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Researchers develop safer, lighter and more efficient lithium battery
ClimateWire; 1/28/13
Researchers at Oak Ridge National Laboratory have developed a component for rechargeable batteries that can increase energy densities while improving safety.
The component is a nanostructured electrolyte engineered from bulk lithium thiophosphate to conduct ions 1,000 times faster. "This is a solid electrolyte," explained Chengdu Liang, a co-author and a research staff member in the chemical functionality group at the Center for Nanophase Materials Sciences at Oak Ridge. "In a conventional [lithium-ion] battery, the electrolyte is a liquid."
Electrolytes help carry electrical charges inside a battery, and with a solid electrolyte there is a lower chance of the battery shorting out or catching on fire. Researchers found that this electrolyte was stable up to 5 volts in a coin-sized test cell.
Adam Rondinone, who heads the chemical functionality group at the nanophase materials center and co-authored the report, explained that through manipulating the electrolyte at the nanometer level, they could engineer its performance. The team published its findings last week in the Journal of the American Chemical Society.
"By essentially restructuring it so it's porous at the nanoscale, it allows the materials to stabilize at a different crystal structure at room temperature," he said. This increases the electrolyte's surface area, making it conduct energy more efficiently.
The solid electrolyte also enables other battery improvements, like a lithium anode. Most lithium-ion batteries use a graphite anode as a scaffold for lithium, which adds weight and cuts into the battery's energy density.
Problems of lithium firesDevelopers generally avoid solid lithium components because the metal itself is flammable and tends to form dendrites, branching projections that emerge as the battery charges and discharges. Lithium dendrites can then short-circuit the battery, leading to overheating and fires. A solid electrolyte can prevent shorting inside the battery and enable new battery variations like lithium-sulfur.
With the Federal Aviation Administration's recent order to ground all Boeing 787 aircraft following an on-board lithium-ion battery fire earlier this month, storing large amounts of energy safely in these batteries has become a growing concern.
Rondinone noted that lithium-ion batteries are well-understood in small mobile devices like phones and laptops, where there isn't that much energy stored and where ambient air circulation can keep them cool.
"What scares people to death are these multiple-kilowatt batteries," such as those in cars, airplanes and on the electrical grid, he said. "Your tolerance of an [adverse] event is much lower." Large battery fires can take days to put out and require special procedures from first responders.
A solid electrolyte could make these larger batteries more reliable and less prone to failure. The researchers are now looking to refine lithium-sulfur battery chemistries and are conducting further laboratory tests before trying to scale up the production process.
Researchers develop safer, lighter and more efficient lithium battery
ClimateWire; 1/28/13
Researchers at Oak Ridge National Laboratory have developed a component for rechargeable batteries that can increase energy densities while improving safety.
The component is a nanostructured electrolyte engineered from bulk lithium thiophosphate to conduct ions 1,000 times faster. "This is a solid electrolyte," explained Chengdu Liang, a co-author and a research staff member in the chemical functionality group at the Center for Nanophase Materials Sciences at Oak Ridge. "In a conventional [lithium-ion] battery, the electrolyte is a liquid."
Electrolytes help carry electrical charges inside a battery, and with a solid electrolyte there is a lower chance of the battery shorting out or catching on fire. Researchers found that this electrolyte was stable up to 5 volts in a coin-sized test cell.
Adam Rondinone, who heads the chemical functionality group at the nanophase materials center and co-authored the report, explained that through manipulating the electrolyte at the nanometer level, they could engineer its performance. The team published its findings last week in the Journal of the American Chemical Society.
"By essentially restructuring it so it's porous at the nanoscale, it allows the materials to stabilize at a different crystal structure at room temperature," he said. This increases the electrolyte's surface area, making it conduct energy more efficiently.
The solid electrolyte also enables other battery improvements, like a lithium anode. Most lithium-ion batteries use a graphite anode as a scaffold for lithium, which adds weight and cuts into the battery's energy density.
Problems of lithium firesDevelopers generally avoid solid lithium components because the metal itself is flammable and tends to form dendrites, branching projections that emerge as the battery charges and discharges. Lithium dendrites can then short-circuit the battery, leading to overheating and fires. A solid electrolyte can prevent shorting inside the battery and enable new battery variations like lithium-sulfur.
With the Federal Aviation Administration's recent order to ground all Boeing 787 aircraft following an on-board lithium-ion battery fire earlier this month, storing large amounts of energy safely in these batteries has become a growing concern.
Rondinone noted that lithium-ion batteries are well-understood in small mobile devices like phones and laptops, where there isn't that much energy stored and where ambient air circulation can keep them cool.
"What scares people to death are these multiple-kilowatt batteries," such as those in cars, airplanes and on the electrical grid, he said. "Your tolerance of an [adverse] event is much lower." Large battery fires can take days to put out and require special procedures from first responders.
A solid electrolyte could make these larger batteries more reliable and less prone to failure. The researchers are now looking to refine lithium-sulfur battery chemistries and are conducting further laboratory tests before trying to scale up the production process.
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