Modern-day gadgets demand safer (ever hear about exploding smartphones?), more compact and less expensive batteries. Magnesium batteries may fit the bill and are considered a hopeful successor to lithium ion batters, but their development remains a challenge. Part of that challenge is getting the battery’s electrolyte, the chemical medium that produces electrical conductivity, to “play nice” and allow consistent high performance required for reliable energy storage.
Utah State University chemists report new findings that uncover impediments to electrolyte performance and how to remedy them in the April 2017 issues of the Journal of Materials Chemistry A (in which the USU research is the highlighted cover story) and ACS Energy Letters. Authors are postdoctoral researchers Shuijian He and Jian Luo, along with faculty mentor Tianbiao (Leo) Liu, assistant professor in USU’s Department of Chemistry and Biochemistry.
The team’s research is supported by USU and a Utah Science Technology and Research (USTAR) initiative University Technology Acceleration Grant (UTAG).
The culprit inhibiting electrolyte performance?
“Water,” says Liu. “It’s a simple, but important, explanation. To control the chemical reactions involved in preparing magnesium electrolytes, we have to control the water.”
Unlike lithium electrolytes used in lithium ion batteries, he says, magnesium (Mg) electrolytes are “touchy” and yield inconsistent performance.
“To address this challenge, we developed extensive testing to study water’s influence on an inorganic, magnesium electrolyte system,” Liu says. “We prepared electrolyte solutions in dry and wet solvents to examine their performance. As we lowered the water content, performance improved.”
But getting desired results isn’t as straightforward as eliminating water, he says.
“Water and other impurities in magnesium electrolytes can be introduced from solvents, reactants and the reaction atmosphere,” Liu says.
The researchers found adding magnesium powder to the electrolyte solution allowed them to control the purity of the solution.
“The magnesium powder acts as a scavenger, eliminating impurities and allowing reliable electrochemical Mg deposition and stripping, a reversible process occurring at the Mg anode in a Mg battery.” Liu says. “The approach is rather simple and convenient, and can be applied in other Mg electrolytes.”
The ability to produce the optimal composition of electrolytes for rechargeable magnesium batteries paves to the way for reliable, high performance and cost-effective energy storage.
“It’s an important breakthrough that could lead to the development of advanced Mg batteries that enable smaller, more compact mobile devices, as well as applications needed for widespread battery storage of environmentally friendly energy sources, such as solar and wind,” Liu says. “Magnesium batteries could meet the demands of these energy sources, which present challenges because of unstable grid energy, heavy cycling that requires charging and discharging and irregular full recharging.”
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