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Primeur weekly 2014-10-20

Special

High Performance Computing Centre in Stuttgart to focus on Cloudification ...

Cash flow calculations using Monte Carlo simulations ...

The Cloud

IBM and SAP partner to accelerate enterprise Cloud adoption ...

EuroFlash

European Commission to launch survey on EU-Brazil co-operation in the area of ICT - Work Programme 2016-2017 ...

Big Data Value Association and European Commision sign Big Data Public Private Partnership ...

New forecasting method: Predicting extreme floods in the Andes mountains ...

Symposium on HPC and Data-Intensive Applications in Earth Sciences: Challenges and Opportunities@ICTP ...

Jülich renews co-operation with Oak Ridge National Laboratory ...

Johannes Gutenberg University Mainz joins Germany's Gauss-Allianz as a full member ...

PRACE supports HPC for Health ...

HP and VMware dramatically simplify and accelerate the delivery of software-defined infrastructure services with EVO: RAIL ...

Supermicro highlights VMware EVO: RAIL, FatTwin Virtual SAN Ready nodes and NVIDIA GRID vGPU SuperServer at VMworld Barcelona ...

Calling on universities to submit their HPCAC-ISC 2015 Student Cluster Competition application ...

PRACE SHAPE and NSilico pool HPC knowledge to develop faster sequencing methods ...

A novel platform for future spintronic technologies ...

Future computers could be built from magnetic 'tornadoes' ...

USFlash

New SGI UV for SAP HANA enables real-time business for large enterprises ...

Cray adds new advanced analytics solution to its Big Data product portfolio ...

Australian teams set new records for silicon quantum computing ...

IBM announces first commercial application of IBM Watson in Africa ...

Among DOE supercomputing facilities, NERSC is at the forefront of data management and storage innovations ...

SC14 announces ACM/IEEE-CS George Michael HPC Fellowships ...

Fujitsu partners with Singapore to set up Centre of Excellence for sustainable urbanisation ...

UC Santa Cruz leads $11 million Center for Big Data in Translational Genomics ...

Australian volcanic mystery explained ...

Supermicro enhances VMware EVO: RAIL and Virtual SAN offerings with Nexenta ...

Dispelling a misconception about Mg-ion batteries ...

Dispelling a misconception about Mg-ion batteries


David Prendergast, Berkeley Lab
16 Oct 2014 Berkeley - Lithium (Li)-ion batteries serve us well, powering our laptops, tablets, cell phones and a host of other gadgets and devices. However, for future automotive applications, we will need rechargeable batteries with significant increases in energy density, reductions in cost and improvements in safety. Hence the big push in the battery industry to develop an alternative to the Li-ion technology.

One promising alternative would be a battery based on a multivalent ion, such as magnesium (Mg). Whereas a Li-ion with a charge of +1 provides only a single electron for an electrical current, a Mg-ion has a charge of +2, which means Mg-ions, in principle, can provide twice the electrical current of Li-ions if present with the same density. Mg-ion batteries would also be safer and less expensive than Li-ion batteries. However, the additional charge on a multivalent ion creates other problems that have hampered the development of Mg-ion batteries. This situation may soon change thanks to new findings from the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory as part of the Joint Center for Energy Storage Research (JCESR), a DOE Energy Innovation Hub.

David Prendergast and Liwen Wan, scientists working in the Theory of Nanostructured Materials group at the Molecular Foundry, a DOE nanoscience research facility hosted by Berkeley Lab, ran a series of computer simulations that dispelled a long-standing misconception about Mg-ions in the electrolyte that transports the ions between a battery's electrodes.

"The catch for multivalent ions is that their increased charge draws more attention to them - they become surrounded in the battery's electrolyte by other oppositely charged ions and solvent molecules - which can slow down their motion and create energetic penalties to exiting the electrolyte for the electrodes", stated David Prendergast. "However, we found the problem may be less dire than is widely believed."

Based on X-ray absorption experiments with Mg-containing solids, such as the salt magnesium chloride, and crystals derived from the class of working electrolytes used for Mg-based batteries (dichloro-complex solutions), it has been assumed that Mg-ions are surrounded - or strongly co-ordinated - by six nearest neighbours, which could be counter-ions, such as chlorides, or solvent molecules, in this case tetrahydrofuran. This bulky six-fold coordination sphere would make it difficult for Mg-ions to move through a battery, if it were also present in the liquid electrolyte. Running first-principles molecular dynamics simulations on the supercomputers at Berkeley Lab's National Energy Research Scientific Computing Center (NERSC), as well as the Vulcan computer cluster system at the Molecular Foundry, Prendergast and Wan found that Mg-ions are coordinated by only four nearest neighbours in the electrolyte.

