EES Blog

In their recent perspective article in Energy and Environmental Science, Professor Doron Aurbach and co-workers highlight key developments in magnesium-ion battery technology.

Rechargeable batteries are ubiquitous in portable electronics, and are expected to play an important role in electric vehicles and grid storage in the future. While lithium-ion technology is the current state of the art, concerns remain about the supplies of lithium on Earth. As such, alternative systems such as magnesium-ion batteries are being developed. Magnesium is the fifth most abundant element in the Earth’s crust and its bivalency means that it can in principle store more energy per unit volume than lithium metal.

A key requirement in magnesium-ion battery technology is reversible deposition of magnesium on the magnesium metal anode. However, most organic solvents and simple magnesium salts react with magnesium to form a so-called passivation layer on the anode, precluding reversible magnesium deposition and further charge-discharge cycles. Vital progress was made with the discovery of electrolytes that were stable in the presence of the magnesium anode. In particular, reaction of AlCl_3-nR_n lewis acids with R₂Mg lewis bases in ether solvents yielded electrolyte solutions which were stable up to voltages of 2.1 V vs. magnesium metal. The combination of these so-called dicholoro-complex (DCC) electrolytes with Chevrel phase intercalation cathodes (e.g. Mo₆S₈) and magnesium anodes yielded the first working prototypes for reversible magnesium-ion batteries.

While these first prototypes constituted a great breakthrough, relatively low energy densities and lacking performance at high rates precluded their commercialisation. Ongoing work focuses on finding new electrolytes with wider electrochemical stability windows, as well as new cathode and anode materials. One interesting possibility is to replace the magnesium anode with metal alloys of bismuth and antinomy, sidestepping the problems associated with the reactivity of magnesium and allowing more conventional electrolytes to be used.

Read more in the perspective article in Energy and Environmental Science:

Mg rechargeable batteries: an on-going challenge
Hyun Deog Yoo, Ivgeni Shterenberg, Yosef Gofer, Gregory Gershinsky, Nir Pour and Doron Aurbach
Energy Environ. Sci., 2013, Advance Article
DOI: 10.1039/C3EE40871J

By Alexander Forse

Take a look at our selection of exciting articles that have been recently published online:

Post-combustion carbon dioxide capture using electrochemically mediated amine regeneration
Michael C. Stern, Fritz Simeon, Howard Herzog and T. Alan Hatton
DOI: 10.1039/C3EE41165F

Improving the long-term stability of PBDTTPD polymer solar cells through material purification aimed at removing organic impurities
William R. Mateker, Jessica D. Douglas, Clément Cabanetos, I. T. Sachs-Quintana, Jonathan A. Bartelt, Eric T. Hoke, Abdulrahman El Labban, Pierre M. Beaujuge, Jean M. J. Fréchet and Michael D. McGehee
DOI: 10.1039/C3EE41328D

New materials based on a layered sodium titanate for dual electrochemical Na and Li intercalation systems
Mona Shirpour, Jordi Cabana and Marca Doeff
DOI: 10.1039/C3EE41037D

Towards high energy density sodium ion batteries through electrolyte optimization
Alexandre Ponrouch, Rémi Dedryvère, Damien Monti, Atif E. Demet, Jean Marcel Ateba Mba, Laurence Croguennec, Christian Masquelier, Patrik Johansson and M. Rosa Palacín
DOI: 10.1039/C3EE41379A

Charge transport in lithium peroxide: relevance for rechargeable metal–air batteries
Maxwell D. Radin and Donald J. Siegel
DOI: 10.1039/C3EE41632A

Thomas Jaramillo and co-workers developed of a very sensitive experiment to identify and quantify CO₂ electroreduction products. Their results, presented in their recent EES article, provide a comprehensive view of the reaction chemistry.

A recent C&EN article discusses the work of Jaramillo’s group. The C&EN article focuses on recent developments towards the interesting goal of converting CO₂ into useful products using electrochemistry: “Carbon dioxide gets a lot of attention—most of it negative—as a greenhouse gas. But if CO₂ could be converted in a cost-effective manner to valuable products, the ubiquitous small molecule so often reviled for its role in climate change might start to lose its bad rap.”

Read more in the C&EN article here…

…and read the article in EES:

New insights into the electrochemical reduction of carbon dioxide on metallic copper surfaces
Kendra P. Kuhl, Etosha R. Cave, David N. Abram and Thomas F. Jaramillo
DOI: 10.1039/C2EE21234J

Scientists from the US have derived a metric to analyse the cost of power generation using thermoelectric technology. The metric shows that thermoelectric devices have greater potential in large-scale power generation than previously thought.

Thermoelectric generators convert heat into electricity by a physical phenomenon called the Seebeck effect. They are compact, robust, and have no moving parts. This means they are useful for low-maintenance applications, such as in spacecrafts. However, their device efficiencies – the power produced for a certain heat flow – are low, so they are not used for large-scale power generation.

Thermoelectric research has typically focussed on the dimensionless figure-of-merit ZT, a metric that relates directly to device efficiency. Shannon Yee from the University of California Berkeley, part of the team that performed the analysis, explains that for power generation to be commercially viable, what really matters is a technology’s capital cost per watt and not just its device efficiency: ‘we found that the design that minimises a system’s cost per watt value is generally very different to the design that maximises efficiency.’

Interested to know more? Read the full news article in Chemistry World here…

Read the article by Yee, Dames et al. in EES:

$/W Metrics for Thermoelectric Power Generation: Beyond ZT
Shannon K Yee, Saniya LeBlanc, Ken Goodson and Chris Dames
DOI: 10.1039/C3EE41504J

Net primary energy balance of a solar-driven photoelectrochemical water-splitting device
Pei Zhai, Sophia Haussener, Joel Ager, Roger Sathre, Karl Walczak, Jeffery Greenblatt and Thomas McKone
DOI: 10.1039/C3EE40880A, Analysis

A hybrid energy cell for self-powered water splitting
Ya Yang, Hulin Zhang, Zong-Hong Lin, Yan Liu, Jun Chen, Ziyin Lin, Yu Sheng Zhou, Ching Ping Wong and Zhong Lin Wang
DOI: 10.1039/C3EE41485J, Communication

Sr- and Mn-doped LaAlO3−δ for solar thermochemical H2 and CO production
Anthony H. McDaniel, Elizabeth C. Miller, Darwin Arifin, Andrea Ambrosini, Eric N. Coker, Ryan O’Hayre, William C. Chueh and Jianhua Tong
DOI: 10.1039/C3EE41372A, Communication

This week we have chosen one Paper, one Analysis article and one Perspective Article that we recommend you check out:

Photocatalytic water gas shift using visible or simulated solar light for the efficient, room-temperature hydrogen generation
Francesc Sastre, Marica Oteri, Avelino Corma and Hermenegildo García
DOI: 10.1039/C3EE40656C, Paper

Technical and economic feasibility of centralized facilities for solar hydrogen production via photocatalysis and photoelectrochemistry
Blaise A. Pinaud, Jesse D. Benck, Linsey C. Seitz, Arnold J. Forman, Zhebo Chen, Todd G. Deutsch, Brian D. James, Kevin N. Baum, George N. Baum, Shane Ardo, Heli Wang, Eric Miller and Thomas F. Jaramillo
DOI: 10.1039/C3EE40831K, Analysis

Mg rechargeable batteries: an on-going challenge
Hyun Deog Yoo, Ivgeni Shterenberg, Yosef Gofer, Gregory Gershinsky, Nir Pour and Doron Aurbach
DOI: 10.1039/C3EE40871J, Perspective