"This is good news for Mg-based batteries, since it means that there are less species to carry around and shed as the battery undergoes discharging or charging", David Prendergast stated. "Our findings also suggest that the performance bottlenecks experienced with Mg-ion batteries to date may not be so much related to the electrolyte itself, but to what happens at the interface between the electrolyte and electodes as the Mg-ions shed their coordination spheres."

David Prendergast and Wan have published the results of their work inJACS, theJournal of the American Chemical Society. Their paper is titled "The Solvation Structure of Mg Ions in Dichloro Complex Solutions from First-Principles Molecular Dynamics and Simulated X ray Absorption Spectra".

In their simulations, David Prendergast and Liwen Wan considered Mg monomer and dimer structures in both neutral and positively-charged states interacting with a combination of chloride anions (Cl-) and tetrahydrofuran solvent molecules in the so-called dichloro-complex (DCC) solution. They found that, at room temperature, the Mg-ions tend to be tetra-co-ordinated in the solution instead of hexa-co-ordinated, which is the predominant solid-phase coordination. As to why recent X-ray absorption experiments on a DCC electrolyte pointed to a hexa-coordination of the Mg-ions, the theorists have an idea.

"Our hypothesis is that the dissolved magnesium chloride salt may be precipitating out of solution, or at least forming the seeds of magnesium chloride crystals in cases where the initial salt concentration is high and approaching its solubility limit", stated Liwen Wan. "Local fluctuations in concentrations near electrode surfaces may be enough to drive this switch to solid-phase coordination and create problems in working cells by trapping active material in an insoluble form."

David Prendergast and Liwen Wan said their findings provide an alert for battery designers to be wary of high electrolyte concentrations for Mg-ions.

"Also", stated David Prendergast, "our results might inspire the design of future experiments to explore the switch from soluble four-fold co-ordinated multivalent ion species to the formation of poorly soluble six-fold species - especially since we have predicted that (Mg K-edge) X-ray absorption measurements should provide a clear contrast between these limiting cases."

This research was carried out within JCESR, an Energy Innovation Hub funded by DOE's Office of Science. JCESR is a multipartner collaboration that is led by Argonne National Laboratory and includes Berkeley Lab. The goal of JCESR is to overcome critical scientific and technical barriers and create new breakthrough energy storage technologies. The Molecular Foundry and NERSC are DOE Office of Science User Facilities.
Source: DOE/Lawrence Berkeley National Laboratory

Back to Table of contents

Primeur weekly 2014-10-20

Special

High Performance Computing Centre in Stuttgart to focus on Cloudification ...

Cash flow calculations using Monte Carlo simulations ...

The Cloud

IBM and SAP partner to accelerate enterprise Cloud adoption ...

EuroFlash

European Commission to launch survey on EU-Brazil co-operation in the area of ICT - Work Programme 2016-2017 ...

Big Data Value Association and European Commision sign Big Data Public Private Partnership ...

New forecasting method: Predicting extreme floods in the Andes mountains ...

Symposium on HPC and Data-Intensive Applications in Earth Sciences: Challenges and Opportunities@ICTP ...

Jülich renews co-operation with Oak Ridge National Laboratory ...

Johannes Gutenberg University Mainz joins Germany's Gauss-Allianz as a full member ...

PRACE supports HPC for Health ...

HP and VMware dramatically simplify and accelerate the delivery of software-defined infrastructure services with EVO: RAIL ...

Supermicro highlights VMware EVO: RAIL, FatTwin Virtual SAN Ready nodes and NVIDIA GRID vGPU SuperServer at VMworld Barcelona ...

Calling on universities to submit their HPCAC-ISC 2015 Student Cluster Competition application ...

PRACE SHAPE and NSilico pool HPC knowledge to develop faster sequencing methods ...

A novel platform for future spintronic technologies ...

Future computers could be built from magnetic 'tornadoes' ...

USFlash

New SGI UV for SAP HANA enables real-time business for large enterprises ...

Cray adds new advanced analytics solution to its Big Data product portfolio ...

Australian teams set new records for silicon quantum computing ...

IBM announces first commercial application of IBM Watson in Africa ...

Among DOE supercomputing facilities, NERSC is at the forefront of data management and storage innovations ...

SC14 announces ACM/IEEE-CS George Michael HPC Fellowships ...

Fujitsu partners with Singapore to set up Centre of Excellence for sustainable urbanisation ...

UC Santa Cruz leads $11 million Center for Big Data in Translational Genomics ...

Australian volcanic mystery explained ...

Supermicro enhances VMware EVO: RAIL and Virtual SAN offerings with Nexenta ...

Dispelling a misconception about Mg-ion batteries ...